Macular telangiectasia type 2 has also been termed idiopathic perifoveal telangiectasia or idiopathic juxtafoveal telangiectasis type 2 [1-3]. It is now referred to as MacTel type 2, and it is a bilateral perifoveal vasculopathy which originates in the deep retinal capillary plexus in the temporal juxtafoveal region [4]. As it progresses, it involves the superficial retinal capillary plexus, and continues to progress anteriorly, posteriorly, and circumferentially. This is called the non-proliferative stage of the disease [5-9]. Mactel type 2 becomes proliferative when the vasogenic process extends under the retina, forming detachment and a retinal–retinal anastomosis. This form of the disease may eventually lead to disciform scarring.

In the early stages of the disease, fluorescein angiography (FA) imaging shows abnormal hyperfluorescence and leakage from the temporal, juxtafoveal capillary plexus, as the disease progresses, the hyperfluorescence and leakage spreads circumferentially around the fovea [7]. While FA provides a definitive diagnosis of MacTel2, it also involves the intravenous injection of a dye that can result in adverse effects such as nausea or vomiting, and rarely fluorescein can elicit an anaphylactic response [10-12]. Autofluorescence (AF) imaging is also useful in diagnosing MacTel2 [13], Due to the depletion of luteal pigment in the temporal juxtafoveal retina, a relative increase in AF is observed in this region [14-16]. As the disease progresses, luteal pigment is lost circumferentially around the fovea and an increase in the relative hyperfluorescence is observed. In the later stages of the disease, atrophy of the RPE is observed, resulting in decreased AF within the central macula.

Optical coherence tomography (OCT), a noninvasive imaging modality, has revealed structural abnormalities in the inner retina such as retinal cavitation with draping of the internal limiting membrane and abnormalities in the outer retina such as disruption of the photoreceptor inner segment/outer segment/ellipsoid (IS/OS/E) region that were not previously appreciated by FA or AF imaging [17-25]. OCT imaging has improved the early detection of MacTel2 by identifying these early subtle changes in retinal anatomy, and OCT has proven to be useful for following these alterations in macular anatomy as the disease progresses to foveal atrophy, the formation of intraretinal pigment plaques, and subretinal neovascularization. With the development of spectraldomain OCT (SDOCT) instruments with increased scanning speeds and highspeed sweptsource OCT (SSOCT) instruments, OCT microangiography imaging has emerged as a noninvasive strategy to visualize the retina and choroidal microvasculature without the use of an exogenous intravenous dye injection, [26-37] and identifying distinct characteristics of the capillary networks located within different layers of the retina and choroid.

Aim and Objectives

Diagnosis and staging of macular telangiectasia type 2 (MacTel2) using Swept Source optical coherence tomography Angiography.

Patient and Method

We retrospectively review a 60 year old patient with bilateral MacTel2 evaluated using a swept source OCT (SSOCT). The patient underwent a comprehensive ocular examination and imaging tests as part of the evaluation of her condition. The imaging tests included color fundus imaging (Topcon, Tokyo, Japan), digital fundus AF imaging, FA and Swept Source OCT with OCT Angio (TRITON TOPCON OCT).

The patient had no any other retinal pathology such as diabetic retinopathy or pathologic myopia and not previously treated with photodynamic therapy (PDT), thermal laser, intravitreal injections, or any retinal surgery. Information about previous medical conditions and ocular treatments was obtained by reviewing the medical charts.

(SS-OCT A) detected abnormal microvasculature in all MacTel2 eyes, predominantly in the middle retinal layer. These vessels correlated well with the FA alterations. The abnormal temporal, juxtafoveal microvasculature in MacTel2 became apparent as the disease progressed and in later stages tended to extend circumferentially, with anastomotic vessels temporally.

In our Case, the Right Eye was in Early, Nonproliferative MacTel2, Best corrected visual acuity (BCVA) in her left eye was 20/30. The horizontal Bscan with the retinal flow in different layers represented by colors shows the dilated vessels in the deep retinal capillary plexus found in the middle retinal layer, most pronounced in the region temporal to the fovea as observed in green (Figure 1A and B).With intact IS-OS Junction (Figure 3), Fluorescein angiography shows telangiectatic abnormalities with mild hyperfluorescence and leakage in the temporal juxtafoveal region (Figure 2).

Figure 1: Horizontal Bscan with the retinal flow in different layers represented by colors.

Figure 2: Fluorescein angiography showing telangiectatic abnormalities with mild hyperfluorescence and leakage in the temporal juxtafoveal region.

Figure 3: IS-OS Junction.

The left eye was in Proliferative MacTel 2, best corrected visual acuity (BCVA) in her left eye was 20/50, and The Bscan shows cavitation in the outer retina and disruption of the IS/OS/E boundary in the temporal juxtafoveal region. The Bscan representing the microvascular flow (Figure 4A and B) details the presence of abnormal microvasculature (green and blue corresponding to an area with retinal vascular anastomoses. Disruption of the microvasculature extends into the outer retina where the IS/OS/E is disrupted. Microvascular abnormalities, such as a distorted juxtafoveal capillary plexus with prominent anastomoses, FA imaging demonstrates hyperfluorescence in the temporal juxtafoveal region in the earliest stage associated with late leakage (Figure 5).

Figure 4: Bscan representing the microvascular flow.

Figure 5: FA imaging demonstrates hyperfluorescence in the temporal juxtafoveal region in the earliest stage associated with late leakage.

We used the SS-OCT angio technique to investigate eyes with MacTel2 using a TRITON SSOC. To extract the blood flow information and visualize the microvasculature of the central macula, the central macular microvasculature was visualized better than with FA imaging. In addition, the better visualization of the juxtafoveal microvasculature with SS-OCT Angio may also be due, in part, to the absence of leakage on OCT Angio imaging, and it is this leakage that could obscure the normal vasculature seen on routine FA imaging. By using this ability to extract and visualize these retinal layers in MacTel2 and other diseases, SS-OCT Angio imaging may help facilitate the early diagnosis of disease and provide a better understanding of disease progression and the efficacy of treatments and to differentiate MacTel2 from other diseases affecting the retinal microvasculature associated with fluorescein angiographic leakage, such as neovascular agerelated macular degeneration, diabetic macular edema, vein occlusions, and cystoid macular edema from differing conditions.