# Structural and microvascular retinal changes following bariatric surgery: a prospective study

## TL;DR

This study found that bariatric surgery in obese patients leads to improved retinal blood flow and structural changes in the eye.

## Contribution

The study is the first to show microvascular retinal improvements after bariatric surgery using advanced imaging techniques.

## Key findings

- Bariatric surgery increased macular and peripapillary vascular density, indicating better retinal blood flow.
- Central foveal thickness and macular volume increased six months after surgery.
- No significant changes were observed in foveal avascular zone metrics or choroidal thickness.

## Abstract

This study sought to evaluate structural retinal changes, mainly microvascular ones, in obese patients undergoing bariatric surgery.

Obese patients who were candidates for bariatric surgery at University of São Paulo Medical School Clinics Hospital were recruited. Each participant underwent ophthalmic evaluation with ultra-widefield retinography, optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) obtained within one month before and six months following the surgical procedure. Structural OCT parameters (subfoveal choroidal thickness, mean peripapillary nerve fiber layer thickness, central foveal thickness, and macular volume) and OCTA parameters (peripapillary vascular density, macular vascular density, area, perimeter and circularity of the foveal avascular zone - FAZ - of both superficial and deep vascular complexes) were calculated and compared.

42 participants were included (83.3% female, mean age 47 years) of whom 24 (57.14%) were diabetic and 18 (42.86%) were non-diabetic. Of this sample, 81 eyes were evaluated. Six months after bariatric surgery, a significant increase in central foveal thickness (from 258±26 μm to 260±25 μm, p < 0.001), macular volume (from 8.6 ± 0.4 mm³ to 8.7 ± 0.4 mm³, p < 0.001), peripapillary vascular density (from 63 ± 8% to 65 ± 8%, p = 0.003) and macular vascular density in the superficial (from 27 ± 4.7% to 28 ± 4.4%, p = 0.005) and deep vascular complexes (29 ± 3.9% to 31 ± 3.5%, p < 0.001) were observed. No significant changes were detected in the metrics of the FAZ, subfoveal choroidal thickness and mean peripapillary nerve fiber layer thickness.

In this study, bariatric surgery was associated with improved retinal microvascular perfusion, as demonstrated by the increase in macular and peripapillary vascular density. The increase in central foveal thickness and macular volume may be secondary to improved microvascular perfusion.