Br J Ophthalmol 2002;86:114–123

114

PostScript

..............................................................................................
such as super oxide dismutase.4 5 This could be
a plausible explanation as to why such an
extraordinarily high level of copper was
bound safely in this patient’s liver.
Untreated Wilson’s disease has progressive,
irreversible consequences, and ultimately
causes death.4 The identification of a KayserFleischer ring remains the most important
clinical sign for the diagnosis of Wilson’s disease.

LETTERS
Dense Kayser-Fleischer ring in
asymptomatic Wilson’s disease
(hepatolenticular degeneration)
The Kayser-Fleischer ring is the single most
important diagnostic sign in Wilson’s disease;
it is found in 95% of patients. Virtually all
patients with Kayser-Fleischer rings have
neurological manifestations.1 Pseudo rings
have been described in other conditions.1 The
density of a Kayser-Fleischer ring correlates
with the severity of Wilson’s disease.2 We
describe a rare case of a dense KayserFleischer ring in an asymptomatic patient
with an extremely high liver copper content.
The recent significant genetic advances, and
the clinical implications are discussed.

Case report

At the age of 14 this 23 year old white woman
had an evisceration of her left eye for painful
rubeotic glaucoma following chronic retinal
detachment, resulting from ANA positive
iridocyclitis. Her optician referred her because
over the past few years, her left prosthetic eye
had repeatedly needed an increasingly dense
brown ring painted onto it, to match her
remaining eye. On examination the visual
acuity in the right eye was 6/6 with a heavily
pigmented red brown Kayser-Fleischer ring
(Fig 1). Her systemic and neurological examinations were normal.
Baseline biochemistry, liver function, haematology, and cerebral magnetic resonance
image (MRI) were normal. She was ANA
positive 1 in 20, serum copper 11.6 µmol/l
(normal 11–22), and ceruloplasmin 0.15 g/l
(normal 0.15–0.45). Twenty four hour urinary
copper 9.2 µmol/24 h (normal 0.9 µmol/24 h).
Haematoxylin and eosin stained liver biopsy
showed normal architecture. Orcein and
rhodanine stains showed patchy excessive
copper binding protein, and copper within the
hepatocytes. The quantified copper content of
the sample was hugely elevated at 3000 µg/g
(normal 20–50 µg/g).
She was treated with trientine dihydrochloride.3 The Kayser-Fleischer ring initially became denser but has faded considerably over
the past 5 years; a thin rim still persists (Fig 2).

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Charlotte Anne Sullivan
Figure 1 The right eye showing a heavily
pigmented red brown Kayser-Fleischer ring.
The patient remains well with no hepatic or
neurological manifestations.

Department of Ophthalmology, Birmingham and
Midlands Eye Hospital, City Hospital, Western
Road, Birmingham B18 7QU, UK

A Chopdar
Department of Ophthalmology, East Surrey
Hospital, Surrey, UK

G A Shun-Shin

Comment

This patient had an extremely elevated liver
copper level, 60 times the normal level. She
had to our knowledge the highest ever
published liver copper content level over twice
the highest level recorded in other
publications.4 She had a very dense KayserFleischer ring, but no neurological or hepatic
abnormalities. Despite the severity of her condition she remained neurologically asymptomatic with normal liver architecture.
Wilson’s disease is inherited as an autosomal recessive trait. The defect has been
mapped and sequenced to the long arm of
chromosome 13 (13q14.3). The Wilson’s gene
is responsible for a defective membrane
bound P-type ATPase copper transport molecule, ATP7B. This is located in the trans golgi
network; the ATPase delivers copper to copper
binding ceruloplasmin. During elevated copper levels vesicles containing the ATPase and
copper are released by exocytosis into bile. In
patients with a defective gene there is an
abnormal accumulation and, in comparison,
low excretion of stored liver copper.5 These
findings contrast with previous theories that
Wilson’s disease was caused by a defect of
apo-ceruloplasmin post-translational modification,
and
abnormal
binding
to
ceruloplasmin.4
There are a large number of copper binding
ATP7B mutations.6 The clinical heterogeneity
and overlap of clinical manifestations suggest
that locus heterogeneity alone is unlikely to
be responsible. It has been hypothesised that
there is a subset of pedigrees in which an
additional gene is affected other than that for
ATP7B.5 Genes encode proteins for detoxification of stored copper—for example, metallothionein, and neutralisation of free radicals

Department of Ophthalmology, Wolverhampton
Eye Infirmary, Wolverhampton, West Midlands, UK
Correspondence to: Miss C A Sullivan, Birmingham
and Midlands Eye Hospital, City Hospital, Western
Road, Birmingham B18 7QU, UK
Accepted for publication 6 June 2001

References
1 Finelli PF, Kayser-Fleischer ring:
hepatolenticular degeneration (Wilson’s
disease). Neurology 1995;45:1261–2.
2 Rodman R, Burnstine M, Esmaeli B, et al.
Wilson’s disease: presymptomatic patients
and Kayser-Fleischer rings. Ophthalmic Genet
1997;18:79–85.
3 Tankanow RM. Pathophysiology and
treatment of Wilson’s disease. Clin Pharm
1991;10:839–49.
4 Brewer GJ, Yuzbasiyan-Gurkan V, Wilson’s
disease. Medicine 1992;71:139–64.
5 Camakaris J, Voskoboinik I, Mercer JF.
Molecular mechanisms of copper homeostasis.
Biochem Biophys Res Commun
1999;261:225–32.
6 Thomas GR, Forbes JR, Roberts EA, et al. The
Wilson disease gene: spectrum of mutations
and their consequences. Nat Genet
1995;9:210–17.

Rapidly developing intimal
fibrosis mimicking giant cell
arteritis
Temporal headache associated with a tender
superficial temporal artery and decreased
pulse on palpation are characteristics of giant
cell arteritis. We report the clinical and biopsy
findings in a patient in whom these symptoms were caused by a rapid developing
intimal fibrosis.

Case report

Figure 2
later.

A thin rim still persists 5 years

A 51 year old woman presented with a 2
month history of a tender and painful left
superficial temporal artery (STA). First she
noticed a “thickened cord” on the left temple
which felt pulsatile on palpation. Within 6
weeks the throbbing pulse disappeared and
was followed by tenderness and pain. She also
reported arthritic pain in the limbs and a
morning cough over a 2 year period. She has
smoked 40 cigarettes per day for 30 years. On
examination the left STA felt hardened, knotted, non-pulsatile, and was slightly tender
over a 2 cm distance (Fig 1, cross). There were
no bruits on auscultation of major arteries.
The facial and maxillary arteries were soft and

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115
CRP were normal. She continued having
diffuse body pain.

(2) An unreactive paretic pupil that returns
slowly to normal.

Comment

(3) Irreversible pupil dilatation with iris atrophy.
This syndrome has also been reported when
no dilating drops were used.2
In addition to the pupil and iris abnormalities, Urrets-Zavalia also described other
features—iris ectropion, pigment dispersion,
anterior subcapsular cataract and posterior
synechiae. No early postoperative pressure
rises were documented, although some had
peripheral anterior synechiae and secondary
glaucoma. Gasset also describes the glaucoma
as a secondary phenomenon, commenting
that it is not integral to the syndrome.2 In the
series presented by Pouliquen et al, severe
anterior uveitis, fibrinous exudate, and broad
posterior synechiae are described.7 An early
postoperative intraocular pressure rise is
documented in two of the three cases
presented by Tuft and Buckley.8
We describe the case of a patient undergoing deep lamellar keratoplasty for keratoconus who developed a permanently dilated
pupil with iris atrophy. In addition she had
marked anterior uveitis and posterior synechiae similar to the cases presented by
Pouliquen et al.7 Dilating drops were not used.

