Prevalence and Progression of Pigment Clumping Associated With Idiopathic Macular Telangiectasia Type 2

Abstract

Purpose To investigate pigment clumping in idiopathic macular telangiectasia type 2 (IMT2) for its incidence, development, and progression during the course of the disease. Methods Patients with a diagnosis of IMT2 and greater than 12 months of follow-up were reviewed retrospectively. Measurements of the area of pigment clumping were performed and correlated with visual acuity and findings on spectral domain optical coherence tomography (OCT) and microperimetry (MP1). Results Fifty-three eyes in 27 patients with a mean follow-up of 42.5±14.2 months (range 12–79 months) were included. At study baseline, 16 eyes (30%) had evidence of pigment clumping without associated neovascular changes. During follow-up, 8/33 (24%) additional study eyes without prior pigment clumping developed it in stage 3 (Gass-Blodi classification) disease. Pigment clumping increased in overall area as a function of follow-up time. Pigment clumping was associated with increased intraretinal reflectivity on OCT and development of scotomas on microperimetry. Conclusions Pigment clumping commonly develops in stage 3 IMT2 disease, enlarges in area continuously over time, and is associated with declining visual function. Longitudinal measurements of the total area of pigment clumping may be helpful in following disease progression and may constitute a useful outcome measure for interventional clinical studies.

Characteristics of Pigmented Lesions in Type 2 Idiopathic Macular Telangiectasia

“…Consistent with the findings of Meleth et al 18 , our data indicate that in the majority (on average 75%) of cases pigment plaques precede subretinal neovascular proliferation. SRNV may however also appear simultaneously with pigment or with no MacTel-type pigment detectable prior to the incidence of SRNV.…”

“…Meleth et al 18 noted in a sample of 22 non-neovascular MacTel eyes followed for on average 42.5 months (range=12–79 months) a linear growth rate of 8.3±1.7×10 3 μm 2 /month (mean±SEM) based on measurements in colour fundus photographs.…”

An unusual presentation of macular telangiectasia type 2 with a large pigment deposit

“…Pigment clumping is initiated in the areas of outer retinal thinning and disruption, which suggests that atrophic changes in the photoreceptor layer may create a permissive environment for RPE transformation. Pigment clumps increase in size over time, and in some cases, separate pigment clumps can coalesce and form a large contiguous pigment clump [ 6 ]. Similarly, intraretinal migration of RPE can be noted in retinitis pigmentosa and intermediate dry age-related macular degeneration.…”

SD-OCT Stages of Progression of Type 2 Macular Telangiectasia in a Patient followed for 3 Years

“…Several investigations showed that early changes in type 1 and 2 MT were associated with differences in macular pigment distributions, seen by autofluorescence spectrometry, and not with vascular abnormalities. Pigment clumping has been noted recently in late-stage idiopathic type 2 MT, revealing that its area is enlarging continuously over time, with associated visual function decline (3).…”