The aim of this review is to evaluate the ocular safety of orthokeratology (OrthoK) treatment of myopia correction and retardation. Clinical studies published in English and Chinese were identified from MEDLINE, EMBASE CNKI, CQVIP, and WANFANG DATA (all from 1980 to April 2015). The reference lists of the studies and the Science Citation Index were also searched. Relevant clinical studies including case series, case reports, patient/practitioner surveys, retrospective and prospective cohort studies, and clinical trials were all included in the review. The material of OrthoK lenses was limited to gas-permeable lens. This review incorporated a total of 170 publications, including 58 English and 112 Chinese literature. The risk of microbial keratitis in overnight OrthoK was similar to that of other overnight modality. The most common complication was corneal staining. Other clinically insignificant side effects included epithelial iron deposit, prominent fribrillary lines, and transient changes of corneal biomechanical properties. There was no long-term effect of OrthoK on corneal endothelium. There is sufficient evidence to suggest that OrthoK is a safe option for myopia correction and retardation. Long-term success of OrthoK treatment requires a combination of proper lens fitting, rigorous compliance to lens care regimen, good adherence to routine follow-ups, and timely treatment of complications.

Purpose: To evaluate the visual performance in adolescents undergoing orthokeratology (OrthoK) treatment with two different optical zone diameters (OZDs). Methods: This randomized, double-masked, self-controlled prospective study was conducted at Tianjin Eye Hospital (Tianjin, China) in June 2022. Thirty-six eligible schoolchildren were enrolled and fitted with corneal refractive therapy lenses with two sizes of OZDs (5 mm [5OZ] and 6 mm [6OZ]). Each participant was randomized to wear the 5OZ in one eye and the 6OZ in the contralateral eye. Subjective visual quality was assessed using visual acuity, refraction, contrast sensitivity function, and visual symptoms, and the objective optical quality was assessed using ocular higher order aberrations (HOAs) and modulation transfer function (MTF). Results: Thirty-five myopic children completed a 1-month follow-up visit. The 5OZ lens induced significantly smaller treatment zone diameters than the 6OZ lens (P < 0.001). Subjective visual quality did not differ significantly between the two groups. Compared to baseline, aberrations of Z₄⁰, coma-like, spherical-like, and total HOAs in both groups increased significantly (P < 0.05). For the 3-mm pupils, spherical aberration in the 5OZ group was significantly higher than that in the 6OZ group (P < 0.05). The MTF value of the 6OZ group was significantly higher than that of 5OZ group for 0.3 and 1.5 cycles per degree for the 3-mm pupils (P = 0.006 and P = 0.026, respectively). However, HOAs or MTF did not differ significantly between the two groups for the 5-mm pupils. Conclusions: The difference induced by varying OZD was significant only in the smaller pupil condition. The selection of OZD in OrthoK designs in real-world patient management should be done while considering individual pupil size. Translational Relevance: This study revealed that the objective visual quality of small OZD lenses was only slightly affected for the small pupil size.

The Euclid Emerald lens designs for orthokeratology have been available in global markets for over 20 years and is used extensively by clinicians for slowing myopia progression in children. This paper comprehensively reviews data from published studies of the efficacy of this lens. A comprehensive systematic search was performed in March 2023 using Medline with the following search terms: orthokeratology AND myopi* AND (axial or elong*) NOT (review or meta). The original search identified 189 articles, of which 140 reported axial elongation. Of those, 49 reported data on the Euclid Emerald design. Unique axial elongation data could be extracted from 37 papers-14 of which included an untreated control group. Among these, the mean 12-month efficacy-the difference in axial elongation between orthokeratology wearers and controls-was 0.18 mm (range: 0.05-0.29 mm), and the mean 24-month efficacy was 0.28 mm (range: 0.17-0.38 mm). The orthokeratology wearers in 23 studies without an untreated comparison group showed similar axial elongation to those in the 14 studies with a control group. For example, the mean 12-month axial elongation for the studies with controls was 0.20 ± 0.06 mm compared with 0.20 ± 0.07 mm for the studies without controls. This extensive body of literature on a single device for myopia control is unique and demonstrates the efficacy of this design in slowing axial elongation in myopic children.

