Ryan Eyn Kidd Man1, Muhammad Bayu Sasongko2, Jing Xie1, William J Best1, Jonathan E Noonan1, Tiffany Ching Shen Lo1, Jie Jin Wang3, Chi D Luu1, Ecosse L Lamoureux4. 1. Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia. 2. Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia Department of Ophthalmology, Faculty of Medicine, Gadjah Mada University, Yogyakarta, Indonesia. 3. Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia Centre for Vision Research, Westmead Millennium Institute, University of Sydney, Sydney, New South Wales, Australia. 4. Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia Singapore Eye Research Institute, National University of Singapore, Singapore Duke-NUS Graduate Medical School, Singapore.
Abstract
PURPOSE: The mechanisms supporting the protective relationship between a longer axial length (AL) and a decreased risk of diabetic retinopathy (DR) remain unclear. Previous studies have demonstrated reduced retinal blood flow in axial myopia, and it has been suggested that the compromised retinal capillaries in diabetes are less likely to leak and rupture as a result of this decreased flow. In this study, we therefore investigated if reduced retinal capillary flow (RCF) is a potential mechanism underpinning this protective relationship. METHODS: Retinal capillary flow was assessed using the Heidelberg Retinal Flowmeter in 150 eyes of 85 patients with diabetes aged 18+ years from the Royal Victorian Eye and Ear Hospital and St. Vincent's Hospital (Melbourne), Australia. Axial length was measured using the Intraocular Lens Master. Diabetic retinopathy was graded from two-field retinal photographs into none, mild, moderate, and severe DR using the modified Airlie House classification system. RESULTS: A total of 74 out of 150 eyes (49.3%) had DR. A longer AL was associated with decreased odds of DR presence (per mm increase in AL, odds ratio [OR] 0.61, 95% confidence interval [CI] 0.41-0.91) and DR severity (OR: 0.65; 95% CI: 0.44-0.95). However, no association was found between AL and RCF (per mm increase in AL, regression coefficient [β] -1.80, 95% CI -13.50 to 9.50) or between RCF and DR (per unit increase in RCF, OR 1.00; 95% CI 0.99-1.00). CONCLUSIONS: Our finding suggests that diminished RCF may not be a major factor underlying the protective association between axial elongation and DR. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.
PURPOSE: The mechanisms supporting the protective relationship between a longer axial length (AL) and a decreased risk of diabetic retinopathy (DR) remain unclear. Previous studies have demonstrated reduced retinal blood flow in axial myopia, and it has been suggested that the compromised retinal capillaries in diabetes are less likely to leak and rupture as a result of this decreased flow. In this study, we therefore investigated if reduced retinal capillary flow (RCF) is a potential mechanism underpinning this protective relationship. METHODS: Retinal capillary flow was assessed using the Heidelberg Retinal Flowmeter in 150 eyes of 85 patients with diabetes aged 18+ years from the Royal Victorian Eye and Ear Hospital and St. Vincent's Hospital (Melbourne), Australia. Axial length was measured using the Intraocular Lens Master. Diabetic retinopathy was graded from two-field retinal photographs into none, mild, moderate, and severe DR using the modified Airlie House classification system. RESULTS: A total of 74 out of 150 eyes (49.3%) had DR. A longer AL was associated with decreased odds of DR presence (per mm increase in AL, odds ratio [OR] 0.61, 95% confidence interval [CI] 0.41-0.91) and DR severity (OR: 0.65; 95% CI: 0.44-0.95). However, no association was found between AL and RCF (per mm increase in AL, regression coefficient [β] -1.80, 95% CI -13.50 to 9.50) or between RCF and DR (per unit increase in RCF, OR 1.00; 95% CI 0.99-1.00). CONCLUSIONS: Our finding suggests that diminished RCF may not be a major factor underlying the protective association between axial elongation and DR. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.