Abstract
Purpose: :
Power-Doppler optical coherence tomography (Pd-OCT) provides non-invasive, three-dimensional images of the retinal vasculature by calculating phase changes in blood circulation. Macular pigment optical density (MPOD) is a non-invasive psychophysical procedure to quantitate the distribution of macular cartotenoids. These methods were used to evaluate eyes at various stages of progression of macular juxtafoveal telangiectasia type 2 (MacTel) to better understand the pathogenesis and progression of this condition.
Methods: :
Nine eyes (five subjects) with MacTel and best corrected visual acuity (BCVA) of 20/100 or better were imaged by Pd-OCT. Clinical staging of MacTel was performed based on fundus photography, fluorescein angiography, and OCT. MPOD was measured using heterochromic flicker photometry in six eyes with BCVA of 20/40 or better.
Results: :
Median BCVA was 20/25. One eye diagnosed clinically with Stage 1 MacTel (i.e. non-proliferative deep capillary stage) had subtle punctate vascular signal confined to the outer aspect of the outer plexiform layer on Pd-OCT. Two eyes with Stage 2 MacTel (i.e. superficial capillary stage of disease) showed oblique vascular signal extending into deeper layers. Among three eyes with Stage 3 MacTel (i.e. subinternal limiting membrane and foveal stage of disease), progressive disruption of outer retinal morphology with superficial retinal vasculature piercing into deeper layers was observed. Three eyes with Stage 4 MacTel (i.e. proliferative disease stage) showed photoreceptor disruption with retinal vascular channels connecting the superficial and deep retinal layers, and extending into the subretinal space forming retinal-choroidal anastomosis similar to neovascularization associated with retinal angiomatous proliferation. MPOD distribution was unremarkable in three eyes with Stage 1 to 2 disease; three eyes with Stage 3 to 4 MacTel had loss of foveal MPOD when compared to age-matched controls.
Conclusions: :
Pd-OCT imaging is useful for non-invasively visualizing the progression of vascular abnormalities associated with MacTel. Early stages of the disease are characterized by penetration of the superficial retinal capillaries into the deeper retinal layers, subsequently leading to retinal-choroidal anastomosis in more advanced disease. The central depletion of MPOD is a common finding associated with MacTel, but may be absent in eyes with early stages of this condition.
Keywords: macula/fovea • imaging/image analysis: clinical • macular pigment