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A. R. Shah, L. V. Del Priore; Progression of Occult, Minimally Classis and Predominantly Classic Choroidal Neovascularization in Exudative Age-related Macular Degeneration: A Meta-Analysis. Invest. Ophthalmol. Vis. Sci. 2009;50(13):723.
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The progression of visual acuity loss in untreated exudative age-related macular degeneration (AMD) can effectively be captured using Lineweaver-Burke plots after adjusting for difference in time of entry into clinical trials. Herein we use this technique to examine the pattern of vision loss experienced by untreated exudative AMD eyes that are sorted by fluorescein angiography into 3 subgroups, namely predominantly classic (PC), minimally classic (MC), and occult with no classic (occult).
Data from patients enrolled in the Macular Photocoagulation Study (MPS), Treatment of Age-related Macular Degeneration with Photodynamic Therapy (TAP) Study, the Verteporfin in Photodynamic Therapy (VIP) study, anecortave acetate (AA) trial, the VEGF Inhibition Study in Ocular Neovascularization (VISION), and the Minimally Classic/Occult Trial of the Anti-VEGF Antibody Ranibizumab in the Treatment of Neovascular Age-Related Macular Degeneration (MARINA) trials. Visual acuity (VA) data of untreated control eyes for each study from appropriate subgroups were plotted on a double reciprocal (Lineweaver-Burke) plot of 1/ [letters lost] versus 1/ [months]. Horizontal shifts were calculated by a previously published natural history function to correct for differences in time of entry into clinical trials.
On a Lineweaver-Burke plot, the cumulative subgroups had an overall coefficient of determination of only r2 < 0.01 for the raw data. The average horizontal shifts used to adjust for initial visual acuity at time of enrollment were 3.9, 7.8, and 8.2 months for occult, minimally classic, and predominantly classic eyes respectively. Once adjust for these differences the coefficient of determination improved to a remarkably high r2=0.90. For each individual subgroup the coefficient of determination was greater than 0.90 as well.
Lineweaver-Burke plots are able to effectively capture the progression of visual loss in various subgroups of exudative AMD based on strong correlation of visual acuity as a function of time. This relationship appears to be minimally affected by differences in the fluorescein angiography classification of the lesion. Thus while lesion subgroup may still exert a more minor effect on the natural history of vision loss in exudative AMD, initial visual acuity appears to be the major determinant of changes in visual acuity.
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