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1. Definition of Orthokeratololgy ----------------------------------------------- Orthokeratology is a nonsurgical contact lens program to control the progression of or to temporarily reduce or eliminate myopia and astigmatism. Myopia = nearsightedness Astigmatism = cylindrical refractive error mainly coming from aspheric cornea. |
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2. Description of ortho-K ------------------------------------
In simply description, Orthokeratology is a program of fitting gas permeable contact lenses
with very high oxygen permeability to give corneal mold effect smoothing out the myopia
and astigmatism. These lenses produce a temporary improvement in unaided visual
acuity (UVA) by reducing refractive error.  Back to contents |
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3. History of ortho-K ---------------------------------- Starting from the 1950s these lenses have been being improving from decade to decade, from no gas permeability material to very high oxygen permeability material, from old design of lens to the most advanced current one. Since 1962, it has been estimated that more than 1.2 million patients have benefited from orthokeratologic correction. (Wesley NK. National Eye Research Foundation Global I Congress, Chicago, July 16-18, 1993) Back to contents |
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4. Typical Program of orhto-K ------------------------------------------- The typical program is as follows:- [Phase 1] Reshape the cornea and adapt to rigid lens wear for about 1 to 6 weeks. Vision is corrected to 20/20 ro uncorrected natural functional vision during this phase. [Phase 2] The holding phase keeps the eye shape stable for 3 to 6 months, this is the phase to train the tissue to be stable over a 24 hour period. [Phase 3] This is a wearing off phase, the final pair of ortho-K is called to be the "Retainer Lens" for retainer wear schedule determined on an individual basis. Some case is at best need a few hours a week, or at worst 2 to 4 hrs per day of wearing a day. And, quite often, under great care of accessment, every night wear alone sleeping with retainer lens and putting off next morning is used and effective enough. Back to contents |
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5. Merits of ortho-K --------------------------- The best merit of Ortho-K: You have all future options open. Including future prescription changes. Tissue is 100% maintained and conservative treatment should always be the FIRST choice. Back to contents |
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6 Future of ortho-K For certain levels of myopia, orthokeratology can still be offered
as an option to radial keratotomy and photorefractive keratectomy. Back to contents |
