Akshaya C Balakrishnan1, Aparna Badrinarayanan2, Viswanathan Sivaraman3, Ramar Mahesh Kumar2, Asif Iqbal2. 1. Elite School of Optometry, Unit of Medical Research Foundation, Sankara Nethralaya, Chennai, India. 2. Department of Contact Lens, Unit of Medical Research Foundation, Sankara Nethralaya, Chennai, India. 3. Department of Optometry, Contact Lens and Optical Services, Elite School of Optometry, Unit of Medical Research Foundation, Sankara Nethralaya, Chennai, India.
Abstract
PURPOSE: To investigate the effect of varying the fluid reservoir (FR) thickness of scleral lenses (SL) on corrected distance visual acuity (CDVA), contrast sensitivity (CS) and higher-order aberrations (HOAs) in keratoconic eyes. METHODS: Forty eyes with keratoconus were fitted with a diagnostic Boston Sight SL having three different FR thicknesses. CDVA, CS and HOAs were measured before and after 30 min of lens wear. An i-Trace aberrometer and anterior segment optical coherence tomography (AS-OCT) were used to measure HOAs and FR thickness, respectively. RESULTS: Statistically significant improvements in CDVA and CS were seen with different FR thickness lenses (p < 0.01). Baseline CDVA (0.22 ± 0.15) improved to 0.03 ± 0.06, 0.04 ± 0.07 and 0.07 ± 0.08 with low, standard and high FR lenses, respectively. Post-hoc testing showed better CDVA with low (p = 0.006) and standard FR (p = 0.009) lenses compared to high FR lenses. Before lens wear, CS was 1.27 ± 0.27, which improved to 1.67 ± 0.11, 1.73 ± 0.12 and 1.66 ± 0.89 with low, standard and high FR lenses, respectively. Lenses with standard FR showed better CS compared with those having low (p = 0.009) and high FRs (p < 0.001). A statistically significant reduction of higher order-root mean square aberrations (HO-RMS), coma, spherical aberration, secondary astigmatism and trefoil were found with all FR thickness lenses compared to baseline (p < 0.01). No significant difference was noted between lenses (p = 0.01). All three lenses corrected almost equal amount of HOAs. A moderate positive correlation was observed between CDVA and HO-RMS (r = 0.61, p < 0.001) for low FR lenses. CONCLUSIONS: BostonSight SCLERALs were found to be very effective in improving vision, CS and reducing HOAs in keratoconus. Lenses with varying FR thickness showed equal effectiveness in visual performance and reducing HOAs. FR thickness should be considered an important factor to provide better vision and CS by minimising HOAs, as well as to maintain the normal physiology of eyes with keratoconus.
PURPOSE: To investigate the effect of varying the fluid reservoir (FR) thickness of scleral lenses (SL) on corrected distance visual acuity (CDVA), contrast sensitivity (CS) and higher-order aberrations (HOAs) in keratoconic eyes. METHODS: Forty eyes with keratoconus were fitted with a diagnostic Boston Sight SL having three different FR thicknesses. CDVA, CS and HOAs were measured before and after 30 min of lens wear. An i-Trace aberrometer and anterior segment optical coherence tomography (AS-OCT) were used to measure HOAs and FR thickness, respectively. RESULTS: Statistically significant improvements in CDVA and CS were seen with different FR thickness lenses (p < 0.01). Baseline CDVA (0.22 ± 0.15) improved to 0.03 ± 0.06, 0.04 ± 0.07 and 0.07 ± 0.08 with low, standard and high FR lenses, respectively. Post-hoc testing showed better CDVA with low (p = 0.006) and standard FR (p = 0.009) lenses compared to high FR lenses. Before lens wear, CS was 1.27 ± 0.27, which improved to 1.67 ± 0.11, 1.73 ± 0.12 and 1.66 ± 0.89 with low, standard and high FR lenses, respectively. Lenses with standard FR showed better CS compared with those having low (p = 0.009) and high FRs (p < 0.001). A statistically significant reduction of higher order-root mean square aberrations (HO-RMS), coma, spherical aberration, secondary astigmatism and trefoil were found with all FR thickness lenses compared to baseline (p < 0.01). No significant difference was noted between lenses (p = 0.01). All three lenses corrected almost equal amount of HOAs. A moderate positive correlation was observed between CDVA and HO-RMS (r = 0.61, p < 0.001) for low FR lenses. CONCLUSIONS: BostonSight SCLERALs were found to be very effective in improving vision, CS and reducing HOAs in keratoconus. Lenses with varying FR thickness showed equal effectiveness in visual performance and reducing HOAs. FR thickness should be considered an important factor to provide better vision and CS by minimising HOAs, as well as to maintain the normal physiology of eyes with keratoconus.