Three-Year Clinical Trial of Low-Concentration Atropine for Myopia Progression (LAMP) Study: Continued Versus Washout: Phase 3 Report.

PURPOSE: (1) To compare the efficacy of continued and stopping treatment for 0.05%, 0.025%, and 0.01% atropine during the third year. (2) To evaluate the efficacy of continued treatment over 3 years. (3) To investigate the rebound phenomenon and its determinants after cessation of treatment. DESIGN: A randomized, double-masked extended trial. PARTICIPANTS: A total of 350 of 438 children aged 4 to 12 years originally recruited into the Low-Concentration Atropine for Myopia Progression (LAMP) study. METHODS: At the beginning of the third year, children in each group were randomized at a 1:1 ratio to continued treatment and washout subgroups. Cycloplegic spherical equivalent (SE) refraction and axial length (AL) were measured at 4-month intervals. MAIN OUTCOME MEASURES: Changes in SE and AL between groups. RESULTS: A total of 326 children completed 3 years of follow-up. During the third year, SE progression and AL elongation were faster in the washout subgroups than in the continued treatment groups across all concentrations: -0.68 ± 0.49 diopters (D) versus -0.28 ± 0.42 D (P < 0.001) and 0.33 ± 0.17 mm versus 0.17 ± 0.14 mm (P < 0.001) for the 0.05%; -0.57 ± 0.38 D versus -0.35 ± 0.37 D (P = 0.004) and 0.29 ± 0.14 mm versus 0.20 ± 0.15 mm (P = 0.001) for the 0.025%; -0.56 ± 0.40 D versus -0.38 ± 0.49 D (P = 0.04) and 0.29 ± 0.15 mm versus 0.24 ± 0.18 mm (P = 0.13) for the 0.01%. Over the 3-year period, SE progressions were -0.73 ± 1.04 D, -1.31 ± 0.92 D, and -1.60 ± 1.32 D (P = 0.001) for the 0.05%, 0.025%, and 0.01% groups in the continued treatment subgroups, respectively, and -1.15 ± 1.13 D, -1.47 ± 0.77 D, and -1.81 ± 1.10 D (P = 0.03), respectively, in the washout subgroup. The respective AL elongations were 0.50 ± 0.40 mm, 0.74 ± 0.41 mm, and 0.89 ± 0.53 mm (P < 0.001) for the continued treatment subgroups and 0.70 ± 0.47 mm, 0.82 ± 0.37 mm, and 0.98 ± 0.48 mm (P = 0.04) for the washout subgroup. The rebound SE progressions during washout were concentration dependent, but their differences were clinically small (P = 0.15). Older age and lower concentration were associated with smaller rebound effects in both SE progression (P < 0.001) and AL elongation (P < 0.001). CONCLUSIONS: During the third year, continued atropine treatment achieved a better effect across all concentrations compared with the washout regimen. 0.05% atropine remained the optimal concentration over 3 years in Chinese children. The differences in rebound effects were clinically small across all 3 studied atropine concentrations. Stopping treatment at an older age and lower concentration are associated with a smaller rebound.

Efficacy and Safety of 8 Atropine Concentrations for Myopia Control in Children: A Network Meta-Analysis.

TOPIC: Comparative efficacy and safety of different concentrations of atropine for myopia control. CLINICAL RELEVANCE: Atropine is known to be an effective intervention to delay myopia progression. Nonetheless, no well-supported evidence exists yet to rank the clinical outcomes of various concentrations of atropine. METHODS: We searched PubMed, EMBASE, Cochrane Central Register of Controlled Trials, the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov on April 14, 2021. We selected studies involving atropine treatment of at least 1 year's duration for myopia control in children. We performed a network meta-analysis (NMA) of randomized controlled trials (RCTs) and compared 8 atropine concentrations (1% to 0.01%). We ranked the atropine concentrations for the corresponding outcomes by P score (estimate of probability of being best treatment). Our primary outcomes were mean annual changes in refraction (diopters/year) and axial length (AXL; millimeters/year). We extracted data on the proportion of eyes showing myopia progression and safety outcomes (photopic and mesopic pupil diameter, accommodation amplitude, and distance and near best-corrected visual acuity [BCVA]). RESULTS: Thirty pairwise comparisons from 16 RCTs (3272 participants) were obtained. Our NMA ranked the 1%, 0.5%, and 0.05% atropine concentrations as the 3 most beneficial for myopia control, as assessed for both primary outcomes: 1% atropine (mean differences compared with control: refraction, 0.81 [95% confidence interval (CI), 0.58-1.04]; AXL, -0.35 [-0.46 to -0.25]); 0.5% atropine (mean differences compared with control: refraction, 0.70 [95% CI, 0.40-1.00]; AXL, -0.23 [-0.38 to -0.07]); 0.05% atropine (mean differences compared with control: refraction, 0.62 [95% CI, 0.17-1.07]; AXL, -0.25 [-0.44 to -0.06]). In terms of myopia control as assessed by relative risk (RR) for overall myopia progression, 0.05% was ranked as the most beneficial concentration (RR, 0.39 [95% CI, 0.27-0.57]). The risk for adverse effects tended to rise as the atropine concentration was increased, although this tendency was not evident for distance BCVA. No valid network was formed for near BCVA. DISCUSSION: The ranking probability for efficacy was not proportional to dose (i.e., 0.05% atropine was comparable with that of high-dose atropine [1% and 0.5%]), although those for pupil size and accommodation amplitude were dose related.

