Christie Hang-I Lam

Diabetic retinopathy (DR) was identified as a leading cause of blindness and vision impairment in 2020. In addition to vasculopathy, DR has been found to involve retinal neurons, including amacrine cells and retinal ganglion cells. Despite possessing features that are susceptible to diabetic conditions, photoreceptor cells have received relatively little attention with respect to the development of DR. Until recently, studies have suggested that photoreceptors secret proinflammatory molecules and produce reactive oxygen species that contribute to the development of DR. However, the effect of hyperglycemia on photoreceptors and its underlying mechanism remains elusive. In this study, the direct effect of high glucose on photoreceptor cells was investigated using a 661w photoreceptor-like cell line. A data-independent sequential window acquisition of all theoretical mass spectra (SWATH)-based proteomic approach was employed to study changes induced by high glucose in the proteomic profile of the cells. The results indicated that high glucose induced a significant increase in apoptosis and ROS levels in the 661w cells, with mitochondrial dysfunction among the major affected canonical pathways. The involvement of mitochondrial dysfunction was further supported by increased mitochondrial fission and reduced mitochondrial bioenergetics. Collectively, these findings provide a biological basis for a possible role of photoreceptors in the pathogenesis of DR.

SIGNIFICANCE: Growing popularity of handheld digital devices imposes significant challenges to our visual system and clinical management. This study aimed to determine the effects of lens design on parameters that may influence the refractive management of pre‐presbyopic adult computer users. PURPOSE: To determine the effects of wearing conventional single‐vision lenses (SVL) versus progressive addition lenses (PAL) on the working distance and refractive status. METHODS: Adult computer users, recruited from two age cohorts (18 to 25 years, n = 19; 30 to 40 years, n = 45), were prescribed SVLs and PALs designed for use with handheld digital devices. For each lens type, the working distance and refractive shift (post‐task − pre‐task) were measured immediately after lens delivery (T0) and after 1 month of lens wear (T1). Working distances were recorded with an automatic ultrasound device while the participants were playing a video game. Refractive status through the subjects' glasses was measured before (pre‐task) and after playing the game (post‐task). Questionnaires assessing the frequencies of 10 digital work–related visual symptoms were conducted for both lens types at T1. RESULTS: Switching from SVL to PAL increased the working distance in both cohorts (mean ± SEM = 1.88 ± 0.60 cm; P =. 002) and induced a small but significant positive refractive shift (+0.08 ± 0.04 D, P =. 021) in the older cohort at T1. In the younger cohort, the changes in working distance due to the switching lens design were correlated with myopic error ( r = +0.66, P =. 002). In the older cohort, the changes in refractive shift due to switching lens design were correlated with amplitude of accommodation at both time points ( r for T0 and T1 = −0.32 and −0.30, respectively; both P <. 05). Progressive addition lens was rated as causing less “increased sensitivity to light” compared with SVL. CONCLUSIONS: Switching from SVL to PAL increased the working distance and induced a positive refractive shift in the majority of pre‐presbyopic adults.

Purpose: To investigate the characteristics of retinal electrophysiological activity in relation to early myopia development in children. Methods: Fifty-six children aged 6 to 9 years with emmetropic refractive error (defined as ≥ −0.5 diopter [D] and ≤ +0.5 D) were recruited. Cycloplegic refraction, axial length, and global flash multifocal electroretinogram (MOFO mfERG) at 49% and 96% contrast levels were recorded in all children at their first visit. The refraction and axial length measurements were repeated after 1 year. The amplitudes and implicit times of the direct component (DC) and the induced component (IC) of the MOFO mfERG obtained at the initial visit were analyzed. Correlations between the MOFO mfERG parameters and changes in refractive error and axial length were investigated. Results: The mean spherical equivalent refractive error and axial length of the eyes of the children at the first visit were +0.19 ± 0.33 D and 23.14 ± 0.6 mm, respectively. After 1 year, the mean refractive error increased by −0.55 ± 0.53 D, whereas axial length increased by 0.37 ± 0.22 mm. The changes in refractive error and axial length were significantly correlated with the central IC amplitudes at 49% contrast level measured at the initial visit (ρ = 0.46, P < 0.001 and ρ = −0.34, P = 0.01, respectively). Conclusions: The prospective changes we have shown are believed to derive from central inner retina. These changes appear to precede myopia and could be a potential reference for juvenile myopia development.

Purpose: People in Hong Kong generally live in a densely populated area and their homes are smaller compared with most other cities worldwide. Interestingly, East Asian cities with high population densities seem to have higher myopia prevalence, but the association between them has not been established. This study investigated whether the crowded habitat in Hong Kong is associated with refractive error among children. Methods: In total, 1075 subjects [Mean age ( S.D. ): 9.95 years (0.97), 586 boys] were recruited. Information such as demographics, living environment, parental education and ocular status were collected using parental questionnaires. The ocular axial length and refractive status of all subjects were measured by qualified personnel. Results: Ocular axial length was found to be significantly longer among those living in districts with a higher population density ( F _2,1072 = 6.15, p  =   0.002) and those living in a smaller home ( F _2,1072 = 3.16, p = 0.04). Axial lengths were the same among different types of housing ( F _3,1071 = 1.24, p  =   0.29). Non‐cycloplegic autorefraction suggested a more negative refractive error in those living in districts with a higher population density ( F _2,1072 = 7.88, p  <   0.001) and those living in a smaller home ( F _2,1072 = 4.25, p  =   0.02). After adjustment for other confounding covariates, the population density and home size also significantly predicted axial length and non‐cycloplegic refractive error in the multiple linear regression model, while axial length and refractive error had no relationship with types of housing. Conclusions: Axial length in children and childhood refractive error were associated with high population density and small home size. A constricted living space may be an environmental threat for myopia development in children.

Purpose: To solicit parents' knowledge on myopia control strategies available; to investigate their attitudes toward the use of orthokeratology (ortho‐k), daily wear soft lenses, and spectacles for myopia control, assuming all three optical strategies were equally effective for myopia control; and to collect their opinion on the age at which children can commence contact lens wear for vision correction. Methods: Telephone interviews were conducted on parents who responded to the advertisement for two myopia control studies, one on ortho‐k and one on soft lenses. Results: Most of the 196 respondents (ortho‐k group, 56%; soft lens group, 44%) were mothers, aged 36 to 45 years. Ortho‐k was the most commonly known myopia control strategy (86%). Parents in the ortho‐k group selected ortho‐k (49%) and spectacles (45%) (p < 0.001) as their preferred myopia control strategy, whereas parents in the soft lens group had no preference (p = 0.57). Decision was affected by prior knowledge of myopia control strategy. Major considerations were convenience and safety among parents selecting contact lenses and spectacles, respectively, as their preferred options. Overall, because of the lack of confidence in safety in contact lens wear, most parents (75%) were of the opinion that contact lenses for vision correction were only for children older than 14 years (53%) and not indicated for children younger than 8 years. Conclusions: Parents in Hong Kong were open to the use of contact lenses for myopia control in young children and they appeared to regard myopia control contact lenses as “treatment” and not as visual aids. They were more conservative in the use of contact lenses for vision correction in children. Parents' decision in selecting a myopia control strategy, assuming all three strategies to be equally effective, was affected by an individual's concerns of safety and additional benefits as well as influenced by positive evidence on myopia control effects.