Short-Term Effect of Diffusion Optics TechnologyTM (DOT) Contrast Management Spectacle Lenses on Ocular Biometrics and Lag of Accommodation in Emmetropic Children

Abstract

Purpose: Myopia, a prevalent refractive error of the eye, is experiencing a rapid increase in prevalence. According to Holden et al., approximately 50% of the global population is projected to be myopic by the year 2050. In response to this growing concern, various myopia control treatments have been developed, including spectacles, contact lenses, and pharmaceutical options. One innovative treatment is the use of Diffusion Optics Technology ™ (DOT) spectacle lenses. These lenses are designed to modulate retinal contrast, thereby reducing signals for axial elongation. The lenses incorporate thousands of microscopic dots to manage contrast, which helps reduce signal disparities between adjacent cones while maintaining good visual acuity and functional peripheral vision. However, there is a lack of published literature on the generalized effects of these contrast management spectacles (CMS) on ocular structures over a short period of wear. This thesis aimed to address this gap and determine the short-term effect of CMS on ocular structures and lag of accommodation. Additionally, the thesis also examined the repeatability of various methods of measurement of choroidal thickness. Methods and Materials: Chapters 3, 4, 5, 6: This study was a two-visit, prospective, randomized, controlled, participant-masked trial involving 30 emmetropic participants aged 8 to 14. The participants’ eligibility was confirmed during a screening visit, which utilized non-cycloplegic auto-refraction to ensure that the spherical equivalent was between +1.00D and -0.75D, with astigmatism not exceeding -0.75DC. During the first study visit, ocular biometrics were assessed using the IOL Master and a Topcon DRI OCT for baseline measurements. The parameters measured included central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), retinal thickness, choroidal thickness, choroidal vascularity index (CVI), and axial length (AL). After these measurements, participants were randomly assigned to wear either CMS spectacles with a 0.2 DOT pattern that covered the entire lens surface or clear +3.00D control spectacles (which acted as a positive control to induce myopic defocus). While wearing the spectacles, participants watched an age-appropriate video for 60 minutes. After 30 minutes and again after 60 minutes of viewing, the IOL Master and OCT examinations were repeated. On the second visit, participants wore spectacles that they had not used during the first visit, and the same measurements were repeated. Subsequently, the baseline OCT scans from both visits were exported, and sub-foveal choroidal thickness was measured using four different methods to evaluate the repeatability between methods. The most reliable measurement method was then used for further analysis. Chapter 7: This was a single-visit, prospective, randomized, subject-masked study. Participants were eligible if they had ±1.00D mean sphere prescription or less and they had no history of previous myopia control treatment. The logMAR visual acuity was measured, and ocular dominance was tested using the sighting method. Participants then wore a pair of plano CMS spectacles with a 0.2 DOT pattern that covered the entire lens surface and standard plano spectacles (control) in a randomized order and, after 5 minutes of adaptation to the lenses, ten open-field autorefraction measurements (Grand Seiko 5500) were taken for each eye, with the target at 6m and 40cm. Analysis was conducted on the mean auto-refraction to determine differences in the lag of accommodation (LOA) between lens types for the right eye and also for the dominant eye. Results: Chapters 3,4,5,6: A total of 30 participants were enrolled in the study and completed all assessments (17 females and 13 males). The mean age of the participants was 10.9 ± 1.7 years (median 11 years, ranging from 8 to 13 years). The mean refractive error was +0.35 ± 0.29 spherical equivalent refraction (SER). • Chapter 3: After one hour of wearing CMS spectacles, a two-way RMANOVA revealed a statistically significant reduction in AL (6µm) with p = 0.001. Similarly, a significant difference in CCT was observed, with p < 0.001 between baseline and both the 30-minute and 60-minute time points. Additionally, pairwise comparisons indicated a significance of p = 0.02 at the 30-minute time point between CMS and control spectacles. A similar reduction in AL (6µm) was noted with +3.00 control spectacles after one hour of wear. A significant difference (p < 0.001) was also observed for both ACD and LT with the +3.00D control spectacles at baseline versus 30 minutes and baseline versus 60 minutes. Furthermore, pairwise comparisons demonstrated significant differences between CMS and +3.00 control spectacles at the 30-minute (2.16 µm) time point for CCT and at both 30 (0.04 mm, 0.04 mm) and 60-minute (0.04 mm, 0.04 mm) time points for ACD and LT. • Chapter 4: When comparing the different methods of measurement for choroidal thickness, the manual method overestimated the choroidal thickness by 40 µm when compared to the semi-automated and automated AI-based method. Although repeatability between the measurements was satisfactory, the manual method did not show an acceptable Bland-Altman agreement when compared to the other three methods. However, a good agreement was observed between the semi-automated and the automated methods. • Chapters 5 & 6: The retinal thickness, choroidal thickness, and CVI were measured at all nine Early Treatment Diabetic Retinopathy Study (ETDRS) regions. In terms of choroidal thickness, only the outer inferior region of the retina showed a significant difference (p = 0.02) between the 30-minute and 60-minute marks when using CMS spectacles. Additionally, a significant difference was found between the CMS spectacles and the +3.0 control spectacles at the 30-minute point in 4 out of 9 macular regions. In contrast, no significant differences were found in any of the regions when using the +3.00D control spectacles. The retinal thickness and CVI did not exhibit any significant differences in any of the nine ETDRS regions for both CMS and +3.00D control spectacles. Chapter 7: A total of 30 participants (20 females and 10 males) with a mean age of 10.4 ± 2.8 (7 to 17) years completed the study. There was no significant difference in right eye mean LOA with CMS (+0.57 ± 0.39D) versus control spectacles (+0.62 ± 0.34D); Mann-Whitney U test, p = 0.64. For dominant eyes, LOA values were +0.60 ± 0.40D and +0.68 ± 0.33D with CMS and control spectacles, respectively (p = 0.25, not significant). Additionally, no significant difference was observed in mean LOA between males and females or between age groups (7-11 years vs 12-17 years) for either right or dominant eyes with CMS or control spectacles (all p = > 0.05). Conclusions: Chapter 3: Short-term wear of full-field myopia control CMS did not result in significant changes in anterior segment biometrics, retinal thickness, choroidal thickness, CVI and AL. There was only a minimal decrease of 3 µm in CCT after 60 minutes of wear; however, this minimal change was considered clinically insignificant. Chapter 4: This study concluded that manual, semi-automated, OCT inbuilt software and AI-based customized software methods are reproducible and repeatable. The manual method tends to overestimate the ChT and is time-consuming, as compared with both automated methods, which showed encouraging results for the OCT based TABS automated software. Chapters 5 & 6: Short-term exposure to full-field CMS did not lead to any notable changes in retinal or choroidal thickness. However, a significant difference in choroidal thickness was noted between the spectacles at the 30-minute time point, suggesting a rapid yet transient response. Further research with larger sample sizes and extended monitoring durations may be necessary to determine the clinical significance of these transient changes. Similarly, short-term exposure to CMS and +3.00D control spectacles did not lead to any notable change in CVI. Chapter 7: Full-field CMS had no significant effect on LOA compared to standard single-vision spectacle lenses, indicating no differential impact on accommodative response over the short period of lens wear tested.