We reported a 6-year follow-up of a clinical case of a 67-year-old man affected with IMT in both eyes. He had no illnesses and was not taking any medication. Ocular history was negative for radiation retinopathy, occlusive, and/or inflammatory disorders. Best-corrected visual acuity (BCVA) was 3.2/10 in the right eye and 9/10 in the left eye. He had no family history of hereditary eye diseases. On the first visit in 2011, anterior segment examination was unremarkable in both eyes. At the fundus examination, we reported juxtafoveal telangiectasia with small preretinal hemorrhages, crystalline deposits at the vitreoretinal interface, and one blunted and slightly dilated venule in both eyes. In the right eye, macular cysts were detectable, whereas in the left eye at the fovea, it was possible to discern a small round yellow spot (pseudovitelliform deposit) (Figures 1 and 2). At the optical coherence tomography (OCT) examination in the right eye, a severe cystoid macular edema was reported with an initial alteration of the ellipsoid zone and the retinal pigment epithelium (RPE). In the left eye, small cysts with hyperreflective subfoveal alteration (pseudovitelliform foveal deposit) were detected (Figure 3). Characteristic findings on fluorescein angiography (FA) were juxtafoveal telangiectatic capillaries in the early phase and a marked and diffused hyperfluorescence in the late phase (Figures 1 and 2).
Fundus imaging follow-up of the right eye. (A) Color fundus and red-free photographs, early phase and late-phase fluorescein angiography (FA) of the right eye at first evaluation (July 2011). Color fundus photograph shows macular telangiectasia with small preretinal hemorrhages, macular cysts, and crystalline deposits. These findings are better detected on red-free imaging (small box). Early phase FA reveals ectatic capillaries at the posterior pole not only at the perifovea (green circles) and one blunted slightly dilated venule (arrow). Late-phase FA shows leakage from ectatic capillaries. (B) Color fundus and red-free photographs, early-phase and late-phase FA (November 2012). Color fundus photograph and red-free images show a reduction of the ectatic capillaries and the preretinal hemorrhages. (C) Color fundus and red-free photographs, early phase and late-phase FA (August 2013). The telangiectasia is almost imperceptible at the color fundus and red-free imaging although it is well seen at the early and late FA stages. Ectatic capillary (arrowhead). Pre-retinal dot hemorrhage (arrow). (D) Color fundus and red-free photographs, early phase and late-phase FA. In this figure at the color fundus and red-free imaging, telangiectasia and hemorrhages are not detectable (October 2016). (E) Color fundus photograph, optical coherence tomography angiography (OCTA) of superficial and deep vascular network. On the left, the first two images show 6 × 6 OCTA scans; the other two images show 3 × 3 OCTA scans (May 2017). OCTA revealed saccular capillary telangiectasia and loss of parafoveal vascular density. In particular, it is possible to see the dilated vessels in the deep retinal capillary plexus that are the most pronounced in the region temporal to the fovea. (F) OCTA of superficial and deep vascular network, outer retinal segments, and choriocapillaris (January 2018). Images show 4.5 × 4.5 OCTA scans. Outer retinal segments and choriocapillaris do not show flow signal.
Fundus imaging follow-up of the left eye. (A) Color fundus and red-free photographs, early phase and late-phase fluorescein angiography (FA) of the left eye at first evaluation (July 2011). Color fundus and red-free image shows perifoveal ectatic capillary and crystalline deposits. Early stage FA shows more ectatic capillaries with mild leakage at the late-stage FA. (B) Color fundus and red-free photograph, early phase and late-phase FA (November 2012). Telangiectasia is not detectable at the color fundus and red-free images. Early stage and late-stage FA show several macular telangiectasia with leakage phenomena. (C) Color fundus and red-free photographs, early phase and late-phase FA (August 2013). (D) Color fundus and red-free photographs, early-phase and late-phase FA (October 2016). (E) Color fundus photograph and optical coherence tomography angiography (OCTA) of superficial and deep vascular network (May 2017). The figures show dilated vessels in the deep retinal capillary plexus that are the most pronounced in the region temporal to the fovea. (F) OCTA of superficial and deep vascular network, outer retinal segments, and choriocapillaris (January 2018). Images show 4.5 × 4.5 OCTA scans.
Optical coherence tomography (OCT) examination of the right eye (on the left) and of the left eye (on the right). In the right eye, horizontal OCT scan at baseline shows retinal thickening and cystoid spaces in the macular area. In particular, it is possible to discern foveal serous detachment with focal alteration of the ellipsoid zone. It is possible to see the atrophic evolution of the macular edema during the follow-up. In the left eye, OCT images show mild hyperreflective alteration at the fovea involving the outer retinal segments. Small intraretinal cysts are detectable. During the follow-up, the OCT images show the fluctuation of the intraretinal cysts.
