The Dry Eye Zone

Rebecca's Blog

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Study: Conventional vs wavefront scleral lenses, over time

This study highlights the potential vision improvements of wavefront-guided scleral lenses over conventional, and also draws attention to the fact that when you test somebody soon after they’ve been fitted, you may get substantially different results than after you let them get used to the lenses for awhile. I think we all know our experiences are different down the road than the day we walk out the door with our first pair.

Wavefront-guided lenses are definitely in my future as my acuity and vision quality are both much below what I would like them to be, so I love seeing new research on this. And… I’m also kicking myself for failing to realize till I pored over the author list for this study that Ray Applegate is actually at University of Houston where I just visited recently. Would have loved to meet the legend.

Comparison of Wavefront-guided and Best Conventional Scleral Lenses after Habituation in Eyes with Corneal Ectasia

Hastings et al, Optometry and Vision Science, April 2019

SIGNIFICANCE 

Visual performance with wavefront-guided (WFG) contact lenses has only been reported immediately after manufacture without time for habituation, and comparison has only been made with clinically unrefined predicate conventional lenses. We present comparisons of habitual corrections, best conventional scleral lenses, and WFG scleral lenses after habituation to all corrections.

PURPOSE 

The purpose of this study was to compare, in a crossover design, optical and visual performance of eyes with corneal ectasias wearing dispensed best conventional scleral lens corrections and dispensed individualized WFG scleral lens corrections.

METHODS

Ten subjects (20 eyes) participated in a randomized crossover study where best conventional scleral lenses and WFG scleral lenses (customized through the fifth radial order) were worn for 8 weeks each. These corrections, as well as each subject's habitual correction and normative data for normal eyes, were compared using (1) residual higher-order aberrations (HORMS), (2) visual acuity (VA), (3) letter contrast sensitivity (CS), and (4) visual image quality (logarithm of the visual Strehl ratio, or logVSX). Correlations were performed between Pentacam biometric measures and gains provided by WFG lenses.

RESULTS:

Mean HORMS was reduced by 48% from habitual to conventional and 43% from conventional to WFG. Mean logMAR VA improved from habitual (+0.12) to conventional (−0.03) and further with WFG (−0.09); six eyes gained greater than one line with WFG over conventional. Area under the CS curve improved by 26% from habitual to conventional and 14% from conventional to WFG. The percentage of the eyes achieving normal levels were as follows: HORMS, 40% for conventional and 85% for WFG; VA, 50% for conventional and 85% for WFG; and CS, 60% for conventional and 90% for WFG. logVSX improved by 16% from habitual to conventional and 25% further with WFG. Reduction in aberrations with WFG lenses best correlated with posterior cornea radius of curvature.

CONCLUSIONS

Visual performance was superior to that reported with nonhabituated WFG lens wear. With WFG lenses, HORMS and logVSX significantly improved, allowing more eyes to reach normal levels of optical and visual performance compared with conventional lenses.