Topographic Relationship between Telangiectasia and Cone Mosaic Disruption in Macular Telangiectasia Type 2

Abstract

In this cross-sectional observational study, we investigated the relationship between photoreceptor layer disruption and telangiectasia in patients diagnosed with early stage macular telangiectasia type 2 (MacTel). A total of 31 eyes (17 patients) with MacTel were imaged with adaptive optics scanning laser ophthalmoscopy (AOSLO) and optical coherence tomography angiography (OCTA). Confocal AOSLO was used to visualize dark regions of nonwaveguiding outer segments, which we refer to as “photoreceptor lesions”. En-face OCTA images of the deep capillary plexus (DCP) were used in conjunction with confocal AOSLO to evaluate the topographic relationship between areas of capillary telangiectasias and photoreceptor lesions. Among seven eyes with early stage MacTel (stage 0–2 based on OCT), we identified ten photoreceptor lesions, all of which were located within parafoveal quadrants containing DCP telangiectasia on OCTA. Seven of the lesions corresponded to the intact ellipsoid zone on spectral-domain OCT (SD-OCT), and three of these also corresponded to the intact interdigitation zone. This work demonstrates a topographic relationship between AOSLO photoreceptor lesions and DCP telangiectasias, and it also suggests that these lesions with normal SD-OCT appearance may represent areas of photoreceptors at risk for dysfunction. Thus, confocal AOSLO may have a meaningful role in detecting early photoreceptor abnormalities in eyes with MacTel.

Early-stage macular telangiectasia type 2 vascular abnormalities are associated with interdigitation zone disruption

“…These results are consistent with an overall model of IZ disruption occurring in the early stages, which then progresses to combined IZ and EZ changes in the later stages (Tables 2 and 3 and Fig 3). Our results are also consistent with qualitative data from previous small studies of MacTel eyes from our group and others, which found that areas of IZ disruption colocalize with hyporeflective lesions on AOSLO in zones where the EZ is still intact [27,29].…”

“…The current neurodegenerative model of MacTel would suggest that vascular changes are secondary to underlying photoreceptor dysfunction [3,40]. These isolated telangiectatic areas may represent an earlier, "pre-IZ" stage of photoreceptor dysfunction that cannot be assessed on SD-OCT but may be visualized on imaging modalities like AOSLO [29]. Additionally, while both SD-OCT and AOSLO ultimately assess structural integrity of the photoreceptors, functional disruption will most likely precede observable structural damage.…”

“…While extensive research has documented the importance of EZ loss as a metric in MacTel progression, the role of the IZ band has not been systematically explored in MacTel patients beyond small case studies [27][28][29]. Recently, in eyes with early MacTel, our group identified cone mosaic lesions on AOSLO corresponding to areas of qualitative IZ disruption in areas where the EZ was completely intact [29].…”

“…While extensive research has documented the importance of EZ loss as a metric in MacTel progression, the role of the IZ band has not been systematically explored in MacTel patients beyond small case studies [27][28][29]. Recently, in eyes with early MacTel, our group identified cone mosaic lesions on AOSLO corresponding to areas of qualitative IZ disruption in areas where the EZ was completely intact [29]. Considering the spatial and temporal relationships between IZ and EZ disruption observed in other degenerative retinal diseases, we sought to investigate the extent of IZ disruption and its spatial overlap with DCP telangiectasia across the entire disease spectrum of MacTel [23][24][25][26].…”

Optical Coherence Tomography Angiography of Volumetric Arteriovenous Relationships in the Healthy Macula and Their Derangement in Disease

“…Our group has previously shown an intricate and complex relationship between outer retinal telangiectasias and photoreceptor loss with progression of MacTel. 57 , 58 As MacTel progresses, the photoreceptors degenerate, with retinal thinning in those areas. 56 , 59 DCP telangiectasias and subsequent retinal deformation in areas of local photoreceptor loss and outer retinal degeneration may contribute to the appearance of outer retinal vascular abnormalities in MacTel.…”