Ocular size and shape in lens-induced Myopization in young Guinea pigs.

BACKGROUND: Lens-induced myopization in guinea pigs has been used as model for the process of myopization in humans. It has not been explored yet whether the change in globe shape in eyes undergoing myopization is similar in experimental myopia in guinea pigs and in clinical myopia in patients. METHODS: The study included 70 guinea pigs (age:2-3 weeks) equally divided into a study group with lens-induced myopization for 5 weeks, and a control group wearing goggles with no refractive power. The globe diameters were measured using a microcaliper after enucleation. RESULTS: The horizontal globe diameter (9.19 ± 0.15 mm versus 9.15 ± 0.18 mm; P = 0.25) and vertical globe diameter (9.02 ± 0.11 mm versus 8.99 ± 0.14 mm; P = 0.29) did not differ significantly between the study group and control group. The sagittal diameter was significantly longer in the study group (8.96 ± 0.15 mm versus 8.84 ± 0.14 mm; P = 0.001). While the vertical and horizontal globe diameters were correlated with each other in a ratio of approximately 1:1 (non-standardized regression coefficient B:0.94;95% confidence interval (CI):0.73,1.15), the steepness of the regression lines of the associations of both diameters with the sagittal diameter were flatter (horizontal to sagittal diameter: B: 0.64; 95% CI: 0.44,0.83; vertical to sagittal diameter:B:0.55;95% CI:0.41,0.69). Correspondingly, the ratios of horizontal-to-sagittal globe diameter and of vertical-to-sagittal globe diameter decreased (P < 0.001) with longer sagittal diameter. CONCLUSIONS: For each mm axial elongation in young guinea pigs the horizontal globe diameter increased by 0.64 mm (95%CI:0.44,0.83) and the vertical diameter by 0.55 mm (95% CI:0.41,0.69), indicating that the globe enlargement occurred predominantly in the sagittal direction. Axial elongation in guinea pigs led to a similar relative change in ocular shape as in humans.

Accuracy of swept-source optical coherence tomography based biometry for intraocular lens power calculation: a retrospective cross-sectional study.

BACKGROUND: To evaluate the accuracy of biometric measurements by a swept-source optical coherence tomography (SS-OCT) based biometry for intraocular lens (IOL) power calculation. METHODS: This retrospective observational study enrolled 431 patients undergoing cataract surgery. The charts were reviewed to investigate the failure rate of axial length (AL) measurement of the SS-OCT biometer, partial coherence interferometry (PCI), and A-scan ultrasonography (US) according to cataract type and severity. AL and keratometry in 164 eyes with the same IOL inserted were measured using the SS-OCT biometer, PCI, and A-scan US. The SRK/T formula was used to calculate IOL power. The mean absolute error (MAE) and percentage of eyes with a prediction error (PE) of ±0.50 D were compared. RESULTS: The AL measurement failure rate was 0.00% for A-scan US, 2.32% for the SS-OCT biometer, and 15.31% for PCI. The number of eyes measured using three devices (SS-OCT biometer, PCI, and A-scan US) was 128 (Group A) and the number of eyes measured using two devices (SS-OCT biometer and A-scan US) was 36 (Group B). The score of posterior subcapsular opacity was significantly different between two groups (p < .001). The SS-OCT biometer and PCI showed significantly lower MAE compared to A-scan US in Group A (p = 0.027). Using SS-OCT biometer, MAE showed no significant difference between Group A (0.36 ± 0.27) and Group B (0.36 ± 0.31) (p = 0.785). Whereas, MAE of A-scan US was significantly higher than Group A (0.47 ± 0.39) in Group B (0.64 ± 0.36) (p = 0.023). CONCLUSIONS: Using biometry with advanced OCT is useful in clinical practice as it is more effective in obtaining biometric measurements in the eyes with PSC and provides accurate measurements for IOL power calculation regardless of cataract type and severity. TRIAL REGISTRATION: Retrospectively registered. Registration number: KC16RISI1020 . Registered 03 January 2018.

