Correlation of IOL Models and Their Orientation in Eye With Postoperative Dysphotopsia
To try and find out the cause of negative dysphotopsias by correlating their incidence with various models of intraocular lenses (IOL) and with the orientation of the IOL within the eye
30 IOL each of 6 different models were randomized to be implanted either in the horizontal axis or the vertical axis in the capsular bag following phacoemulsification. Square edge, rounded edge, spherical IOL, aspherical IOL, hydrophobic and hydrophilic IOL were included. A simple questionnaire was designed to find out the incidence of negative dysphotopsia in each group. Statistical analysis was done to find out the incidence in each group and thereby elucidate the likely cause of negative dysphotopsia.
360 patients were randomized into 12 groups to receive either SN60WF (Alcon), Acrysof MA60BM (Alcon), Tecnis-1 IOL (AMO), CT Asphina 509M (Zeiss), Adapt-AO (Bausch Lomb) or Auroflex (Aurolab), with the haptic-optic junction in the horizontal or vertical axes. The incidence of temporal negative Dysphotopsia in the vertical axis on postoperative Day 1 & 14 was: SN60WF, MA60BM & Tecnis 1 Piece IOL: 11.2%, Adapt AO 12.4%, Auroflex 12.1%, Asphina 509M 12.3%. In the horizontal axis it was: SN60WF & Tecnis-1: 9.0%, MA60BM 11.3%, Adapt-AO 10.1%, Auroflex 10.6% & Asphina 509M 0.0%. At 45 days no-one complained of dysphotopsia.
Dysphotopsia was less when the narrow haptics of single piece IOLs were horizontal. Dysphotopsia occurs in square edge IOLs due to total internal reflection at the IOL-Aqueous interface nasally. Horizontally placed Asphina 509M with large broad plate haptics-optic junctions did not have an exposed IOL-Aqueous interface nasally thus preventing dysphotopsia.