Eye size and shape in newborn children and their relation to axial length and refraction at 3 years.

PURPOSE: To determine if eye size and shape at birth are associated with eye size and refractive error 3 years later. METHODS: A subset of 173 full-term newborn infants from the Growing Up in Singapore Towards healthy Outcomes (GUSTO) birth cohort underwent magnetic resonance imaging (MRI) to measure the dimensions of the internal eye. Eye shape was assessed by an oblateness index, calculated as 1 - (axial length/width) or 1 - (axial length/height). Cycloplegic autorefraction (Canon Autorefractor RK-F1) and optical biometry (IOLMaster) were performed 3 years later. RESULTS: Both eyes of 173 children were analysed. Eyes with longer axial length at birth had smaller increases in axial length at 3 years (p < 0.001). Eyes with larger baseline volumes and surface areas had smaller increases in axial length at 3 years (p < 0.001 for both). Eyes which were more oblate at birth had greater increases in axial length at 3 years (p < 0.001). Using width to calculate oblateness, prolate eyes had smaller increases in axial length at 3 years compared to oblate eyes (p < 0.001), and, using height, prolate and spherical eyes had smaller increases in axial length at 3 years compared to oblate eyes (p < 0.001 for both). There were no associations between eye size and shape at birth and refraction, corneal curvature or myopia at 3 years. CONCLUSIONS: Eyes that are larger and have prolate or spherical shapes at birth exhibit smaller increases in axial length over the first 3 years of life. Eye size and shape at birth influence subsequent eye growth but not refractive error development.

Prognostic factor analysis of vitrectomy for retinal detachment associated with myopic macular holes.

PURPOSE: To describe the anatomic and functional outcomes in a cohort of subjects undergoing vitrectomy for retinal detachment (RD) resulting from myopic macular hole (MH) and to analyze the prognostic and surgical factors predicting retinal reattachment and MH closure. DESIGN: Retrospective case series. PARTICIPANTS: All patients who underwent vitrectomy for RD resulting from myopic MH between 2000 and 2009 at our center. METHODS: Case records were reviewed at 6 months after surgery. Retinal reattachment and complete anatomic success, defined as retinal reattachment with MH closure, were assessed. Multivariate logistic regression models, including age, gender, duration of symptoms, spherical equivalent refraction (SE), internal limiting membrane peeling, tamponade choice, and concurrent scleral buckling, were constructed to assess associations with covariates. MAIN OUTCOME MEASURES: Retinal reattachment and complete anatomic success (retinal reattachment with MH closure). RESULTS: In total, 114 subjects were analyzed. Most were women (n = 79 [69.3%]), and the mean age was 57.5±13.3 years. The mean SE was -9.88±6.37 diopters. At 6 months, 98 subjects (86.0%) demonstrated retinal reattachment, of whom 93 subjects required only 1 operation. Complete anatomic success was achieved in 61 subjects (53.5%), of whom 55 needed only 1 operation. Subjects with retinal reattachment had better best-corrected visual acuity (BCVA; mean BCVA, 1.22±0.81 logarithm of the minimum angle of resolution [logMAR] units) than those without (mean BCVA, 1.98±1.26 logMAR units; P < 0.001), and subjects with complete anatomic success had better BCVA (mean BCVA, 1.05±0.87 logMAR units) than those without (mean BCVA, 1.62±0.87 logMAR units; P < 0.001). In multivariate analyses, increasing age and the use of perfluoropropane (C3F8) tamponade were predictive of anatomic success (per 1-year increase: odds ratio [OR], 1.049; 95% confidence interval [CI], 1.002-1.099; P = 0.04; and for tamponade: OR, 10.71; 95% CI, 1.08-106.29; P = 0.04). CONCLUSIONS: Vitrectomy is effective in the repair of RD resulting from MH in myopic eyes, with retinal reattachment achieved more frequently than MH closure. Retinal reattachment and MH closure are important for improving visual outcomes. Greater age at presentation and use of C3F8 are associated with a greater likelihood of anatomic success.