Evaluation of eye-related parameters and adverse events of rigid gas permeable contact lens and spectacles correction in infants with monocular aphakia after congenital cataract surgery: a retrospective clinical study.

BACKGROUND: Congenital cataract is currently one of the leading blindness-causing eye diseases in children. Surgical treatment only opens the visual pathway for children. The postoperative recovery of visual function is also dependent on effective optical correction and visual function training. In this study, we analyzed the changes in eye-related parameters, adverse events and the annual cost of rigid gas permeable contact lens (RGPCL) and spectacles correction in infants with monocular aphakia after congenital cataract surgery. METHODS: To analyze the postoperative visual acuity, strabismus, nystagmus, myopic shift, globe axial length growth, adverse events, patient adherence to patching, and annual cost for patients with unilateral congenital cataract who underwent cataract surgery. Rigid gas permeable contact lenses or spectacles were used to correct aphakia after congenital cataract. RESULTS: Of the 49 patients, 20 patients with unilateral aphakia who used RGPCL were in group 1. Group 2 comprised 14 patients with persistent fetal vasculature (PFV) who used RGPCL, and there were 15 patients with spectacles in group 3. In group 1, there were important improvements in visual acuity, strabismus and nystagmus. In groups 2 and 3, there were no significant improvements in visual acuity, strabismus or nystagmus. Patients with a good adherence to patching had better visual acuity after the operation than patients who did not, in groups 1 and 3. There were no significant differences in myopic shift or rate of globe axial length growth among the 3 groups. No patients in group 1 had ocular disease that affected visual acuity. The mean annual expenses of the RGPCL group was 3965 yuan, and the mean annual cost of spectacles was 1140 yuan to 2500 yuan. CONCLUSION: RGPCL is a safe and effective optical correction method for patients with monocular aphakia after congenital cataract surgery. Spectacles are not an ideal optical correction. Using RGPCL to correct patients with PFV, the final visual acuity improved, but the difference was not statistically significant. There were no improvements in strabismus or nystagmus in patients with PFV.

Twenty-four hour ocular and systemic diurnal rhythms in children.

PURPOSE: Ocular diurnal rhythms have been implicated in myopia, glaucoma, diabetes, and other ocular pathologies. Ocular rhythms have been well described in adults; however, they have not yet been fully examined in children. The goal of this study was to investigate ocular and systemic diurnal rhythms over 24 h in children. METHODS: Subjects, ages 5 to 14 years (n = 18), wore a light, sleep, and activity monitor for one week to assess habitual sleep/wake patterns, then underwent diurnal measurements every 4 h for 24 h. Measurements included blood pressure, heart rate, body temperature, intraocular pressure (IOP), ocular biometry, and optical coherence tomography imaging. Saliva was collected for melatonin and cortisol analysis. Mean ocular perfusion pressure was calculated from IOP and blood pressure. Central corneal thickness, corneal power, anterior chamber depth, lens thickness, vitreous chamber depth, and axial length were determined from biometry. Total retinal thickness, retinal pigment epithelium (RPE) + photoreceptor outer segment thickness, photoreceptor inner segment thickness, and choroidal thickness were determined for a 1 mm diameter centred on the fovea. Subjects' amplitude and acrophase of diurnal variation for each parameter were determined using Fourier analysis, and mean acrophase was calculated using unit vector averaging. RESULTS: Repeated measures analysis of variance (ANOVA) showed that all parameters except anterior chamber depth exhibited significant variations over 24 h (p ≤ 0.005 for all). Axial length underwent diurnal variation of 45.25 ± 6.30 µm with an acrophase at 12.92 h, and choroidal thickness underwent diurnal variation of 26.25 ± 2.67 µm with an acrophase at 1.90 h. IOP was approximately in phase with axial length, with a diurnal variation of 4.19 ± 0.50 mmHg and acrophase at 11.37 h. Total retinal thickness underwent a significant diurnal variation of 4.09 ± 0.39 µm with an acrophase at 15.04 h. The RPE + outer segment layer was thickest at 3.25 h, while the inner segment layer was thickest at 14.95 h. Melatonin peaked during the dark period at 2.36 h, and cortisol peaked after light onset at 9.22 h. CONCLUSIONS: Ocular and systemic diurnal rhythms were robust in children and similar to those previously reported in adult populations. Axial length and IOP were approximately in phase with each other, and in antiphase to choroidal thickness. These findings may have important implications in myopia development in children.

Interocular Axial Length and Corneal Power Differences as Predictors of Postoperative Refractive Outcomes after Cataract Surgery.

