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KMID : 1159320160180040477
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Korean Journal of Vision Science
2016 Volume.18 No. 4 p.477 ~ p.488
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Effect of Orthokeratology on Visual Correction in Myopic Regressive Patients after Laser Refractive Surgery
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Lee Su-Yeon
Lee Hea-Jung
Lee Koon-Ja
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Abstract
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Purpose: To evaluate the effect of orthokeratology (ortho-K) contact lenses on visual correction and corneal shape in myopic regressive patients after refractive surgery.
Methods: Seventeen myopic patients (average age 31.87 ± 4.74 years, range: 23 ~ 45 years) with myopic regression after laser refractive surgery, were fitted with Paragon CRT ortho-K contact lenses. The base curve of ortho-K lenses which were selected based on flat K and spherical refractive error and final lens parameters were determined with the fluorescein pattern assessment. Refractive errors were measured using the autorefraction, retinoscopy and subjective refraction. Monocular visual acuities were measured both in photopic and mesopic lighting conditions using 100% and 10% ETDRS chart and followed up for 1 month.
Results: In photopic lighting condition, high contrast visual acuities (HCVA) and low contrast visual acuities (LCVA) were 0.61 ± 0.35 logMAR and 0.75 ± 0.35 logMAR before ortho-K and improved to 0.09 ± 0.14 logMAR, 0.27 ± 0.23 logMAR after ortho-K (p<0.05). In mesopic lighting condition, HCVA and LCVA were 0.74 ± 0.31 logMAR, 0.93 ± 0.30 logMAR before ortho-K and improved to 0.19 ± 0.22 logMAR and 0.50 ± 0.20 logMAR after ortho-K (p<0.05). The visual improvement effect of ortho-K was better in low and medium myopes than in high myopes before laser refractive surgery. Spherical equivalent refractive errors were reduced from -2.01 ± 1.15 D to -0.30 ± 0.76 D after ortho-K. Q-values were changed more oblate shape from 0.17 ± 0.25 to 0.40 ± 0.22 (p<0.001) and the central corneal curvature changed from 8.54 ± 0.31 ㎜ to 8.79 ± 0.40 ㎜ (p<0.05) after ortho-K. However, corneal thickness was not changed significantly after ortho-k.
Conclusions: Corneal curvature and asphericity are changed and visual acuity is improved after Ortho-K in patients with myopic regression after laser refractive surgery.
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KEYWORD
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Orthokeratology contact lens, Keratorefractive surgery, Myopic regression
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