Evaluating the impact of overnight orthokeratology on myopia control in patients with moderate myopia and astigmatism – A prospective study

Background: Myopia, a prevalent refractive error, is projected to affect nearly half of the global population by 2050. Traditional corrective measures like spectacles and daytime contact lenses do not address myopia progression. Orthokeratology (Ortho-K), a nonsurgical procedure that reshapes the cornea overnight, has emerged as a promising approach to correct refractive errors and potentially slow myopia progression. This study aims to evaluate the impact of overnight Ortho-K lenses on visual acuity, corneal thickness, and axial length in young adults with moderate myopia, with or without astigmatism. Methods: This was a prospective interventional study conducted at a tertiary care hospital in North India over a year. Sixty patients aged 15–30 years with myopia up to -5.0 D and corneal astigmatism up to -1.50 D were included. Baseline measurements of refractive error, corneal thickness, and axial length were taken, followed by follow-ups at 3 months, 6 months, and 1 year. Ortho-K lenses were worn overnight for an average of 6 hours. Statistical analysis was performed using repeated measures ANOVA and post hoc paired Student’s t-tests. Results: The study observed a significant improvement in unaided visual acuity (VA) among participants. At baseline, a large proportion of participants had poor VA, but by the first follow-up, 7.02% achieved 6/6 vision, and this percentage increased to 85.11% by Day 90. The axial length remained stable throughout the study, with minimal fluctuations from the baseline of 24.10 mm, indicating effective control of myopia progression. The LogMAR values showed significant reductions, from 0.757 at baseline to 0.034 by Day 90, highlighting improved visual clarity. The central corneal thickness decreased from 512.23 µm at baseline to 500.24 µm by Day 90, reflecting the reshaping effect of Ortho-K. Changes in nasal, temporal, superior, and inferior corneal thickness were observed, with statistically significant variations in different regions. Conclusions: Overnight orthokeratology is an effective nonsurgical option for the temporary correction of moderate myopia in young adults. The treatment resulted in significant visual improvement and measurable changes in corneal thickness and axial length. However, the short follow-up period and lack of a comparative control group necessitate further research, particularly randomized controlled trials, to establish the long-term safety and efficacy of Ortho-K as a myopia management strategy.