PURPOSE: To determine whether differences between eyes in axial length (AL) and corneal power (K) on optical biometry are predictive of refractive outcomes. DESIGN: Retrospective cohort study. PARTICIPANTS: A total of 729 patients (1458 eyes) who underwent bilateral phacoemulsification at TLC (Mississauga, Ontario, Canada) from September 2013 to August 2015. METHODS: We compared the proportion of patients having >0.5 diopters (D) of refractive error from target stratified by interocular axial length differences (IALDs) and interocular K differences (IKDs) between eyes as measured by optical biometry (IOL-Master, Carl Zeiss Meditec, Oberkochen, Germany). Analysis was repeated for 0.25 D or 1.0 D targets and for patients with uncorrected visual acuity (UCVA) >0.3 logarithm of the minimum angle of resolution (logMAR) postoperatively. MAIN OUTCOME MEASURES: Proportions, odds ratios (ORs), and corresponding 95% confidence intervals (CIs) were computed using generalized estimating equations to account for within-patient correlation. RESULTS: Some 79.1% of eyes were ≤0.5 D of refractive target, 47.0% were ≤0.25 D, and 97.2% were ≤1.0 D. The OR of having a refractive outcome >0.5 D from target for IALD cutoff of 0.2 mm was 1.4 (1.1-1.8), of 0.3 mm was 1.6 (1.2-2.1), and of 0.4 mm was 1.8 (1.3-2.5). This translates to 70.0% (63.5-75.7) within target for IALD of ≥0.4 mm versus 80.7% (78.4-82.9) for <0.4 mm. For a given patient with IALD, the chance of being off target was similar for the shorter and longer eye. Eyes outside of target were twice as likely to be <-0.5 D than >0.5 D. Interocular K difference was largely not associated with prediction error, yet larger IKD-flat, steep, and average were associated with increased odds of UCVA >0.3 logMAR postoperatively. CONCLUSIONS: Interocular axial length difference of as little as ≥0.2 mm is associated with a higher chance of >0.5 D of refractive error from target and worse UCVA. Interocular K difference was not associated with worse refractive error from target, although a difference of ≥0.4 D was associated with worse UCVA. These cutoffs should be considered in preoperative planning and discussion with patients. Future study is required to assess whether repeating measurements, using adjunctive measurement devices, or attempting to separate true differences from artifact based on preoperative refractive characteristics reduces residual refractive error.

Anterior lens capsule strains during simulated accommodation in porcine eyes.

Experimental protocols have been developed to measure the spatial variation of the mechanical strains induced in the lens capsule during ex vivo lens stretching. The paper describes the application of these protocols to porcine lenses. The deformations and mechanical strains developed in the anterior capsule during each experiment were determined using full field digital image correlation techniques, by means of a speckle pattern applied to the lens surface. Several speckling techniques and illumination methods were assessed before a suitable combination was found. Additional data on the cross section shape of the anterior lens surface were obtained by Scheimpflug photography, to provide a means of correcting for lens curvature effects in the determination of the strains developed in the plane of the capsule. The capsule strains in porcine lenses exhibit non-linear behaviour, and hysteresis during loading and unloading. Peripheral regions experience higher magnitude strains than regions near the lens pole. The paper demonstrates the successful application of a procedure to make direct measurements of capsule strains simultaneously with ex vivo radial lens stretching. This experimental technique is applicable to future investigations on the mechanical characteristics of human lenses.

Altered gene expression in tree shrew retina and retinal pigment epithelium produced by short periods of minus-lens wear.

