Defocus-induced spatial changes in choroidal thickness of chicks observed by wide-field swept-source OCT.

Choroid has been claimed to be of importance during ocular development. However, how the choroid responds spatially to different visual cues has not been fully understood. The aim of this study was to investigate defocus-induced spatial changes in choroidal thickness (ChT) in chicks. Eight 10-day-old chicks were fitted monocularly with -10 D or +10 D lenses (day 0), which were removed seven days later (day 7). The ChT was measured on days 0, 7, 14, and 21 using wide-field swept-source optical coherence tomography (SS-OCT) and analyzed with custom-made software. Comparisons of the ChT in the central (1 mm), paracentral (1-3 mm), and peripheral (3-6 mm) ring areas and the ChT in the superior, inferior, nasal, and temporal regions were conducted. Axial lengths and refractions were also evaluated. In the negative lens group, the global ChT of the treated eyes was significantly less than that of the fellow eyes on day 7 (interocular difference: 179.28 ± 25.94 µm, P = 0.001), but thicker on day 21 (interocular difference: 241.80 ± 57.13 µm, P = 0.024). These changes were more pronounced in the central choroid. The superior-temporal choroid changed more during induction but less during recovery. In the positive lens group, the ChT of both eyes increased on day 7 and decreased on day 21, with most changes occurring in the central region, too. The inferior-nasal choroid of the treated eyes changed more during induction but less during recovery. These results provide evidence for regionally asymmetric characteristics of the choroidal response to visual cues and insights into the underlying mechanisms of emmetropization.

Refractive and corneal astigmatism in Chinese 4-15 years old children: prevalence and risk factors.

BACKGROUND: To investigate the prevalence and risk factors of refractive astigmatism (RA) and corneal astigmatism (CA) in preschool children and school-aged children in Shanghai, China. METHODS: In this school-based, cross-sectional study, 4-15 years old children across three learning stages of kindergarten, primary school, and junior high school underwent noncycloplegic autorefraction and completed comprehensive questionnaires involving time spent on daily homework and outdoor activities. Data from the right eyes were analysed. RESULTS: Overall, 7084 children (mean ± standard deviation (SD) of age: 8.08 ± 3.11 years) were included, and the prevalence rates of RA/CA ( ≤ - 1.0 D) in children were 15.8%/64% in kindergartens, 16.5%/65% in primary schools, and 32.8%/76.9% in junior high schools. The magnitude and prevalence of RA and CA all increased with age or with learning stage (all P < 0.001). The presence of RA was associated with more myopic spherical power (odds ratio (OR) 0.956, P = 0.021), junior high school (OR 1.973, P < 0.001), longer homework time on weekdays (OR 1.074, P = 0.029), and shorter outdoor activity time on weekends (odds ratio 0.929, P = 0.013). CONCLUSION: In the wide age range of 4 to 15 years, the magnitude and prevalence of RA and CA increased with the learning stage, and these increases mainly began at the primary school stage. Factors, including longer homework time and shorter outdoor time were correlated with the presence of RA.

Seven-year corneal densitometry changes after small incision lenticule extraction and femtosecond laser-assisted in situ keratomileusis.

This study aims to investigate the 7-year changes in corneal densitometry (CD) after small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK). Forty-two eyes undergoing SMILE and thirty-one undergoing FS-LASIK were included in this retrospective study. CD was measured preoperatively and at 3 and 7 years postoperatively. Three concentric radial zones (0-2, 2-6, and 6-10 mm) of three different corneal depths (anterior 120 µm, posterior 60 µm, and central layer) were analyzed. In all three zones of the three corneal layers, no significant difference in CD was found between the two groups preoperatively and at 3 and 7 years postoperatively (all P > 0.05). All CD values in the three zones of the anterior and central layers significantly declined at 3 years postoperatively (all P < 0.001), and then increased at 7 years postoperatively compared to corresponding 3-year values (all P < 0.01). In the posterior layer, CD values in the 0-2-mm and 2-6-mm zones decreased at 3 years postoperatively (all P < 0.01) and continued to decrease at 7 years postoperatively (all P < 0.01). Similar CD trends were observed after SMILE and FS-LASIK. Posterior layer CD showed a decrease throughout the study period. In the anterior and central layers, CD values decreased and then increased at 7 years postoperatively. The transparency changes might have been due to age-related three-dimensional growth of collagen fibers and wound-healing reactions.

A 20-year bibliometric analysis of Fuchs endothelial corneal dystrophy: from 2001 to 2020.

PURPOSE: The aim of this study was to identify trends and focuses in the field of Fuchs endothelial corneal dystrophy (FECD) research. METHODS: A bibliometric analysis based on the Web of Science Core Collection was conducted. All publications related to FECD from 2001 to 2020 were extracted and analyzed. VOSviewer v.1.6.17 was used to construct a visualization map and evaluate the trends and focuses in FECD research. RESULTS: A total of 1,041 publications were extracted. The rate of global publications has steadily increased. The United States produced the highest number of publications (461), the highest number of citations (18,757), and the highest H index (69). Melles GRJ published the highest number of papers (60), and Price FW had the highest number of citations (4,154) in the FECD research field. The highest number of publications came from the journal Cornea (279). Keywords were classified into four clusters: (1) corneal transplantation surgery, (2) surgical techniques and instruments, (3) corneal parameter measurement, and (4) genetic and molecular pathomechanisms. The average appearing years (AAYs) of the keywords were evaluated. Recently appearing keywords included "Tcf4 gene" (AAY of 2018.3), "ctg18.1" (AAY of 2017.2), "trinucleotide repeat expansion" (AAY of 2018.3), "rock inhibitor" (AAY of 2017.4), and "descemetorhexis" (AAY of 2017.4). CONCLUSIONS: The United States has a dominant position in FECD research. Although corneal transplantation surgery has been the most mainstream area of FECD research field for a long time, gene mutations such as the TCF4 CTG trinucleotide repeat expansion, nonsurgical interventions such as rho-associated kinase inhibitors, and newer surgical methods such as descemetorhexis without endothelial keratoplasty are potential research hotspots.

