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Increasing the treatment zone in orthokeratology through a larger optical zone diameter

1 December 2004


Standard ortho-k lenses have a treatment zone (area of corneal flattening) of 5.0mm in diameter. If the pupil dilates to more than 5.0mm, at night for example, the result is glare. Currently, standard ortho-k lenses have an optical zone of 6.0mm, leading to a 5.0mm treatment zone. In our experiment, we attempted to increase the treatment zone to 6.0m by using ortho-k lenses with a 7.0mm optical zone. Increasing the treatment zone would not only significantly reduce complaints of night-time glare, but it would put us on par with corrective laser surgery, which also has a 6.0mrn treatment zone. This would ultimately make orthokeratology a more viable option to a larger segment of the population. Originally 16 subjects were used for the experiment. The 1 half of the experiment consisted of fitting the students with standard 5.Om treatment zone ortho-k lenses. This trial period allows for lens parameter changes to achieve the optimum fit. The second trial consisting of the larger treatment zone has not been reached as of right now. The initial standard fits are being refined to custom fits for many patients. There have also been significant complications in terms of allergic reactions, undercorrection/overcorrection, non-compliance and high patient discomfort. The study has yet to be completed and therefore any results regarding the treatment zone expansion are inconclusive. The study will be completed within 1 year of this paper's release date and definitive conclusions will be made at that time.


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