AN INTERESTING CASE OF REFRACTIVE SURPRISE

Cataract surgery with intraocular lens (IOL) implantation is one of the most commonly performed ophthalmic procedures and achieving a postoperative refractive outcome close to emmetropia remains a key area of concern for surgeons. Inaccurate biometry measurements can lead to wrong intraocular lens power calculations and result in refractive surprise following cataract surgery.

A 63-year-old myopic female, with a history of contact lens wear, underwent uncomplicated phacoemulsification with posterior chamber intraocular lens (IOL) implantation aiming for emmetropia. Post-operatively, her uncorrected visual acuity was 3/60 (20/400), with pinhole improving to 6/24 (20/80). 

An anterior segment exam showed a clear cornea with no punctate staining, no corneal oedema, a quiet anterior chamber, a well-centred posterior chamber IOL, and no posterior capsular opacity. The posterior segment exam was normal. The macula was flat with a sharp foveal reflex and peripheral retinal myopic degenerative changes

A review of the biometry confirmed IOL power insertion consistent with pre-operative calculations. With manifest refraction of -5.25/-0.25x45, her visual acuity improved to 6/6. Further investigation revealed that the patient had failed to remove her contact lens prior to biometry measurement and calculation was performed with a contact lens of power -4.75DS insitu in her eye giving rise to a refractive surprise post-operatively

Contact lens wear may affect biometry measurements and subsequent IOL power selection. It is advisable to repeat biometry measurements after a contact lens hiatus to improve the accuracy of IOL calculations.