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F. W. Fitzke, S. Schmitz-Valckenberg, E. Ong, G. S. Rubin, T. Peto, A. Tufail, C. Egan, A. C. Bird; Structural and Functional Changes in Patients With Type 2 Macular Telangiectasia Over Time. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3204.
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© ARVO (1962-2015); The Authors (2016-present)
In a cross-sectional analysis of patients with type 2 macular telangiectasia (MacTel), we have previously demonstrated severe localized dysfunction next to fixation despite good central visual acuity and that scotopic loss was deeper and larger compared to photopic scotoma (ARVO 2007). Here, we investigate structural and functional changes over a one year review analysis.
As part of the MacTel-Study Project, 6 eyes of 6 patients (median age 69.5 years, range 64-74) with MacTel underwent repeated scotopic and photopic fine matrix mapping (FMM), 10-2 photopic microperimetry (Nidek MP-1, MP) and imaging studies including fundus photography, fluorescein angiography, optical coherence tomography and scanning laser ophthalmoscopy imaging (exc. = 488 nm, em.>500 nm and exc. = 790 nm, em.>810 nm). Retinal sensitivity was compared with individual baseline results and the number of test points with loss ≥ 10 dB with FMM compared to age-matched control values was determined.
ETDRS visual acuity assessment showed a mean difference between examinations of 1.3 letters (range -3 to 4). The mean difference of sensitivity values of all test points was 3.8 dB (1.5 to 5.4) for microperimetry, 0.7 dB (0.1 to 1.2) for photopic and -3.6 dB (1.0 to -6.1) for scotopic FMM, respectively. The difference in number of test points with loss of ≥ 10 dB was significantly higher for scotopic than for photopic testing (p = 0.043, Wilcoxon Signed Ranks test). Small progression of scotoma correlated with slight increase in retinal blood vessel dilatation and hyperfluorescence and subtle enlargement of pigmented plaques.
In this cohort, changes in central visual acuity and MP testing after one year most likely do not extend beyond test-retest variability. The deterioration of scotopic sensitivity confirms our previous results of more severe rod compared to cone dysfunction in MacTel. Changes in function testing over a one year period may be useful parameters in assessing disease progression and in monitoring intervention studies in patient with MacTel.
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