Correction of myopic astigmatism by combined treatment with PRK and T-incision and photoastigmatic refractive keratectomy |
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Authors: | Nahel Alkara Uwe Genth Theo Seiler |
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Institution: | Augenklinik im Universit?ts-Klinikum ?Carl Gustav Carus“ der Technischen Universit?t Dresden, XX
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Abstract: | Background: In contrast to the correction of simple myopia there is no widely accepted technique for the correction of myopic astigmatism.
Currently two techniques are available: the photoastigmatic refractive keratectomy (PARK) and the combination of arcuate keratotomies
with standard PRK (PRK-T).
Methods: In two groups, 67 patients underwent a correction of myopic astigmatism in a total of 87 eyes (19 by PRK-T and 68 by PARK),
and were followed for 1 year. The spherical equivalent was − 6.7 D in both groups and the refractive astigmatism ranged from
− 1.0 to − 6.5 D. The PARK procedure was performed by means of an elliptic ablation (Kertom I, Schwind) with a 5.8 × 8.1 mm
zone. The PRK-T technique consisted of two arcuate keratotomies with a free optical zone of 7 mm and a standard myopic PRK
at least 6 weeks later.
Results: The 1 year follow-up was completed in 57 out of 87 eyes included in the study. At 1 year post-operation, 83 % of the PRK-T
group and 80 % of the PARK group had an uncorrected visual acuity of 20/40 or better. The refractive astigmatism was reduced
by 76 % in the PRK-T group and by 67 % in the PARK group. The spherical equivalent was − 0.59 ± 1.1 D at 1 year after PRK-T
and − 0.28 ± 1.04 D after PARK. In three eyes of the PARK group (6.7 %) a visual loss of more than one Snellen line occured.
Two of these eyes had a preoperative myopia of more than − 6 diopters.
Conclusion: Both techniques have the potential to reduce myopic astigmatism, however, the success rate is not as high compared to spherical
PRK. Also, the complication rate of 2.5 % in corrections to − 6 D is significantly higher than that with spherical myopic
PRK.
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Keywords: | Myopic astigmatism • PRK • PARK • T-incision • Excimer laser |
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