During phacoemulsification, what is the ideal diameter of a continuous curvilinear capsulorhexis relative to the IOL optic?
- A Slightly smaller than the optic, around 5 to 5.5 mm, so the optic overlaps the rhexis edge ✓
- B About 1 mm larger than the optic so the edge lies free in the bag
- C About 2 mm smaller than the optic to prevent any contact between optic and epithelium
- D Exactly equal to the optic diameter so the edge aligns precisely with the optic rim
Correct answer: A. Slightly smaller than the optic, around 5 to 5.5 mm, so the optic overlaps the rhexis edge
Explanation
C capsulorhexis about 0.5 mm smaller than the optic allows the IOL optic edge to overlap the anterior capsule rim. This overlap blocks migration of residual lens epithelial cells onto the posterior capsule, reducing posterior capsule opacification, and also secures a stable in-the-bag position. C rhexis larger than the optic loses this barrier effect.
Reference: Kanski's Clinical Ophthalmology, 9th ed.
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Written and medically reviewed by the StethoPrep medical team.