Abstract
Abstract: :
Purpose: Overnight orthokeratology (Ortho–K) is a method for temporarily eliminating myopia. A special geometry of rigid gas permeable lenses (double reverse back curve) enables transformation of the cornea to a flatter form. The aim of our study was to evaluate the efficacy of Ortho–K for treatment of myopia and to evaluate pathologic corneal alterations. Methods:The study was performed with a group of 20 volunteers. Both eyes were fitted with Ortho–K lenses, and uncorrected visual acuity, refractive correction, corneal curvature and corneal changes, including measurements of corneal endothelial alterations, were achieved. The control group consisted of 5 volunteers, who have worn glasses as vision correction. Neither group exhibited any eye disease at the beginning of the study. Results: Before fitting the Ortho–K lenses, the wearing group had a mean spherical correction (oculus dexter/oculus sinister) of –2.06/–2.25±0.90/0.84D, a mean uncorrected vision of 0.64±0.31 (visus logmar) and a mean central corneal radius of 7.78/7.77±0.31/0.30mm. One week afer initiation of the study the majority of the volunteers had such a good response, that no statistical difference in visual acuity between the two groups was detectable. Corneal irritations which occurred at the beginning of the study in the Ortho–K wearing group included corneal staining (40%, Grading scale 1.1), corneal edema (10%), microcystes (5%). Problems with halos were frequently noticed (90%), but the wearers get accustomed to that. The study was completed after a mean observation period of 4 months. At that time the mean spherical correction had changed significantly to +0.14/+0.02 ± 0.25/0.14 D, the mean uncorrected vision was –0.12 ± 0.06 D and the mean central corneal radius was 8.09/8.08 ± 0.35/0.34 mm. After 4 months no corneal edema could be observed, and in the whole observation period no corneal endothelial alterations, and no infectious corneal complications occured. Other corneal findings were reduced corneal staining (25%, Grading scale 0.5) and a reduced number of microcystes in the above mentioned volunteer. Altogether, 5 volunteers discontinued the study from the wearing group and 1 volunteer in the control group was discontinued for retinal bleeding. Conclusions:Overnight orthokeratology, as an alternative to refractive corneal surgery, is a very safe method for temporarily eliminating minor myopia.
Keywords: contact lens • myopia • clinical (human) or epidemiologic studies: outcomes/complications