PREDICTING PSEUDOACCOMMODATION IN THE HUMAN EYE

To develop a mathematical model for predicting the probability of achieving pseudoaccommodation and to identify the most critical factor influencing pseudoaccommodation.

Experimental study

Multivariate analysis from the ‘Monofocal extended range of vision study’ funded by the European Society of Cataract & Refractive Surgery found four factors to be responsible for achieving pseudoaccommodation (lower spherical equivalent, shorter preoperative axial length, low total ocular spherical aberration and smaller mesopic pupil size). A logistic regression method derived a mathematical formula using these four variables to predict pseudoaccommodation. Change in probability was assessed by changing one variable at a time whilst others remained constant to determine the factor which improved the probability of pseudoaccommodation the most.

The following formula was derived to predict pseudoaccommodation: Logit (P) = 12.54 - (0.484 X preoperative axial length) – (0.884 X mesopic pupil size) – (13.1 X total eye spherical aberration) – (0.714 X spherical equivalent). Where logit(p) = natural log (P/1-P) and P is the probability of having pseudoaccommodation. Changing the total ocular spherical aberration to -0.3mm or less gave the maximum probability of achieving pseudoaccommodation (³98%) compared to changes in other variables.

Our study showed that changing the total ocular spherical aberration between -0.3 to -0.5mm gave ³98% probability of achieving pseudoaccommodation.