Page 144 - July-August 2020

pupils to light (direct and consensual
reflex). First test the direct light
reflex – a normal pupil will constrict
when light is directed to it. However,
observe the other eye – the other
pupil will constrict even without
exposure to light (consensual light
reflex). In this manner defects in the
afferent or efferent pathways of the
light reflex can be established.

Step 3 – Swinging flashlight
test / relative afferent pupillary
defect. This test is used to detect
an afferent defect. When light is
shone on the normal side, the pupil
constricts but when the light is
quickly shifted to the abnormal side, FIGURE 3: A PATIENT WITH LEFT SIDED ADIE’S PUPIL
that pupil will dilate. When the light
is moved back to the normal pupil neuritis), chiasm compression, accommodation (Figure 3).
again, that pupil will reconstrict retinal detachment, large unilateral
again as there was no consensual macular lesion or advanced This is referred to as a light-near
reflex from the abnormal pupil. This unilateral glaucoma. dissociation. The pupil usually shows
clinical sign is known as a relative slow constriction on prolonged
afferent pupillary defect (RAPD). Step 4 – Accommodation. Finally, near effort and slow re-dilatation
accommodation can be tested by to distance. It is due to damage of
Even in the presence of bilateral asking the patient to fixate on a the post-ganglionic fibres of the
optic nerve disease, an RAPD can distant point and then asking them parasympathetic pathway. In 90%
still be detected as in most cases, to shift their focus quickly to a near of patients, it presents unilaterally
the damage will not be equal: thus object. Normally, the pupils constrict initially but often becomes bilateral.
the optic nerve with the greater and the eyes converge while fixating
damage will manifest in a RAPD. In on a near object. In exams, but Eventually, the pupil becomes tonic
exceptional cases, when the degree certainly not in real life, pupils that with time and even miotic, a so
of damage to both optic nerves is constrict through accommodation called ‘little old Adie’s pupil’. This
very similar, both pupils will show but not through direct light condition usually affects females
sluggish reactions to light. Causes of stimulation, if due to neurosyphilis, and can be caused by viral infection,
RAPD include: optic nerve disorders are called Argyll Robertson pupils. I diabetes or trauma but is often
(optic nerve compression, optic guarantee you will never see a case idiopathic. If decreased tendon
reflexes are present it is referred to
of this in your entire career, but you as Holmes Adie syndrome. Diagnosis
THE USE OF will be punished by examiners for not is confirmed by denervation
EYEDROPS knowing it. hypersensitivity to weak cholinergic
SHOULD ALWAYS CONDITIONS WITH agents (0.125% pilocarpine), an
abnormal pupil will constrict whilst a
BE CONSIDERED PATHOLOGICAL PUPIL SIZE: normal pupil remains unaffected.
WHEN SINGLE LARGE PUPIL ACUTE ANGLE CLOSURE
PRESENTED ADIE’S TONIC PUPIL GLAUCOMA

WITH BILATERAL An Adie’s tonic pupil is an This happens when the anterior
CONSTRICTED OR anisocoria where the abnormal chamber angle is closed mechanically
DILATED PUPILS pupil is larger and does not constrict by the crowding of the peripheral
to light but slowly constricts to iris when the pupil is semi dilated.

| JULY-AUG 2020 | 140 OPHTHALMOLOGY