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What Is Unilateral Aphakia?

Unilateral aphakia means the natural crystalline lens is absent in one eye. It most often happens after cataract surgery without placement of an intraocular lens, or after trauma that dislocates or removes the lens. Without the lens, the affected eye has marked farsightedness and loses normal focusing ability for near. Because only one eye is affected, patients may experience image-size differences between eyes and reduced binocular vision unless corrected.

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What Is Unilateral Aphakia?

Unilateral aphakia means the natural crystalline lens is absent in one eye. It most often happens after cataract surgery without placement of an intraocular lens, or after trauma that dislocates or removes the lens. Without the lens, the affected eye has marked farsightedness and loses normal focusing ability for near. Because only one eye is affected, patients may experience image-size differences between eyes and reduced binocular vision unless corrected.

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Common causes

Most unilateral aphakia is acquired rather than congenital. Causes include:

  • Cataract extraction without an intraocular lens, often due to surgical complexity or complications
  • Trauma that ruptures the lens capsule or dislocates the lens
  • Lens removal during repair of severe eye injuries
  • Rare congenital absence of the lens

The cause influences the safest correction method and timing of any secondary surgery.

Symptoms and vision effects

Symptoms include blurred vision, difficulty with near focus, and reduced depth perception. A large prescription difference between eyes can cause anisometropia and aniseikonia, which may lead to headaches, eyestrain, or double vision. Some patients notice distortion with thick glasses, especially if only one eye is aphakic. In children, untreated aphakia can quickly lead to amblyopia, so early correction is critical.

How it is diagnosed

Diagnosis is made during a comprehensive eye exam using slit-lamp evaluation to confirm the lens is absent. Refraction measures the high plus power needed to focus light on the retina. The clinician also evaluates the cornea, retina, and eye pressure, especially after trauma or complex surgery. In children, the exam includes binocular vision and amblyopia assessment.

Treatment options

Optical correction is the main treatment and often uses a contact lens for the aphakic eye because it reduces image-size differences and distortion compared with glasses. Aphakic spectacles can work better when both eyes are aphakic, but they are often poorly tolerated for unilateral cases. Many patients are candidates for a secondary intraocular lens implant once the eye is stable and the anatomy allows it. Children often need a combined plan that includes optical correction plus amblyopia therapy and frequent follow-up.

FAQs on unilateral diplopia

Can unilateral aphakia be corrected with glasses?

Glasses can correct the focus, but unilateral aphakic glasses may cause significant image-size differences and distortion. Many patients tolerate a contact lens better for one-eye aphakia. Your clinician can advise based on comfort and binocular needs.

Why are contact lenses often recommended?

A contact lens sits close to the eye and reduces magnification differences compared with thick spectacle lenses. This can improve binocular vision and comfort in unilateral cases. It is also a common approach in children to support normal visual development.

Can an intraocular lens be implanted later?

Often, yes. Secondary intraocular lens implantation may be considered once the eye is stable and the supporting structures are suitable. The timing and technique depend on the reason for aphakia and the health of the eye.

What follow-up is needed?

Follow-up checks vision, prescription, and ocular health, including eye pressure and retinal status after trauma or surgery. Children need close monitoring for amblyopia and proper lens fit. New pain, redness, flashes, or sudden vision loss should be evaluated urgently.

References

Prescribing Glasses for Aphakia. StatPearls Publishing (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK592414/. Date Accessed: February 19, 2026.

Hyperopia. StatPearls Publishing (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK560716/. Date Accessed: February 19, 2026.

Pediatric Cataract. StatPearls Publishing (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK572080/. Date Accessed: February 19, 2026.

Amblyopia. StatPearls Publishing (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK430890/. Date Accessed: February 19, 2026.

Secondary Intraocular Lens (IOL) Implantation. American Academy of Ophthalmology (EyeWiki). https://eyewiki.org/Secondary_Intraocular_Lens_(IOL)_Implantation. Date Accessed: February 19, 2026.