UNDESIRED LIGHT IMAGES ASSOCIATED WITH OVOID INTRAOCULAR LENSES

Ovoid intraocular lenses (IOLs) accounted for approximately 35% of the lenses implanted in 1991. Despite their popularity among surgeons, pa tient observations and complaints suggest that ovoid lenses are associ ated with undesired optical images postoperatively. A pilot clinical s tudy was carried out to test that hypothesis. A multicentered investig ation of 289 cases with well-centered lOLs determined that 45% of 168 patients with ovoid lenses observed unwanted optical phenomena at some time after surgery, whereas 17% of 121 patients with round lOLs had s imilar complaints. Based upon the preliminary clinical study a laborat ory investigation was designed to assess optical performance differenc es between ovoid and round lOLs. One testing system used scatterometry and a second, ray tracing analysis. Both methods determined that the truncated, thickened edge of ovoid lenses was associated with signific ant light scattering, possibly accounting for the extraneous light ima ges observed by some patients. The results of the clinical and laborat ory investigations suggest that undesired optical images produced by o void lOLs are due to lens shape rather than to the reduced dimension o f the optic.