GCA is a neurological emergency which,
when left unrecognised and untreated frequently leads to permanent blindness.1 ESR
can be normal in 5–30% of patients,2 3 but this
is an exceptionally rare diagnosis in middle
aged patients.
In summary, our patient presented with a
clinical picture suspicious of vasculitic occlusion of the superficial temporal artery, polymyalgia, and cough. We present this case as an
illustration that this clinical picture can result
from rapidly developing intimal fibrosis without any evidence of inflammation.
A Petzold, G T Plant
Moorfields Eye Hospital, City Road, London
EC1 2PD, UK

F Scaravilli
Department of Neuropathology, Institute of
Neurology, Queen’s Square, London WC1N 3BG,
UK

Figure 1 Thickened, tender, and painful
superficial temporal artery in a 51 year old
woman. At the site of biopsy the artery was
pulselessness (cross). A knotted appearance
is also present distally and rostrally (arrow).
pulsatile on both sides. The C reactive protein
(CRP) was normal and the erythrocyte
sedimentation rate (ESR) was 4 mm in the
first hour. Blood pressure was 135/75.
It was considered necessary to exclude an
inflammatory cause, given the similarity of
the presentation to giant cell arteritis. The
biopsy was taken at the site where the STA
was pulseless and most prominent (Fig 1).
The tissue was examined using the serial
block, serial section technique in order to
minimise the chance of a false negative result.
The histological appearances were those of a
severely fibrosed artery devoid of any inflammatory changes and consistent with arteriosclerosis. The intima was considerably thickened, the internal elastic lamina was
preserved, and the media had some degree of
fibrosis (Fig 2). The thickened intima, which
had led to tightening of the lumen consisted
of collagen and concentrically arranged layers
of elastic fibres. No thrombotic material could
be observed.
The patient remained stable over a 3 year
follow up period and subsequent ESR and

Figure 2 Photomicrograph showing a
segment of the superficial temporal artery
with severely narrowed lumen (asterisk). The
internal elastic lamina (a) is well preserved
(elastica stain). The intima is considerably
thickened (b) and shows tissue proliferation.
There are no signs of necrosis, inflammation,
or thrombus.

Correspondence to: Dr Petzold
Accepted for publication 9 July 2001

References

1 Font C, Cid MC, Coll-Vinent B, et al. Clinical
features in patients with permanent visual loss
due to biopsy-proven giant cell arteritis. Br J
Rheumatol 1997;36:251–4.
2 Zweegman S, Makkink B, Stehouwer CD.
Giant-cell arteritis with normal erythrocyte
sedimentation rate: case report and review of
the literature. Neth J Med 1993;42:128–31.
3 Ellis ME, Ralston S. ESR in the diagnosis and
management of polymyalgia
rheumatica/giant cell arteritis syndrome. Ann
Rheum Dis 1983;42:168.

Fixed dilated pupil following
deep lamellar keratoplasty
(Urrets-Zavalia syndrome)
A fixed dilated pupil following penetrating
keratoplasty is a well recognised if rare
postoperative complication. We report a case
of Urrets-Zavalia syndrome following a deep
lamellar keratoplasty (DLK). To our knowledge this association has not been previously
described.
The mydriasis following penetrating
keratoplasty was first described by Castroviejo
(Castroviejo R, personal communication) but
it was Urrets-Zavalia who first published his
observations on a series of six cases and suggested an association of fixed dilated pupil,
iris atrophy, and secondary glaucoma.1
The incidence of this syndrome is estimated
at 5.8%, from pooled data on 445 eyes undergoing penetrating keratoplasty for keratoconus, of which 24 eyes developed a fixed
dilated pupil.2 Davies and Ruben also found a
similar incidence.3 However, other more recent studies find no cases,4–6 and some even
question its continued existence. This may in
part reflect improved surgical technique and
differing diagnostic criteria.
The pupil can become abnormally dilated
following penetrating keratoplasty for keratoconus, particularly if dilating drops are used.
There are three main groups of pupillary
dilatation.2
(1) A pupil with normal light and near
reaction which is at least 1.5 mm larger than
its fellow unoperated eye. It fully constricts
with topical miotics. An incidence of approximately 90% has been reported for this type of
abnormality.3

Case report

A woman with keratoconus underwent a left
deep lamellar keratoplasty at the age of 28
because of unstable contact lens fit and
central corneal scarring. A 7.75 mm graft into
a 7.5 mm diameter recipient DLK was
performed under peribulbar anaesthesia with
sedation. Disposable Baron Hessburg suction
trephines were used and the deep lamellar
dissection performed after air injection, as
described by Tuft and Buckley.9 A paracentesis
was performed and no viscoelastic or air was
injected into the anterior chamber. The procedure was uncomplicated.
In her medical history of note was atopic
eczema and hay fever.
The eye became painful during the first
postoperative evening. At the first dressing
the next morning she was comfortable again
but the pupil was noted to be semidilated with
an intraocular pressure of 10 mm Hg. The
anterior chamber was deep and quiet.
Three weeks postoperatively, despite using
her topical steroids, she developed a marked
anterior uveitis with posterior synechiae to
the lens. This responded well to an increase in
her topical steroids. However, the iris has
remained fixed, dilated, and non-reactive.
The visual acuity at 1 month postoperatively was 6/9+ with −1.75/−1.50 × 125.
Unfortunately 11 weeks postoperatively she
developed an inferior retinal detachment. No
breaks were identified but she underwent a
cryobuckle procedure with an encircling
band. Six months after her initial surgery she
sees 6/12 wearing a contact lens correction of
−2.25/−3.50 × 65. She is still troubled by glare
and is somewhat unhappy with the cosmetic
appearance of the eye.

Comment

The precise aetiology of this syndrome is
unknown; it has been suggested that iris
ischaemia can develop if it is compressed
between the lens and cornea during surgery.3
This cannot be the explanation in patients
undergoing deep lamellar keratoplasty.
Urrets-Zavalia syndrome has also been described after penetrating keratoplasty for
other indications3 and after cataract surgery.
Urrets-Zavalia suggested that the strong
mydriasis produced by atropine at the time of

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PostScript

surgery brought the iris into contact with the
peripheral cornea to produce peripheral anterior synechiae and glaucoma.1 Davis and
Ruben noted the condition was more common in the absence of a peripheral iridotomy
and proposed a mechanism of relative pupil
block.3 Naumann comments that in over 1000
cases of penetrating keratoplasty he has never
seen this condition and suggests that performing a peripheral iridotomy in phakic
patients is protective.4 Interestingly he always
uses dilating drops.
It has been suggested that the iris is in some
way abnormal in keratoconus, supported by
the observation that these pupils remain
dilated for longer periods following mydriasis
than in normal eyes.2 Keratoconic eyes seem
to hyperreact to application of mydriatics as
far as speed of dilation and duration of effect,
this observation is also seen the eyes of
patients with Down’s syndrome.2
An abnormality of the sympathetic nervous
system in the keratoconic eye remains unproven.
Davies and Ruben also suggest that direct
iris trauma during surgery could result in
strangulation of iris vessels in the midperiphery and ischaemic paralysis of the
sphincter pupillae.3
Tuft and Buckley suggest in the presence of
raised intraocular pressure, the low ocular
rigidity of the keratoconic eye permits occlusion of the vessels at the root of iris within the
sclera, which results in iris ischaemia while
preserving ciliary body function.9
This case, the first to our knowledge,
describes the Urrets-Zavalia syndrome following a lamellar keratoplasty. The compressive
theory cannot play a part in this instance and
it may lend support to the theory of an intrinsic iris abnormality in keratoconus. Equally,
the pain she experienced on the first postoperative evening may have been secondary to
raised intraocular pressure and perhaps supports the ischaemic theory.9 In either case, this
syndrome is still poorly understood.
Meg Minasian, William Ayliffe
Croydon Eye Unit, Mayday University Hospital
NHS Trust, London Rd, Thornton Heath, Surrey
CR7 7YE, UK
Correspondence to: Meg Minasian, Adnexal Unit,
Moorfields Eye Hospital, City Road, London
EC1V 2PD, UK; megminasian@hotmail.com
Accepted for publication 11 July 2001

