Abstract
Background: :
Pupil size, age and cataract are all factors known to influence the magnitude of high order RMS (HO RMS) wavefront error. While comparative studies generally consider the role of pupil size and age, to our knowledge none have considered the role of pupil size, age, and nuclear cataract together.
Purpose: :
To determine the relative roles of pupil size, age and nuclear cataract on the measurement of HO RMS wavefront error (Zernike 3rd – 10th radial orders).
Methods: :
112 individuals in good ocular and systemic health, well distributed across age between 21.8 to 78.4 years, served as subjects. Shack–Hartmann wavefront error was obtained through dilated pupils. This measurement was used to calculate wavefront error over 3, 4, 5, 6 and 7 mm pupils. Slope data in each calculation was limited to the pupil size of interest. Severity of cataract was assessed using the Lens Opacities Classification System–III. Nuclear opalescence (NO) ranged from 0.8 to 5.2, nuclear color (NC) from 0.68 to 5.34. Subjects with significant cortical and/or posterior subcapsular cataract were excluded. Data was analyzed using a three factor (age, NO, NC) general linear model versus HO RMS for each pupil size (p < 0.05).
Results: :
Pupil size is by far the most important factor (p < 0.001) determining RMS error (69% of the variance in HO RMS). For any given pupil size age was a significant contributor to high order RMS error (p < 0.001). NO and NC were not significant contributors to high order RMS error when pupil size and age were included in the models. Pupil size and age together in a general linear model account for 83% of the variance in high order RMS.
Conclusions: :
Pupil size is the largest contributing factor to high order RMS wavefront error at any age. For any given pupil size age is a significant contributor to high order RMS error. When pupil size and age are controlled for, nuclear opalescence and nuclear color do not contribute significantly to high order RMS error.
Keywords: optical properties • aging • cataract