Visual and Corneal Changes in Overnight Orthokeratology Using Menicon Z Lenses – A Malaysian Study

Abstract

Reverse geometry lens is a specially designed orthokeratology (OK) lens used to treat myopia. Menicon Z night OK lens is unique because software supplied by the manufacturer generates its parameters. No reports have been published on its effectiveness in reducing myopia among young Malay adults. This prospective study involved young Malay adults 22.5 ± 1.2 years old. Participants who met the inclusion criteria were fitted with OK lenses and the following parameters were measured at baseline: Refractive errors, visual acuity and corneal curvatures. Participants were asked to sleep with the lenses and remove them in the morning before re-examining them at 24 hours, one week, one month and six months. Repeated measure analysis of variance was carried out to find any significant differences in the parameters measured over the six months. The correlation was also done between refractive error, corneal curvatures and visual acuity. Significant reductions in refractive error, corneal curvatures and improvement in visual acuity were found during the six months. The greatest change occurred after 24 hours of lens wear. There was no change in corneal toricity. Changes in refractive error correlated significantly with visual acuity and corneal curvatures. In conclusion, the OK lenses significantly flattened corneal curvature and reduced refractive power to almost zero, which improved visual acuity in young Malay adults. Myopes with low refractive power who want to be free from spectacles may benefit from this alternative myopic management.