OP8.5 | Aphakia — Summary & Reflection

KEY TAKEAWAYS

Aphakia is defined as absence of the crystalline lens from its normal position, causing high hypermetropia (~+10D) and total loss of accommodation. Causes: surgical (post-cataract extraction without IOL), traumatic, or congenital (rare). Clinical signs include deep anterior chamber, iridodonesis (iris trembling — pathognomonic), and absence of lens on slit-lamp. Three optical correction modalities exist: (1) Aphakic spectacles (+10D convex lenses) — introduce ~25–30% image magnification, ring scotoma, jack-in-the-box phenomenon, and multiple aberrations; suitable only for bilateral aphakia; CONTRAINDICATED in unilateral aphakia due to intolerable aniseikonia. (2) Contact lenses — reduce magnification to ~7–8%; tolerable in unilateral aphakia; preferred for infants; requires compliance with hygiene. (3) IOL implantation — current standard, magnification ~1–2%, no aberrations; pseudophakia = eye with IOL. In unilateral aphakia, spectacles are contraindicated — IOL or contact lens is mandatory. In paediatric aphakia (e.g. after congenital cataract surgery), immediate optical correction AND aggressive amblyopia treatment (patching the fellow eye) are both essential — delay causes permanent, irreversible amblyopia.

REFLECT

Return to Baby Priya and Mr. Krishnamurthy from the opening scenario. For Priya: she is 4 months old, unilateral aphakia, critical amblyopia period underway. What is your plan? How do you choose between IOL and contact lens? How do you explain the need for eye patching to her mother — a young woman who may feel guilt about 'hiding' her baby's eye? For Mr. Krishnamurthy, who has bilateral aphakia and wears aphakic spectacles: he complains of 'things jumping' in his peripheral vision. How do you explain the jack-in-the-box phenomenon using an analogy a 70-year-old farmer would understand? And if he asks whether he can have an IOL now, 20 years after his ICCE, how would you counsel him about secondary IOL implantation — its feasibility, the likely choice of AC-IOL in the absence of capsular bag, and the realistic visual outcome? These scenarios capture the full clinical competency that OP8.5 demands — history, examination, and patient-centred management discussion.