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Dawn Sim, Pearse Keane, Javier Zarranz-Ventura, Catey Bunce, Marcus Fruttiger, Praveen Patel, Adnan Tufail, Catherine Egan; Predictive Factors for the Progression of Diabetic Macular Ischemia. Invest. Ophthalmol. Vis. Sci. 2013;54(15):211. doi: https://doi.org/.
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To investigate the predictive factors for diabetic macular ischemia (DMI) progression, through the analysis of fluorescein angiography (FA) parameters.
DMI severity was assessed using Early Treatment Diabetic Retinopathy Study (ETDRS) protocols, and custom software was used to quantify areas of the foveal avascular zone (FAZ). 79 patients with Type 2 diabetes mellitus, and ETDRS-DMI grades “mild”, “moderate” or “severe”, with at least two macula centered FA images (separated by a minimum time interval of 6 months) were included. Multivariable logistic regression models were used to assess the relationship between FAZ enlargement rate (mm2/year) and its clinical co-variates.
The median FAZ areas, in mild, moderate, and severe ETDRS-DMI grades, at baseline, were 0.28, 0.37, and 0.73 mm2 respectively. This was significantly increased within grades, at the final FA - 0.31, 0.41, and 1.23 mm2. (p<0.001) The mean duration of follow-up between baseline and final FA (39.0, 45.8, and 30.6 months) was not significantly different between groups. (p=0.24) The overall median FAZ enlargement rate was 0.023 mm2/year (IQR, 0.001 to 0.060), representing an enlargement rate of 7.42% of the baseline FAZ area per year. Enlargement rates were significantly higher in (1) more advanced ETDRS-DMI grades - “severe” [(0.073 mm2 (10.4%)/year)] compared to “mild” [(0.021 mm2 (7.50%)/year)] (p=0.02) or “moderate” [(0.019 (5.13%) mm2/year] (p=0.03), and (2) in eyes which showed a worsening VA of greater than 0.05 LogMar (1 Snellen line) per year [0.057 mm2 (19.0%)/year], compared to eyes which did not [0.018 mm2 (5.62%)/year) (p=0.002). Predictors for DMI progression include, ETDRS-DMI severity grade, (OR=2.47, CI=1.21 to 5.05, p=0.02) and a worsening VA (OR=4.98, CI=1.60 to 15.5, p=0.01). DMI progression was also an independent predictive factor for VA deterioration ((OR=4.60, CI=1.54 to 13.7, p=0.03).
The rate of FAZ enlargement increases with DMI severity, and ranges from 5 to 10% of baseline FAZ area per year. A greater ETDRS-DMI grade and worsening VA were independently predictive for DMI progression in eyes with established ischemia. DMI progression itself, was also independently predictive of VA deterioration.
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