Repeat corneal transplantation in Southern China: Indications, surgical technique, outcomes, and risk factors for repeat keratoplasty failure.

PURPOSE: To report the indications, surgical techniques, and outcomes of repeat keratoplasty and evaluate the risk factors for graft failure in the Chinese population. METHODS: The medical records of 216 patients (243 cases) who underwent at least two keratoplasties at a leading eye hospital in southern China between 2011 and 2020 were retrospectively reviewed. Indications and surgical procedures for repeat corneal transplantation were analyzed. Kaplan-Meier survival analysis was used to determine the graft survival rate after repeat keratoplasty. A multivariable survival model was used to assess the risk factors. RESULTS: Repeated keratoplasties increased continuously from 2011 to 2020 (P = 0.002). The most common primary indication was infectious keratitis (38.7%), and the most common reason for repeat keratoplasty was graft rejection (30.04%). Regraft techniques included penetrating keratoplasty (PK) in 165 cases (67.9%), deep lamellar keratoplasty (DALK) in 52 cases (21.40%), and endothelial keratoplasty (EK) in 26 cases (10.7%). Median survival was 5.3, 6.8, and 6.4 years for PK, DALK, and EK, respectively. The 5-year survival rate was 53.5%, 66.6%, and 69.8% for PK, DALK, and EK, respectively. The median LogMAR visual acuity was 1.4 for PK, 0.75 for DALK, and 1.2 for EK at the end of the follow-up. Multivariate analysis revealed that graft rejection is a risk factor for repeat keratoplasty failure (P = 0.002). CONCLUSIONS: DALK and EK may provide better outcomes than PK in treating graft failure. Preventing and treating postoperative graft rejection may be key to improving regraft survival. These findings will aid in the management of failed corneal grafts.

Interaction network of extracellular vesicles building universal analysis via eye tears: iNEBULA.

Discovering the secrets of diseases from tear extracellular vesicles (EVs) is well-recognized and appreciated. However, a precise understanding of the interaction network between EV populations and their biogenesis from our body requires more in-depth and systematic analysis. Here, we report the biological profiles of different-size tear EV subsets from healthy individuals and the origins of EV proteins. We have identified about 1800 proteins and revealed the preferential differences in the biogenesis among distinct subsets. We observe that eye-related proteins that maintain retinal homeostasis and regulate inflammation are preferentially enriched in medium-size EVs (100 to 200 nm) fractions. Using universal analysis in combination with the Human Protein Atlas consensus dataset, we found the genesis of tear EV proteins with 37 tissues and 79 cell types. The proteins related to retinal neuronal cells, glial cells, and blood and immune cells are selectively enriched among EV subsets. Our studies in heterogeneous tear EVs provide building blocks for future transformative precision molecular diagnostics and therapeutics.

Myopia progression and stabilization in school-aged children with single-vision lenses.

PURPOSE: To investigate the longitudinal changes in myopia from onset to stabilization in school-aged children with single-vison lenses (SVLs). METHODS: The medical records of patients wearing SVLs with long-term follow-up data between 2006 and 2016 were retrospectively reviewed. The patients who were 6-10 years old at the initial visit and 16 years old at the last assessment were included and analysed. The periods of progression and stabilization of myopia were evaluated by plotting fitted curves of the changes in spherical equivalent (SE). RESULTS: Seven hundred and seventy-three patients (median initial age 9 years) were accessed over an average of 7 years (IQR, 6-7 years). The initial mean SE was -1.92 ± 1.57 D and increased to -6.05 ± 2.14 D at 16 years old. The average age at myopia stabilization was 14.6 years, and girls slightly stabilized earlier than boys. 73.7% of the 6-year-olds and 85.7% of the 7-year-olds had high myopia at 16 years old, and the risk decreased each year from 7 to 10 years old. Children who had SE greater than -4 D up to 10 years had 89.0% risk of high myopia at 16 years old. Children with SE between -0.5 D and -2 D still had 34% risk of developing high myopia at 16 years old. CONCLUSION: This study provides a comprehensive picture of myopia progression from onset to stabilization in school-aged children with SVLs in China. All children who have myopia onset below 10 years of age were at risk for high myopia, and children who have myopia onset below 8 years of age require more attention.

Refractive status and prevalence of myopia among Chinese primary school students.

