Assessment of large‐diameter and small‐diameter SoftK specialty contact lenses for early‐stage keratoconus

Abstract

IntroductionSoft contact lenses may be a good alternative for early‐stage keratoconus (KC) patients who do not tolerate rigid gas permeable (RGP) lenses due to ocular discomfort or complications. This prospective study compared outcomes obtained after 2 weeks of wearing two types of soft silicone hydrogel contact lenses for keratoconus that varied in their diameter and central thickness (cc).MethodsPatients with Amsler–Krumeich grades I or II KC were fitted with small‐diameter (14.2 or 14.8 mm) SoftK (SD‐SoftK, cc = 0.48 mm) and large‐diameter (17 mm) SoftK (LD‐SoftK, cc = 0.60 mm) lenses, each worn for 2 weeks in a crossover design. Low (10%;10VA) and high (100%;100VA) contrast visual acuity, contrast sensitivity (CS, Pelli‐Robson), higher order aberrations (HOAs, Visionix Vx130), the number of trial lens modifications during fitting and the subjectively preferred lens were compared using Friedman tests with post‐hoc analysis.ResultsForty eyes (N = 20, 10 males, mean age: 39.0 ± 9.9 years, range: 23–55 years) were examined. Their habitual median (interquartile1, interquartile3) 10VA (LogMAR), 100VA (LogMAR) and CS (LogCS) were 0.52 (0.30, 0.50), 0.14 (0.10, 0.15) and 1.35 (1.35, 1.50), respectively. For the SD‐SoftK condition, the values were 0.23 (0.17, 0.30), 0.02 (0.00, 0.05) and 1.50 (1.50, 1.65), respectively. For the LD‐SoftK condition, the respective values were 0.36 (0.27, 0.44), 0.09 (0.05, 0.13) and 1.50 (1.50, 1.60). SD‐SoftK lenses significantly improved 10VA compared with habitual and LD‐SoftK. SD‐SoftK also significantly improved CS compared with habitual, but not LD‐SoftK. LD‐SoftK significantly improved spherical aberration compared with uncorrected (0.03 ± 0.10 μ vs. 0.07 ± 0.13 μ) but not SD‐SoftK (0.04 ± 0.07 μ). Both lenses required a mean of 1.5 modifications prior to final lens fitting. Fewer adverse events were seen with SD‐SoftK (N = 3) compared with LD‐SoftK (N = 8), and 75% of participants preferred SD‐SoftK lenses.ConclusionSD‐SoftK lenses were preferred by 75% of subjects, were associated with fewer adverse events and significantly improved 10VA compared with LD‐SoftK lenses. SD‐SoftK lenses also significantly improved CS compared with the habitual correction, but this did not differ significantly from the LD‐SoftK lenses.