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Roopa Vemala, Sobha Sivaprasad, John L Barbur; A study of chromatic sensitivity loss in Age Related Maculopathy (ARM) with emphasis on reticular drusen, soft drusen and other ARM morphologies.. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify red / green (RG) and yellow-blue (YB) chromatic sensitivity loss in relation to structural changes in various ARM morphologies. To establish whether an appropriate colour assessment protocol can become a valuable risk stratification tool for conversion to AMD (Age related macular degeneration).
The Colour Assessment and Diagnosis (CAD) test (City University London) was used to measure chromatic sensitivity in 90 eyes with ARM and correlated to structural changes derived from fundus photography and spectral domain OCT. The CAD test provides monocular/ binocular upper, normal, age limits for RG /YB colour thresholds. All patients were asymptomatic with a visual acuity of 6/12 or better.CAD thresholds correlated to the below classifications/parameters;1.Clinical classification in all ARM eyes (Ferris et al 2013) 2.Eyes with drusen stratified as Normal aging (NA), Soft drusen and Reticular pseudodrusen (RPD) 3. Eyes with Soft drusen characterised according to international classification / grading system for ARM/AMD (1995) 4.Autofluorescence pattern (FAM study group 2004) and 5.Central macular thickness (CMT).
All ARM eyes exhibited loss of either RG / YB or both (p<0.0001) in comparison to the age matched normative data set. Both RG / YB loss extended across the severity grades, but YB preceded RG losses. Mean colour thresholds increased with increased grade of clinical classification (R2=0.9), in spite of large inter subject variability. The mean loss of colour vision increased from normal aging to soft drusen to reticular drusen (NA < soft drusen < RPD, R2=0.9). Drusen size and patchy autofluorescence correlated with loss of chromatic sensitivity in agreement with AREDS study and FAM group, respectively. Early GA eyes and eyes with CMT < 200 µ had significantly greater CAD thresholds . Six eyes with abnormal baseline, but variable CAD thresholds converted to wet AMD at one year.
Loss of chromatic sensitivity may be the earliest detectable change in ARM. The means of RG and YB losses correlate well with various ARM classifications, in spite of wide inter subject variation. Reticular drusen corresponded to the greatest chromatic loss. The loss of chromatic sensitivity was a sensitive indicator of early macular atrophy, but less sensitive in identifying eyes at risk of conversion to wet AMD.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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