Abstract
Purpose: :
To determine whether correction of higher order aberrations (HOA) in pseudophakic eyes provides a visual benefit relative to correction of defocus and astigmatism alone.
Methods: :
An adaptive optics system equipped with a large stroke deformable mirror and a Shack-Hartmann wavefront sensor was used to measure contrast sensitivity (CS) on 4 pseudophakic eyes of 4 different patients. All patients had standard cataract surgery with a monofocal intraocular lens. All surgeries were uncomplicated except for a small posterior capsule tear in one eye. The eyes had best corrected visual acuity of 20/25 or better, and were three to six months post-surgery with an average age of 68.5±7.6 years. The eyes had varied mild pathology including guttata, fine macular drusen, blepharitis, and suspicion of glaucoma. CS was measured at 4, 8, 12, and 16 cycles per degree (c/deg) over a 5 to 6 mm pupil with correction of all aberrations and with correction of defocus and astigmatism only. Visual benefit was defined as the ratio of CS with HOA correction to CS with only defocus and astigmatism correction.
Results: :
The eyes had an average higher order rms of 0.46±0.08µm. The greatest contribution from HOA were from trefoil (Z-33), spherical aberration, trefoil (Z+33), and horizontal coma with average magnitudes of 0.30±0.08µm, 0.19±0.09µm, 0.13±0.06µm, and 0.12±0.10µm respectively. The residual rms after the correction was approximately 0.1µm in all patients. The average CS with HOA correction was 23.4±3.8, 14.8±5.4, 6.3±2.7, and 2.7±0.7 at 4, 8, 12, and 16 c/deg respectively. For the same frequencies, the average CS with correction of only defocus and astigmatism was 12.1±5.5, 4.3±1.1, 2.4±0.7, and 1.2±0.2. The differences in CS were statistically significant for 4, 8, and 16 c/deg with p values less than 0.03; the p value was 0.054 at 12 c/deg. All patients experienced visual benefit at all spatial frequencies. The average visual benefit including all spatial frequencies was 2.7.
Conclusions: :
Correction of HOA with customized intraocular lenses or wavefront-guided refractive surgery may have the potential to improve visual performance in pseudophakic eyes that have mild eye pathology.
Keywords: cataract • refractive surgery: other technologies • contrast sensitivity