Sir,

Idiopathic Perifoveal Telangiectasia (IPT), or type 2 macular telangiectasia, is an uncommon, nonexudative, bilateral condition of obscure etiology.1, 2, 3 Cone dystrophy is another uncommon macular disease.4 Here, we describe a patient who developed clear signs of IPT years after being diagnosed with cone dystrophy. It seems unlikely that two conditions arose independently.

Case report

A 57-year-old male presented with gradual impairment of reading vision and photophobia in 2004, 20/50 OU. Fundus examination showed subtle, relatively discrete retinal pigment epithelial (RPE) abnormalities in the central maculae. Central-foveal reflexes were attenuated (Figure 1a and b) without loss of macular transparency. Fluorescein angiography revealed a central window defect corresponding to RPE abnormalities in both eyes without discernible vascular changes (Figure 1c–f). Some mild, diffuse hyperfluorescence in the temporal maculae was present (Figure 1e and f). Both eyes had normal rod-driven responses; cone-driven responses to both single-flash and 30 Hz flicker showed significantly reduced amplitudes in Ganzfeld–electroretinography5 (Figure 1i–l). Interestingly, OCT examination showed prominent inner–lamellar holes (Figure 1g and h). A diagnosis of a progressive cone dystrophy was made.

Figure 1
figure 1

Right (a) and left eye (b) fundus photographs in 2004 show pigment changes in the central macula. Early fluorescein angiographs (c and d) reveal a central window defect. Late fluorescein angiography images (e and f) show irregularities in background fluorescence. No telangiectasis or vessel staining is visible. OCT images (g and h) exhibit foveal inner-lamellar holes. Ganzfeld–ERG recordings demonstrate normal rod-driven responses (i and j) and reduced amplitudes in cone-driven responses (k and l).

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By 2007, visual acuity had dropped to 20/200 OU. Funduscopy revealed vascular telangiectasis and right-angled vessels in the temporal perifoveal region of both eyes (Figure 2b). Features typical of IPT, such as reduced macular transparency and superficial white crystals, had developed since the previous visit (Figure 2b). Changes were similar in both eyes. Fluorescein angiography showed telangiectatic changes in the early phase as well as diffuse–late hyperfluorescence (Figure 2c–f). Inner-lamellar holes seen in OCT in 2004 were still present and somewhat larger (Figures 2g and h).

Figure 2
figure 2

Fundus photographs taken in 2007 (a and b) show a loss of transparency (arrows) of the central macula and pigment abnormalities with right-angled vessels (*) and crystalline deposits in the temporal perifovea. Early fluorescein angiography images (c and d) show telangiectatic vessels in the temporal perifoveal zone, while late angiographs (e and f) show more generalised hyperfluorescence. OCT images (g and h) still show slightly larger inner-lamellar holes. Rod-driven responses in Ganzfeld-ERG (i and j) are still normal while cone-driven responses have decreased further (k and l).

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Comment

The clinical findings in IPT are most obvious in the retinal blood vessels, however, it is possible that the primary defect lies in other retinal components, such as the retinal pigment epithelium, neural cells (including photoreceptors) or Muller/glia. The inner-lamellar holes may result from the neuroretinal decay rather than being of exudative origin since they were already present before vascular changes and are not visible during fluorescein angiography. The precession of typical vascular changes of IPT by the less well-recognised neuronal changes, as demonstrated in this case, suggests that photoreceptor damage may contribute to the early pathogenesis of the disease.