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.

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.

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.

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.

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.