Hyperopic refractive error is detected by retinal neurons, which generate GO signals through a direct emmetropization signaling cascade: retinal pigment epithelium (RPE) into choroid and then into sclera, thereby increasing axial elongation. To examine signaling early in this cascade, we measured gene expression in the retina and RPE after short exposure to hyperopia produced by minus-lens wear. Gene expression in each tissue was compared with gene expression in combined retina + RPE. Starting 24 days after normal eye opening, three groups of juvenile tree shrews (n = 7 each) wore a monocular -5 D lens. The untreated fellow eye served as a control. The "6h" group wore the lens for 6 h; the "24h" group wore the lens for 24 h; each group provided separate retina and RPE tissues. Group "24hC" wore the lens for 24 h and provided combined retina + RPE tissue. Quantitative PCR was used to measure the relative differences (treated eye vs. control eye) in mRNA levels for 66 candidate genes. In the retina after 6 h, mRNA levels for seven genes were significantly regulated: EGR1 and FOS (early intermediate genes) were down-regulated in the treated eyes. Genes with secreted protein products, BMP2 and CTGF, were down-regulated, whilst FGF10, IL18, and SST were up-regulated. After 24 h the pattern changed; only one of the seven genes still showed differential expression; BMP2 was still down-regulated. Two new genes with secreted protein products, IGF2 and VIP, were up-regulated. In the RPE, consistent with its role in receiving, processing, and transmitting GO signaling, differential expression was found for genes whose protein products are at the cell surface, intracellular, in the nucleus, and are secreted. After 6 h, mRNA levels for 17 genes were down-regulated in the treated eyes, whilst four genes (GJA1, IGF2R, LRP2, and IL18) were up-regulated. After 24 h the pattern was similar; mRNA levels for 14 of the same genes were still down-regulated; only LRP2 remained up-regulated. mRNA levels for six genes no longer showed differential expression, whilst nine genes, not differentially expressed at 6 h, now showed differential expression. In the combined retina + RPE after 24 h, mRNA levels for only seven genes were differentially regulated despite the differential expression of many genes in the RPE. Four genes showed the same expression in combined tissue as in retina alone, including up-regulation of VIP despite significant VIP down-regulation in RPE. Thus, hyperopia-induced GO signaling, as measured by differential gene expression, differs in the retina and the RPE. Retinal gene expression changed between 6 h and 24 h of treatment, suggesting evolution of the retinal response. Gene expression in the RPE was similar at both time points, suggesting sustained signaling. The combined retina + RPE does not accurately represent gene expression in either retina or, especially, RPE. When gene expression signatures were compared with those in choroid and sclera, GO signaling, as encoded by differential gene expression, differs in each compartment of the direct emmetropization signaling cascade.

The distribution of retinal nerve fiber layer thickness and associations with age, refraction, and axial length: the Gutenberg health study.

PURPOSE: To evaluate the distribution of peripapillary retinal nerve fiber layer thickness as measured by optical coherence tomography and its associations with ocular parameters in a population-based setting. METHODS: In the population-based Gutenberg Health Study, 1974 subjects from the Mainz-Bingen region were scheduled for ophthalmologic examinations, including visual acuity, refraction, tonometry, biometry, and measurements of peripapillary retinal nerve fiber layer thickness (pRNFL) by optical coherence tomography (SD-OCT, Spectralis®, Heidelberg Engineering, Germany). The associated factors in the global and sectoral pRNFL data were analyzed using multivariable linear mixed models related to age, sex, and ocular parameters. RESULTS: Advanced age and longer axial length were associated with a thinner pRNFL, whereas pRNFL thickness was independent of sex, intraocular pressure (IOP), and central corneal thickness (CCT). Spherical equivalent was positively associated with pRNFL thickness, except in the temporal pRNFL sector. CONCLUSIONS: In this large, population-based study, pRNFL thickness decreased with age. Longer eyes had thinner pRNFL thickness. Sex, IOP, and CCT showed no significant association with pRNFL thickness. These data may improve the interpretation of pRNFL data.

Association between blood pressure and retinal arteriolar and venular diameters in Chinese early adolescent children, and whether the association has gender difference: a cross-sectional study.

BACKGROUND: To establish the independent association between blood pressure (BP) and retinal vascular caliber, especially the retinal venular caliber, in a population of 12-year-old Chinese children. METHODS: We have examined 1501 students in the 7th grade with mean age of 12.7 years. A non-mydriatic fundus camera (Canon CR-2, Tokyo, Japan) was used to capture 450 fundus images of the right eyes. Retinal vascular caliber was measured using a computer-based program (IVAN). BP was measured using an automated sphygmomanometer (HEM-907, Omron, Kyoto, Japan). RESULTS: The mean retinal arteriolar caliber was 145.3 µm (95% confidence interval [CI], 110.6-189.6 µm) and the mean venular caliber was 212.7 µm (95% CI, 170.6-271.3 µm). After controlling for age, sex, axial length, BMI, waist, spherical equivalent, birth weight, gestational age and fellow retinal vessel caliber, children in the highest quartile of BP had significantly narrower retinal arteriolar caliber than those with lower quartiles (P for trend< 0.05). Each 10-mmHg increase in BP was associated with narrowing of the retinal arterioles by 3.00 µm (multivariable-adjusted P < 0.001), and the results were consist in three BP measurements. The association between BP measures and retinal venular caliber did not persist after adjusting for fellow arteriolar caliber. And there was no significant interaction between BP and sex, age, BMI, and birth status. CONCLUSIONS: In a large population of adolescent Chinese children, higher BP was found to be associated with narrower retinal arterioles, but not with retinal venules. Sex and other confounding factors had no effect on the relationship of BP and retinal vessel diameter.

The repeatability of superficial retinal vessel density measurements in eyes with long axial length using optical coherence tomography angiography.

