Frequency-dependent effects of 0.05% atropine eyedrops on myopia progression and peripheral defocus: a prospective study.

BACKGROUND: Atropine, specifically 0.05% eyedrops, has proven effective in slowing myopia progression. This study aims to investigate peripheral refraction (PR) characteristics in myopic children treated with 0.05% atropine eyedrops at different frequencies. METHODS: One hundred thirty-eight myopic children completed this one-year prospective study, randomly assigned to once daily (7/7), twice per week (2/7), or once per week (1/7) groups. Spherical equivalent (SE) and axial length (AL) were measured. PR was assessed using a custom-made Hartmann-Shack wavefront peripheral sensor, covering a visual field of horizontal 60° and vertical 36°. Relative peripheral refraction (RPR) was calculated by subtracting central from peripheral measurements. RESULTS: After one year, SE increased more significantly in the 1/7 group compared to the 7/7 group (P < 0.001) and 2/7 group (P = 0.004); AL elongation was also greater in the 1/7 group compared to the 7/7 group (P < 0.001). In comparison with higher frequency groups, 1/7 group exhibited more myopic PR in the fovea and its vertical superior, inferior, and nasal retina; and less myopic RPR in the periphery retina after one-year (P < 0.05). Additionally, RPR in the 7/7 group demonstrated myopic shift across the entire retina, the 2/7 group in temporal and inferior retina, while the 1/7 group showed a hyperopic shift in the superior retina (P < 0.05). Moreover, myopic shift of RPR in the temporal retina is related to less myopia progression, notably in the 7/7 group (P < 0.05). CONCLUSIONS: Atropine inhibits myopia progression in a frequency-dependent manner. The once-daily group showed the slowest myopia progression but exhibited more myopic shifts in RPR. Additionally, RPR in the temporal retina was related to myopia progression in all groups. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2100043506. Registered 21 February 2021, https://www.chictr.org.cn/showproj.html?proj=122214.

The induced defocus by Defocus Incorporated Soft Contact lenses is dependent on visual distance and ambient illuminance.

PURPOSE: Defocus Incorporated Soft Contact (DISC) lenses, a commonly used type of multifocal lens in clinical practice, may slow down myopia progression by inducing myopic retinal defocus. The purpose of this study was to explore whether the induced defocus across the retina could be affected by visual environments encountered in the real world, such as differences in viewing distance and ambient illuminance. METHODS: In this cross-over trial, 30 myopic adults wore both DISC lenses and single vision contact (SVC) lenses in random order. An open-view Hartmann-Shack scanning wavefront sensor was used to measure defocus at different retinal locations along the horizontal meridian under four experimental conditions: far target (3 m) and near targets (0.33 m) under scotopic (<1 lux) or photopic (~300 lux) conditions. RESULTS: The results showed that DISC lenses induced more myopic retinal defocus than SVC lenses in all conditions (all p < 0.05), except for the scotopic near target. In addition, for DISC lenses, the defocus was greater in the photopic than the scotopic conditions for both the far and near targets (both p < 0.05). CONCLUSION: In conclusion, the retinal defocus induced by these multifocal lenses was dependent on both visual distance and ambient illuminance, indicating that the visual conditions might affect the anti-myopia efficacy of these devices.

The efficacy of orthokeratology lenses with smaller back optic zone diameter in myopia control. A meta-analysis.

PURPOSE: This study was conducted to determine whether orthokeratology (OK) lenses with a smaller back optic zone diameter (BOZD) could exhibit stronger myopia control effects. METHOD: A meta-analysis was registered in PROSPERO (CRD42023408184). A comprehensive systematic database search was conducted, encompassing PubMed, Cochrane Library, EMBASE, MEDLINE, Web of Science, Ovid, CNKI and CBM, to identify relevant studies up to 25 March 2023. The primary inclusion criteria for this meta-analysis were studies that investigated the myopia control effect of OK lenses with a small optical treatment area (≤5 mm). To assess the quality of the retrieved articles, two researchers evaluated them using the Cochrane bias risk assessment criteria. The primary outcome measures were the changes in axial length (AL) and refractive error, using the weighted mean differences (WMD) and 95% confidence intervals (CI) to assess differences between small and traditional back optical treatment zone groups in terms of these outcomes. RESULTS: The analysis encompassed five eligible studies, with a 1 year duration. The average difference in AL between the groups was 0.12 mm (WMD = -0.12, 95% CI [-0.16, -0.09], p < 0.00001). Likewise, the average difference in refractive error between the two groups was 0.44 D (WMD = 0.44, 95% CI [0.30, 0.57], p < 0.00001). None of the studies reported severe adverse events. CONCLUSIONS: Current evidence suggests that OK lenses with smaller back optical treatment zone are more effective in preventing myopia progression than traditional lenses. However, a longer-term evaluation is warranted.