1 Year Surgical Outcomes and Safety of Combined Trans Pars Plana Vitrectomy with Iris Fixated Posterior Chamber Intraocular Lens for Subluxated Intraocular Lens and Cataracts.

IMPORTANCE/BACKGROUND: To describe the characteristics and 1-year postoperative surgical outcomes of primary combined trans pars plana vitrectomy (TPPV) with iris-fixated posterior-chamber intraocular lens (IF-PCIOL) implantation for subluxated cataracts and intraocular lenses (IOLs). METHODS: Consecutive cases of significantly subluxated cataracts and IOLs from January 2014 to May 2019 were included in this retrospective case series. RESULTS: A total of 103 eyes of 103 patients were included. Median age was 67.4 (interquartile range [IQR] 27-89) years. Thirty-two (31.1%) had subluxated cataracts, while 71 (68.9%) had subluxated IOLs. Overall median preoperative logMAR BCVA was 0.9 (IQR 0-2.5). Median logMAR BCVA improved to 0.3 (0-1.9) and 0.2 (0-1.8) for the subluxated cataract and IOL groups, 81.2% and 75% of eyes achieved logMAR ≤ 0.3, and 94% and 97% achieved IOL stability at month 12, respectively. Eyes with subluxated IOLs had a significantly less myopic median SE if a new IOL was implanted compared to iris-fixating the dislocated IOL. CONCLUSION: Combined primary TPPV and IF-PCIOL implantation is a good surgical option for subluxated IOL or cataract without sufficient capsular support, with at least 75% achieving logMAR BCVA ≤ 0.3 and 95% IOL stability at postoperative year 1. In eyes with subluxated IOLs, explanting that IOL and iris-fixating a new IOL led to a reduced SE and better visual outcome at postoperative month 12 when compared to iris-fixating the dislocated IOL.

Are myopic eyes less likely to have diabetic retinopathy?

PURPOSE: Eyes with myopia may be less likely to develop diabetic retinopathy (DR). The relationship between refractive error, ocular biometry, and DR therefore was investigated. DESIGN: Population-based, cross-sectional study. PARTICIPANTS: Persons with diabetes from the Singapore Malay Eye Study (SiMES). METHODS: Diabetes mellitus was defined as random glucose of 11.1 mmol/l or more, use of diabetic medication, or a physician diagnosis of diabetes. Spherical equivalent refraction (SE) was assessed using an autokeratorefractometer and subjective refraction. Axial length (AL) and anterior chamber depth (ACD) were measured by IOLMaster (Carl Zeiss Meditec AG, Jena, Germany). Diabetic retinopathy was graded from retinal photographs. MAIN OUTCOME MEASURES: Any DR was defined by characteristic lesions defined by the Early Treatment Diabetic Retinopathy Study (ETDRS); moderate DR by ETDRS retinopathy severity scores of 43 or higher; and vision-threatening retinopathy by severe nonproliferative retinopathy, proliferative DR, or clinically significant macular edema. RESULTS: Of 3280 adult Malay participants (78.7% response), 629 persons with diabetes contributed to this analysis. In multivariate analyses adjusting for age, gender, education, height, cataract, hypertension, hemoglobin A1c, and other factors, eyes with myopic SE were less likely to have any DR (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.84-0.96; P = 0.002, per 1-diopter [D] decrease), moderate DR (OR, 0.83; 95% CI, 0.73-0.93; P = 0.001, per 1-D decrease), and vision-threatening DR (OR, 0.77; 95% CI, 0.67-0.88; P<0.001, per 1-D decrease). Eyes with longer AL were less likely to have any DR (OR, 0.86; 95% CI, 0.75-0.99; P = 0.041, per 1-mm increase), moderate DR (OR, 0.80; 95% CI, 0.62-1.05; P = 0.11, per 1-mm increase), and vision-threatening DR (OR, 0.63; 95% CI, 0.40-0.99; P = 0.044, per mm increase). Eyes with deeper ACD were less likely to have moderate DR (OR, 0.32; 95% CI, 0.16-0.64; P = 0.001, per 1-mm increase) and vision-threatening DR (OR, 0.14; 95% CI, 0.06-0.36; P = 0.001, per 1-mm increase). CONCLUSIONS: Myopic refraction and longer AL are associated with a lower risk of DR, particularly vision-threatening retinopathy, without any evidence of a threshold.