References

1 Urrets-Zavalia A. Fixed dilated pupil, iris
atrophy and secondary glaucoma: a distinct
clinical entity following penetrating
keratoplasty for keratoconus. Am J
Ophthalmol 1963;56:257–65.
2 Gasset AR. Fixed dilated pupil following
penetrating keratoplasty in keratoconus
(Castroviejo syndrome). Ann Ophthalmol
1977;9:623–8.
3 Davies PD, Ruben M. The paretic pupil: its
incidence and aetiology after keratoplasty for
keratoconus. Br J Ophthalmol
1975;59:223–8.
4 Naumann GO. Iris ischaemia following
penetrating keratoplasty for keratoconus
(Urrets-Zavalia syndrome). Cornea
1997;16:120.
5 Krachmer JH, Feder RS, Belin MW.
Keratoconus and related non-inflammatory
corneal thinning disorders. Surv Ophthalmol
1984;28:293–322.
6 Kirkness CM, Ficker LA, Steele ADMcG, et
al. The success of penetrating keratoplasty for
keratoconus. Eye 1990;4:673–88.
7 Pouliquen Y, Ginmaraes R, Petroutsos G, et
al. Le syndrome d’Urrets-Zavalia: existe-t-il
encore? J Fr Ophtalmol 1983;6:325–6.
8 Pouliquen Y, Bernard J, Mezarik B. A propos
de 4 cas de mydriase aiguë irido-atrophiante

www.bjophthalmol.com

après kératoplastie pour kératocone. Arch
Ophthalmol (Paris) 1970;30:219–26.
9 Tuft SJ, Buckley RJ. Iris ischaemia following
penetrating keratoplasty for keratoconus
(Urrets-Zavalia syndrome). Cornea
1995;14:618–22.

Peter Cackett, Clifford R Weir, Zaw
Minn-Din
Tennent Institute of Ophthalmology, Gartnavel
General Hospital, Great Western Road, Glasgow
G12 0YN, UK
Correspondence to: Dr Cackett
Accepted for publication 12 July 2001

Asymptomatic oculopalatal
myoclonus: an unusual case
Oculopalatal myoclonus is characterised by
rhythmic pendular vertical eye movements
associated with synchronous contraction of
the soft palate.1 It produces intractable
oscillopsia,2 and is normally the result of
brainstem haemorrhage.2 However, it is does
not usually become manifest until several
months or even years later, with the longest
recorded interval being 49 months.3 We
present an unusual case of a patient who sustained a brainstem haemorrhage following
trauma. Eight years later he was incidentally
noted to have oculopalatal myoclonus, and
surprisingly was asymptomatic.

Case report

A 61 year old man was admitted to the neurosurgery department following head trauma. A
computed tomography (CT) scan showed
subarachnoid bleeding. An magnetic resonance image (MRI) revealed left frontal and
posterior parietal contusions and a small
brainstem haemorrhage. Following the head
injury he complained of double vision on
downgaze. Examination revealed bilateral
fourth cranial nerve palsies, which resolved
spontaneously.
Nine months later the patient developed
acute angle closure glaucoma in his right eye,
which was unresponsive to medical therapy.
He subsequently underwent a right trabeculectomy. Thereafter, his visual acuities
were 6/18 in the right eye and 6/6 in the left
eye, and he was reviewed annually at a
glaucoma clinic.
While attending 8 years after his head
injury, an audible click was heard emanating
from the patient. He was unaware of this
because of longstanding sensorineural deafness. However, on further questioning his wife
stated that she had been aware of the clicking
for several months. Examination of the soft
palate revealed rhythmic contractions that
were synchronised with the auditory clicking.
There was a right unilateral vertical pendular
nystagmus, although no nystagmus was
noted in the left eye. A diagnosis of oculopalatal myoclonus secondary to the brainstem
haemorrhage 8 years previously was made.
An MRI scan (T2 weighted images with
contrast) was performed and found to be normal. The patient was unaware of oscillopsia,
presumably as a consequence of his reduced
visual acuity secondary to the previous episode of angle closure glaucoma. As he was
asymptomatic no treatment was indicated.

References

1 Leigh RJ, Zee DS. The neurology of eye
movements. 3rd ed. New York: Oxford
University Press, 1999.
2 Talks SJ, Elston JS. Oculopalatal myoclonus:
eye movement studies, MRI findings and the
difficulty of treatment. Eye 1997;11:19–24.
3 Matsuo F, Ajax ET. Palatal myoclonus and
denervation supersensitivity in the central
nervous system. Ann Neurol 1979;5:72–8.
4 Koeppen AH, Barron KD, Dentinger MP.
Olivary hypertrophy: histochemical
demonstration of hydrolytic enzymes.
Neurology 1980;30:471–80.

Bilateral exudative retinopathy
as the initial manifestation of
retinitis pigmentosa
A Coats’-like retinopathy affects approximately 1–4% of cases of longstanding retinitis
pigmentosa (RP).1 2 As a presenting sign of RP,
however, Coats’-like retinopathy is extremely
rare.3 We present a case of bilateral exudative
retinopathy suggestive of Coats’ disease in a
12 year old boy in whom investigation
revealed previously undiagnosed RP.

Case report

A 12 year old male presented with a 3 week
history of blurred vision in both eyes. There
was no significant medical or family history.
Visual acuities were 6/120 in the right eye and
6/15 in the left eye. Anterior segment examination was normal. The posterior segment of

Comment

Oculopalatal myoclonus is a rare condition
normally resulting in intractable oscillopsia,
thought to be caused by a lesion in the
myoclonic triangle, which consists of the red
nucleus, the ipsilateral inferior olive, and the
contralateral dentate nucleus.4 To our knowledge, this is the first reported case of
asymptomatic oculopalatal myoclonus. It also
illustrates that the latency period may be
longer than that previously described.

Figure 1 (A) Fundus photograph of the
right eye showing subretinal exudation,
serous retinal detachment, and telangiectatic
retinal vessels. (B) Fundus photograph of the
left eye showing mottled granularity of the
retinal pigment epithelium.

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117
consider an underlying diagnosis of retinitis
pigmentosa in any patient presenting a
picture of bilateral exudative retinopathy.

Acknowledgments
Support provided by the International Award of
Merit in Retina Research, Houston, Texas (JA
Shields); Macula Foundation (CL Shields), and Eye
Tumor Research Foundation, Philadelphia, PA, USA.

Arun D Singh, Carol L Shields,
Jerry A Shields
Oncology Service, Wills Eye Hospital, USA

Alan Goldfeder
Thomas Jefferson University, Philadelphia and
Ophthalmic Physicians, Union, New Jersey, USA
Correspondence to: Arun D Singh, MD, Oncology
Service, Wills Eye Hospital, 900 Walnut Street,
Philadelphia, PA 19107, USA;
arunsingh@eyetumors.com
Accepted for publication 16 July 2001

References

Figure 2 (A) Fluorescein angiogram of the
right eye showing retinal ischaemia with
adjacent telangiectasia. (B) Scotopic
electroretinogram showing isoelectric
response in both eyes.
both eyes showed extensive subretinal exudation, serous retinal detachment, and overlying
retinal telangiectasia (Fig 1A). There was
cystoid macular oedema with a lamellar
macular hole in the left eye. The optic discs
appeared normal. Additionally, mottled
granularity of the retinal pigment epithelium
(RPE) was noted in the mid-periphery of both
retinas (Fig 1B). Upon further questioning, he
admitted to night blindness.
A fluorescein angiogram confirmed retinal
telangiectasia, serous retinal detachment, and
macular oedema (Fig 2A). An electroretinogram (ERG) showed an isoelectric response
under both scotopic and photopic conditions
(Fig 2B). Visual field testing revealed marked
constriction in both eyes.
A diagnosis of retinal telangiectasia, exudative retinopathy, and retinitis pigmentosa was
made and the areas of most severe telangiectasia were treated with retinal cryotherapy. One year later the retinal telangiectasia had mostly resolved, the exudation was
slightly less extensive and the visual acuity
was unchanged.

