Comparison of function and fixation of small incision circular and oval poly(methyl methacrylate) intraocular lenses

A prospective study of function and fixation was done on 40 patients implanted with small incision poly(methyl methacrylate), single piece, biconvex intraocular lenses after in situ phacoemulsification cataract extraction via a continuous curvilinear capsulorhexis. A 5.0 mm circular optic (Pharmacia 740 P), 14 mm length lens was compared with an oval 5.0 x 6.0 mm optic (IntraOptics SP18UB), 12.75 mm lens. Twenty patients were implanted with each design and were surveyed three months postsurgery. Satisfactory visual acuity and absence of motor vehicle headlight glare was found in all 40 patients. One glare disability of 35% occurred in a patient with an off-center capsulorhexis that formed a Soemmering's ring partially posterior to a circular optic lens. Fixation was clinically central in all patients. A space between optic and posterior capsule persisted in seven eyes with an oval optic lens and in eight eyes with a circular optic lens. Therefore both designs were associated with a "no space, no cells" situation that should decrease eventual pearl formation. Total Soemmering's rings formed posterior to 9 of 20 circular optic lenses if the capsulorhexis was 5 mm or larger in diameter (only one oval optic lens formed a Soemmering's ring). Compression of the posterior capsule occurred in seven of the nine patients with circular optic lenses and total Soemmering's rings. I conclude that the circular optic design was best implanted via a 5 mm or slightly larger central capsulorhexis to promote both Soemmering's ring formation and posterior capsule compression. Both designs provided satisfactory clinical results.