MRI of posterior eye shape and its associations with myopia and ethnicity.

PURPOSE: To evaluate posterior eye shape variations across a wide refractive error range using brain MRI in a multiethnic cohort. METHODS: Adult subjects in the multiethnic Singapore Epidemiology of Eye Disease study were included. Spherical equivalent (SE) was measured using subjective refraction, and axial length (AL) was measured using optical biometry. MRI was performed using a 3-Tesla whole body scanner with a 32-channel head coil. The radii and asphericity based on fitting of the posterior two-thirds of the eye (240°) were calculated. The refractive error status was categorised as myopic (SE<-0.5 D) or non-myopic (SE≥-0.5 D). RESULTS: A total of 450 adult participants (mean age 64.2±6.5 years old) were included. Less oblate asphericity was associated with more myopic SE, longer AL and with a refractive error categorisation of myopia (p<0.001 for all). Asphericity values were less oblate in myopic compared with non-myopic eyes (p<0.001). Multivariate analysis showed that Chinese subjects had less oblate eyes than Malay and Indian subjects, especially in non-myopic eyes. CONCLUSIONS: A less oblate posterior eye shape was associated with myopic eyes. Chinese eyes have less oblate shapes than Malay and Indian eyes, especially in non-myopic eyes.

Retinal Vascular Oxygen Saturation and Its Variation With Refractive Error and Axial Length.

PURPOSE: To evaluate the relationships between refractive error, axial length (AL), and retinal vascular oxygen saturation in an adult population. METHODS: This was a hospital-based, prospective observational study. The left eyes of phakic adult subjects without media opacity were analyzed. Subjective undilated manifest refraction was performed, and refractive errors were defined as myopia (spherical equivalent [SE], <-1 D), emmetropia (SE between -1 D and +1 D) and hyperopia (SE >+1 D). Retinal oximetry was performed using the Oxymap system (Oxymap Inc., Reykjavik, Iceland). Multivariate linear regression models were constructed to assess the relationship between retinal vascular oxygen saturation, SE, and AL obtained with optical biometry, with adjustments for age, sex, race, blood pressure, hyperlipidemia, and diabetes mellitus. RESULTS: There were 85 subjects, with mean age of 66.1 ± 11.3 years. The majority were female (60%) and Chinese (84%). A total of 60% were myopic, 28% emmetropic, and 12% hyperopic. Mean SE was -5.29 ± 6.51 D and mean AL was 25.30 ± 2.99 mm. In multivariate analyses, more myopic SE and longer AL were associated with lower retinal arteriolar oxygen saturation (regression coefficient B = 0.61 [95% confidence interval, 0.28, 0.95], P = 0.001; and B = -1.13 [95% confidence interval, -1.71, -0.56], P < 0.001, respectively). Subjects with myopic SE and AL also had lower retinal arteriolar oxygen saturation than emmetropes and hyperopes (P = 0.03 and P = 0.02, respectively). CONCLUSIONS: Eyes with more myopic SE and longer AL have lower retinal arteriolar oxygen saturation. TRANSLATIONAL RELEVANCE: This study provides direct evidence of a link between retinal oxygenation and hypoxia and myopia by using a novel device that quantifies retinal vascular oxygenation in vivo.

Prognostic factor analysis of vitrectomy for myopic foveoschisis.