1 Kajiwara Y. Ocular complications of retinitis
pigmentosa. Association with Coats’
syndrome. Jpn J Clin Ophthalmol
1980;34:947–55.
2 Pruett RC. Retinitis pigmentosa: clinical
observations and correlations. Trans Am
Ophthalmol Soc 1983; 81:693–735.
3 Kim RY, Kearney JJ. Coats-type retinitis
pigmentosa in a 4-year-old child. Am J
Ophthalmol 1997;114:846–8.
4 Zamorani G. Una rara associazone di
retinite di Coats con retinite pigmentosa. Gior
Ital Oftalmol 1956;9:429–43.
5 Khan JA, Ide CH, Strickland MP. Coats’-type
retinitis pigmentosa. Surv Ophthalmol
1988;32:317–32.
6 Witschel H. Retinopathia pigmentosa and
“morbus Coats”. Klin Monatsbl Augenheilkd
1974;164:405–11.

Resolution of proliferative
venous stasis retinopathy after
carotid endarterectomy
Ocular ischaemic syndrome (OIS) may
present as an asymmetric retinopathy in

diabetic patients. We report a case of asymmetric diabetic retinopathy with posterior
segment neovascularisation due to OIS associated with critical ipsilateral carotid stenosis
where the neovascularisation resolved after
carotid endarterectomy.

Case report

A 50 year old woman presented in May 1996
with left sided weakness. She had hypercholesterolaemia, hypertension, a family history
of vascular disease, and was a smoker. She
was found to be diabetic with peripheral retinal ischaemia and disc neovascularisation in
the right eye, and minimal retinal ischaemia
in the left eye (Fig 1). Her visual acuities were
6/12 in the right eye and 6/9 on the left. There
was no anterior segment neovascularisation
in either eye. Carotid Doppler and carotid
angiography showed critical stenosis at the
origin of the right internal carotid artery. The
right middle cerebral artery branches were
visualised as a result of retrograde flow
through the ophthalmic artery. The left internal carotid artery was narrowed by 50% and
there were no collaterals to the right hemisphere (Fig 2). Fluorescein angiography revealed a prolonged transit time with slow filling of choroidal and retinal vasculature,
peripheral retinal capillary closure, and leakage from the disc neovascularisation.
One year later the optic disc neovascularisation and retinal ischaemia were unchanged
with no iris neovascularisation. In April 1997
she underwent an uneventful right carotid
endarterectomy. Two months later she developed clinically significant macular oedema in
the right eye that was treated with focal argon
laser photocoagulation.
Six months later the maculopathy had
resolved and 14 months after surgery there
was complete resolution of the optic disc neovascularisation. Three years after surgery the
right eye had a visual acuity of 6/9, a near
normal fluorescein angiogram transit time,
minimal peripheral retinal ischaemia, and no
posterior segment neovascularisation.

Comment

The association between retinitis pigmentosa
and exudative retinopathy was first described
in 19564 and has been termed a “Coats’-like
RP.”5 Various studies have suggested that 1–4%
of RP cases will show such a response.1 2 This
entity differs from true Coats’ disease in that
Coats’-like RP often occurs bilaterally, has no
sex predisposition, and shows diffuse pigmented alterations in both fundi.5 6 The cause
is unknown but it may represent a vasodilatory response to toxic products of
photoreceptor/RPE degeneration.2 Our case is
unusual in that almost all previous reported
cases have occurred in the setting of longstanding RP.2 3 Our patient had never consulted an ophthalmologist despite being night
blind and having markedly constricted visual
fields. We recommend that ophthalmologists

Figure 1 Presenting fundus photograph showing disc neovascularisation (A) with
corresponding fluorescein angiogram showing leakage from these vessels (B). The
neovascularisation has resolved 14 months after surgery (C) and is confirmed on fluorescein
angiography (D).

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Comment

Ocular ischaemic syndrome (OIS) is characterised in the anterior segment by flare and
initial hypotony, with later iris neovascularisation. Retinopathy with neovascular proliferation occurs in the fundus because of chronic
hypoperfusion. The development of neovascular glaucoma can lead to permanent
blindness.1 2 In the diabetic patient OIS is
superimposed on any pre-existing diabetic
retinopathy, and markedly asymmetric retinopathy should prompt a search for underlying
ischaemia from carotid occlusive disease. Diabetic patients with marked proliferative
changes require treatment with panretinal
photocoagulation (PRP), which has been
shown to reduce the risk of severe visual loss
and neovascular glaucoma. However, there is
no clear evidence for the benefit of PRP in
patients with OIS. In one study only 36% of
OIS patients with iris neovascularisation
responded to PRP, which may be due to uveal
rather than retinal ischaemia.3 4 In the case
presented the patient was not treated with
immediate PRP but reviewed regularly. The
disc new vessels did not progress in the year
before carotid endarterectomy and there was
no immediate threat to vision.
Carotid stenosis can result in changes in the
ophthalmic artery blood flow ranging from
reduced antegrade to reversal of flow. If there
is inadequate crossflow in the circle of Willis
from the contralateral internal carotid, reversal of flow occurs in the ophthalmic artery
as a consequence of a collateral circulation
from branches of the external carotid artery.5
Although some series show no correlation
between direction of flow and the severity of
OIS Kerty et al in a study of 45 patients found
that only reversal of flow was associated with
structural changes of OIS. 6
One similar case exists in the literature
where neovascularisation resolved within several days of carotid endarterectomy (CEA).7
Other case reports also show that the retinopathy without neovascularisation can improve following surgery. However, the benefit
of carotid endarterectomy in patients with
ocular ischaemic syndrome is not quantified
and it has never been shown to reverse

PostScript
neovascular glaucoma.8–10 The European Carotid Surgery Trial showed that the risk of
ischaemic stroke in symptomatic patients
with 70–99% carotid stenosis with medical
treatment was only 20% over 3 years and CEA
lowered this by 50%. Based on the results of
this a risk factor score suggested that a
cerebral rather than an ocular event had a
greater risk for stroke on medical treatment
and would therefore derive greater benefit
from surgery.2
In the absence of iris neovascularisation
and severe peripheral retinal ischaemia the
ocular changes in patients with OIS can be
monitored closely for the development of iris
neovascularisation but the retinal vascularisation may not require early treatment with
PRP.
Christina A Rennie, Declan W Flanagan
Department of Ophthalmology, Addenbrooke’s
Hospital, Cambridge, UK
Correspondence to: Dr C Rennie, Department of
Ophthalmology, Princess Margaret Hospital, Okus
Road, Swindon, Wilts, SN1 4JU, UK
Accepted for publication 23 July 2001

References

1 Brown G, Magargal L. The ocular ischaemic
syndrome. Clinical, fluorescein angiographic
and carotid angiographic features. Int
Ophthalmol 1988;11:239–51.
2 Malhotra R, Gregory-Evans K. Management
of ocular ischaemic syndrome. Br J
Ophthalmol 2000;84:1428–31.
3 Mizener JB, Podhajsky P, Hayreh SS. Ocular
ischaemic syndrome. Ophthalmology
1997;104:859–64.
4 Sivalingam A, Brown GC, Magargal LE. The
ocular ischemic syndrome. III. Visual
prognosis and the effect of treatment. Int
Ophthalmol 1991;15:15–20.
5 Riordan-Eva P, Restori M, Hamilton AMP, et
al. Orbital ultrasound in the ocular ischaemic
syndrome. Eye 1994;8:93–6.
6 Kerty E, Eide N, Horven I. Ocular
hemodynamic changes in patients with
high-grade carotid occlusive disease and
development of chronic ocular ischaemia II.
Clinical findings. Acta Ophthalmol Scand
1995;73:72–6.
7 Neupert JR, Brubaker RF, Kearns TP, et al.
Rapid resolution of venous stasis retinopathy

after carotid endarterectomy. Am J
Ophthalmol 1976;81:600–2.
8 Kearns TP, Younge BR, Piepgras DG.
Resolution of venous stasis retinopathy after
carotid endarterectomy. Mayo Clin Proc
1980;55:342–6.
9 Ino-ue M, Azumi A, Kaijura-Tsukahara Y, et
al. Ocular ischemic syndrome in diabetic
patients. Jpn J Ophthalmol 1999;43:31–5.
10 Geroulakos G, Bothchway L, Pai V, et al.
Effect of carotid endarterectomy on the ocular
circulation and on ocular symptoms unrelated
to emboli. Eur J Vasc Endovasc Surg
1996;11:359–63.

