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Contact lens fitting for post-radial-keratotomy residual myopia
Jeewan S Titiyal1, Ranjan Dutta, Rajesh Sinha
1Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. titiyal@rediffmail.com
Purpose:
To formulate guidelines for contact lens fitting following radial keratotomy and to achieve a relationship between contact lens fitting parameters and refractive and keratometric parameters.
Methods:
Thirty-five eyes of 30 patients who had post-radial-keratotomy residual myopia were evaluated for contact lens fitting. The base curve was selected by 'hit and trial' method until a proper fit was achieved, following which an over-refraction was done and final power of the contact lens obtained.
Results:
The mean contact lens base curve was 43.04 +/- 1.62 D, which was steeper than the postoperative keratometry by 2.35 +/- 0.74 D. The base curve and the postoperative keratometry were correlated by regression analysis (r = 0.895, P < 0.001). The mean overall diameter of the contact lenses was 9.64 +/- 0.08 mm. The mean contact lens power was 5.81 +/- 3.07 D, which was more myopic than the residual myopia by 2.79 +/- 1.67 D. Regression analysis showed definite correlation between the contact lens power and postoperative myopia (r = 0.854, P < 0.001).
Conclusion:
For correction of post-radial-keratotomy residual myopia, contact lens fitting parameters can be determined by a regression formula using keratometric and refractive values.