PURPOSE: To describe the anatomical and functional outcomes in a cohort of subjects undergoing vitrectomy for myopic foveoschisis, and to analyse the factors predicting foveal reattachment and visual improvement. METHODS: This retrospective case series evaluated case records and optical coherence tomography images 6 months after surgery. Multivariate linear and logistic regressions were performed to assess the factors predicting anatomical and visual improvement. RESULTS: In total, 55 eyes of 54 patients were analysed. The mean spherical equivalent refraction was -11.83±4.94D. Foveal detachment was present in 63.5% of eyes preoperatively and subjects with foveal detachment had 0.70 logMAR units (95% CI 0.02 to 1.39) poorer visual acuity than subjects without (p=0.046). The mean preoperative visual acuity was 0.84±0.59 logMAR units and the mean postoperative visual acuity was 0.64±0.64 logMAR units (mean difference 0.20±0.68 logMAR units (p=0.04)). The proportion of eyes with foveal detachment was significantly lower after surgery (12.5%; p<0.001). However, the proportion of eyes with ellipsoid zone disruption was significantly higher after surgery (59.6% vs 34.0%; p<0.001). In multivariate analyses, the preoperative central foveal thickness significantly predicted postoperative visual improvement by two or more lines (OR 1.004 (95% CI 1.000 to 1.007), per µm increase; p=0.049). The presence of ellipsoid zone disruption preoperatively was associated with 0.96 logMAR (95% CI 0.2 to 1.72) poorer final acuity (p=0.02). CONCLUSIONS: Eyes with myopic foveoschisis with preoperative ellipsoid disruption and thinner central foveal thickness tend to have poorer visual outcomes. While current surgical manoeuvres are effective in reattaching the fovea, they may also cause iatrogenic injury to the photoreceptors.

Retinal vessel oxygen saturation increases after vitrectomy.

PURPOSE: To evaluate the effects of vitrectomy on retinal vascular oxygen saturation in an adult population. METHODS: This was a prospective observational study. Twenty-seven eyes of 27 patients who underwent vitrectomy for macular conditions were included. Retinal oximetry was performed using the Oxymap system prior to vitrectomy and 3 months after surgery and the mean retinal arterial and venous oxygen saturation were measured. The arterial-venous difference (AVD) was calculated as the difference between the arterial and venous saturations. Multivariate linear regression models were constructed to compare oxygen saturation before and after surgery, with adjustments for age, sex, hypertension, hyperlipidemia, diabetes mellitus, and indication for surgery. RESULTS: The mean age of the subjects was 68.4 ± 8.9 years, 15 (55%) were male and the majority were of Chinese ethnicity (93%). The mean arterial saturation increased significantly after vitrectomy (101.93 ± 8.36% vs. 96.16 ± 14.14%, P = 0.01). The mean venous saturation also increased significantly after surgery (59.76 ± 8.52% vs. 50.40 ± 11.72%, P = 0.02). The mean AVD significantly decreased from 45.76 ± 12.18% before surgery to 42.17 ± 10.94% after surgery (P = 0.02). CONCLUSIONS: Retinal arterial and venous oxygen saturation are significantly increased after vitrectomy, while the AVD is decreased after vitrectomy.

Asian Age-Related Macular Degeneration: Current Concepts and Gaps in Knowledge.

Data on the epidemiology and treatment of age-related macular degeneration (AMD) in Asian populations have been scarce. Recently, significant advances in the current knowledge of AMD in Asia have been made, but deficiencies in important areas remain. Epidemiological data on AMD in those 80 years or older are lacking.There are also few incidence data on AMD or polypoidal choroidal vasculopathy (PCV), an important variant of AMD that seems to be more common in Asia. The risk factors for PCV have not been clearly defined to the extent that those for AMD have. No trials of nutritional supplementation for AMD prevention in Asia exist, and there is also a lack of long-term clinical trial data on combination therapy for PCV and indeed very few trial data on PCV. These represent opportunities for future research. With aging populations in Asia, increased data on the prevalence, risk factors, prevention, and treatment of AMD and PCV in Asian populations will be needed to formulate evidence-based public health and clinical guidelines.