This study aimed to evaluate the static and dynamic pupil changes, and light sensitivity following a single dose of low-dose atropine at concentrations of 0.01%, 0.025%, and 0.05% over a 24 h period. Healthy young adults (20–22 years; n = 25) participated in this randomized, double-blind study. Each participant received one of three atropine concentrations in a masked fashion. Baseline mesopic and dynamic pupil sizes were measured at various post-instillation intervals (5 min, 30 min, 1 h, 2 h, 4 h, and 24 h). A minimum 48 h washout period was observed between treatments. Subjective light sensitivity was assessed using the Visual Light Sensitivity Questionnaire (VLSQ-8) at 24 h. All atropine concentrations caused significant pupil dilation (p < 0.001), with the 0.05% concentration producing the greatest dilation (peak mesopic size: 7.4 mm, p < 0.001) and the slowest recovery at 24 h (6.4 mm, p < 0.001). The dynamic pupil constriction range was most restricted with 0.05% (1.7 mm, p < 0.05), compared to 0.025% (2.2 mm) and 0.01% (2.6 mm). Subjective symptoms, including light sensitivity and glare, followed a dose-dependent pattern (p < 0.05). In 60% participants, 0.05% caused the most symptoms, while in 70% participants, 0.01% caused the least. Despite significant pupil dilation, the pupil center coordinates did not shift significantly along the horizontal or vertical axes (p > 0.05). Low-dose atropine induced dose-dependent pupil dilation and light sensitivity; 0.05% atropine caused the most pronounced effects. These findings underscore the importance of tailoring the atropine dosage to balance its efficacy and tolerability. Further studies are needed to explore the long-term impact of repeated dosing on pupillary behavior and subjective symptoms.

Purpose: To evaluate the impact of a myopia control (MC) spectacle lens incorporating peripheral defocus on functional visual parameters compared to conventional single vision (SV) lenses. Methods: Thirty-nine young adults (age 21.1 ± 1.3 years; spherical equivalent −2.85 ± 2.8 D) participated in this single-session, within-subject crossover design. Distance and near LogMAR VA were assessed centrally and at 22° nasal and temporal off-axis. Distance contrast sensitivity (CS) was measured across five spatial frequencies (1.5–18 cpd) and the Area Under the Log CS Function (AULCSF) calculated. Retinal sensitivity was evaluated using automated static perimetry. Dynamic visual performance was assessed using a standardized video game platform. Outcomes were compared using repeated measures ANOVA or Wilcoxon signed-rank tests. Results: Central VA was comparable between lens types. MC lenses significantly reduced off-axis distance VA (nasal: 0.35 ± 0.15 LogMAR; temporal: 0.20 ± 0.14 LogMAR; both p < 0.001) and near VA (nasal: 0.72 ± 0.25 LogMAR; temporal: 0.34 ± 0.2 LogMAR; both p < 0.001). Off-axis AULCSF was significantly reduced with MC lenses (nasal: 12.07 ± 5.06 vs. 26.37 ± 5.00 units; temporal: 13.00 ± 6.93 vs. 27.14 ± 4.64 units; both p < 0.001), while central AULCSF remained similar between lens types (SV: 27.87 ± 5.04 vs. MC: 27.15 ± 5.02 units; p = 0.277). No significant differences were found for visual field indices (all p > 0.05). Video game accuracy was comparable between lenses, but task completion time was slower with MC lenses (20.71 ± 10.08 vs. 18.39 ± 6.65 s; p = 0.012). Conclusions: MC spectacle lenses preserve central VA, CS, and visual field sensitivity but induce significant off-axis VA and off-axis CS reductions. Dynamic visuomotor accuracy is maintained, though task completion speed is modestly reduced. These functional trade-offs should be considered when prescribing MC lenses.

Purpose: To investigate the short-term impact of scleral lens wear on intraocular pressure (IOP) and retinal nerve fiber layer (RNFL) thickness. We hypothesized that scleral lens wear would produce a measurable elevation in IOP accompanied by detectable RNFL thinning compared with soft contact lens wear. Methods: This prospective, randomized, contralateral-eye crossover study included 31 healthy participants (mean age: 26 ± 3 years). Each participant wore a 16.5 mm scleral lens over one eye and a soft contact lens over the fellow eye for 8 h, with assignments reversed between visits. IOP was measured using two tonometers: a transpalpebral Diaton tonometer and a non-contact tonometer (NCT), and RNFL thickness was measured by optical coherence tomography at four time points: pre- and post-lens application, and pre- and post-lens removal. Results: Eyes fitted with scleral lenses exhibited a significant IOP increase immediately after lens application (pre-application: 11 ± 3 mmHg vs. post-application: 16 ± 4 mmHg, p < 0.001), sustained throughout 8 h of wear (pre-removal: 16 ± 4 mmHg), and returned to baseline after removal (11 ± 3 mmHg). No significant IOP changes were observed in soft contact lens-wearing eyes (p > 0.05). Scleral lens wear was also associated with small but statistically significant peripapillary RNFL thinning (pre-application: 110 ± 11 µm vs. post-application: 107 ± 11 µm, p < 0.001), which returned to baseline after lens removal. No significant RNFL changes were observed with soft contact lens wear (p > 0.05). Bland–Altman analysis revealed poor agreement between Diaton and NCT measurements, consistent with the published literature on transpalpebral tonometry. Conclusions: Short-term scleral lens wear was associated with transient IOP elevation and peripapillary RNFL thinning, both reversible upon lens removal, in healthy young adults. These findings highlight the need for further longitudinal investigation in at-risk populations such as those with ocular hypertension, keratoconus, or early glaucoma before clinical monitoring recommendations can be established.