Abstract
Purpose To assess the changes and the diurnal variation of visual quality after orthokeratology in myopic children. Methods Forty-four eyes of 22 subjects with a mean age of 10.55 ± 1.53 years (8 to 14 years) were enrolled in this prospective study. Their spherical equivalent ranged from −1.25 to −4.25 diopters (D) and astigmatism was less than 1.00 D. Parameters including corneal curvature, ocular objective scatter index (OSI), the modulation transfer function (MTF), root mean square of ocular and corneal wavefront aberrations, and contrast sensitivity function (CSF) were measured before and at two time points during the same day after 1 month of orthokeratology. Results After orthokeratology, uncorrected visual acuity (UCVA) and spherical equivalent were significantly improved from baseline (P < 0.001), and their diurnal variation was not significant (P=0.083, 0.568). OSI increased from 0.29 ± 0.15 to 0.65 ± 0.31 (P < 0.001). MTF decreased significantly (P < 0.01). Corneal curvature and ocular total aberration decreased (P < 0.001), while the ocular and corneal higher-order aberration increased significantly (P < 0.01). The CSF under photopic condition decreased at 3 cpd (P=0.006) and increased at 18 cpd (P=0.012). The diurnal variation of CSF at 18 cpd under mesopic and high glare conditions and at 12 cpd under photopic condition was significant (P=0.002, 0.01, 0.017). Conclusions Orthokeratology can effectively improve UCVA and high spatial frequency CSF by decreasing the low-order aberrations. However, MTF and CSF at low spatial frequency decreased because of the increase of intraocular scattering and high-order aberrations. Meanwhile, CSF at high spatial frequency fluctuates significantly at two times during the same day after 1 month orthokeratology.
Highlights
Orthokeratology involves wearing of specially designed gaspermeable contact lenses which temporarily reshape corneal contour [1]. is procedure can offer patients useful vision during waking hours without involving additional corrective devices, such as spectacles or daily wear contact lenses
Several short-term studies have reported that the influence of orthokeratology on refraction and visual acuity gradually diminished during the day once the lens was removed [7,8,9,10], which may cause uncomfortable visual experience as mentioned above. ese studies focus mostly on wavefront aberration, visual acuity, and refraction
Research based on double-pass technique have revealed that the retinal image quality may be overestimated by aberrometric techniques which often failed to take the effect of diffuse light into account, and the double-pass system has been proven to be a useful tool for comprehensive evaluation of optical quality of the eye because it can provide parameters that included intraocular scattering [12,13,14]. ere were few studies using double-pass technique to evaluate the visual quality after orthokeratology
Summary
Orthokeratology involves wearing of specially designed gaspermeable contact lenses which temporarily reshape corneal contour [1]. is procedure can offer patients useful vision during waking hours without involving additional corrective devices, such as spectacles or daily wear contact lenses. Is procedure can offer patients useful vision during waking hours without involving additional corrective devices, such as spectacles or daily wear contact lenses. Ese studies focus mostly on wavefront aberration, visual acuity, and refraction. These assessments are insufficient to fully understand the effects of orthokeratology on visual quality because retinal image is affected by ocular aberration and by intraocular scattering [11, 12]. Ere were few studies using double-pass technique to evaluate the visual quality after orthokeratology. Jeon et al [15] used the double-pass system in 13 patients (24 eyes) and found that the intraocular scattering increased after 1 month of orthokeratology lenses wear.
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