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