Abstract
Background: Accelerated orthokeratology uses reverse-geometry rigid gas-permeable lenses worn overnight to reshape the anterior cornea and temporarily reduce myopic refractive error. Penta-curve designs, which add a second alignment curve to the conventional reverse-geometry profile, are intended to improve lens centration and stability, but published data on their short-term refractive and corneal effects in Indian adults are limited. Objectives: To evaluate the course of uncorrected visual acuity, refractive error, anterior corneal curvature, central corneal thickness and tear secretion over twelve weeks of overnight penta-curve orthokeratology lens wear, and to examine whether these changes vary with the degree of pre-treatment myopia. Methods: Forty eyes of twenty myopic adults aged 18 years or above were enrolled in a prospective, single-arm interventional study at a tertiary teaching hospital. Eligible participants had spherical myopia of less than −5.0 D, with-the-rule astigmatism up to −1.0 D or against-the-rule astigmatism up to −0.75 D, and keratometric radius below 8.25 mm. Participants wore penta-curve reverse-geometry lenses for at least eight hours nightly. Uncorrected visual acuity (logMAR), cycloplegic best-vision sphere, keratometry in horizontal & vertical axis, central corneal thickness by ultrasound pachymetry and Schirmer I tear secretion were recorded at baseline and after lens removal on day 1 and at weeks 1, 2, 4, 6, 8 and 12. Eyes were additionally stratified by baseline spherical error into three groups. Outcomes were analysed by repeated-measures analysis of variance with Bonferroni-adjusted post hoc comparisons. Results: Mean uncorrected visual acuity improved from 0.84 ± 0.22 to 0.02 ± 0.05 logMAR at twelve weeks (p < 0.0001), and mean bestvision sphere from −2.96 ± 1.31 D to −0.09 ± 0.20 D (p < 0.0001), a mean reduction of 2.87 ± 1.21 D. The axial radius of curvature flattened from 7.89 ± 0.15 mm to 8.21 ± 0.16 mm, a change of 0.32 ± 0.12 mm (p < 0.0001). Central corneal thickness fell from 566.60 ± 30.72 µm to 556.32 ± 30.02 µm, a reduction of 10.28 ± 3.37 µm (p < 0.0001). The largest changes in every optical variable occurred after the first night, with stabilization by one week for acuity and refraction and by week four for corneal thickness. Change was greatest in eyes with the highest pre-treatment myopia. Schirmer I values did not change significantly (p = 0.799). One eye developed mild superficial punctate staining, which resolved with lubricant drops; all twenty participants completed follow-up. Conclusion: Overnight penta-curve accelerated orthokeratology produced rapid, substantial and well-tolerated improvement in unaided vision and reduction in myopic refractive error over twelve weeks, with anterior corneal flattening and central corneal thinning as the structural correlates. The magnitude and latency of change scaled with baseline myopia. Because the study was uncontrolled & small, these findings require confirmation in larger controlled cohorts with longer follow-up.