"In addition, the relative hypoxic conditions in hyperopic eyes may cause increased cytokine production. Jonas et al  reported that the intraocular concentration of vascular endothelial growth factor (VEGF) decreased significantly with increasing myopia, and as a corollary, with increasing AL. The larger ocular volume in myopic eyes was thought to dilute intraocular VEGF, leading to decreased angiogenesis. "
[Show abstract][Hide abstract] ABSTRACT: To summarize relevant evidence investigating the associations between refractive error and age-related macular degeneration (AMD).
Systematic review and meta-analysis.
We searched Medline, Web of Science, and Cochrane databases as well as the reference lists of retrieved articles to identify studies that met the inclusion criteria. Extracted data were combined using a random-effects meta-analysis. Studies that were pertinent to our topic but did not meet the criteria for quantitative analysis were reported in a systematic review instead.
Pooled odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between refractive error (hyperopia, myopia, per-diopter increase in spherical equivalent [SE] toward hyperopia, per-millimeter increase in axial length [AL]) and AMD (early and late, prevalent and incident).
Fourteen studies comprising over 5800 patients were eligible. Significant associations were found between hyperopia, myopia, per-diopter increase in SE, per-millimeter increase in AL, and prevalent early AMD. The pooled ORs and 95% CIs were 1.13 (1.06-1.20), 0.75 (0.56-0.94), 1.10 (1.07-1.14), and 0.79 (0.73-0.85), respectively. The per-diopter increase in SE was also significantly associated with early AMD incidence (OR, 1.06; 95% CI, 1.02-1.10). However, no significant association was found between hyperopia or myopia and early AMD incidence. Furthermore, neither prevalent nor incident late AMD was associated with refractive error. Considerable heterogeneity was found among studies investigating the association between myopia and prevalent early AMD (P = 0.001, I2 = 72.2%). Geographic location might play a role; the heterogeneity became non-significant after stratifying these studies into Asian and non-Asian subgroups.
Refractive error is associated with early AMD but not with late AMD. More large-scale longitudinal studies are needed to further investigate such associations.
PLoS ONE 03/2014; 9(3):e90897. DOI:10.1371/journal.pone.0090897 · 3.23 Impact Factor
"There has been several studies about the role of VEDF and PEDF in development of CNV, and anti-VEGF therapy has been used for treating CNV. In the previous study [17,18], it has been reported that the VEGF concentration in the aqueous humor of patients with myopic CNV is lower than in normal controls  and there are significantly lower concentrations of VEGF in myopic eyes than in hyperopic eyes . However, it is unknown whether these results are due to dilution effect in larger eyes or degeneration of retinal pigment epithelium (RPE) and choroid. "
[Show abstract][Hide abstract] ABSTRACT: To compare the aqueous humor levels of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) in high myopic eyes and control eyes.
Aqueous humor samples were collected from 21 highly myopic eyes of 20 patients (high myopia group) and from 30 cataract eyes of 30 patients with no choroidal neovascularization (CNV) or other ocular or systemic diseases (control group). Of the 21 high myopic eyes, 13 had no complications secondary to high myopia (high myopia with no complications group), 3 had posterior staphyloma (high myopia with staphyloma group), and 5 had chorioretinal atrophy (high myopia with chorioretinal atrophy group). The aqueous humor levels of VEGF and PEDF were determined by using commercially available enzyme-linked immunosorbent assay kits.
Aqueous humor levels of VEGF were significantly lower in the high myopia group compared to that in the control group (p<0.001). VEGF levels decreased with an increase in the axial length (p<0.001). PEDF levels tended to be higher in the high myopia group compared to that in the control group; however, the difference was not significant. Three high myopia groups had significantly lower VEGF/PEDF ratios than the control group (p=0.000, 0.002, and 0.005).
Aqueous humor levels of VEGF in the high myopia group were significantly lower than those in the control group. The differing levels of VEGF and PEDF in the high myopia and control groups suggest that high myopia disrupts the VEGF/PEDF balance in retinal pigment epithelium (RPE) cells.
[Show abstract][Hide abstract] ABSTRACT: To assess associations between age-related macular degeneration (AMD) and ocular and general parameters.
The Central India Eye and Medical Study, a population-based study performed in rural Central India, included 4711 subjects (aged 30+ years) out of 5885 eligible subjects (response rate: 80.1%). Fundus photographs were assessed using the Wisconsin Age-Related Maculopathy Grading system.
Fundus photographs were available for 4542 (96.4%) subjects. Early AMD was present in 215/4542 subjects (4.7 ± 0.3%), and late AMD was detected in 8/4542 (0.2 ± 0.03%) subjects. After adjustment for age, prevalence of AMD was significantly associated with hyperopic refractive error (p = 0.001), shorter axial length (p = 0.01), and higher corneal refractive power (p = 0.02). Each dioptre increase in hyperopic refraction or each millimetre decrease in axial length was associated with a 15% [odds ratio (OR):1.15; 95% confidence interval (CI): 1.06, 1.24] and 19% (OR: 0.81; 95%CI: 0.69, 0.95) increased probability of early AMD, respectively. AMD was not significantly associated with blood pressure, serum concentration of cholesterol, glycosylated haemoglobin Hb1Ac, high-density lipoproteins and postprandial glucose, gender, level of education, any parameter of smoking, alcohol consumption, psychiatric depression or of daily activities, anterior chamber depth, lens thickness, intraocular pressure, size of the optic disc, neuroretinal rim and parapapillary atrophy, nor amount of nuclear cataract and status after cataract surgery. If the statistical analysis was adjusted for age and refractive error, age-related macular degeneration was marginally significantly associated with a low intake of fruits (p = 0.06).
Hyperopia (and short axial length) besides age was the single most important associated factor for AMD in adult Indians.
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