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

Abstract

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.-To compare, in a cross-over 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 cross-over study where best conventional scleral lenses and WFG scleral lenses (customized through the 5th radial order) were worn for eight 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 (logVSX). Correlations were performed between Pentacam biometric measures and gains provided by WFG lenses. Results.-Mean HORMS reduced 48% from habitual to conventional, and 43% from conventional to WFG. Mean logMAR VA improved from habitual (+0.12) to conventional (−0.03

Safety and Efficacy of Scleral Lenses for Keratoconus

“…Other outcomes included the numbers of lenses lost or broken and dropouts during the period surveyed. True logMAR visual acuities, contrast sensitivity, and higher-order aberrations, although important measures of visual performance in scleral lenses, 49 – 52 were not obtained because they are not readily available in the clinical setting.…”

Customised aberration‐controlling corrections for keratoconic patients using contact lenses

“…Although the authors reported that both sets of lenses were worn on a ‘daily’ basis, for each eight‐week period, specific data on how many hours of lens wear per day were not presented in their paper. Expectedly, Hastings et al found that the mean HORMS error reduced from +0.46 ± 0.24 μm with the conventional lenses, to +0.26 ± 0.08 μm with the customised lenses (p = 0.004). However, although improved, the difference in the mean area under the log contrast sensitivity function did not reach statistical significance between the two lens types (conventional lenses = 13.91 ± 2.20 log units, customised lenses 15.82 ± 2.34 log units [p = 0.09]).…”

“…Further studies are needed to explore this concept; for example, it is currently unclear if the degree of neural deficit is related to the severity of the patient's disease and/or age, or whether such deficits could be overcome through regular perceptual learning/training . At present, only one study has explored the impact of allowing keratoconic patients to habituate to a wavefront‐guided, customised scleral lens correction for a substantial time period . Using the customisation methodology outlined in their previous investigation, Hastings et al conducted a randomised study, which included a crossover design, allowing comparisons between ‘conventional’ scleral lenses (acting as a control) and ‘customised’ scleral lenses, over two eight‐week (approximate) periods, for eight patients with keratoconus.…”

“…Compared to customised soft lenses, which typically induce superfluous aberrations due to their unavoidable degree of 'on-eye' movement and their variable conformity to the keratoconic corneal profile, customised scleral contact lenses are likely to offer a greater degree of on-eye stability for keratoconic patients. 52,53,109 Moreover, scleral lenses also have the added benefit of improving optical performance, by providing a 'regular', rigid first optical surface, while also simultaneously increasing lens wear comfort by allowing a majority of the lens' weight to bear onto the conjunctiva. 110 Sabesan et al 52 designed customised scleral lenses, for six keratoconic patients (11 eyes), by first identifying their 'bestfitting' conventional lenses.…”

“…111 At present, only one study has explored the impact of allowing keratoconic patients to habituate to a wavefront-guided, customised scleral lens correction for a substantial time period. 109 Using the customisation methodology outlined in their previous investigation, 53 Hastings et al 109 conducted a randomised study, which included a crossover design, allowing comparisons between 'conventional' scleral lenses (acting as a control) and 'customised' scleral lenses, over two eightweek (approximate) periods, for eight patients with keratoconus. Although the authors reported that both sets of lenses were worn on a 'daily' basis, for each eightweek period, specific data on how many hours of lens wear per day were not presented in their paper.…”