Abstract
Purpose :
Visual acuity (VA) is a typical outcome measure used to evaluate treatments in clinical trials and to manage treatment in individual patients with retinal diseases such as diabetic retinopathy and age-related macular degeneration. VA is impacted by several factors common in the aging eye, e.g. lens and tear-film status and pupil size. To provide improved confidence limits on VA tasks in aging eyes, we determined the impact of selected higher order aberrations on the means and standard deviations of VA.
Methods :
A novel three channel device was designed (OpticStudio, Zemax) and built to study factors in the aging eye that impact the relation between wavefront aberrations and acuity. The display channel provided a high pixel density VA target (Pixel 6, Google) in Maxwellian view with a 3 mm pupil, thus avoiding a decrease of contrast from insufficient whole pixels for acuities < 20/20 or intermediate steps. Four-alternative (left, right, up or down), forced-choice trials with continuous viewing of an E and method of constant stimuli provided full psychometric function data for modelling mean and standard deviations. Each subject was adjusted to best focus using a Badal optometer. Then a 40 actuator piezo deformable mirror (Thorlabs) in the display path was set using vendor software control of Zernike terms for the following conditions, including higher order aberrations with some that mimic aging optical changes: no added aberrations, +.25 X coma, +.25 Y coma, and +.25, -.25, +.35, and -.35 spherical aberration in arbitrary units[GTJ1] . In situ calibrations of Zernicke polynomials were obtained with a second wavefront sensor (Wfs 30, Thorlabs) at the entrance pupil to the eye, using a tungsten filament light source conjugate to the screen of the display. Five subjects (2 females, 3 males) were tested, selected to have minimal lower aberrations and who were too young to be expected to have significant aging changes: 26-37 yr, mean =30 +/- 4.6 yr.
Results :
All subjects performed the task at a level of 20/20 with no added aberrations. All subjects performed worse for the conditions with -.25, -.35, and +.35 added spherical aberration (Figs 1,2.), well fit by a linear function of calibrated spherical aberration. With added coma 3 of 10 blocks had worse VA.
Conclusions :
This method simulates higher order aberrations found in older eyes. A linear model fit the VA vs spherical aberration data.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.