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N. Stuebiger, M. Ronecker, R. Michels, H. Specht; The Effects of Overnight Orthokeratology Lens Wear . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2054.
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Purpose: Overnight orthokeratology (Ortho–K) is a method for temporarily eliminating myopia. A special geometry of rigid gas permeable (RGP) lenses (double reverse back curve) enables transformation of the cornea to a flatter form. The aim of our study was to evaluate the effectiveness of Ortho–K for treatment of myopia, to evaluate possible pathologic corneal alterations and changes of the intraocular pressure (IOP). Methods: A group of 20 volunteers (m:f=9:11) with a mean age of 25.92 ± 5.86 years were included in our study. 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 6 volunteers, who have worn glasses as vision correction. Neither group exhibited any eye disease or any pathological symptom 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 ± 0.90/0.84 diopter (D), a mean uncorrected vision of 0.64 ± 0.31 (visus logmar) and a mean central corneal radius of 7.78/7.77 ± 0.31/0.30 mm. After one week of wearing contact lenses the majority of the volunteers had such a good response, that no statistical difference in visual acuity between the two groups was detectable (the mean spherical correction was +0.14/–0.02 ± 0.25/0.14 D, the mean uncorrected vision was –0.12 ± 0.06 and the mean central corneal radius was 8.09 / 8.08 ± 0.35/0.34 mm). Corneal irritations which occurred at the beginning of the study in the wearing group included corneal staining (40%, Grading scale 1.1), acute 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 8 months and, . At that time no corneal edema could be observed, and in the whole observation period no corneal endothelial alterations, no infectious corneal complications, in none of the volunteers IOP changes occured, and altogether, five volunteers discontinued the study from the wearing group . Conclusions: Overnight orthokeratology, as an alternative to refractive corneal surgery, is a very safe method for temporarily eliminating minor myopia. We achieved in our study stable remaining visual changes for all walking hours of the day, which allow patients enjoy excellent device–free vision.
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