BACKGROUND: The aim of this study was to investigate the prevalence of myopia in key (university-oriented) and non-key elementary schools in China using a traditional and a new criterion for myopia diagnosis in an epidemiological study. METHODS: This school-based, cross-sectional study examined students from four key schools and seven non-key schools. Non-cycloplegic autorefraction and visual acuity (VA) were performed on each student. Myopia was defined as a spherical equivalent (SE) refractive error not better than -1.00 D. A questionnaire was also administered. RESULTS: Of the 13,220 students examined, 6,546 (49.5 per cent) had myopia using the criterion of SE not better than -1.00 D. However, 2,246 (34.3 per cent) of these myopes had VA ≥ 0 logMAR in both eyes, indicating they were not functioning as myopes. Thus, a second myopia criterion was adopted: SE refractive error not better than -1.00 D + uncorrected VA ≥ 0 logMAR in at least one eye. By this definition, only 32.5 per cent of the overall sample had myopia. Students in key schools had a higher prevalence of myopia than those in non-key schools (53.8 per cent versus 44.7 per cent) by the initial criterion. By the new criterion, the prevalence of myopia was 41.2 per cent versus 22.7 per cent. Myopia was equal in grade 1 of both school types, but accelerated faster in key schools, where there was a much higher prevalence of myopia by fourth grade, and continued up to 79.2 per cent prevalence by sixth grade based on SE refractive error not better than -1.00 D. CONCLUSION: Students in more competitive university-oriented elementary schools developed myopia much faster than those in regular schools, although they started with the same level of myopia. Since one-third of the 'myopes' had VA ≥ 0 logMAR in both eyes, they would not be prescribed a correction, or be clinically treated as myopes. A new criterion of SE refractive error not better than -1.00 D + uncorrected VA ≥ 0 logMAR in at least one eye was tested. This criterion is more clinically appropriate and could be used in future epidemiological studies.

Retinal Microvasculature in Amblyopic Children and the Quantitative Relationship Between Retinal Perfusion and Thickness.

Purpose: To quantify retinal vascular density in amblyopic children and to investigate the relationship between superficial and deep retinal vessel density and retinal thickness. Method: In this prospective cross-sectional study, 85 amblyopic children (5-12 years) and 66 age-matched control subjects participated at a pediatric ophthalmology clinic. Macular vessel densities of the superficial and deep capillary plexuses (SCP, DCP, respectively) and retinal thickness were measured by clinical optical coherence tomographic angiography (OCTA). Vessel density and retinal thickness were compared between amblyopic groups and the control group, and correlations among these two variables were analyzed. Results: Of the 85 amblyopic children, 52 children had anisometropic amblyopia, 16 had strabismic amblyopia, and 17 had bilateral amblyopia. The foveal and parafoveal macular vessel density in the SCP was lower in amblyopic than control children (P ≤ 0.008). Compared to strabismic and bilateral amblyopias, anisometropic amblyopia SCP differed the most from controls (P ≤ 0.005). Macular vessel density in the DCP of amblyopic children was similar to controls. Multiple linear regression analyses showed SCP vessel density was positively correlated with inner retinal thickness in the fovea (P < 0.001) and in the temporal, nasal, and inferior quadrants of the parafovea (P ≤ 0.008). Conclusions: Macular vessel density is decreased in anisometropic amblyopia, and to a lesser extent, the other amblyopias. Retinal small vessel density was correlated with the thickness of the macular inner retina. The causality of retinal change (i.e., whether it is primary or secondary to the onset of amblyopia) has not yet been determined.

Thickness of retinal layers in the foveas of children with anisometropic amblyopia.

PURPOSE: To use highly precise spectral-domain optical coherence tomography (SD-OCT) to determine whether there were structural abnormalities in the layers of different regions of the fovea in children with anisometropic amblyopia. METHODS: Eighteen children (mean age 7.8 years old; range 5-11 years) with unilateral anisometropic amblyopia and 18 age-matched control subjects participated. Foveal thickness was measured with an enhanced depth imaging system, SD-OCT and segmented into layers using custom developed software. The thickness of each layer of the fovea was compared among amblyopic eyes, fellow eyes and control eyes with optical magnification correction for axial length and statistical correction for age and sex. RESULTS: The total thickness and each intra-ocular layer of the central fovea were the same for each group. However, the amblyopic eyes were significantly thicker than the normal control eyes in 2 of 4 quadrants of the peripheral retina. Exploring intra-retinal layers in these two quadrants, the nasal nerve fiber layer (NFL) and inferior inner nuclear layer (INL)were significantly thicker in amblyopic eyes than in control eyes (p = 0.01 and 0.012, respectively, by ANCOVA). CONCLUSION: The SD-OCT data revealed marginal differences in some foveal layers at peripheral locations and indicated that structural differences might exist between individuals with amblyopia and visually normal control subjects. However, the differences were scattered and represented no identifiable pattern. More studies with large samples and precise locations of the retinal layers must be performed to extend the present results.

Macular choroidal thickness in unilateral amblyopic children.

