A 62-year-old woman with pre-existing against-the-rule astigmatism of 1.25 D undergoes cataract surgery planned through a temporal clear corneal incision rather than a superior limbal incision. What is the main optical advantage of the temporal approach?

• A It induces greater surgically induced astigmatism that corrects the pre-existing cylinder
• B It lies near the steep meridian in most eyes, minimising surgically induced astigmatism because the incision is farther from the visual axis ✓
• C It avoids the need for any suturing regardless of incision size
• D It reduces the rate of posterior capsule rupture during nucleus removal

Explanation

A temporal clear corneal incision sits farthest from the centre of the cornea and away from the palpebral aperture pressure of the upper lid, so it flattens the cornea less and induces minimal surgically induced astigmatism. A superior incision sits close to the vertical meridian and causes greater against-the-rule shift, worsening pre-existing against-the-rule astigmatism.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

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Written and medically reviewed by the StethoPrep medical team.