A new cross-sectional observational study published in Investigative Ophthalmology & Visual Science examined retinal vascular changes in macular telangiectasia type 2 (MacTel) using swept-source OCT angiography (SS-OCTA).
The findings suggest that measurable vascular alterations may emerge later in the disease process rather than in early stages.
Let’s start with the basics: What is MacTel?
MacTel is a bilateral retinal disease that affects the macula and gradually disrupts central vision. The condition is often described as a neurodegenerative disorder with secondary vascular abnormalities involving the tiny blood vessels around the fovea.
Historically, clinicians have relied on clinical examination and fluorescein angiography to classify disease severity.
- However: Advances in imaging technology have made it possible to evaluate microvascular changes in much greater detail.
Speaking of imaging …
Optical coherence tomography angiography (OCT-A), in particular, is widely used to evaluate vascular abnormalities in MacTel.
Why: It allows clinicians to visualize retinal and choroidal circulation without dye injection while providing layer-specific vascular information like changes in superficial and deep capillary plexuses.
Give me some background on this …
Although vascular abnormalities are considered a hallmark of MacTel, their precise role in disease progression remains unclear.
Some evidence suggests that neurodegenerative changes may precede visible vascular abnormalities, raising questions about when vascular alterations become detectable.
Researchers therefore sought to better characterize how retinal and choriocapillaris vascular metrics change across different stages of MacTel.
So where does this study fit in?
Here's how it starts to peel back the layers: The investigators conducted a cross-sectional observational study examining retinal vascular and choriocapillaris alterations in MacTel using OCT-A metrics.
Using swept-source OCT-A imaging, the team assessed several vascular parameters across the macula, including:
- Vessel density
- Vessel skeletonized density
- Choriocapillaris flow deficit measurements
These vascular metrics were analyzed across the seven disease grades defined by the MacTel classification system.
The goal: To determine whether vascular abnormalities appear early in MacTel or whether they become more evident as the disease progresses.
Who was included in the study?
The study included:
- 111 eyes from 56 patients with MacTel
- 120 control eyes from 60 patients (without MacTel)
Among the MacTel cohort: Disease severity varied across the grading system, allowing investigators to evaluate vascular metrics at multiple stages of the disease.
- The distribution included early-stage eyes with no structural OCT abnormalities as well as advanced stages associated with pigment changes and neovascular complications.
So what did they find?
The most notable finding was that vascular differences were largely confined to advanced disease stages.
The results showed measurable vascular alterations across several retinal layers, but these changes were most pronounced in advanced disease stages.
Significant differences in vascular metrics were observed in grades 5 and 6 compared with early-stage MacTel and control eyes.
In these advanced stages, researchers noted changes in vessel density, vessel skeletonized density and increased choriocapillaris flow deficits.
- Importantly: Early MacTel stages did not demonstrate significant retinal vascular differences compared with healthy controls, suggesting that vascular abnormalities become more prominent later in the disease course.
What patterns emerged in the vascular changes?
The study also identified regional differences in vascular metrics.
MacTel eyes demonstrated increased vascularization around the foveal avascular zone along with vessel rarefaction in the inner ring and temporal macular sectors.
Researchers also observed impairment of the macular choriocapillaris in affected eyes.
Advanced disease grades were associated with increased vascular metrics in the central macular region, which corresponded with structural changes seen on OCT such as pigment migration and outer retinal hyperreflectivity.
Any limitations to consider when interpreting the data?
As with many observational imaging studies, several limitations should be considered.
- The study used a cross-sectional design, which limited the ability to determine how vascular changes evolve over time within the same individuals.
- Longitudinal data would be needed to confirm the temporal sequence of neurodegenerative and vascular alterations.
Additionally, while OCT-A provides detailed vascular imaging, certain vascular metrics may vary depending on segmentation methods or imaging artifacts.
What do the findings suggest about disease progression?
The findings support the idea that vascular abnormalities may be secondary features of MacTel rather than early drivers of disease. If vascular changes primarily appear in later stages, this reinforces the concept that neurodegenerative processes may occur earlier in the disease course.
Why does this matter clinically?
Understanding when vascular changes occur in MacTel may help clinicians better interpret imaging findings and monitor disease progression.
For clinicians: If vascular alterations primarily appear in later stages, OCT-A metrics may be particularly useful for identifying disease advancement or complications such as macular neovascularization rather than for detecting the earliest disease stages.
Take home.
In this OCT-A study of macular telangiectasia type 2, significant vascular alterations were most evident in advanced disease grades rather than in early stages.
These results suggest that retinal vascular changes may develop later in the disease course, highlighting the potential value of OCT-A in monitoring disease progression and identifying complications.