PURPOSE: To investigate the choroidal thickness (CT) in children with amblyopia through spectral-domain optical coherence tomography (SD-OCT). METHODS: Thirty-seven children with unilateral amblyopia and 22 children with normal vision participated in the study. Cross-sectional images of the choroid of evaluated eyes were obtained by SD-OCT. The choroidal thickness was measured directly below the fovea and at eight other locations: 1 and 2 mm superior, temporal, inferior, and nasal to the fovea. The researchers compared the choroidal thickness among amblyopic eyes, fellow eyes of children with amblyopia, and the eyes of children with normal vision. Age, sex, refractive error, axial length, and best-corrected visual acuity were also recorded. A paired t-test was used to compare measurements between amblyopic eyes and fellow eyes in patients with amblyopia. A generalized estimating equation (GEE) was used to compare measurements among amblyopic eyes, fellow eyes, and control eyes, adjusting for the possible effects of age, sex, and axial length on CT. The correlation between choroidal thickness and other continuous variables was determined using the Pearson correlation coefficient. RESULTS: The choroidal thickness at the fovea, 1 and 2 mm superior, 1 mm inferior, 1 mm nasal, and 1 mm temporal to the fovea was greater in amblyopic eyes and in fellow eyes of children with amblyopia than in the eyes of children with normal vision. The choroidal thickness at the fovea and 2 mm nasal to the fovea in amblyopic eyes was greater (P = 0.002, P = 0.043) than in the fellow eyes of the children with amblyopia. The subfoveal CT in amblyopic eyes negatively correlated with axial length (r = -0.501, P = 0.002), but did not correlate with spherical equivalent, logMAR visual acuity, or age. CONCLUSIONS: In the subfoveal area, the choroid was thicker in amblyopic eyes than in fellow eyes in children with amblyopia. Furthermore, differences were found in the choroidal thickness in both eyes of children with amblyopia compared with participants with normal vision. A thicker choroid is somehow related to amblyopia, and this may be a useful diagnostic parameter for amblyopia.

Comparison of macular and retinal nerve fiber layer thickness in untreated and treated binocular amblyopia.

PURPOSES: To identify morphological retinal relationships to visual acuity (VA), refraction and axial length in binocular hyperopic amblyopia. MATERIALS AND METHODS: Children (n = 118), ages 5-12 years, were divided into three groups: those with current amblyopia (n = 53), those with fully corrected previous amblyopia (n = 26) and those with emmetropia and normal VA (n = 39). Macular thickness and peripapillary retinal nerve fiber layer (RNFL) thickness were measured by optical coherence tomography (OCT) and compared among the three groups. RESULTS: The outer macular ring and RNFL of the current amblyopia group were significantly (independent t-test) thicker than those of the emmetropia group. However, significance of this difference disappeared after adjustment for axial length and refractive error. There was no significant difference in foveal or inner macular ring thickness among the three groups, either before or after adjustment for age, gender, axial length, and refractive error. When controlled for age, gender and VA, outer macular ring and RNFL thicknesses correlated with axial length (r = -0.350 and -0.334, respectively; p < 0.001) and refraction (r = 0.298 and -0.237, respectively; p ≤ 0.011). CONCLUSIONS: Macular and RNFL thicknesses appear to be more extensively associated with differences in axial length and refraction than with amblyopic development, based on the fact that these thicknesses remained unchanged after amblyopic treatment.

Retinal nerve fibre layer thickness and macular thickness in patients with esotropic amblyopia.

BACKGROUND: The objective of this study was to evaluate the retinal nerve fibre layer thickness (RNFLT) and retinal macular thickness (RMT) in esotropic amblyopic children. METHODS: Twenty-one children diagnosed with esotropic amblyopia at Strabismus and Amblyopia Department of Wenzhou Medical College Affiliated Eye Hospital, China, were enrolled in the study. Their fellow eyes were normal and were used as controls. RNFLT and RMT were measured by optical coherence tomography (OCT). RESULTS: The fovea and the central sector of the retina in amblyopic eyes were slightly but not significantly thicker than those in the normal fellow eyes. There was no significant difference in any section of macular thickness between amblyopic and fellow eyes (p > 0.05). In addition, no significant differences in thickness were found between the retinal nerve fibre layers of amblyopic and normal fellow eyes (p > 0.05). CONCLUSION: There were no differences in the thickness of the foveal and the retinal nerve fibre layers found between eyes with esotropic amblyopia and the normal fellow eyes in children aged seven to 14 years.

Visual outcome in isoametropic amblyopic children with high hyperopia and the effect of therapy on retinal thickness.

