关键词: 角膜塑形镜, 角膜后表面, 前房深度, 前房体积, 角膜生物力学

Abstract: Objective To observe the changes of corneal curvature, anterior chamber depth (ACD) and anterior chamber volume (ACV) after wearing orthokeratology lens and investigate the relationship between corneal biomechanical properties and changes of corneal surfaces. Design Retrospective cases series. Participants Twenty-four orthokeratology patients (24 eyes) from Janurary to April in 2013 at the Optometry Center of the Ophthalmology Department in the First Affiliated Hospital of Harbin Medical University with age ranged from 8~16 years old, and spherical equivalent (SE) varied from -4.00~-5.00 D. Methods We applied Pentacam to analyze central corneal thickness (CCT), anterior flat keratometry (anterior Kf), anterior steep keratometry (anterior Ks), posterior flat keratometry (posterior Kf), posterior steep keratometry (posterior Ks), ACD, ACV before, overnight and after one month wearing or thokeratology lens. Ocular response analyzer (ORA) was used to analyze corneal hysteresis (CH), corneal resistance factor (CRF) be fore and after wearing orthokeratology. Main Outcome Measures Mean SE, anterior Kf, anterior Ks, posterior Kf, posterior Ks, ACD and ACV. Results After overnight wearing orthokeratology lens, the SE value significantly dropped (-2.35±0.85) D, anterior corneal surface became flattened, the value of anterior Kf reduced (1.31±0.64) D and anterior Ks decreased (1.20±0.76) D. After one-month wearing orthokeratology lens, SE decreased (-4.02 ± 0.54) D, the value of anterior Kf and Ks decreased (2.54 ± 1.13) D and (2.90 ±1.01) D respectively. ACD and ACV respectively reduced (0.02±0.02) mm and (1.71±3.54) mm3 after overnight wearing and with one month wearing respectively reduced (0.03±0.02)mm and (4.96±2.25)mm3. ACD and ACV significantly decreased after one-month, compared to the values before and overnight wearing orthokeratology (t=23.081, P=0.000; t=8.847, P=0.000; t=8.877, P=0.000; t=10.772, P=0.000). Posterior corneal curvature had no significant change (t=-0.365, P=0.718; t=-0.238, P=0,814), and there was no correlation between changes of ACD and ACV and corneal biomechanics (all P>0.05). But the changes of ACD and ACV had a trend to decrease with increasing corneal biomechanics properties. Conclusion Orthokeratology lens works well in correcting myopia. Posterior corneal surface becomes flatter after wearing orthokeratology lens, and the degrees of flatness may be influenced by corneal biomechanics properties. (Ophthalmol CHN, 2015, 24: 112-116)

Key words: orthokeratology, posterior corneal surface, anterior chamber depth, anterior chamber volume, corneal biomechanics