Identifying the proportion of age
related macular degeneration
patients who would benefit from
photodynamic therapy with
verteporfin (Visudyne)
Verteporfin has recently been licensed for the
treatment of subfoveal exudative cases of age
related macular degeneration (AMD); however,
it is not clear how many patients would
actually benefit from this treatment.1 2 This
question has far reaching implications in terms
of verteporfin’s introduction into the National
Health Service in the United Kingdom.

Case report

We have recently looked at a cohort of 1418
new referrals (out of a possible 1481 (95.7%))
seen in the 166 consultant outpatient clinics
at Southampton Eye Unit, between 1 December 2000 and 31 January 2001. Diagnoses
were obtained from the consultant’s letter to
the referring doctor following the clinic visit
to obtain the spectrum of diagnoses made.
When two eyes were similarly affected this
was recorded as a single diagnostic event.
Cataract related diagnoses3 were found to
be most frequent, accounting for 28.8% (597)
of the total. This was followed by retinal
disease3 at 23.4% (485).
Within the retinal disease group AMD was
the single most frequent diagnosis even
though it may not have been the primary reason for referral, accounting for 22.3% (108) of
the 485 retinal disease cases recorded. Of the
108 AMD patients identified, 62% (67) were
female and 38% (41) male, the majority being
above the age of 75 (90.7%). Approximately
78% (84) of the total number of patients had
AMD affecting both eyes with unilateral
involvement in the remaining 22% (24).
Of the 108, most were not felt to need
further investigation, having either established and untreatable disease or mild
changes. Only 13% (14) underwent further
investigation with fluorescein angiography. Of
these, four were thought to be possibly
suitable for verteporfin treatment with only
one fully meeting the criteria for treatment,
having a predominantly classical subfoveal
membrane.1 2
Co-existing ocular diseases such as cataract
and glaucoma were treated in 49% (53) of the
108 patients, cataract extraction predominating (70% (37)).
The majority of the 107 patients (77) who
did not receive verteporfin therapy did not
require or were not suitable for any further
assistance for their AMD. The remainder (30)
were assessed for low vision aids and/or registered as partially sighted/blind.

Comment
Figure 2 Angiography showing narrowing of the right internal carotid artery (A, arrow) and
angiogram of the left side (B) revealing lack of crossflow to the right cerebral hemisphere
allowing the development of collateral circulation via the ophthalmic artery.

www.bjophthalmol.com

Photodynamic therapy with verteporfin has
caused much excitement, as it is heralded as a
breakthrough in the treatment of exudative
AMD.4 5 A recent editorial in the BMJ suggested

PostScript

119

that 20–30% of the 200 000 cases of exudative
AMD that present to ophthalmologists each
year in the United States would benefit from
such photodynamic therapy.6 Southampton
Eye Unit serves approximately 570 000 people
as part of its main catchment area, corresponding to approximately 1% of the UK population,
and produced only one person over the 2
month study period suitable for treatment with
verteporfin by the strict criteria for its use.1 2
The period studied was before the awareness of
photodynamic therapy was fully developed and
represents an unselected group of patients
having some degree of AMD. Subsequent studies might show a higher proportion of suitable
patients once their referral is with a view for
verteporfin treatment. Between August 2000
and April 2001 a total of 24 patients were
assessed for verteporfin therapy resulting in
seven receiving treatment, in keeping with the
4:1 ratio of those assessed and treated in the 2
month study. While it is difficult to extrapolate
from such a small number it would seem that
the number likely to benefit from verteporfin
treatment may well be smaller than suggested
even if the treatment criteria was extended to
include occult, myopic, and idiopathic
lesions.7 8
Even with the addition of verteporfin
therapy to the ranks of the treatment modalities available, the vast majority of AMD
patients are still considered untreatable if the
treatment criteria are observed.1 2 Rehabilitation in the form of low vision aids, registration
as partially sighted or blind, and the treatment of co-existing ocular disease remains
the mainstay of help that the ophthalmologist
can offer.9 However, the interest created and
accepted value of verteporfin should not be
underestimated as it represents a new and
non-destructive approach to the problem (in
contrast with laser photocoagulation) and the
first of a novel treatment option likely to be
joined by others in the not too distant future.
N Mandal, I H Chisholm
Southampton Eye Unit
Correspondence to: Nakul Mandal, c/o Sheila
Davies, Southampton Eye Unit, Southampton
SO16 6YD, UK; nm397@soton.ac.uk
Accepted for publication 25 July 2001

References

1 Treatment of Age-related Macular
Degeneration with Photodynamic Therapy
(TAP) Study Group. Verteporfin (Visudyne)
therapy of subfoveal choroidal
neovascularization in AMD: one-year results
of two randomised clinical trials-TAP Report 1.
Arch Ophthalmol 1999;117:1329–45.
2 Treatment of Age-related Macular
Degeneration with Photodynamic Therapy
(TAP) Study Group. Verteporfin (Visudyne)
therapy of subfoveal choroidal
neovascularization in AMD: two-year results of
two randomised clinical trials-TAP Report 2.
Arch Ophthalmol 2001;119:198–207.
3 Ellwein LB, Friedlin V, McBean AM, et al.
Use of eye care services among the 1991
Medicare population. Ophthalmology
1996;103:1732–43.
4 Stokkermans TJW. Treatment of age-related
macular degeneration. Clin Eye Vis Care
2000;12:15–35.
5 Margherio RR, Margherio AR, DeSantis ME.
Laser treatment with verteporfin therapy and
its potential impact on retinal practices. Retina
2000;20:325–30.
6 Bressler NM, Gills JP. Age-related macular
degeneration: new hope for a common
problem comes from photodynamic therapy.
BMJ 2000;321:1425–7.
7 Sickenberg M, Schmidt-Erfuth U, et al. A
preliminary study of photodynamic therapy
using verteporfin for choroidal

neovascularisation in pathologic myopia,
ocular histoplasmosis syndrome, angioid
streaks, and idiopathic causes. Arch
Ophthalmol 2000;118:327–36.
8 Mones J, for the Verteporfin in Photodynamic
Therapy (VIP) Study Group. Photodynamic
therapy with verteporfin of the subfoveal
choroidal neovascularisation in age-related
macular degeneration: study design and
baseline characteristics in the VIP randomized
clinical trials. Invest Ophthalmol Vis Sci
1999;40:S321.
9 Chisholm IH, Bird AC, Grey RHB, et al.
Age-related macular degeneration best clinical
practice guidelines. Trans Roy Coll
Ophthalmol 2000:3–19.

A new technique for delivering
sub-Tenon’s anaesthesia in
ophthalmic surgery
Sub-Tenon’s local anaesthesia has become an
accepted technique for anterior and posterior
segment eye surgery.1–5 It is a safe, quick, and
effective method of local anaesthesia. However, it requires a certain amount of skill for
dissection into the sub-Tenon’s space. This
dissection can lead to bleeding and chemosis.
We describe a modification of the current
technique of sub-Tenon’s anaesthesia which
aims to simplify the method of local anaesthetic delivery, avoid bleeding, and chemosis
while maintaining effective anaesthesia.