BACKGROUND: To investigate the repeatability of superficial retinal vessel density measurements in healthy eyes with long axial length (AL) using optical coherence tomography angiography (OCTA). METHODS: There were 60 eyes of 31 volunteers enrolled in this cross-sectional observational study. All subjects underwent OCTA, AL and refraction test. The enrolled eyes were divided into the long AL group (26 mm ≤ AL < 28 mm) and normal AL group (22 mm ≤ AL < 26 mm). The vessel length density (VLD), perfusion density (PD), and fovea avascular zone (FAZ) of the superficial retinal vessel were evaluated. Repeatability was assessed by intraclass correlation coefficients (ICCs) and Bland-Altman analysis. Pearson's r correlation was used to analyze the relation of AL and the absolute difference between two measurements. RESULTS: The 3 × 3 mm scan pattern showed good repeatability with all ICCs over 0.7. For all parameters of all scan patterns, the ICCs of the normal AL group were distinctly higher than those of the long AL group; this finding was also confirmed by Bland-Altman analysis. The correlation analysis of AL and repeatability of OCTA parameters showed significant negative correlations between the ALs and repeatability of VLD in 6 × 6 mm inner ring (r2 = 0.13, p = 0.01), VLD in 6 × 6 mm outer ring (r2 = 0.09, p = 0.02) and PD in 6 × 6 mm outer ring (r2 = 0.08, p = 0.03). CONCLUSIONS: The AL and the scanned area will both affect the repeatability of superficial retinal vessel density measurements in OCTA.

Efficacy of Trial Fitting and Software Fitting for Orthokeratology Lens: One-Year Follow-Up Study.

OBJECTIVE: To observe and compare the clinical efficacy of 1-year trial fitting and software fitting orthokeratology lenses. METHODS: One hundred myopes who received vision correction with the use of orthokeratology lenses form July 2016 to September 2017 were included in this study. Subjects were assigned randomly into the two groups: the trial fitting group (group A) and the software fitting group (group B). For the right eye of each subject, measurements, such as uncorrected visual acuity (UCVA, logarithm of minimal angle of resolution), refractive error, corneal topography, ocular health status, and the fitting situation, were obtained at baseline, 1 week, 1 month, 3 months, 6 months, and 12 months after lens wear. Axial length and corneal endothelium cells (CECs) were also measured at baseline and 12 months after wearing the lens. RESULTS: Compared with the baseline, the spherical equivalent refraction, UCVA, and central corneal curvature changed significantly after orthokeratology (OK) lens wear (all P<0.05). Between groups A and B, the parameters aforementioned were insignificant at each time point (all P>0.05). Axial length and CECs showed no significant changes during the first year of OK treatment (all P>0.05). Rate of corneal staining between two groups revealed no difference during 1-year visit (P<0.05). CONCLUSION: Both the trial lens fitting and software fitting approaches were effective in temporarily reducing myopia, providing good UCVA and delaying the elongation of axial length for moderate and high myopic adolescents. Both the two approaches can be combined in OK lens fitting.

Short-Term and Long-Term Changes in Corneal Power Are Not Correlated With Axial Elongation of the Eye Induced by Orthokeratology in Children.

PURPOSE: To assess the relationship between short-term and long-term changes in power at different corneal locations relative to the change in central corneal power and the 2-year change in axial elongation relative to baseline in children fitted with orthokeratology contact lenses (OK). METHODS: Thirty-one white European subjects 6 to 12 years of age and with myopia -0.75 to -4.00 DS and astigmatism ≤1.00 DC were fitted with OK. Differences in refractive power 3 and 24 months post-OK in comparison with baseline and relative to the change in central corneal power were determined from corneal topography data in eight different corneal regions (i.e., N[nasal]1, N2, T[temporal]1, T2, I[inferior]1, I2, S[superior]1, S2), and correlated with OK-induced axial length changes at two years relative to baseline. RESULTS: After 2 years of OK lens wear, axial length increased by 0.48±0.18 mm (P<0.001), which corresponded to an increase of 1.94±0.74% ([2-years change in axial length/baseline axial length]×100). However, the change in axial elongation in comparison with baseline was not significantly correlated with changes in corneal power induced by OK relative to baseline for any of the corneal regions assessed (all P>0.05). CONCLUSION: The reduction in central corneal power and relative increase in paracentral and pericentral power induced by OK over 2 years were not significantly correlated with concurrent changes in axial length of white European children.

Axial Elongation in Myopic Children and its Association With Myopia Progression in the Correction of Myopia Evaluation Trial.

