[The long-term clinical effects of orthokeratology in high myopia children].

OBJECTIVE: To investigate the long-term clinical effects of orthokeratology (ortho-k) in high myopia children with 5 years of follow-ups.

METHODS: Prospective study. We chose 30 high myopia patients to wear ortho-k contact lenses (CLs) for controlling or delaying myopia progression from 2003. Among them, there were 10 boys and 20 girls whose average age was (15 ± 2) years, spherical diopters were (-7.34 ± 0.91) D, corneal astigmatism diopters were (-1.06 ± 0.62) D, uncorrected visual acuity was LogMAR 0.89 ± 0.29, corneal flattened curvature was (43.54 ± 1.16) D, and axial length was (26.38 ± 0.94) mm. All patients, with informed consent before fitting of ortho-k CLs, had conventional refraction and ocular tests. We compared the values of spherical diopters, visual acuity, corneal flattened curvature and axial length before and 6 months, 1 year, 2 years, 3 years, 4 years and 5 years after wearing CLs, respectively. The results were analyzed by SPSS 16.0 software.

RESULTS: During the five years of observation periods, all patients' visual acuity and corneal flattened curvature were different from the pre-fitting (P < 0.05). Compared to the pre-fitting, the naked visual acuity was some degree improved, it was LogMAR 0.45 ± 0.31, 0.49 ± 0.32, 0.43 ± 0.30, 0.47 ± 0.31, 0.58 ± 0.35, 0.53 ± 0.27, respectively. F = 10.725, P = 0.000. Corneal flatten curvature was tend to be flatter, such was 41.14 ± 1.54, 41.75 ± 1.88, 41.54 ± 2.10, 41.73 ± 1.89, 41.94 ± 1.61, 40.70 ± 1.67. F = 10.161, P = 0.000 (All P < 0.05). The spherical diopters during the first two years after wearing ortho-k CLs were significantly reduced, compared with the previous values (it was -5.23 ± 1.81, -5.59 ± 2.75, -6.29 ± 2.12, -6.63 ± 2.31, -6.83 ± 2.33, -7.01 ± 1.81, respectively, F = 4.929, P = 0.000), and kept stable in the long-term observation. The axial length checked at 5 years was slightly elongated (it was 26.41 ± 0.90, 26.68 ± 0.93, 26.69 ± 1.06, 26.75 ± 0.94, 26.81 ± 1.04, 27.04 ± 1.01. F = 1.831, P = 0.094). The axial elongation was retarded by using ortho-k CLs in high myopia children. All patients were not subjected to severe complications which may lead to quitting the enrollments.

CONCLUSIONS: Orthokeratology used in controlling or delaying high myopia progression is definitely outstanding in 5 years observations. Standard lens wearing and regular lens check improve safety of lens use in high myopia.