Purpose To investigate choroidal and ocular biological variables that influence axial length (AL) elongation in children wearing defocused incorporated multiple segments (DIMS) spectacle lenses. Methods This cohort study included 106 myopic children aged 7–14 years with a 1-year follow-up. Participants were divided into two groups according to the increase in AL in one year: rapid (>0.2 mm) and slow (≤0.2 mm) axial elongation groups. Cycloplegic autorefraction and AL were measured at baseline and after 6 and 12 months. The area of choriocapillaris flow voids (FVs) and choroidal thickness (ChT) at baseline were measured. Results Univariate linear regression analysis showed that AL elongation were significantly associated with the FVs area (standardised β = 0.198, P < 0.05) and age (standardised β = −0.201, P < 0.05). Multiple linear regression showed that the FVs area, age, and average K reading were associated with AL elongation. Multiple logistic regression analyses showed that greater degrees of myopia and larger FVs areas were risk factors for rapid axial elongation, while older age, large pupil diameter and steeper cornea were protective factors. In estimating axial elongation, the FVs area alone demonstrated an area under the curve (AUC) of 0.672 (95% CI, 0.569–0.775, P < 0.01), and that of FVs area and other ocular variables was 0.788 (95% CI, 0.697–0.878, P < 0.001). Conclusion Larger choriocapillaris FVs area at baseline may help to predict axial elongation in myopic eyes. The association between FVs area and axial elongation should be taken into consideration in further myopic cohort studies.

Objectives To examine the ocular biometric parameters and predict the annual growth rate of the physiological axial length (AL) in Chinese preschool children aged 4–6 years old. Methods This retrospective cross-sectional study included 1090 kindergarten students (1090 right eyes) between the ages of 4 and 6 years from Pinggu and Chaoyang District, Beijing. Dioptre values were ascertained following cycloplegic autorefraction. Predicted AL was obtained through the application of the Gaussian process regression model as an optimisation technique. Subsequently, the annual growth rate of physiological AL for non-myopic preschool children (n=1061) was computed via the backward difference method. Results In total, 85.4% of preschool children (931 individuals) had hyperopic refractive status in the 4–6 years age group, while only 2.7% (29 individuals) showed myopia. Boys had longer AL, larger AL-to-corneal radius ratio, deeper anterior chamber depth and lower lens power. The average physiological axial growth for boys and girls ranged from 0.050 mm/year to 0.165 mm/year and 0.063 mm/year to 0.168 mm/year, respectively. As age increased, the physiological AL growth in non-myopic cases decreased. Additionally, as hyperopic spherical equivalent refraction error lessened, the physiological AL growth component slowed down. Conclusions In preschool children, refractive development predominantly exhibits mild hyperopia. The concept of physiological AL provides valuable insights into the complexities of ocular development.

Purpose: This study aimed to identify the key demographic, biometric, and behavioral factors that impact the treatment effect of Ortho-K in low myopia and to discover the management ideas for low myopes undergoing Ortho-K treatment. Methods: A 12-month retrospective study examined 380 individuals who received Ortho-K treatment. Stratification and multinomial logistic regression were conducted to identify biometric features and behavioral indicators associated with Ortho-K treatment outcomes in low myopes. Results: The 12-month axial length growth was significantly longer in the low myopia group than in the moderate myopia group (P<0.0001). Multivariate logistic regression analysis showed that Ortho-K only was 2.23 times more likely to have rapid axial growth than Ortho-K combined with 0.01% atropine in patients with low myopia (P=0.01; odds ratio [OR]=2.23; 95% confidence interval [CI], 1.19–4.20). Multinomial logistic regression analyses showed that in patients with low myopia, female sex (P<0.0001; OR=0.4; 95% CI, 0.22–0.72), young age (P=0.01; OR=0.79; 95% CI, 0.66–0.93), flatter K mean (P=0.004; OR=0.74; 95% CI, 0.61–0.91), and having two myopic parents (P=0.03; OR=0.18; 95% CI, 0.05–0.71) were associated with worse treatment outcomes. A diet rich in white meats, such as fish and duck (P=0.01; OR=0.06; 95% CI, 0.01–0.54), was protective behavioral factors associated with slower axial length growth in children with low myopia. Conclusions: Patients with low myopia who exhibit one or more of the demographic and biometric risk factors (young age, female, flat mean K, and two myopic parents) require heightened attention in clinic settings because of their increased risk of myopia progression. Ortho-K combined with 0.01% atropine may achieve better efficacy than Ortho-K only in low myopes. A diet rich in white meat is protective and controlled behavioral factors for these patients.

Objective: The objective of this study was to examine the association between parental smoking, a questionnaire-based proxy for secondhand smoke exposure, and incident right-eye corneal astigmatism (CA). Methods: This nested case–control reanalysis included 78 pairs matched on sex and follow-up duration. The primary endpoint, revised after peer review, was CA < 1.0 diopter (D) at cohort entry and ≥1.0 D at the index visit. Conditional logistic regression adjusted for entry age, entry CA, parental astigmatism, and afterschool outdoor time. Subsequent refractive astigmatism (RA) change was examined as an exploratory secondary outcome in the same selected sample. Results: Keratometry-based classification agreed with all original case–control labels. Parental smoking was reported for 61/78 cases and 48/78 controls. The adjusted odds ratio was 2.257 (95% profile-likelihood confidence interval, 1.016–5.434; likelihood-ratio p = 0.0456; Wald p = 0.0538). RA change was available for all 156 children after 19 blank cylinder entries were confirmed as measured zeros. The adjusted difference in RA change was 0.266 D (95% confidence interval, 0.181–0.351; p < 0.001). Conclusions: The CA estimate suggested higher odds with parental smoking, but wide intervals and inference sensitive to the statistical method indicate substantial uncertainty. The exploratory RA association is susceptible to selection bias because participants were sampled according to CA case status; adjustment for case status does not itself remove this bias. These findings do not establish causality or population-level astigmatism progression.