Fractal dimensions represent a promising biomarker for assessing retinal vascular damage.
At the 2023 annual meeting of the American Academy of Ophthalmology (AAO), Marco H. Ji, MD, delivered a presentation titled, “Fractal Changes of the Retinal Microvasculature in Birdshot Chorioretinopathy.” The meeting took place November 3 to 6, in San Francisco.
Compared with healthy controls, fractal analysis of the different retinal vascular layers in patients with birdshot chorioretinopathy revealed significant involvement in the choriocapillaris, deep capillary plexus, and superficial capillary plexus, according to Dr. Ji.
PW interviewed Dr. Ji to learn more about his presentation.
“There Is a Gradual Transition Toward More Objective Assessments”
The fractal dimension, he explains, is a mathematical descriptor of the complexity and irregularity of a structure. “Assessing the fractal dimension of the retinal microvasculature may offer valuable support in the diagnosis and ongoing monitoring of birdshot chorioretinopathy,” he says “Traditionally, retinal examinations relied heavily on subjective interpretations of structural observations. However, with the advent of advanced imaging technologies, there is a gradual transition toward more objective assessments. This transition also opens up the possibility of quantifying observations objectively. Fractal analysis, in particular, can provide insights into how the disease affects the distinct layers of the retinal microvasculature.”
Based on previous research, lower fractal dimension is correlated with retinal vascular disorders. Dr. Ji and colleagues focused on patients with birdshot chorioretinopathy and evaluated the fractal dimension of the retinal microvasculature. The team conducted a retrospective cohort study that compared patients with birdshot chorioretinopathy with healthy controls.
Fractal Dimension of Birdshot Chorioretinopathy Is Lower Compared With Controls
“We performed optical coherence tomography angiography (OCT-A) using Heidelberg Spectralis HRA+OCT,” Dr. Ji says. “Our team examined the fractal dimension of the choriocapillaris, deep capillary plexus, and superficial capillary plexus, analyzing 18 eyes (n=9 patients) with birdshot chorioretinopathy and 24 eyes (n=12 patients) in the healthy control group.
Dr. Ji and colleagues observed that fractal dimension of birdshot chorioretinopathy was lower when compared with the control group in the choriocapillaris (mean: 1.804 vs 1.925, P=0.001), deep capillary plexus (mean: 1.580 vs 1.789, P<0.001) and superficial capillary plexus (mean: 1.545 vs 1.705, P=0 0.001). They noted that neither age nor gender were associated with the changes in the fractal dimension in any of the three analyzed vascular layers (P>0.05).
“We identified alterations in the fractal characteristics of the retinal microvasculature among individuals with birdshot chorioretinopathy when compared with a group of control subjects,” he says. “Notably, these changes in the fractal dimension were observed across all three layers of the retinal microvasculature, including the superficial capillary plexus, deep capillary plexus, and choriocapillaris”
Dr. Ji and colleagues are optimistic about the potential of fractal dimensions. “Fractal dimensions represent a promising biomarker for assessing retinal vascular damage, and their application can be seamlessly integrated into both clinical practice and research settings,” Dr. Ji says. “The incorporation of this supplementary data can significantly enhance the monitoring of disease progression and treatment responses in chronic retinal conditions like birdshot chorioretinopathy. Utilizing fractal analysis holds the potential to advance diagnostics, inform treatment strategies, and deepen our comprehension of intricate eye diseases.”
