February 2009

 

CATARACT/ IOL

 

Reduced spherical aberration improves post-op photopic, mesopic visual function


   

A study in the January issue of the Journal of Cataract & Refractive Surgery concluded that post-op spherical aberrations have a significant effect on visual function under photopic and mesopic conditions.

In the study, the authors noted that wavefront analysis for quantifying lower-order and higher-order aberrations has provided an explanation for the deficit in visual function measured by contrast sensitivity testing that could not be detected by conventional visual acuity testing. The use of these measurements has opened new possibilities for evaluating post-op results and for predicting and customizing spherical aberration after cataract surgery.

Conventional monofocal intraocular lenses (IOLs) have positive spherical aberration that can degrade post-op image quality, said Kazuno Negishi, M.D., Keio University School of Medicine, Tokyo, and colleagues. So in the study they sought to evaluate the post-op contrast sensitivity and spherical aberration calculated with the natural pupil diameter in cataract patients under photopic and mesopic conditions.

For the study, the researchers included 107 eyes from 79 patients that had undergone cataract extraction followed by an implantation of an acrylic intraocular lens (IOL). The mean age of the 49 women and 30 men was 68 ± 9.6 years (range: 49 to 89 years).

According to the study, the patients’ mean pupil diameter was 2.9 ± 0.5 mm under photopic conditions and 3.6 ± 0.57 mm under mesopic conditions. The mean spherical aberration was 0.03 ± 0.04 microns (range: –0.12 to 0.34 microns) under photopic conditions and 0.05 ± 0.1 microns (range: –0.14 to 0.55 microns) under mesopic conditions.

Dr. Negishi reported that the post-op area under log contrast sensitivity function (AULCSF) without glare under photopic conditions was significantly negatively correlated with spherical aberration (P=0.014). The post-op AULCSF with and without glare under mesopic conditions also was significantly negatively correlated with spherical aberration (P<0.001 and P=0.01, respectively). There was no significant correlation between spherical aberration and post-op AULCSF under photopic conditions with glare.

From their results, the researchers concluded that it is desirable not only to decrease spherical aberration but also to optimize post-op spherical aberration for each patient’s corneal spherical aberration to improve visual quality.

Source: EyeWorld News Services

Reduced spherical aberration improves post-op photopic, mesopic visual function Reduced spherical aberration improves post-op photopic, mesopic visual function
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