Opthalmology & Visual Sciences publications

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Browsing Opthalmology & Visual Sciences publications by Author "Abhary, S."

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    Association between erythropoietin gene polymorphisms and diabetic retinopathy
    (Amer Medical Assoc, 2010) Abhary, S.; Burdon, K.; Casson, R.; Goggin, M.; Petrovsky, N.; Craig, J.
    Objective: To determine whether sequence variation in the erythropoietin gene (EPO) is associated with the development of diabetic retinopathy (DR). Methods: This was a multicenter study based on 518 subjects with long-standing diabetes mellitus (DM), 173 with type 1DM (T1DM) and 345 with type 2DM (T2DM). Study groups consisted of 233 control subjects with no DR, 155 subjects with nonproliferative DR, 126 with proliferative DR, and 90 with clinically significant macular edema. Subjects with end-stage renal disease were excluded. DNA extracted from blood of each subject was genotyped for 3 EPO single-nucleotide polymorphisms (SNPs). Results: All 3 SNPs in EPO were associated with overall DR status in the combined T1DM and T2DM and T2DM alone groups (CC genotype of rs507392, P < .008; GG genotype of rs1617640, P < .008; and CC genotype of rs551238, P < .008) in the multivariate analysis. The GCC haplotype was also associated with overall DR status in the combined DM and T2DM alone groups (P=.008) by multivariate analysis. All SNPs and the GCC haplotype were also associated with proliferative DR and clinically significant macular edema in the combined DM andT2DMalone groups. No associations were found with T1DM alone. Conclusion: Sequence variation in EPO is associated with the risk of DR independent of duration of DM, degree of glycemic control, and nephropathy. Clinical Relevance: Identifying EPO genetic markers for high risk of developing DR could lead to the possibility of developing novel treatments or preventive therapies.
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    Common sequence variation in the VEGFA gene predicts risk of diabetic retinopathy
    (Assoc Research Vision Ophthalmology Inc, 2009) Abhary, S.; Burdon, K.; Gupta, A.; Lake, S.; Selva-Nayagam, D.; Petrovsky, N.; Craig, J.
    Purpose. Vascular endothelial growth factor (VEGF) is a multifunctional cytokine that plays a role in angiogenesis and microvascular permeability. This study was conducted to determine whether common sequence variation in the VEGFA gene plays a role in the development of diabetic retinopathy (DR). Method. Five hundred fifty-four subjects with diabetes mellitus (DM) including 190 type 1 DM (T1DM) and 364 type 2 DM (T2DM) were recruited. The study group consisted of 235 participants without DR, 158 with nonproliferative DR (NPDR), 132 with proliferative DR (PDR), and 93 with clinically significant macular edema (CSME). Blinding DR was defined as severe NPDR, PDR, or CSME. Fifteen VEGFA tag single-nucleotide polymorphisms (SNPs) were genotyped in all subjects and tested for association with blinding DR. Results. Multiple tag SNPs in the VEGFA gene were associated with blinding DR. After controlling for sex, HbA1c, and duration of disease, in T1DM, the AA genotype of rs699946 (P = 0.007, odds ratio [OR], 4.1; 95% confidence interval [CI], 1.5–11.4) and the GG genotype of rs833068 (P = 0.017, OR, 3.1; 95% CI, 1.3–7.2) were most significantly associated. In T2DM, the C allele of rs3025021 (P = 0.002; OR, 3.8; 95% CI, 1.5–10.0) and the G allele of rs10434 (P = 0.002; OR, 2.6; 95% CI, 1.3–5.3) were most significantly associated with blinding DR. Haplotype analyses suggested an important role for the haplotype TCCGCG in blinding DR (P = 0.0004). Conclusions. Sequence variation in the VEGFA gene is associated with risk of developing blinding DR in T1DM and T2DM. Identifying specific genetic markers will allow for refined screening algorithms and earlier intervention in patients at highest risk.
