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The effect of corneal wavefront aberrations on corneal pseudoaccommodation
Elizabeth Yeu1, Li Wang, Douglas D Koch
1Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas 77030, USA. yeu@bcm.edu
American Journal of Ophthalmology
|February 10, 2012
Summary
Corneal wavefront aberrations influence pseudoaccommodation. Spherical aberration is key in normal eyes, while coma is crucial after laser eye surgery like LASIK or PRK.
Area of Science:
- Ophthalmology
- Optical Engineering
- Computational Vision
Background:
- Corneal pseudoaccommodation is crucial for visual function.
- Anterior corneal wavefront aberrations can impact visual quality.
- Previous laser refractive surgeries (myopic PRK, hyperopic LASIK/PRK) alter corneal shape and aberrations.
Purpose of the Study:
- To investigate the effect of anterior corneal higher-order aberrations (HOAs) on pseudoaccommodation.
- To compare these effects in normal corneas versus those with prior myopic photorefractive keratectomy (PRK) or hyperopic laser-assisted in situ keratomileusis (LASIK).
Main Methods:
- A theoretical study computed anterior corneal HOAs (third to sixth order) for normal, myopic-PRK, and hyperopic-LASIK/PRK eyes.
- Corneal optical image quality was assessed using the polychromatic modulation transfer function (CMTF).
- Depth of focus (DOF80 and DOF50) was calculated by adding defocus to HOAs and analyzing CMTF values.
Main Results:
- Depth of focus varied significantly, particularly in hyperopic-LASIK/PRK corneas.
- Myopic-PRK and hyperopic-LASIK/PRK corneas showed greater depth of focus than normal corneas (6-mm pupil).
- Specific Zernike terms (spherical aberration, astigmatism, coma, tetrafoil) were identified as significant contributors to depth of focus in different groups.
Conclusions:
- Anterior corneal wavefront aberrations demonstrably affect corneal pseudoaccommodation.
- Spherical aberration is the primary predictor in normal eyes.
- Coma is the most significant Zernike term for predicting pseudoaccommodation after laser corneal surgery.
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