Intraocular lens exchange due to incorrect lens power

To evaluate patients who had intraocular lens (IOL) exchange for unexpected postoperative refractive errors, determine the sources associated with the errors, and derive an empiric approach to estimating the power for IOL exchange.

Retrospective review of interventional case series.

Twenty-two eyes that underwent IOL exchange for correcting unexpected refractive errors after cataract surgery with IOL implantation were reviewed.

All the IOLs for IOL exchange were placed in-the-bag. The same type of IOLs was used for original IOL implantation and IOL exchange in 91% (20/22) of eyes.

Uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), refraction, and reasons for IOL exchange. The equation derived from refractive change and change in IOL power was developed to calculate IOL power for exchange.

Of the 22 cases, the identified reasons were keratometry errors in 5 (23%) and incorrect axial length (AL) determination in 3 (14%). In 3 other cases, a wrong IOL was implanted. After IOL exchange, 82% (18/22) of eyes were within +/-0.50 diopters (D) and 86% (19/22) within +/-1.00 D of emmetropia. Uncorrected visual acuity was 20/40 or better in 82% of eyes, and BSCVA was 20/40 or better in 95% (21/22) of eyes. The correlation between change of refraction and IOL power was significant (P<0.002).

Among the identified causes, incorrect corneal power determination was the most frequent reason for incorrect IOL power implantation, followed by error in AL measurement and inserting a wrong IOL. The pre-exchange refraction can be used theoretically to calculate the IOL power for exchange.