Comparison of Visual Outcomes and Higher-order Aberrations Between FS-LASIK and SMI-LIKE for Moderate to High Hyperopia: A 2-Year Result.

PURPOSE: The aim of the study was to evaluate and compare the long-term visual outcomes and higher-order aberrations (HOAs) between femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small-incision lenticule intrastromal keratoplasty (SMI-LIKE) in the correction of moderate to high hyperopia. METHODS: In this study, 16 subjects (20 eyes) underwent FS-LASIK and 7 subjects (10 eyes) underwent SMI-LIKE. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, mean keratometry (Km), anterior asphericity (Q), and HOAs preoperatively and 2 years postoperatively were obtained in both procedures. RESULTS: The efficacy indices of the FS-LASIK group and the SMI-LIKE group were 0.85 ± 0.14 and 0.87 ± 0.17, respectively. The safety indices of the FS-LASIK and SMI-LIKE groups were 0.99 ± 0.15 and 1.08 ± 0.24, respectively. No significant difference in safety index or efficacy index was found between the FS-LASIK and SMI-LIKE groups (all P > 0.05). The correlation coefficient of the attempted versus achieved spherical equivalent postoperatively was 0.69 ( P < 0.01) and 0.89 ( P < 0.01) in the FS-LASIK group and SMI-LIKE groups, respectively. The front Km, negative Q value, negative spherical aberrations (SAs), coma, and total HOAs significantly increased postoperatively in the 2 groups ( P < 0.05). The FS-LASIK group had greater changes in Q value and SA postoperatively than the SMI-LIKE group ( P < 0.01). CONCLUSIONS: SMI-LIKE had similar safety and efficacy to FS-LASIK in the correction of moderate to high hyperopia. However, SMI-LIKE may equip better visual quality postoperatively for its lower Q value and SA changes than FS-LASIK.

The Effects of High Lighting on the Development of Form-Deprivation Myopia in Guinea Pigs.

Purpose: To investigate the effects of high ambient lighting on refraction and ocular biometry in guinea pig models of form-deprivation myopia (FDM). Methods: Forty 3-week-old guinea pigs were randomly assigned to groups exposed to either high light (HL, 10,000 lux) or normal light (NL, 500 lux) with normal vision or form deprivation. Throughout the 10-week rearing period, animals were exposed to high light or normal light for 12 hours with a 12-hour light/dark cycle. Refraction, axial length (AL), and radius of corneal curvature (CCR) were measured by cycloplegic retinoscopy, A-scan ultrasonography, and keratometer, respectively. Results: At the end of treatment, form-deprived eyes under high ambient lighting exhibited more hyperopic refraction and shorter AL than those under normal ambient lighting (2.06 ± 1.68 diopters [D; mean ± SD] vs. -0.59 ± 1.56 D, P < 0.001; 8.36 ± 0.13 mm vs. 8.56 ± 0.16 mm, P < 0.001). Deprived eyes under high ambient lighting were relatively more myopic than their contralateral control eyes at the end of treatment (2.06 ± 1.68 D vs. 5.44 ± 0.66 D, P < 0.001). High lighting induced a significant hyperopic shift in normal eyes after 4 weeks of exposure. There were no significant differences in CCR between eyes exposed to high and normal light, nor between deprived eyes and contralateral eyes. Conclusions: High ambient lighting could retard, but not fully inhibit, the development of FDM. High light levels contributed to a greater hyperopic shift in normal eyes during the first 4 weeks of treatment. Corneal curvature was unaffected by either high ambient lighting or form deprivation.

Refraction and Ocular Biometry of Preschool Children in Shanghai, China.

PURPOSE: To investigate the refraction and ocular biometry characteristics and to examine the prevalence of refractive errors in preschool children aged 3 to 6 years in Shanghai, China. METHODS: A school-based cross-sectional study was conducted in Jiading and Xuhui District, Shanghai, in 2013. We randomly selected 7 kindergartens in Jiading District and 10 kindergartens in Xuhui District, with a probability proportionate to size. The children underwent comprehensive eye examinations, including cycloplegic refraction and biometric measurements. Myopia, hyperopia, astigmatism were defined as spherical equivalent (SE) ≤ -0.50 D, SE ≥ +2.00 D, and cylindrical diopters ≤ -1.00 D. RESULTS: The mean SE for 3- to 6-year-old children was +1.20 D (standard deviation [SD] 1.05), and the mean axial length (AL) was 22.29 mm (SD 0.73). The overall prevalence of myopia and astigmatism was 3.7% and 18.3%, respectively. No difference in prevalence of astigmatism was found across age groups. There was a statistically significant association between lower cylindrical diopters and higher spherical diopters (Spearman's correlation: -0.21, P < 0.001). CONCLUSION: Chinese children aged 3 to 6 years in the Shanghai area were mostly mildly hyperopic, with a low prevalence of myopia. Refractive astigmatism for children may be relatively stable throughout the preschool stage. Astigmatism was significantly associated with refractive error.