Case report

Fifty consecutive patients undergoing anterior segment surgery scheduled for local
anaesthesia were recruited for this study.
For this procedure, a 22 gauge Venflon
standard intravenous cannula was used. The
conjunctiva was anaesthetised with topical
amethocaine 1%. A Barraquet speculum was
inserted. The conjunctiva was grasped 5 mm
from the limbus using toothed forceps. Under
direct visualisation the tip of a 22 gauge Venflon was used to introduce the plastic cannula
under the conjunctiva and Tenon’s fascia
(keeping the needle tip visible at all times)
(Fig 1A). The plastic cannula was advanced
over the needle, which was drawn back and
removed (Fig 1B). Four millilitres of lignocaine 2% with 30 international units (IU)/ml
of hyalase was then injected through the
plastic cannula (Fig 1C).
All 50 patients had anterior segment surgery.
Forty six were cataract operations with posterior chamber lens implant, and four were
phacotrabeculectomies. None experienced excessive discomfort on delivery of the block. All
local anaesthetic blocks were performed by one
operator and no complication which prevented
surgery occurred. No patient who was scheduled for local anaesthesia was considered
unsuitable for this technique.

Figure 1

All patients had effective anaesthesia and
akinesia for the surgical procedure. None
complained of pain. Top up of anaesthesia was
not required in any case. Twenty eight patients
had complete or partial ptosis.
Subconjunctival haemorrhage extending
more than one quadrant occurred in one
patient, but this did not interfere with
surgery. None had chemosis.

Comment

Sub-Tenon’s local anaesthesia is a well established technique for ophthalmic surgery.
Although the Venflon cannula does have a
sharp needle, it is used simply as an introducer to place the blunt plastic cannula in the
correct tissue plane. The needle tip is kept
under direct visualisation at all times. Thus
there is minimal risk of ocular perforation
with this technique.
Venflon cannulas are used for intravenous
delivery of drugs and fluid so are readily
available, inexpensive, and disposable. SubTenon’s cannulas in current use are specialised cannulas and therefore more costly than
intravenous cannulas.
We describe a modification of the current
technique of sub-Tenon’s anaesthesia which
simplifies the method using an intravenous
cannula. We predict that this method is easier
to learn and that it maintains the efficacy of
this type of anaesthesia without compromising safety.
Sandip Amin
Department of Anaesthesia, Moorfields Eye
Hospital, City Road, London EC1V 2PD, UK

Miriam Minihan
Department of Ophthalmology, St Thomas’s
Hospital, Lambeth Palace Road, London SE1 7EH,
UK

Sarit Lesnik-Oberstein
Department of Ophthalmology, Moorfields Eye
Hospital, City Road, London EC1V 2PD, UK

Caroline Carr
Department of Anaesthesia, Moorfields Eye
Hospital, City Road, London EC1V 2PD, UK
Correspondence to: Sandip Amin;
Samin@talk21.com
Accepted for publication 13 August 2001

References

1 Stevens JD. A new local anaesthesia
technique for cataract extraction by one
quadrant sub-Tenon’s infiltration. Br J
Ophthalmol 1992;76:670–4.
2 Mein CE, Woodcock MG. Local anaesthesia
for vitreoretinal surgery. Retina 1990;10:47–9.
3 Hansen EA, Mein CE, Mazzoli R. Ocular
anaesthesia for cataract surgery: a direct
sub-Tenon’s approach. Ophthalmic Surg
1990;21:696–9.

New technique for delivering sub-Tenon’s anaesthesia injection.

www.bjophthalmol.com

120

PostScript

4 Li HK, Abouleish A, Grady J, et al.
Sub-Tenon’s injection for local anaesthesia in
posterior segment surgery. Ophthalmology
2000;107:41–7.
5 Roman SJ, Chong Sit DA, Boureau CM, et al.
Sub-Tenon’s anaesthesia: an efficient and safe
technique. Br J Ophthalmol 1997;81:673–6.

MAILBOX
IOP measurement and central
corneal thickness

10
5
0
–5

–10
400

500

600

700

CCT (µm)

Figure 1 Dependence of differences in IOP
measurements from CCT. Data of figure 2 of
Feltgen et al obtained by digitisation; 68 of
the 73 data points could be identified. The
four outliers shown by Feltgen et al as open
circles are omitted. These outliers would have
made the use of the same scale in both
diagrams more difficult. Thus n = 64. Same
scale as in Figure 2.

www.bjophthalmol.com

Correction value (mm Hg)

Correction value according to
Ehlers et al (1975) (mm Hg)

In the recent paper by Feltgen and
colleagues,1 the intraocular pressure (IOP)
was measured by Goldmann applanation
tonometry and by using a cannula inserted
into the anterior chamber connected with a
pressure transducer. Thus, the measurement
took place omitting a possible influence of the
cornea on the result. Marx et al2 believed that
by intracameral measurement the “true”
intraocular pressure may be measured. Feltgen et al share his opinion. They believe,
therefore, that they have compared the
intraocular pressure measured with and without the possible influence of the cornea.
Feltgen et al write in their conclusion:
“There is no systematic error of applanation
tonometry with increasing central corneal
thickness (CCT). Therefore it is inadequate to
recalculate IOP based on regression formula
of applanatory IOP versus CCT.” They base
their conclusion on their results. In our opinion their paper shows the following methodological deficits: (1) Both methods used for
measuring IOP are not up to the demands of
the scientific technique of measurement; (2)
their intracamerally measured IOP values do
not reflect the true IOP because of bias; (3) a
non-significant regression coefficient does not
prove that the slope is actually 0 and,
therefore, by a non-significant regression
coefficient it is not proved that applanatory
readings are not influenced by CCT; (4) the
goodness of fit of the linear regression model
is insufficient; and (5) an important covariate
(true IOP value) was omitted in the linear
regression. We would like to discuss these
points in detail.
In the study of Feltgen et al the only
criterion for the quality of measurement is the
stability of the readings on the monitor. However, it is not sufficient to conclude from the
presence of stability that the scale readings

represent the “true” pressure value that is at
the tip of the cannula. If there were a barrier
inside the cannula the reading on the monitor
would also be stable but would not represent
the pressure at the tip. There are many pitfalls
in pressure measurements by thin tubes that
we know from our own studies.3 4 Minute air
bubbles or tiny particles influence the result a
great deal. If we want to know that a display
reading represents the quantity in question
then we have to guarantee that the measurement system has the opportunity to react
freely to changes in the quantity. This guarantee can be obtained by feeding a known signal
to the input of the system and by observing
the output. If the output reacts in the
expected way then the guarantee is given.
Ehlers et al5 realised this in their rabbit experiments and we in electrophysiology.6–9 As long
as this demand is not met the results are not
definitive, giving cause for criticism and leading to misinterpretations.
Feltgen et al write in their paper (p 86):
“ . . .however, we believe intracamerally
measured IOP values reflect the ‘true’ IOP
more accurately.” Scientific facts should not
be a matter of belief. The belief of the authors
in the values they measured is not justified. In
the study under discussion their figure 2
shows the scatter plot of the pressure differences versus central corneal thickness. From
this diagram and from their statistical calculations the authors draw their conclusions.
Their results are quite different from those of
Ehlers et al5 shown in figure 4 of their paper.
Thus we must compare these two data sets. To
facilitate this task, we have digitised the data
presented in the figures of Feltgen et al and of
Ehlers et al. They are shown here in Figures 1
and 2 on the same scale. The difference is
striking.
Let’s first consider a possible reason from
the physical point of view. Ehlers et al5 reduced
the pressure measurement to a basic physical
quantity, here to the length of a water column.
We can, therefore, trust the results of Ehlers et
al more than the results of Feltgen et al who
used a pressure transducer which has a zero
point fluctuation up to 4.5 mm Hg (Abbott
GmbH, data file). It is recommended also by
the manufacturer that the zero point of the
measurement system has to be determined
for each patient by comparison with a water
column (Dr Beer, Abbott GmbH, Wiesbaden,
personal communication). This procedure is
not described by Feltgen et al.
Therefore, none of the methods used in the
article by Feltgen et al may be called a
reference method and all methods may be
prone to error and bias. Hence, analysis of differences in IOP between these models is inap-