OBJECTIVES: Describe axial elongation using 14-year longitudinal data in a large, ethnically diverse group of myopic children, estimate age and axial length (AL) at stabilization, and evaluate associations between the progression and stabilization of AL and myopia. METHODS: Axial length was measured by A-scan ultrasonography annually. Axial length data were fit with individual polynomial functions and curve-based parameters (AL at stabilization and age at stabilization when annual rate of axial elongation ≤0.06 mm) were estimated. For myopia progression, noncycloplegic spherical equivalent refractions were fit with Gompertz functions. RESULTS: Four hundred thirty-one participants, with AL and myopia data fit successfully, were classified into four cohorts: Younger (n=30); Older (n=334); AL Stabilized at Baseline (n=19); and AL Not Stabilized (n=48). At AL stabilization, for participants in the Younger and Older Cohorts, mean (SD) age and AL were 16.3 (2.4) years and 25.2 (0.9) mm, respectively. No associations were found between age at AL stabilization and ethnicity, sex, or number of myopic parents. At stabilization, sex and number of myopic parents (both P<0.003), but not ethnicity, were significantly associated with AL. Axial length and myopia progression curves were highly correlated overall (all r>0.77, P<0.0001). However, unlike AL, the amount of myopia did not differ significantly between males and females. CONCLUSIONS: In most of the participants, AL increased rapidly at younger ages and then slowed and stabilized. The close association between growth and stabilization of AL and myopia is consistent with the suggestion that axial elongation is the primary ocular component in myopia progression and stabilization.

Whole-globe biomechanics using high-field MRI.

The eye is a complex structure composed of several interconnected tissues acting together, across the whole globe, to resist deformation due to intraocular pressure (IOP). However, most work in the ocular biomechanics field only examines the response to IOP over smaller regions of the eye. We used high-field MRI to measure IOP induced ocular displacements and deformations over the whole globe. Seven sheep eyes were obtained from a local abattoir and imaged within 48 h using MRI at multiple levels of IOP. IOP was controlled with a gravity perfusion system and a cannula inserted into the anterior chamber. T2-weighted imaging was performed to the eyes serially at 0 mmHg, 10 mmHg, 20 mmHg and 40 mmHg of IOP using a 9.4 T MRI scanner. Manual morphometry was conducted using 3D visualization software to quantify IOP-induced effects at the globe scale (e.g. axial length and equatorial diameters) or optic nerve head scale (e.g. canal diameter, peripapillary sclera bowing). Measurement sensitivity analysis was conducted to determine measurement precision. High-field MRI revealed an outward bowing of the posterior sclera and anterior bulging of the cornea due to IOP elevation. Increments in IOP from 10 to 40 mmHg caused measurable increases in axial length in 6 of 7 eyes of 7.9 ± 5.7% (mean ± SD). Changes in equatorial diameter were minimal, 0.4 ± 1.2% between 10 and 40 mmHg, and in all cases less than the measurement sensitivity. The effects were nonlinear, with larger deformations at normal IOPs (10-20 mmHg) than at elevated IOPs (20-40 mmHg). IOP also caused measurable increases in the nasal-temporal scleral canal diameter of 13.4 ± 9.7% between 0 and 20 mmHg, but not in the superior-inferior diameter. This study demonstrates that high-field MRI can be used to visualize and measure simultaneously the effects of IOP over the whole globe, including the effects on axial length and equatorial diameter, posterior sclera displacement and bowing, and even changes in scleral canal diameter. The fact that the equatorial diameter did not change with IOP, in agreement with previous studies, indicates that a fixed boundary condition is a reasonable assumption for half globe inflation tests and computational models. Our results demonstrate the potential of high-field MRI to contribute to understanding ocular biomechanics, and specifically of the effects of IOP in large animal models.

CHOROIDAL THICKNESS IN HEALTHY CHINESE CHILDREN AGED 6 to 12: The Shanghai Children Eye Study.

PURPOSE: To explore the characteristics of choroidal thickness (ChT) in Chinese children. METHODS: A total of 144 healthy children, aged 6 years to 12 years old, were enrolled in the study. The ChT of subfovea and peripheral locations 0.5, 1.5, and 2.5 mm away from the fovea were evaluated by enhanced depth imaging optical coherence tomography. The association between subfoveal ChT and systemic, as well as ocular factors, including age, sex, height, weight, body mass index, axial length, refractive error, intraocular pressure, preterm history, and the refractive status of parents were studied. RESULTS: The mean subfoveal ChT was 302 ± 63 µm. In the nasal, superior, and inferior areas, the ChT of locations closer to the fovea was thicker than those farther away from the fovea (all P < 0.05); however, ChT was not significantly different among different locations in the temporal area (P = 0.16). The ChT of the nasal quadrant was significantly thinner than that of other areas (P < 0.01). Subfoveal ChT decreased with age, axial length, preterm history, and increased with height. Sex was not statistically associated with subfoveal ChT. CONCLUSION: In Chinese children, the ChT is thinnest in the nasal quadrant and thicker in central regions than in peripheral areas. The subfoveal ChT independently decreases with age, axial length, preterm history, and increases with height.