Structural changes in the retinal microvasculature and renal function.

PURPOSE: To evaluate the associations between chronic kidney disease (CKD) and microalbuminuria, and a comprehensive range of retinal microvascular abnormalities including traditional and new retinal vascular measures. METHODS: This was a population-based, cross-sectional study on 3280 urban Malay adults. The albumin/creatinine ratio (ACR) was calculated from spot urine samples. Estimated glomerular filtration rate (eGFR) was calculated from serum creatinine concentration. Retinal vascular caliber and geometry were quantified from retinal fundus photographs using a semiautomated computer-assisted program. Qualitative changes including focal arteriolar narrowing, arteriovenous nicking, and opacification of the arteriolar wall were assessed by trained graders. RESULTS: In multivariate analyses adjusting for age, sex, hypertension, diabetes, and smoking, narrower retinal arteriolar caliber (P = 0.008), smaller retinal vascular fractal dimensions (P = 0.014), and the presence of AV nicking and opacification (P = 0.005 and P < 0.001, respectively) were significantly associated with lower eGFR. In multivariate adjusted logistic regression analyses, none of the retinal markers was associated with CKD. A smaller fractal dimension (P < 0.001) and the presence of focal arteriolar narrowing, AV nicking and opacification were associated with higher ACR (P < 0.001, P = 0.01, and P = 0.002, respectively). Narrower retinal arterioles (P = 0.041); smaller fractal dimensions (P = 0.006); and focal arteriolar narrowing, AV nicking, and opacification (P = 0.007, P = 0.007, and P = 0.012, respectively) were associated with higher likelihoods of having microalbuminuria. CONCLUSIONS: Quantitative changes of the retinal vascular geometry and qualitative changes in the vessel architecture are associated with markers of renal dysfunction and damage.

Distribution and determinants of eye size and shape in newborn children: a magnetic resonance imaging analysis.

PURPOSE: To determine the eye size and shape obtained by magnetic resonance imaging (MRI), and to determine associations with antenatal factors in newborn children. METHODS: A subset of 173 full-term newborn children from the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) birth cohort underwent MRI. Eye volume and surface area were measured. Eye shape was assessed qualitatively from three-dimensional models, and quantitatively by measurement of longitudinal axial length (AL, the length from the posterior corneal surface to the retinal surface), and horizontal width and vertical height of the internal eye along the cardinal axes. Oblateness was calculated as 1-(AL/width) or 1-(AL/height). Oblate eyes had oblateness>+0.01, spherical eyes had oblateness between +0.01 and -0.01, and prolate eyes had oblateness<-0.01. RESULTS: A total of 346 eyes of 173 children were included. Mean oblateness using width was -0.06±0.05 (range, -0.23 to +0.08), and mean oblateness using height was -0.01±0.04 (range, -0.19 to +0.13). Using width, most eyes were prolate (294 eyes, 85%); and using height, the largest proportion of eyes was prolate (163 eyes, 47%). Eyes with longer ALs had greater widths, heights, volumes, and surface areas than eyes with shorter ALs (P<0.001 for all). With increasing AL, eyes became increasingly prolate. Children of less educated mothers had longer ALs (P=0.02). Malay children had larger eye volumes and surface areas than Chinese or Indian children. CONCLUSIONS: Most newborn Singaporean Asian children are born with prolate eyes. A longitudinal study is required to determine if globe shape at birth influences subsequent refractive changes.

Influence of refractive error and axial length on retinal vessel geometric characteristics.

