Calculation of posterior chamber intraocular lens ( IOL ) size and dioptric power for use in pet rabbits undergoing phacoemulsification

Objectives To calculate the size and dioptric power of a posterior chamber intraocular lens ( IOL ) to achieve emmetropia in adult rabbits and to compare the dioptric power calculation results using a proprietary predictive formula to a retinoscopy‐based method. Animals studied Three wild rabbit cadavers, seven pet rabbits with cataracts and ten healthy pet rabbits. Materials and Methods Implant size was calculated using a capsular tension ring ( CTR ) (Acrivet ® , Berlin, Germany). Published and cadaveric biometric data were used in the predictive formula. An IOL power‐escalation study compared the predicted values to the refraction results of one pet rabbit (P1) fitted with a + 41D canine IOL (Acrivet ® ) and six pet rabbits (P2‐P7) fitted with prototype IOL s (Acrivet ® ). Retinoscopy of 10 healthy pet rabbits served as controls. Results A 13.5 mm CTR fitted in all rabbits and permitted the use of a 13 mm IOL . The predicted IOL power ranged between +24D and +25D. The +41D IOL resulted in a refraction error of +8D. Progressive recalculation through a calibration formula led to the insertion of three +49D IOL s in two pet rabbits and a refraction of +6D to +8D, followed by seven +58D IOL s in four pet rabbits and a refraction median of 0D (range: −1.5D to +1D). Conclusions A 13 mm prototype IOL of +58D achieves emmetropia and is of adequate size for rabbits. The combined use of a CTR and retinoscopy is a useful method to calculate the size and refractive power of a new, species‐specific, veterinary IOL .