Article
Long-term changes of orthokeratology lens wear: visual and corneal changes
Search Medline for
Authors
-
N. Stübiger
- Department of Ophthalmology, University of Tuebingen and University of Applied Sciences Aalen
-
K. Häussler
- University of Applied Sciences Aalen
-
B. Hard
- University of Applied Sciences Aalen
-
R. Michels
- University of Applied Sciences Aalen
| Published: | September 22, 2004 |
|---|
Outline
Text
Objective
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. Possible diopteric corrections are lasting from -0.75 diopter (D) to -4.5 D. The aim of our study was to evaluate the effectiveness of Ortho-K for treatment of myopia and to evaluate possible 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 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 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 D 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%), acute corneal edema (10%), microcystes (5). The study was completed after a mean observation period of 4 months.
Conclusions
Overnight orthokeratology, perhaps 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.