propriate in order to decide on the necessity of
a conversion formula.
Further, the variability of differences is
large, which is probably the result of errors in
the intracameral measurement of IOP.
Regression lines with a small non-significant
slope (0.38 mm Hg IOP difference per 0.1 mm
cornea thickness in the article by Feltgen et al
may occur in both situations where variability
is both high and low. Only, in the latter case,
when—as a consequence of the small
variability—the confidence interval for the
slope is narrow, may this be interpreted in the
way that the covariate included in the model
(that is, CCT) has no effect. If the variability is
high and the slope is approximately 0, this
may lead to the conclusion that IOP measurement is inappropriate because of too large an
error. This conclusion is allowed if no other
essential covariates were overlooked. If variability is high and the slope of the regression
line is near 0, a large p value may not be interpreted as a proof of no effect of the covariate
considered in the regression model. For better
interpretation of the results a confidence
interval for the estimated slope would have
been much more appropriate than a p value.
As a consequence, the differences between
measurements from applanation tonometry
and a reference method, like the intraocular
hydrostatic pressure done by Ehlers et al,
should be evaluated first. If measurements by
applanatory IOP are highly correlated with
measurements by the reference method a
conversion formula may be derived from
linear regression. Under the assumption of
small variability of residuals (difference between observed value and regression line)—
that is, a satisfactory goodness of fit (for
example, r2>60%), results may lead to the
recommendation of the use of a conversion
formula. In contrast, Feltgen et al report an r2
of 0.2%. Only for small residuals, a slope
approximately 0, and a confidence interval
with limits near to 0, may the recommendation that a conversion formula is not necessary be given.
Moreover, the large variability in IOP differences may occur because Feltgen et al did not
adjust for “true” intraocular hydrostatic pressure as Ehlers et al did. Since Ehlers et al
calculated separate linear regression models
for 10 mm Hg and 30 mm Hg which resulted
in different intercepts and slope parameters,
this might be another source of variation in
the IOP differences from Feltgen et al which
were unadjusted.
We hope our arguments are convincing and
ask that you bring them to the attention of
your readers.
Richard Stodtmeister
St Elisabeth Hospital Rodalben (Palatinate),
Turnstrasse 24, D-66953 Pirmasens, Germany

10

Martina Kron, Wilhelm Gaus
University of Ulm, Department of Biometry and
Medical Documentation, Schwabstrasse 13,
D-89075 Ulm, Germany

5
0

Correspondence to: Professor Dr med Richard
Stodtmeister; Stodtmeister@t-online.de

–5
–10
400

References
500

600

700

CCT (µm)

Figure 2 Dependence of differences in IOP
measurements from CCT. Data of figure 4 of
Ehlers et al5 obtained by digitisation. All data
points could be identified. Thus n = 29.
Same scale as in Figure 1.

1 Feltgen N, Leifert D, Funk J. Correlation
between central corneal thickness,
applanation tonometry, and direct
intracameral IOP readings. Br J Ophthalmol
2001;85:85–7.
2 Marx W, Madjlessi F, Reinhard T, et al. [More
than four years’ experience with electronic
intraocular needle tonometry] Mehr als vier
Jahre Erfahrung mit der elektronischen
intraokularen Nadel-Druckmessung bei

PostScript
irregularen Hornhauten. Ophthalmologe
1999;96:498–502.
3 Stodtmeister R, Kästner R, Pillunat LE.
Saugnapfmethoden. In: Straub W, Kroll P,
Küchle HJ, eds. Augenärztliche
Untersuchungsmethoden. 1st ed.Stuttgart:
Ferdinand Enke, 1995:436–61.
4 Stodtmeister R, Hornberger M, Hofer M, et
al. Okulo-Oszillo-Dynamographie nach Ulrich
und Ulrich: Ergebnisse bei Augengesunden.
Klin Monatsbl Augenheilkd
1988;192:219–33.
5 Ehlers N, Bramsen T, Sperling S. Applanation
tonometry and central corneal thickness. Acta
Ophthalmol (Copenh) 1975;53:34–43.
6 Stodtmeister R, Wilmanns I. Bandpass
measurements in the electroretinographic
electrode circuit. Albrecht Von Graefes Arch
Klin Exp Ophthalmol 1978;208:263–7.
7 Stodtmeister R, Wilmanns I. Changes of the
current pathways in the eye due to coating
agents during electroretinography. Albrecht
Von Graefes Arch Klin Exp Ophthalmol
1978;208:255–60.
8 Stodtmeister R, Wilmanns I, Koenig A, et al.
EEG-Registrierung beim Hirntod. Prakt Anaesth
1978;13:446–9.
9 Wilmanns I, Stodtmeister R. Ein neues
Verfahren zur Kalibrierung
elektrophysiologischer
Untersuchungseinheiten. Albrecht Von Graefes
Arch Klin Exp Ophthalmol 1977;205:33–9.

Authors’ reply
In reply to the comments of Stodtmeister and
colleagues on our recent paper,1 we won’t argue
about the correlation between central corneal
thickness (CCT) and intraocular pressure
(IOP), but we mistrust the clinical application
of correcting factors. Stodtmeister et al compare
our study to that of Ehlers et al2 which is often
cited to prove an influence of corneal thickness
on applanatory measurement.
In our paper simultaneous IOP measurement by applanation and intracameral tonometry was performed. Assuming a normal
CCT of 520 µm, an IOP correction for every 10
µm change in corneal thickness is recommended. But in the Ehlers paper, there are
some confusing arguments.
Ehlers et al2 describe a very good correlation
between direct and intracameral IOP
measurement (correlation coefficient approximated 1). Unfortunately, they didn’t give
the measured IOP values. In figure 2, the
slopes of correlation lines at different CCT are
presented for rabbits (not for human eyes!).
The increase of the slopes are less than 45°.
With the paper of Bland and Altman3 in mind,
a minor methodological agreement is very
likely. It is therefore not allowed to recalculate
the values P10 and P30 (applanatory versus
intracamerally IOP, measured at an adjusted
IOP of 10 and 30 mm Hg) for a relevant IOP
level of 20 mm Hg (P20). It is indeed very
interesting that the group didn’t measure at
an IOP level of 20 mm Hg.
The equipment for intracameral measurement is comparable to our device. We also
calibrated the transducer before each
measurement. When we tested our device on
enucleated human eyes in a preclinical study,
a very sensitive change of IOP values was
noted when touching the eyeball. We therefore decided not to measure the IOP simultaneously. We also confirmed these findings in
vivo. For these reasons, we expected an
unpredictable increase of applanatory
measurement during intracamerally IOP in
the study of Ehlers.2 Unfortunately, there is no
comment about this problem.
Stodtmeister and colleagues pointed out
the “pitfalls in pressure measurement” (bubbles or tiny particles) without mentioning
that Ehlers had not solved these problems in

