Aphakia

Aphakia is the absence of the eye's crystalline lens. It may be congenital or result from surgical removal of the lens (with or without intraocular lens implantation) or from traumatic rupture or dislocation. The loss of the lens eliminates the eye's natural refractive power and accommodation, producing substantial refractive error and changes in vision.

In adults, the most common cause is cataract surgery without lens implantation or with complications. Congenital aphakia is rare but significant in early life due to the risk of deprivation amblyopia. Aphakia creates a large hyperopic error, typically around +8 diopters, and removes accommodation, leading to marked anisometropia and reduced binocular vision in unilateral cases.

Symptoms include blurred vision, glare, and decreased contrast sensitivity. On examination, the lens is not present; in some cases the posterior capsule may be absent if the original surgery involved extracapsular extraction. Diagnosis is clinical, supported by imaging if needed.

Management aims to restore focusing power. Options include aphakic spectacles, which cause magnification and distortion, and contact lenses to reduce image-size differences between eyes. In many cases, intraocular lens implantation is performed to reintroduce refractive power, with a posterior chamber, scleral-fixated, or iris-claw IOL depending on capsular support. In children, optical correction and amblyopia therapy are critical.

Prognosis depends on associated conditions and treatment. Aphakia carries higher risk of glaucoma, retinal detachment, and refractive instability. With appropriate correction and monitoring, visual outcomes can be favorable, though dependence on optical devices and potential complications remain considerations.