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P. Charbel Issa, H.M. Helb, F.G. Holz, H.P. N. Scholl, MacTel–Study Group; Microperimetric Assessment of Patients With Macular Telangiectasia . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5210.
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© ARVO (1962-2015); The Authors (2016-present)
Type 2 macular telangiectasis (MT) is a rare disease of the parafoveal capillaries with angiographically late hyperfluorescence temporal to the fovea without macular edema. To assess retinal light increment sensitivity (LIS) of both the angiographically hyperfluorescent and the adjacent areas at the posterior pole we performed fundus controlled static threshold microperimetry in patients with type 2 MT.
24 eyes of 13 patients (median age: 63 years; range 48 – 73 years) exhibiting MT were included. Patients were examined by means of funduscopy, best–corrected visual acuity, fluorescein angiography, and optical coherence tomography (OCT3). Fundus controlled static threshold perimetry was performed with the MP1 (Nidek). Goldmann III stimuli and a white background illumination, using a 4–2–test strategy in 21 eyes and a 4–2–1–test strategy in 3 eyes. The range of luminance was 0–20 dB.
VA was reduced in all eyes (median VA 20/40; range: 20/200 – 20/25). LIS was reduced within the hyperfluorescent areas temporal to the fovea in all but two eyes. Areas with reduced LIS correlated well with angiographically hyperfluorescent areas and showed a relatively sharp demarcation from areas with normal LIS. There was no apparent correlation between VA and parafoveal LIS–reduction. In eyes with additional hyperfluorecence of the nasal parafoveal region, LIS was considerably higher or within normal limits in the nasal compared to the temporal area. In 14 eyes there was no LIS detectable at least at some test locations temporal to the fovea. Retinal sensitivity of normal appearing areas on angiography at the posterior pole was within normal limits in most areas in all but 2 eyes.
These findings indicate that MT are associated with functional impairment of retinal light sensitivity. There is good topographic correspondence between angiographically visible alterations and parafoveal scotomas, which both are mainly located in the temporal parafoveal area. Abnormal retinal sensitivity represents a different feature from visual acuity loss, i.e. in eyes with profound parafoveal scotomas, VA can be relatively preserved. Therefore, testing for retinal light sensitivity should be included when studying MT.
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