121
his trial on human eyes. We are also missing
any information about the cannula size. Additionally, the device used resembles an “open
system” where fluid could circulate through
the anterior chamber and trabecular meshwork. This can generate a noticeable change in
intraocular pressure.
Ehlers et al2 measured IOP in patients with
an acute eye disease (glaucoma patients
requiring surgery) and cataract patients. He
changed the IOP to 10 and 30 mm Hg. This
method is questionable especially in glaucoma patients, because an acute IOP change
could also entail endothelial alterations which
could alter CCT. Unfortunately, he didn’t
measure the CCT after IOP change. We have
no information about the influence of IOP
alterations on CCT.
In summary, the above mentioned study
gives a hint on the influence of CCT on IOP
measurement, but does not prove this assumption. It is amazing that within the last 25
years nearly 50 published papers refer to the
Ehlers study2 without checking the results by
intracameral measurement themselves.
All papers measuring CCT and applanatory
IOP renouncing intracameral measurement
described an increasing IOP with increasing
CCT. We could also confirm this finding in our
study (y = 14.5 + 8.4 × CCT, where y is
applanatory IOP in mm Hg). Of course, it
would be easiest to claim the cornea for this
correlation. But it is also conceivable that eyes
with thick corneas (for example, OHT) have a
reduced ocular outflow facility and consequently elevated IOP—for instance, because
of a “thick” trabecular meshwork.
With the present study 1 we tried to find out
if the above recommended correcting factors
are clinically applicable or not. According to
our findings they are not. We found quite
variable and unpredictable differences between intraocular pressure and applanatory
measurement in an individual patient. Interestingly, the same results can be found in the
Ehlers study.2 Therefore, we renew our warning to recalculate the IOP depending on
central corneal thickness.
Nicolas Feltgen, Jens Funk
Department of Ophthalmology,
Albert-Ludwigs-University Freiburg, Germany;
feltgen@aug.ukl.uni-freiburg.de

References

1 Feltgen N, Leifert D, Funk J. Correlation
between central corneal thickness,
applanation tonometry, and direct
intracameral IOP readings. Br J Ophthalmol
2001;85:85–7.
2 Ehlers N, Bramson T, Sperling S. Applanation
tonometry and central corneal thickness. Acta
Ophthalmol (Copenh) 1975;53:34–43.
3 Bland JM, Altman DG. Statistical methods for
assessing agreement between two methods of
clinical measurement. Lancet 1986;1:
307–10.

NOTICES
Onchocerciasis

The latest issue of Community Eye Health (No
38) discusses onchocerciasis and the impact
of interventions, with an editorial by Bjorn
Thylefors, former director of the Programme
for the Prevention of Blindness and Deafness,
WHO. For further information please contact
Community Eye Health, International Centre for
Eye Health, Institute of Ophthalmology,
11–43 Bath Street, London EC1V 9EL. (tel:
+44 (0) 20 7608 6909/6910/6923; fax: +44 (0)
7250 3207; email: eyeresource@ucl.ac.uk).

Annual subscription £25. Free to workers in
developing countries.

International Centre for Eye
Health

The International Centre for Eye Health has
published a new edition of the Standard List of
Medicines, Equipment, Instruments and Optical
Supplies (2001) for eye care services in
developing countries. It is compiled by the
Task Force of the International Agengy for the
Prevention of Blindness. Further details: Sue
Stevens, International Centre for Eye Health,
11–43 Bath Street, London EC1V 9EL, UK
(tel: +44 (0) 20 7608 6910; email:
eyeresource@ucl.ac.uk).

Leonhard Klein Award 2002

To promote ophthalmic surgery the Leonhard
Klein Foundation bestows the Leonhard Klein
Award 2002 for innovative, scientific works in
the field of development and application of
microsurgical instruments, as well as for
microsurgical operating techniques.
The award is endowed with 15.000€ and
can be conferred to an individual person as
well as to a group of researchers. The prize
sum must be spent for research in the field of
opthalmic surgery.
Individual and third party applications are
accepted. Five copies of the works must be
submitted in either English or German. The
deadline for applications is 31 March 2002.
Applications should be sent to: Stifterverband
für die Deutsche Wissenschaft e.V., Frau Dr
Marilen Macher, Postfach 164460, D-45224
Essen, Germany.

Second Sight

Second Sight, a UK based charity whose aims
are to eliminate the backlog of cataract blind
in India by the year 2020 and to establish
strong links between Indian and British
ophthalmologists, is regularly sending volunteer surgeons to India. Details can be found at
the charity website (www.secondsight.org.uk)
or by contacting Dr Lucy Mathen
(lucymathen@yahoo.com).

SPecific Eye ConditionS (SPECS)

SPecific Eye ConditionS (SPECS) is a not for
profit organisation which acts as an umbrella
organisation for support groups of any conditions or syndrome with an integral eye disorder. SPECS represents over fifty different
organisations related to eye disorders ranging
from conditions that are relatively common to
very rare syndromes. We also include groups
who offer support of a more general nature to
visually impaired and blind people. Support
groups meet regularly in the Boardroom at
Moorfields Eye Hospital to offer support to
each other, share experiences and explore new
ways of working together. The web site
www.eyeconditions.org.uk acts as a portal
giving direct access to support groups own
sites. The SPECS web page is a valuable
resource for professionals and may also be of
interest to people with a visual impairment or
who are blind. For further details about
SPECS contact: Kay Parkinson, SPECS Development Officer (tel: +44 (0)1803 524238;
email: k@eyeconditions.org.uk; www.eyeconditions.org.uk).

4th International Conference on
the Adjuvant Therapy of
Malignant Melanoma

The 4th International Conference on the
adjuvant therapy of malignant melanoma will

www.bjophthalmol.com

122

PostScript

be held at The Royal College of Physicians,
London on 15–16 March 2002. Further details: Conference Secretariat, CCI Ltd, 2 Palmerston Court, Palmerston Way, London
SW8 4AJ, UK (tel: + 44 (0) 20 7720 0600; fax:
+
44
(0)
20 7720 7177;
email:
melanoma@confcomm.co.uk:
website:
www.confcomm.co.uk/Melanoma).

EUPO 2002 Course Retina

A course on retina will be held on 15–17
March 2002 at Erlangen, Germany, where
European professors will teach European
residents. Further details: Priv Doz Dr Ulrich
Schonherr, Friedrich-Alexander-University of
Erlangen-Nuemberg, Department of Ophthalmology, Schwabachanlage 6 (Kopfklinikum),
D-91054 Erlangen, Germany (tel: +49 9131
853 4379; fax: +49 9131 853 4332; email:
ulrich-schoenherr@augen.imed.unierlangen.de).

XXIXth International Congress of
Opshthalmology

The XXIXth International Congress of Ophthalmology will be held on 21–25 April 2002
in Sydney, Australia. Further details: Congress

Secretariat, C/- ICMS Australia Pty Ltd, GPO
Box 2609, Sydney, NSW 2001, Australia (tel:
+61 2 9241 1478; fax: +61 2 9251 3552;
email: ophthal@icmsaust.com.au; website:
www.ophthalmology.aust.com).

12th Meeting of the European
Association for the Study of
Diabetic Eye Complications
(EASDEC)

The 12th meeting of the EASDEC will be held
on 24–26 May 2002 in Udine, Italy. The deadline for abstracts is 15 February 2002. Three
travel grants for young members (less than 35
years of age at the time of the meeting) are
available. For information on the travel
grants, please contact Pr CD Agardh, President of EASDEC, Malmö University Hospital,
SE-205 02 Malmö, Sweden (tel +46 40 33 10
16; fax: +46 40 33 73 66; email: carldavid.agardh@endo.mas.lu.se). Further details: NORD EST CONGRESSI, Via Aquilea,
21.–33100 Undine, Italy (tel: +30 0432 21391;
fax:
+39
0432
50687;
email:
nordest.congressi@ud.nettuno.it)

International Society for Behçet’s
Disease

The 10th International Congress on Behçet’s
Disease will be held in Berlin 27–29 June
2002. Further details: Professor Ch Zouboulis
(email: zoubbere@zedat.fu-berlin.de).

Singapore National Eye Centre
5th International Meeting

The Singapore National Eye Centre 5th International Meeting will be held on 3–5 August
2002 in Singapore. Further details: Ms Amy
Lim, Organising Secretariat, Singapore National Eye Centre, 11 Third Hospital Avenue,
Singapore 168751 (tel: (65) 322 8374;fax: (65)
227 7290; email: Amy_Lim@snec.com.sg).

CORRECTION
We regret that an error occurred in the mailbox
letter published by Kenawy et al in the November 2001 issue of BJO (2001;85:1394–5). The
name of one of the authors was incorrect and
should have been Omar M Ayoub.

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