Contrast sensitivity function in pseudophakics and aphakics

Abstract

ABSTRACT.Purpose: To study the effect of posterior chamber intraocular lenses and aphakic spectacles on contrast sensitivity. Methods: Contrast sensitivity was evaluated in 20 patients in each group of pseudophakics with post chamber IOL (group I), aphakics with spectacle correction (group II), and age and sex-matched normal subjects (group III) using the Pelli-Robson chart. Results:The mean values of log contrast sensitivity in pseudophakics (1.665∫0.105) and aphakes with spectacle correction (1.5075∫0.1) were found to be statistically significantly low (t: 5.186, p∞0.001; t: 11.302, p∞0.001, respectively) as compared to the mean value of normal phakic subjects (1.8075∫0.0576). Further, mean values of log contrast sensitivity in aphakes with spectacles correction were also found to be statistically significantly low (t: 4.727, p∞0.001) when compared to that in pseudophakes. Conclusion: From observations of the present study, it can be concluded that posterior chamber IOL implantation offers an added advantage of higher contrast sensitivity, over and above the well documented advantages of increased field of vision, negligible effect on image size and elimination of prismatic effect and spherical aberration of thick glasses.

Visual performance and contrast sensitivity after phacoemulsification with implantation of aspheric foldable intraocular lenses

“…Several studies [24][25][26][27][28] have successfully used the PelliRobson chart to study contrast in pseudophakic patients. The Pelli-Robson chart has been shown to provide more repeatable and reliable measurements of contrast sensitivity.…”

Contrast sensitivity after implantation of a spherical versus an aspherical intraocular lens in biaxial microincision cataract surgery

“…In particular, even though standard IOLs provide higher contrast sensitivity than aphakia with spectacle correction, contrast sensitivity in pseudophakic eyes is significantly lower than in normal phakic eyes. [3][4][5] Based on these observations, it has been postulated that an IOL able to restore the cornea-lens balance in the young eye would result in better contrast sensitivity than a conventional IOL. 6 This can be achieved by modifying 1 or both surfaces of the IOL to produce a lens that introduces negative spherical aberration into the system.…”

Visual performance: Comparison of foldable intraocular lenses

“…2,3 Variable reports on the details of the optical performance of the IOL material and its impact on visual function are available. [4][5][6][7][8][9][10][11][12] The biomaterial of the AcrySof Natural and AcrySof IOLs (Alcon Laboratories) is impregnated with covalently bonded ultraviolet-absorbing chromophore. In addition, the AcrySof Natural IOL contains a covalently bonded chromophore that absorbs light in the 400 to 500 nm range.…”