Two-dimensional peripheral refraction in adults.

Peripheral refraction has been studied for decades; however, its detection and description are somehow simplistic and limited. Therefore, their role in visual function and refractive correction, as well as myopia control, is not completely understood. This study aims to establish a database of two-dimensional (2D) peripheral refraction profiles in adults and explore the features for different central refraction values. A group of 479 adult subjects were recruited. Using an open-view Hartmann-Shack scanning wavefront sensor, their right naked eyes were measured. The overall features of the relative peripheral refraction maps showed myopic defocus, slight myopic defocus, and hyperopic defocus in the hyperopic and emmetropic groups, in the mild myopic group, and in other myopic groups, respectively. Defocus deviations with central refraction vary in different regions. The defocus asymmetry between the upper and lower retinas within 16° increased with the increase of central myopia. By characterizing the variation of peripheral defocus with central myopia, these results provide rich information for possible individual corrections and lens design.

Instrument for fast whole-field peripheral refraction in the human eye.

An instrument for fast and objective measurement of the peripheral refraction in the human eye is presented. The apparatus permits the automatic estimation of both defocus and astigmatism at any retinal eccentricity by scanning a near infrared beam. The design includes a Hartmann-Shack wavefront sensor and a steering mirror, which operate in combination with a compounded eyepiece for wide field operation. The basic scanning protocol allows the estimation of refraction in a circular retinal patch of 50 deg diameter (±25 from central fixation) in 3 sec. Combined with additional fixation points, wider retinal fields can be sampled to achieve a whole field. The instrument underwent calibration and testing, and its performance for real eyes was assessed in 11 subjects of varying age and refraction. The results show high repeatability and precision. The instrument provides a new tool for the investigation of peripheral optics in the human eye.

Effects of hydrogen peroxide solution on the biomechanics of porcine cornea.

OBJECTIVES: To determine the biomechanical changes of porcine corneas after the application of hydrogen peroxide(H2O2) solution. METHODS: Fifty-five porcine eyeballs with similar sizes were divided into 11 groups based on the H2O2 application. The eyeballs were treated with the following concentrations of H2O2 solution: 1 mol/L, 500 mmol/L, 250 mmol/L, 125 mmol/L, 62.5 mmol/L, 31.25 mmol/L, 15.63 mmol/L, 7.81 mmol/L, 3.91 mmol/L, 0.9% saline, or blank. The eyeballs were immersed into the solution for 30 min. The biomechanics of each cornea in the different groups was determined soon after the indentation and tensile tests. We calculated the average Young's modulus of the different groups to determine the effects of H2O2 solution on porcine corneas. The comparison between the groups was conducted using ANOVA analysis. Moreover, the safety of each concentration of H2O2 solution on the corneal tissues was determined by histopathological examination. RESULTS: The Young's modulus was significantly different among all the groups (p = 0.003). The modulus was the highest in the group treated with 3.91 mmol/L H2O2 and it was significantly different from that in the group treated with 0.9% saline or the blank group, for both the indentation and tensile tests. Histopathological examination showed that H2O2 at a concentration of ⩾62.5 mmol/L damaged the epithelium, stroma, or both, while H2O2 at a concentration ⩽31.25 mmol/L did not change the morphology of the epithelium or stroma. CONCLUSIONS: Treatment with 3.91 mmol/L H2O2 solution can safely and effectively increase the biomechanical strength of the cornea.