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H. Li, P. Mitchell, G. Liew, E. Rochtchina, T. Y. Wong, W. Hsu, M. L. Lee, Y. P. Zhang, J. Wang; Lens Opacity and Refractive Influences on Retinal Vascular Fractal Dimension Measurement. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1701.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the influence of lens opacity and refraction on retinal vascular fractal dimension (Df) measurement.
Right eye optic disc photographs of 3654 participants (aged 49-97 years) of the Blue Mountains Eye Study (1992-94) were digitized. Df of retinal vasculature was quantified using a computer-based program. Lens opacity scores were the sum of severity scores of nuclear, cortical and posterior subcapsular cataract, assessed from lens photographs. Refractive errors were measured using an autorefractor followed by subjective refraction. Spherical equivalent refraction (SER) was calculated as the sum of spherical plus 0.5 cylinder power. Axial length was measured at the 10-year follow-up examination using an IOL master.
Complete data were available in 2859 subjects. Mean Df of retinal vasculature was 1.444±0.023. Increasing lens opacity scores were associated with significant decrease in Df (β =-0.0030, p<0.0001). Cortical and posterior subcapsular cataract involving lens central area was associated with reduced Df, after controlling for age, gender, refraction and other confounding factors (p≤0.0105). Increasing myopic severity and axial length were associated with decreasing Df after adjusting for age, gender, height, body mass index, blood pressure and lens opacity scores (both ptrend <0.0001). The slope of Df decreasing per SER reduction was -0.0040 in eyes with SER≤-4D and -0.0016 in eyes with SER>-4D. SER remained significant after simultaneously adjusting for axial length.
Ocular media opacity and refraction influence retinal vascular Df measurements. A myopic refraction of ≤-4D was associated with an additional reduction in Df, suggesting rarefaction of retinal vasculature associated with high myopia.
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