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    Genetic study of diabetic retinopathy: recruitment methodology and analysis of baseline characteristics
    (Wiley, 2014) Kaidonis, G.; Abhary, S.; Daniell, M.; Gillies, M.; Fogarty, R.; Petrovsky, N.; Jenkins, A.; Essex, R.; Chang, J.; Pal, B.; Hewitt, A.; Burdon, K.; Craig, J.
    BACKGROUND: Diabetic retinopathy (DR) is a blinding disease of increasing prevalence that is caused by a complex interplay of genetic and environmental factors. Here we describe the patient recruitment methodology, case and control definitions, and clinical characteristics of a study sample to be used for genome-wide association analysis to detect genetic risk variants of DR. METHODS: One thousand six hundred sixty-nine participants with either type 1 (T1) or type 2 (T2) diabetes mellitus (DM) aged 18 to 95 years were recruited in Australian hospital clinics. Individuals with T2DM had disease duration of at least 5 years and were taking oral hypoglycaemic medication, and/or insulin therapy. Participants underwent ophthalmic examination. Medical history and biochemistry results were collected. Venous blood was obtained for genetic analysis. RESULTS: Six hundred eighty-three diabetic cases (178 T1DM and 505 T2DM participants) with sight-threatening DR, defined as severe non-proliferative DR, proliferative DR or diabetic macular oedema were included in this analysis. Eight hundred twelve individuals with DM but no DR or minimal non-proliferative DR were recruited as controls (191 with T1DM and 621 with T2DM). The presence of sight-threatening DR was significantly correlated with DM duration, hypertension, nephropathy, neuropathy, HbA1C and body mass index. Diabetic macular oedema was associated with T2DM (P < 0.001), whereas proliferative DR was associated with T1DM (P < 0.001). CONCLUSIONS: Adoption of a case-control study design involving extremes of the DR phenotype makes this a suitable cohort, for a well-powered genome-wide association study to detect genetic risk variants for DR.
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    The prevalence, severity and risk factors for pterygium in central Myanmar: the Meiktila Eye Study
    (British Med Journal Publ Group, 2008) Durkin, S.; Abhary, S.; Newland, H.; Selva-Nayagam, D.; Aung, T.; Casson, R.
    Aims: To determine the prevalence, severity and risk factors associated with pterygium in adults in central Myanmar. Methods: Population-based, cross-sectional survey of the people 40 years and over residing in rural Myanmar. Pterygium was graded for severity (T1 to T3) by visibility of episcleral vessels, and the apical extent was recorded. An autorefractor was used to measure refractive error. Results: There were 2481 subjects identified, and 2076 (83.7%) participated. The prevalence of pterygium in either eye was 19.6% (95% confidence interval (CI) 16.9 to 22.2) and of bilateral pterygium 8.0% (95% CI 7.7 to 8.3). Outdoor occupation was an independent predictor of pterygium (p<0.01). The mean apical extent from the limbus was 2.2 mm (95% CI 2.05 to 2.35). Higher-grade pterygia did not have a significantly greater apical extent (p = 0.35). The presence of pterygium was associated with astigmatism, (p = 0.01), and the amount of astigmatism increased as both the severity (p<0.01) and apical extent increased (p<0.01). Two people of the 84 people blinded in both eyes were bilaterally blind from pterygium (1.7%; 95% CI 0.2 to 6.1), and pterygium accounted for 2.2% (95% CI 0.7 to 5.0) of blindness in at least one eye. No participant had low vision in both eyes due to pterygium, but pterygium led to 0.8% (95% CI 0.3 to 1.6) of low vision in at least one eye. Pterygium was therefore associated with 0.4% (95% CI 0.04 to 1.3) of binocular visual impairment and 1.0% (95% CI 0.6 to 1.8) of visual impairment in a least one eye. Conclusions: There is a high prevalence of pterygium in central Myanmar, and the risk of developing this condition increases with outdoor occupation. Pterygium in this population is associated with considerable visual morbidity, including blindness.