Abstract

Purpose: To study the relationship between various measures of optical and visual performance in pseudophakic eyes implanted with both conventional and wave–front modified IOLs. 

Methods: Ocular and corneal aberrations, visual acuity and contrast sensitivity are measured in 7 pseudophakic eyes implanted with two IOLs: the Tecnis Z9000 (a wavefront modified IOL), and CeeOn 911A (a spherically surfaced IOL). Ocular aberrations are measured using a Hartmann–Shack wavefront sensor while corneal aberrations are determined by combining ray–tracing techniques with corneal topography. IOL misalignments were measured using a Purkinje image apparatus. Visual acuity and contrast sensitivity of each patient are measured using a robust forced–choice psychophysical approach implemented with a Cambridge Research system. From the ocular wavefront aberration the optical modulation transfer function (MTF) of each individual eye is calculated and compared with the corresponding patient’s visual performance. 

Results: The patients’ measured visual acuities are highly correlated with their measured optical quality in terms of SA, RMS wavefront aberration and MTF (R² = 0.61, 0.45 and 0.56 respectively), as are their measured contrast sensitivities (R² = 0.31, 0.75, 0.71). The optical and visual quality of the Tecnis lens remains superior for a clinically normal range of misalignments (decentration ≤ 0.6mm, tilt ≤ 10°). 

Conclusions: The high degree of correlation between optical and visual data suggest that eye models constructed from clinical data are useful tools in predicting the clinical performance of new IOL designs.

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