PUPILLARY DISORDERS

Normally pupil is ~3-4 mm in size at room light and light reflex is present from 31^st week of gestation.

Examination of pupillary size, symmetry and reactivity to light is of immense value in diagnosis of neurological disorders, poisonings and retinal disease (Table 26.8).

Dyscoria or corectopia, i.e. abnormal shape or location of pupil is secondary to iris deformities, which may congenital or acquired after ocular trauma, uveitis and anterior synechiae formation. Congenital defects are usually associated with ectopia lentis.

Leukocoria, i.e. white pupillary reflex or cat-eye reflex, indicates abnormalities of lens, posterior chamber or retina. It may be developmentally present in preterms due to incomplete regression of fetal hyaloid vascular system, which clears spontaneously in next few weeks. Important causes of pathological leukocoria include—

(a) cataract, (b) retinoblastoma, (c) retinopathy of prematurity, (d) retinal detachment, and (e) leukemic infiltrates in eye.

TABLE 26.8: Abnormal pupilary size and reactivity

Constricted, non-reacting pupil (Fixed miosis)

• Congenital miosis or microcoria

• Drugs: Pilocarpine

• Poisoning: Opium, barbiturate, organophosphorus

• Pontine hemorrhage

• Horner syndrome (Miosis, Ptosis, Anhidrosis)

Dilated, non-reacting pupil (Fixed mydriasis)

• Cardiopulmonary arrest

• Drugs: Atropine, other cycloplegics

• Transtentorial herniation (Hutchinson's pupil)

• Intracranial hypertension

• Ocular trauma or infections (Tonic pupil)

• Riley-Day syndrome

Anisocoria (asymmetrical pupils)

• Congenital coloboma or aniridia

• Unilateral neurological disease

• Post-infective/traumatic synechiae

• Topical drugs, e.g. atropine, pilocarpine

Paradoxical pupil (abnormal constriction in dark)

• Night blindness

• Albinism

• Retinal disorders

Marcus Gunn pupil (Direct LR -ve, consensual LR +ve)

• Retinal or optic nerve disease

Hippus (Rhythmic dilatation and constriction of pupils)

• Retrobulbar neuritis

LR: Light reflex

26.2.9