Limitations of Intraoperative Aphakic Refraction Technique for Intraocular Lens Power Calculation

Intraocular lens (IOL) power calculations are known to be difficult in eyes that have had corneal refractive surgery and several methods have been proposed to estimate IOL power. Among the methods not requiring preoperative data, the apahakic refraction technique has been successfully used to calculate IOL power in post-refractive cases and other conditions that cause unreliability in standard keratometry and ultrasonic or optical biometry. This paper looks at two complex cases of cataract surgery in eyes with previous corneal refractive surgery (LASIK for high myopia and radial keratotomy) in which pre-refractive-surgery corneal power and refraction were unknown. Aphakic autorefraction technique was used to calculate IOL power. The method resulted in an inaccurate estimation of IOL power. The reasons for failure in both cases are analyzed and exposed so that certain limitations of this method that should be taken into account when considering its application in complex cases can be illustrated.