PURPOSE: To evaluate the influence of refractive error and axial length (AL) on retinal vascular network geometry measurements in an adult Asian population. METHODS: This was a population-based, cross-sectional study on 2882 persons with diabetes in the Singapore Malay Eye Study. Spherical equivalent refraction was assessed using an autokeratorefractometer and subjective refraction. AL retinal vascular caliber, tortuosity, and branching characteristics were quantified from retinal fundus photographs using a semiautomated computer-assisted program according to a standardized protocol. RESULTS: In multivariate analyses adjusting for age, sex, education, smoking, blood pressure, diabetes status, and antihypertensive medication use, longer AL and more myopic refraction were associated with narrower retinal arterioles and venules (P ≤ 0.001 for all) and less tortuous (straighter) arterioles (P < 0.001 for both). Longer AL and more myopic refraction were also associated with increased branching coefficients in both arterioles (P < 0.001 for both) and venules (P = 0.02 and P < 0.001, respectively). Longer AL and more myopic refraction were associated with more acute branching angles in arterioles (P < 0.001 for both) but not venules. CONCLUSIONS: Myopic refractive errors and longer AL are associated with narrower retinal arterioles and venules, less tortuous arterioles, and increased branching coefficients in both arterioles and venules. These findings provide insights into ocular blood flow in myopia and also suggest that future studies evaluating these retinal parameters should account for the influence of AL and refractive error.

C-reactive protein, body mass index, and diabetic retinopathy.

PURPOSE: C-reactive protein (CRP) is an inflammatory biomarker that may be associated with diabetic retinopathy (DR), but body mass index (BMI) is an important confounder of this relationship. The purpose of this study was to determine the relationship between CRP, BMI, and existing DR. METHODS: This was a population-based, cross-sectional study on 718 persons with diabetes in the Singapore Malay Eye Study (SiMES). Diabetes was defined as random glucose>or=11.1 mmol/L, on diabetic medication or a history of physician-diagnosed diabetes. CRP was measured in frozen plasma. DR was graded from retinal photographs. RESULTS: Higher CRP and BMI were associated with lower prevalence of DR. After adjustment for age, sex, HbA1c level, hypertension, smoking, total cholesterol level, cholesterol-lowering medication, and insulin use, persons with the highest quartiles of CRP were less likely to have any DR (odds ratio [OR] 0.5; 95% CI, 0.3-0.9, comparing the fourth with the first quartile of CRP), vision-threatening DR (OR 0.3; 95% CI, 0.1-0.7), or CSME (OR 0.2; 95% CI, 0.1-0.6). Similarly, persons with the highest quartiles of BMI were less likely to have any DR (OR 0.5; 95% CI, 0.3-0.7), moderate DR (OR 0.4; 95% CI, 0.2-0.7), vision-threatening DR (OR 0.4; 95% CI, 0.1-0.8) or CSME (OR 0.2; 95% CI, 0.0-1.0). No significant interactions between CRP and BMI on DR were seen. CONCLUSIONS: Persons with diabetes who had higher levels of CRP and BMI were less likely to have DR. Further research is needed to understand the interrelationship role of inflammation, body weight, and microvascular complications.

Distribution and determinants of ocular biometric parameters in an Asian population: the Singapore Malay eye study.

PURPOSE: To examine the distribution and systemic determinants of ocular biometry as measured using partial laser interferometry in an adult Asian population. METHODS: A population-based, cross-sectional study of 3280 persons (78.7% participation rate) ages 40 to 80 years, of Malay ethnicity residing in Singapore, was conducted. Axial ocular dimensions, including axial length (AL), anterior chamber depth (ACD), and corneal curvature (CC), were determined with partial laser interferometry. Participants had a comprehensive interview and a standardized examination. RESULTS: After 492 persons were excluded who had undergone cataract surgery, data on 2788 subjects were available. The mean AL, ACD, and CC were 23.55, 3.10, and 7.65 mm, respectively. AL and ACD decreased with increasing age. In multivariate models that adjusted for age, sex, education, height, weight, number of reading hours, diabetes, and current smoking, longer AL was associated with being male, height, increasing weight, higher education levels, and total reading hours. Increasing CC was associated with greater age and greater height and weight after multivariable adjustment. CONCLUSIONS: Age, sex, and stature were the most consistent predictors of the results of ocular biometry in the Singapore Malay adult population.