GUNN'S DOTS IN RETINAL IMAGES OF 2,286 ADOLESCENTS: Prevalence, Retinal Distribution and Associations.

PURPOSE: To investigate the epidemiology of Gunn's dots and their associations in a population-based cohort of children. METHODS: Red-free fundus photographs from 2,286 children aged 11 years to 14 years from the Sydney Myopia Study were graded. Gunn's dots were manually marked and counted within a 6 mm grid centered on the optic disc. RESULTS: One or more Gunn's dots were seen in at least one eye in 82.6% of children. The median number of Gunn's dots per eye was 46 (range 0-482). Most Gunn's dots were found inferior and superior of the optic disc (49.3% and 45.8%, respectively, of the total number of Gunn's dots in the population). The odds for having 1 or more Gunn's dots were 3-fold greater in children with dark brown irides compared with children with blue irides (odds ratio 2.99, 95% CI 1.81 to 4.94, P < 0.0001 adjusted for age, sex, retinal nerve fiber layer thickness, refraction, ethnicity, and axial length). In the same analysis, the presence of 1 or more Gunn's dots was less frequent in children with thin retinal nerve fiber layers (first quartile) compared with children with thick retinal nerve fiber layers (fourth quartile) (odds ratio 0.68, 95% CI 0.49-0.93, P = 0.016). No disease or disease-marker associations were identified. CONCLUSION: Gunn's dots were visible on fundus photographs in most of the school children, most of the dots being located inferiorly and superiorly to the optic disc. Fundus photographically visible Gunn's dots were associated with darker irides and thicker retinal nerve fiber layers. Gunn's dots are a common and apparently harmless finding in children. Assessment of their clinical significance will require long-term follow-up.

CHOROIDAL THICKNESS IN UNILATERAL IDIOPATHIC MACULAR HOLE: A Cross-Sectional Study and Meta-Analysis.

PURPOSE: To investigate the choroidal thickness in unilateral idiopathic macular hole (IMH) eyes and compare them with normal control eyes using enhanced depth imaging optical coherence tomography (EDI-OCT). METHODS: In this cross-sectional study, the subfoveal choroidal thickness (SFCT) and choroidal thickness at 1 mm and 3 mm nasal, temporal, superior, and inferior to the fovea of IMH eyes and normal control eyes were measured using EDI-OCT. Univariate and multivariate linear regression analyses were performed to evaluate the correlation between choroidal thickness at various locations and clinical factors. A meta-analysis was conducted using the Stata software package to calculate the summary of weighted mean differences (WMDs). RESULTS: Thirty-two unilateral IMH patients and 32 controls were enrolled in this study. The IMH eyes had a thinner choroid than the control eyes at all macular locations (all P < 0.001). Multivariate linear regression analysis further showed that the choroidal thickness at any of the nine points was significantly thinner in association with the IMH diagnosis, as well as being somewhat thinner in association with age and axial length. The result of our cross-sectional study was consistent with the meta-analysis with a pooled WMD of -56.99 (95% confidence interval [CI]: -68.58 to -45.41) for subfoveal choroidal thickness. CONCLUSION: The study of Chinese unilateral IMH patients, along with the comprehensive meta-analysis, suggested that the choroidal thickness at all macular locations in unilateral IMH eyes significantly decreased relative to the control group.

Analysis of various factors affecting pupil size in patients with glaucoma.

BACKGROUND: Pupil size is an important factor in predicting post-operative satisfaction. We assessed the correlation between pupil size, measured by Humphrey static perimetry, and various affecting factors in patients with glaucoma. METHODS: In total, 825 eyes of 415 patients were evaluated retrospectively. Pupil size was measured with Humphrey static perimetry. Comparisons of pupil size according to the presence of glaucoma were evaluated, as were correlations between pupil size and various factors, including age, logMAR best corrected visual acuity (BCVA), retinal nerve fiber layer (RNFL) thickness, spherical equivalent, intraocular pressure, axial length, central corneal thickness, white-to-white, and the kappa angle. RESULTS: Pupil size was significantly smaller in glaucoma patients than in glaucoma suspects (p < 0.001) or the normal group (p < 0.001). Pupil size decreased significantly as age (p < 0.001) and central cornea thickness (p = 0.007) increased, and increased significantly as logMAR BCVA (p = 0.02) became worse and spherical equivalent (p = 0.007) and RNFL thickness (p = 0.042) increased. In patients older than 50 years, pupil size was significantly larger in eyes with a history of cataract surgery. CONCLUSIONS: Humphrey static perimetry can be useful in measuring pupil size. Pupil size was significantly smaller in eyes with glaucoma. Other factors affecting pupil size can be used in a preoperative evaluation when considering cataract surgery or laser refractive surgery.