Baseline peripheral refractive error and changes in axial refraction during one year in a young adult population

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.

Myopia Control Effect Is Influenced by Baseline Relative Peripheral Refraction in Children Wearing Defocus Incorporated Multiple Segments (DIMS) Spectacle Lenses

The aim of this study is to investigate if baseline relative peripheral refraction (RPR) influences the myopia control effects in Chinese myopic children wearing Defocus Incorporated Multiple Segments (DIMS) lenses. Peripheral refraction at 10°, 20°, and 30° nasal (10 N, 20 N, 30 N) and temporal (10 T, 20 T, 30 T) retina were measured at six-month intervals for children who participated in a 2-year randomized controlled trial. The relationship between the baseline peripheral refractions and myopia progression and axial length changes were analysed. A total of 79 children and 81 children in the DIMS and single vision (SV) group were investigated, respectively. In the DIMS group, more baseline myopic RPR spherical equivalent (SE) was associated with more myopic progression (10 N: r = 0.36, p = 0.001; 20 N: r = 0.35, p = 0.001) and greater axial elongation (10 N: r = −0.34, p = 0.001; 20 N: r = −0.29, p = 0.006) after adjusting for co-factors. In the SV group, baseline RPR had association with only myopia progression (10 N: r = 0.37, p = 0.001; 20 N: r = 0.36, p = 0.001; 30 N: r = 0.35, p = 0.002) but not with axial elongation after Bonferroni correction (p > 0.008). No statistically significant relationship was found between temporal retina and myopia progression or axial elongation in both groups. Children with baseline myopic RPR had statistically significant more myopia progression (mean difference around −0.40 D) and more axial elongation (mean difference 0.15 mm) when compared with the children having baseline hyperopic RPR in the DIMS group but not in the SV group. In conclusion, the baseline RPR profile may not influence future myopia progression or axial elongation for the SV lens wearers. However, DIMS lenses slowed down myopia progression and was better in myopia control for the children with baseline hyperopic RPR than the children with myopic RPR. This may partially explain why myopia control effects vary among myopic children. Customised myopic defocus for individuals may optimise myopia control effects, and further research to determine the optimal dosage, with consideration of peripheral retinal profile, is warranted.

Effect of axial length and anterior chamber depth on the peripheral refraction profile

AIM

To evaluate the effect of axial length (AL) and anterior chamber depth (ACD) on peripheral refractive profile in myopic patients compared to emmetropic participants.

METHODS

This cross-sectional study was conducted in right eyes of 58 participants of whom 38 were emmetropic and 20 were myopic. Central and peripheral refraction were measured at 10°, 20°, and 30° eccentricities in nasal and temporal fields using an open-field autorefractor. The Lenstar LS900 was used to measure ACD and AL. The participants were divided into three groups of short (<22.5 mm), normal (22.5-24.5 mm), and long eye (>24.5 mm) according to AL and three groups of low ACD (<3.00 mm), normal ACD (3.00-3.60 mm), and high ACD (>3.60 mm) according to ACD.

RESULTS

The mean age of the participants was 22.26±3.09y (range 18-30y). The peripheral mean spherical refractive error showed a hypermetropic shift in myopic and emmetropic groups although this shift was more pronounced in the myopic group. The results showed significant changes in the spherical equivalent, J0, and J45 astigmatism in all gazes with an increase in eccentricity (P<0.001). The pattern of refractive error changes was more noticeable in long and short eyes versus normal AL eyes. Moreover, the pattern of peripheral refractive changes was much more prominent in the high ACD group versus the normal ACD group and in the normal ACD group versus the low ACD group.

CONCLUSION

Peripheral refraction changes are greater in participants with AL values outside the normal range and deeper ACD values compared to participants with normal AL and ACD.

Different Mechanistic Association of Myopia with Rhegmatogenous Retinal Detachment between Young and Elderly Patients

Objectives

To investigate the mechanism of rhegmatogenous retinal detachment (RRD) in young and elderly Korean patients based on the results of axial length distribution.

Subjects/Methods

We retrospectively reviewed the medical records of 1599 patients with RRD who had bilateral axial length data examined at one center between 2003 and 2018. Axial lengths were measured using ultrasound or IOLMaster500. The frequency of RRD and axial length distribution according to age groups were investigated.

Results

Patients with RRD displayed a bimodal distribution across ages with two age groups showing the highest peak at 55–59 years and a second peak at 25–29 years of age. The mean axial length was significantly longer in patients younger than 50 years old than that in patients ≥ 50 years old (26.18 ± 1.86 mm vs. 24.55 ± 1.67 mm, respectively, p < 0.001). The percentage of patients with high myopia (axial length ≥ 26 mm) in patients < 50 years old was higher than that in those ≥ 50 years old (51.9% vs. 15.0%, respectively, p < 0.001; odds ratio, 6.11; 95% confidence interval, 4.83 to 7.74).

Conclusions

We found a difference in the prevalence of myopia between young and elderly patients with RRD, which corresponds to a bimodal distribution of RRD incidence in East Asian countries. Our data indicate that myopia or high myopia-induced early vitreous detachment appears to be a major mechanism of occurrence of RRD in young East Asian patients, while senile vitreous liquefaction and detachment is the main mechanism of RRD in elderly patients.