Eye (1991)

5, 466-469

The Oval Pupil H. S. DUA. N. J. WATSON. J. Y. FORRESTER

Ahf'/'{/ecn

Summary The dynamics of pupillary dilation induced by Phenylephrine 10% and Cyclopento­ late 1 % have been examined by flash photography. A correlation between anterior chamber depth and the pupil shape on dilation with Phenylephrine Hydrochloride

J00/r, is described. It is postulated that these pupillary dilation dynamics support a s)'mpathetic abnormality as a trigger for acute primary angle closure glaucoma.

The oval pupil is a common clinical sign in acute

prImary

angle

closure

glaucoma

(APACG ).1 APACG has been shown to occur

clinics after ocular and general examination had

excluded conditions kno wn to affect

ocular sympathetic function. Exclusion cri­

more commonly in patients with shallO\v

teria included diabetes mellitus. glaucoma or

anterior chambers.: The acute attack is pre­

ocular hypertension. previous ocular surgery

cipitated by autonomic dysfunction and a

(including extraocular muscle surgery). pre­

modification of physiological pupil block,:

vious intraocular inflammation and topical

During an attack of APACG the pupil is mid­

drug administration. The colour of the iris was

dilated and vertically elongated. a preferen­

noted and the anterior chamber depth was

tial dilation in the vertical meridian producing

measured on a Haag Streit slit lamp using the

the oval shape,' Oval or 'tadpole shaped'

technique described by Smith,' A tine beam is

pupils have also been reported in patients

directed horizontally at the eye from 60°, Its

with Horner's syndrome.-l As both these con­

length is adjusted until the corneal and iridal

ditions with oval pupils have an underlying

reflexes

sympathetic dysfunction. a cause and effect

required is proportional to the depth of the

meet.

The

relationship may be inferred. We undertook

anterior

this study to examine this relationship further

length +0.5(79).

length

chamber

of

the

(1.117 x slit

beam beam

by comparing the dilation characteristics of

Twenty-eight eyes had anterior chamber

Phenylephrine Hydrochloride (a direct acting

depths of less than 2.2 mm and the remaining

amine) and Cyclopentolate Hydrochloride (a

58

parasympathetic agonist).

greater than 2,2 mm.

Particular atten­

tion was paid to any differential dilation in the

eyes had

anterior

chamber depths of Details of the study

group are shown in Table I. Two drops of Phe­ nylephrine hydrochloride 10'/;, were instilled

vertical meridian.

into the inferior fornix of one eye and Cyclo­ pentolate 1 % into the second eye of each sub­

SUbjects and methods

Informed consent was obtained from

(86

43

sub­

ject. The right and left eyes were randomly

26

selected for each of these drugs. Pupillary size

years of age,

was recorded. in dim background illumina­

Recruitment was from general ophthalmic

tion, by flash photography at 0,5, 10, 15.20

jects

eyes). There were 17 males and

females between 15 and

89

Correspondence to: N, J, Watson, Department of Ophthalmology. University of Aberdeen. ForesterhilL Aberdeen AB9 2ZB.

THE OVAL PUPIL

Table I

ride 1 'Yo did not show any meridional prefer­

SlIi>/ecr characrerisrics

Age range

467

ence during dilation. Twenty-seven of the

15-89 years

43

eyes treated with Phenylephrine hydrochlo­ ride 10% showed a preferential dilation in the

Sex Male

17 patients

vertical meridian, the pupils becoming ver­

Female 26 patients

tically oval, prior to resuming a round contour

3).

Chamber depth

on complete mydriasis (Figs. 2 and

Anterior chamber 2.2 111m 58 eyes

minutes after drug instillation. The time point

Iris colour

at which maximal vertical dilation occurred

Light 48 eyes Dark

A

with Phenylephrine hydrochloride 10% had

38 eyes

no

relationship

to the anterior

chamber

depth. The 15 minute dilation ratios of the and 25 minutes. In order to eliminate the

right and left eyes of each subject were com­

problems of magnification the pupil dilation

pared.

was recorded as the ratio of pupil size ver­

between Cyclopentolate and Phenylephrine

tically and horizontally, a vertically oval pupil

treated

having a pupil dilation ratio> 1 (see Fig. 1).

(P

The oval pupil.

The dynamics of pupillary dilation induced by Phenylephrine 10% and Cyclopentolate 1% have been examined by flash photography. A correlation between a...
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