Purpose
The intent of incorporating therapeutic optical designs into the vision correction for myopia is to retard further myopia progression (MP). This study tests the feasibility to alter suspected risk factors using 3 levels of a novel optical design in soft contact lenses (SCLs).
Methods
Twenty children 9 to 15 yrs. (median 13) were enrolled in a double-masked, bilateral study wearing the three Test (T) SCLs for 2 hours each. The lenses were lathe-cut, polymacon 38%, 8.3mm basecurve and 14.5 mm diameter. T lenses had a continuously increasing positive power starting from the center and extending into the periphery of the optical zone (US Patents 6474814 and 7178918). The increase in positive power was T1 < T2 < T3. The outcome measures were distance and near high and low contrast visual acuity (VA), an abbreviated Pediatric Refractive Error Profile (aPREP) quality of life score, a series of vision intensive tasks and subjective ratings (SRs), amplitude (near point push-up, AofA) and lag of accommodation by dynamic retinoscopy (LofA-DR) and by auto-refraction (LofA-A), and peripheral auto-refraction (Grand Seiko WAM-5500, PR).
Results
All 20 subjects completed the study. There were no statistically significant differences in VAs; all differences were < 2 letters; <0.04 logMAR. There were statistically significant differences in aPREP scores, with T3 < T1 on the overall score (65 vs. 75; p<0.01). Some SRs were lower for T3 than T1 (87 vs. 95/100; p<0.01 and 88 vs. 95/100; p<0.02). AofA differences were small, and only T2 was significantly > T1 (12.2 vs. 11.6D; p<0.03). LofA-DR decreased from T1 to T3 (0.47, 0.45, 0.32D), T3 < T1 p<0.02 RE). LofA-A means were higher than using the previous LofA-DR method, T1 to T3 (0.74, 1.16, 1.06D). LofA-A for T1 < T2 (p<0.02). PRs with all test lenses showed systematic increases in minus refraction (various positions; p<0.05 paired-t) compared with the central refraction normalized baseline PRs.
Conclusions
Increasing the power level of optical designs tested in this study decreased the LofA-DR and decreased the hyperopic PR; both suspected risk factors for MP. Small but significant reductions in visual performance were found as the power level of optical designs increased. Further studies are warranted to test these optical designs as an inhibitor against the progression of juvenile-onset myopia.
Keywords: 605 myopia •
477 contact lens •
677 refractive error development