A 45-year-old woman undergoes uncomplicated phacoemulsification with posterior chamber IOL implantation in the right eye. The left eye remains phakic with vision 6/6. Postoperatively she reports image size disparity and spatial distortion between the two eyes. Which feature of her situation most strongly favours contact lens correction of the operated eye over spectacle correction?

• A Contact lenses eliminate the need for accurate biometry
• B Spectacles magnify the image by about 20 to 30 percent in aphakia, exceeding the tolerable aniseikonia limit ✓
• C Spectacle correction induces unwanted myopia at near
• D Contact lenses correct residual astigmatism better than spectacles

Explanation

Unilateral aphakia corrected with spectacles produces roughly 25 percent image magnification, while only about 3 percent aniseikonia (roughly 1.5 to 2 D of anisometropia) is tolerated. B contact lens sits at the corneal plane and keeps image size difference near 6 to 8 percent or less, which is why contact lens or IOL correction is preferred in unilateral aphakia. Biometry accuracy matters equally for both options, and residual astigmatism is often better handled by a toric IOL or RGP rather than a soft contact lens.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.