Fundus autofluorescence examination using green wavelength showed a loss of the normal hypoautofluorescence in the right eye but a normal autofluorescence in the left eye (Figure 4). In the follow-up, the patient underwent four intravitreal (IV) injections of anti-vascular endothelial growth factor (VEGF) (bevacizumab [Avastin; Genentech, South San Francisco, CA]) in the right eye (the last performed in April 2014) in absence of a substantial anatomical or functional results. During the last two follow-up visits, we performed OCT angiography because it was safer and more comfortable for the patient and more easily repeatable (Figures 1 and 2).4,5 In October 2017, he presented a slight reduction of the visual acuity of the right eye (BCVA was 2.5/10), macular atrophic cysts, an interruption of the ellipsoid zone, and RPE atrophy. We performed subthreshold yellow (577 nm) micropulse laser treatment in the right eye. The laser parameters used were 200 μm laser spot diameter, 0.2 seconds exposure, and 5% duty cycle. The laser power was determined on the basis of a single test spot close to the vascular arcades. Subthreshold laser treatment was delivered in a contiguous mode with no free space between each spot application and covered the edematous area. After 3 months, we reported an important reduction of intraretinal cysts and the reappearance of the foveal depression. During the follow-up, the left eye remained substantially stable; in particular, small cyst fluctuation was noticed. (Figure 3)
Fundus autofluorescence (FAF) image of the right eye (A) and the left eye (B). Loss of normal foveal hypoautofluorescence in the right eye (A). Normal FAF in the left eye (B).
In our paper, we reported a long-term follow-up of an atypical case of IMT type 1. We excluded other diagnoses. In fact, IMT must be differentiated from secondary telangiectasia caused by other retinal vascular diseases, especially retinal venous occlusions, diabetic retinopathy, radiation retinopathy, Irvine-Gass syndrome, or hypertensive retinopathy. No medical history of diabetes, ocular surgery, or X-ray treatment was reported in our patient. Based on the funduscopic aspect, the differential diagnosis with IMT type 21,2,6,7 could be not easy, especially for atypical cases of IMT. Diagnosis of IMT type 1 is typically made in the presence of visible and exudative unilateral telangiectasia accompanied by microaneurysms. Our patient presented with bilateral involvement characterized by evident asymmetry. Even though bilateral involvement in IMT type 1 is rare, some clinical cases have been reported.2,3,8 Typically telangiectasia is funduscopically visible in IMT type 1 and appears like aneurysmal lesions, whereas occult presentation is usually observed in IMT type 2.2,3 In our case, telangiectasia was not visible during the follow-up. These observations are in agreement with Bentaleb Machkour et al.8 who suggested that the absence of apparent vascular abnormalities in fundus examination did not exclude the diagnosis of IMT type 1.
In our clinical case, several other features could be compatible for IMT type 2: bilateral reduced retinal transparency, crystalline deposits at the vitreoretinal interface,9 blunted and slightly dilated venule, and the pseudovitelliform deposit.6,8–13 Preretinal hemorrhages were also described in IMT type 2.14
In our patient, hard exudates were not present notwithstanding the important exudation detected in the right eye. The lack of macular exudates was typical for IMT type 2.16 IV anti-VEGF treatment may have contributed to avoiding the accumulation of exudates in our case. In fact, although there is no established treatment for IMT type 1, several studies report a possible role for the use of anti-VEGF in the treatment of IMT type 1.16 The angiographic and tomographic effects after intravitreal inhibition of VEGF using anti-VEGF implicate a possible pathophysiological role of the VEGF pathway in IMT (type 1 and nonproliferative form of type 2).17–19 However, outcomes have been inconsistent.20–26 In fact, we have to point out that in our case, despite the therapy, there have been no major changes in the angiographic pattern (such as reduction of microaneurysms or reduction of leakage) nor in the OCT pattern. Instead, in the left eye in the absence of therapy during follow-up, there was a reduction of the exudative phenomena. In fact, there is a fluctuation of intraretinal cysts, as also reported by Osaka et al.16,27
At the FA examination, the telangiectatic lesions and cystoid macular exudation were evident. In particular, as it is commonly observed in IMT type 1, being considered a form of Coats' disease, we found vascular abnormalities not only at the perifovea. Finally, at the OCT examination, we detected intraretinal cystoid spaces, retinal thickening, and macular detachment in the right eye, typical for IMT type 1, whereas inner and outer lamellar cavities, thinning of the central and paracentral retina, highly reflective areas consistent with intraretinal pigment migration, and outer retinal hyperreflective spots are typical for IMT type 2.6,28–30 The disruption of the line representing the ellipsoid zone can be reported in both types.3,28,31 Focal laser photocoagulation (direct coagulation of aneurysms) has been reported to decrease vascular exudation and may improve visual acuity in some patients.1,2 In order to avoid foveal damage, we performed micropulse laser treatment in October 2017. We reported a reduction of intraretinal cysts after 3 months of micropulse laser treatment. This is the first report on subthreshold micropulse laser treatment on idiopathic macular telangiectasia.32,33
In conclusion, our clinical case allows us to make some important considerations. First, a multi-imaging approach is essential for accurate diagnosis, in particular the evaluation of previous exams, and the entire clinical history is important to better characterize atypical clinical cases such as our case.
At the final visit in January 2018, we reported an improvement on OCT examination. The clinical picture of the final examination could be the natural evolution of the pathology (although longitudinal studies report an increase in telangiectasia during follow-up,34 and although there was a compromise of the outer layers of the retina, there was not a severe atrophy of the neuroepithelium and RPE). Another hypothesis could be the possible contribution of the micropulse laser treatment to the cystoid macular edema reduction.