Patients with higher CVI  have a lower expansion of GA lesion. Photo: Anna Bedwell, OD. Click image to enlarge.

Researchers in Milan have investigated the correlation between choroidal vascularity index (CVI) and the enlargement of geographic atrophy (GA) lesion secondary to age-related macular degeneration (AMD) during two-year follow-up and have found that CVI impairment is strictly related to the rate of enlargement in affected patients. They are led to believe CVI could be considered a predictor of GA progression in the clinical setting and a new potential biomarker in the evaluation of new GA interventions.

The longitudinal, observational study included 26 eyes (26 patients, mean age 75.7), and the researchers calculated CVI in the subfoveal 3000μm area.

During the two-year follow-up, mean GA area increased from 6.99mm² to 10.69mm²accounting for a growth rate of 0.35mm/year and 0.31mm/year after the square root transformation in the first and second year of follow-up, respectively. Stromal choroidal area also significantly decreased during the two-year follow-up. Because of the significant relationship between the CVI and GA lesion, the researchers believe patients with higher CVI (i.e. greater preservation of the vascular component) have a lower expansion of GA lesion during this period.

“The rate of GA enlargement is related not only to the choriocapillaris perfusion but also to the status of the whole choroid,” they noted in their paper. “In other words, the global impairment of the choroidal vascularization is related to the progression of GA lesions during the time.”

The researchers believe that their findings support the theory of a vascular impairment on the basis of GA.

“Although it is still impossible to elucidate which is the first trigger in the pathogenesis of GA based on our analysis (if an RPE dysfunction or a choroidal vascular impairment), a choriocapillaris flow deficit and a global vascular impairment of the choroid appear to play a significant role in the progression of GA lesions,” they said.