PURPOSE: To assess correlations between associated factors and treatment outcome of isoametropic amblyopia attributable to high hyperopia in children and to evaluate changes in retinal thickness during amblyopic treatment. DESIGN: Retrospective (visual outcome) and prospective (retinal thickness) study. METHODS: Isoametropic (spherical equivalent ≥5.00 diopters in both eyes) amblyopic subjects (n = 217) with corrected visual acuity (VA) ≤0.5 (20/40) for children <5 years old and VA ≤0.6 (20/32) for children 6-10 years old were included. Sixty-nine of these children had refractive accommodative esotropia. All subjects were treated by full-time wearing of optical correction. The magnitude of spherical equivalent hyperopia, age at first treatment, VA, treatment duration, and binocular alignment were analyzed. Thicknesses of the retinal macula and nerve fiber layer were measured using optical coherence tomography in selected amblyopic children (n = 27) during treatment and in control subjects (n = 31). RESULTS: The mean follow-up was 28.8 months. The age at first optical correction ranged from 3 to 10 years. The mean VA improved from 0.38 to 0.82, with 74.7% having acuity ≥0.8 and 28.6% having acuity ≥1.0. VA improvement was positively correlated with duration of treatment and negatively correlated with age at first correction. Foveal thickness slightly decreased after treatment; however, it was not correlated with visual improvement. CONCLUSION: Visual acuity of isoametropic amblyopia improved satisfactorily with spectacle correction and vision therapy. Treatment duration had the greatest impact on VA improvement. Age at first correction also influenced VA improvement but was not a good clinical predictor. Foveal thinning occurring with treatment was not correlated with visual improvement.

Scheimpflug-Placido topographer and optical low-coherence reflectometry biometer: repeatability and agreement.

PURPOSE: To assess the repeatability of common measurements with the Sirius Scheimpflug-Placido topographer and Lenstar LS900 optical low-coherence reflectometry (OLCR) biometer and the limits of agreement (LoA) between the devices. SETTING: Eye Hospital of Wenzhou Medical College, Wenzhou, China. DESIGN: Comparative evaluation of a diagnostic test or technology. METHODS: One randomly healthy eye of subjects was scanned 3 times with both devices. The parameters assessed were central corneal thickness (CCT), anterior chamber depth (ACD) from the corneal epithelium and from the endothelium, mean keratometry (K), and white-to-white (WTW) corneal diameter. The repeatability of scans was calculated using the within-subject standard deviation after 1-way analysis of variance was performed. The agreement between devices was assessed using the Bland-Altman LoA method, which equals the mean difference between devices ± 1.96 × standard deviation of the differences. The mean of 3 scans of each device was used to assess the LoA. RESULTS: Forty subjects were evaluated. The repeatability of the Scheimpflug-Placido topographer and OLCR biometer was 3.10 µm and 3.32 µm for CCT, 0.04 mm and 0.05 mm for WTW corneal diameter, and 0.17 D and 0.10 D for mean K, respectively. The repeatability for both devices was 0.02 mm for the ACD from the corneal epithelium and the ACD from the corneal endothelium. On Bland-Altman LoA analysis, all parameters were within clinically acceptable limits. CONCLUSION: Both devices had excellent repeatability for all parameters assessed. Good LoAs were found between the 2 devices, indicating they can be used interchangeably for the parameters assessed.

Measurement of central corneal thickness by high-resolution Scheimpflug imaging, Fourier-domain optical coherence tomography and ultrasound pachymetry.

PURPOSE: To compare the repeatability and reproducibility of central corneal thickness (CCT) measurements by high-resolution (HR) rotating Scheimpflug imaging and Fourier-domain optical coherence tomography (FD-OCT). CCT measurements were compared to those determined by ultrasound pachymetry (UP). METHODS: In 35 healthy eyes, intra-observer repeatability for HR Scheimpflug (Pentacam) and FD-OCT (RTVue) systems was determined in consecutive images taken by an observer in the shortest time possible. Imaging was repeated again by a second observer to evaluate inter-observer reproducibility. The CCT measurements were compared among Scheimpflug, FD-OCT and UP images. RESULTS: Mean coefficients of repeatability were 0.48% for Scheimpflug and 0.26% for FD-OCT. For Scheimpflug, the coefficient of inter-operator reproducibility was 0.87%. For FD-OCT, the coefficient of inter-operator reproducibility was 0.45%. The CCT measurements by Scheimpflug, OCT and UP images were (mean ± standard deviation) 521.7 ± 27.6 µm, 510.8 ± 28.6 µm and 516.5 ± 27.6 µm, respectively. The differences between instruments were statistically significant. The 95% limits of agreement in CCT were -0.7 to 22.5 µm for Pentacam-OCT, -13.4 to 24.0 µm for Pentacam-UP and -26.7 to 15.4 µm for OCT-UP. There was a high degree of correlation between CCT measured by all 3 methods. CONCLUSION: Noncontact measurements of CCT with HR Scheimpflug and FD-OCT systems yielded excellent repeatability and reproducibility and can be used interchangeably. Although both devices were comparable with UP; in clinical practice, the measurements acquired by optical modalities are not directly interchangeable with UP measurements.