Abstract
PurposeLiterature is relatively silent on safety profile and predictability of orthokeratology lenses in terms of myopia correction and prevention of further progression, especially in semi-tropical countries; this study was designed to fill this gap.MethodsThis prospective, intervention case series enrolled 30 eyes of 30 patients with myopia up to –5.5 diopters (D). Patients were randomized into two groups of 15 each; the study group was prescribed overnight orthokeratology (OK) lenses, while the control group used daily wear conventional soft contact lenses. Follow-up examinations were performed after 1 h and 6 h, and then at 1, 7, 15, 30 days, and 4 months post lens wear. Uncorrected visual acuity (UCVA), contrast sensitivity, keratometry, central corneal thickness (CCT), and tear film break up time (TBUT) were evaluated at each follow-up examination.ResultsAll patients attained a visual acuity of 0.00 Logarithm of the Minimum Angle of Resolution (logMAR) after one week of lens use, which was maintained throughout the study period. While patients allotted to the study group had a gain of 8.1 Snellen lines (UCVA), those in the control group gained 8.9 lines (BCVA) at the end of follow-up period. In the OK group, cornea showed a flattening of 0.8 D (mean keratometry) after single overnight usage of OK lens and overall flattening of 1.2 D compared to baseline, at the end of four months. The change in contrast sensitivity, corneal endothelial specular count, axial length and tear film status was not significant in either group.Conclusion Orthokeratology is an effective and safe modality to correct moderate myopia in motivated young adults. No side effects were encountered after a short-term follow-up in participants who resided in semi-tropical environments.
Highlights
Orthokeratology in Moderate Myopia; Singh et al Orthokeratology (OK) is defined as “reduction, modification, or elimination of a refractive error by programmed application of contact lenses.”[1]. Its genesis arose following a serendipitous observation by Wesley and Jessen in the 1950s who found spectacle blur experienced by patients after wearing hard contact lenses
The evaluated parameters were cycloplegic refraction, uncorrected visual acuity (UCVA), bestcorrected visual acuity (BCVA) using a Snellen chart, corneal topography and keratometry by Orbscan IIz (Bausch & Lomb Technolas Topographer, USA), central corneal thickness (CCT) (Sonomed 300P PacScan; Sonomed Escalon, USA), tear film break up time (TBUT), contrast sensitivity, corneal endothelial cell count (Nidek CEM 530, Nidek Co Ltd, Japan), and axial length
Orthokeratology utilizes contact lenses to “reduce, modify, or eliminate refractive errors.”[14]. A resurgence of interest in this technology occurred after the advent of reverse-geometry lens designs and use of an extremely high Dk material which makes these lenses easy to center and safer for the cornea
Summary
Orthokeratology (OK) is defined as “reduction, modification, or elimination of a refractive error by programmed application of contact lenses.”[1] Its genesis arose following a serendipitous observation by Wesley and Jessen in the 1950s who found spectacle blur experienced by patients after wearing hard contact lenses. Further refinement using very high oxygen-permeable materials ushered in an era of overnight lens wear This overnight OK lens reduced daytime visual aid requirements and came to be known as “accelerated orthokeratology” because of the rapid onset of refractive and corneal topographic changes.[8]
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