Sores on the feet can signal problems with the eyes in patients with diabetes.

Prior research and anecdotal experience show that diabetic foot ulcers and diabetic retinopathy frequently co-occur. New research further clarifies this link and shows that patients with foot ulcers may receive fewer treatments to protect their sight.

David J. Ramsey, MD, PhD, MPH, director of ophthalmic research at Lahey Hospital & Medical Center in Burlington, Massachusetts, said when clinicians detect either condition, they should involve a team that can intervene to help protect a patient’s vision and mobility.

For example, they should ensure patients receive comprehensive eye and foot evaluations and help them optimize diabetes management.

The new study, presented at the 2023 annual meeting of the Association for Research in Vision and Ophthalmology, “adds an important dimension” to understanding the association between the conditions, said Ramsey, who recently reviewed correlations between diabetic foot ulcers and diabetic retinopathy and their underlying causes.

“Patients with diabetic foot ulcers appear to receive less attention to their diabetic retinopathy and may receive fewer treatments with eye injections targeting vascular endothelial growth factor [VEGF], an important driver of progression of diabetic retinopathy,” said Ramsey, who is also an associate professor of ophthalmology at Tufts University School of Medicine. He was not involved in the study presented at ARVO 2023.

In the new study, Christopher T. Zhu, a medical student at UT Health San Antonio, and colleagues analyzed data from 426 eyes of 213 patients with type 2 diabetes who had had at least two eye exams between 2012 and 2022; 72 of the patients had diabetic foot ulcers. Patients were followed for about 4 years on average.

Patients with diabetic foot ulcers had a higher percentage of eyes with macular edema on their initial exam (32.6% vs. 28%). By the final exam, the percentage of eyes with macular edema was significantly greater in the group with diabetic foot ulcers (64.6% vs 37.6%; P < .0001), Zhu’s group reported.

Eyes with nonproliferative diabetic retinopathy progressed to proliferative diabetic retinopathy, the worst grade, at a higher rate in the group with foot ulcers (50.6% vs 35.6%; P = .03). In addition, patients with foot ulcers were more likely to experience vitreous hemorrhage (55.6% vs 38.7%), the researchers found.

Despite patients with foot ulcers tending to have worse disease, they received fewer treatments for retinopathy. Those without ulcers received an average of 6.9 anti-VEGF injections per eye, while those with ulcers averaged 4.3.

Foot ulcers may hinder the ability of patients to get to appointments to receive the injections, Zhu and colleagues wrote. “For many patients in our part of the country [South Texas], a lack of transportation is a particular barrier to healthcare access,” Zhu told Medscape.

Zhu’s team conducted their study after noticing that patients with diabetes and foot ulcers who presented to their eye clinics “appeared to progress faster to worse grades of retinopathy” than patients with diabetes who did not have ulcers.

“Similar to how foot ulcers develop due to a severe disruption in blood flow [vascular] and a loss of sensation [neurologic], diabetic retinopathy may have a relation to microvascular disease, neurologic degeneration, and inflammation,” he said.

The findings confirm “that poor perfusion of the eye and foot are linked and can cause ischemic retinopathy leading to the development of proliferative diabetic retinopathy and vitreous hemorrhages, both serious, vision-threatening conditions,” Ramsey said.

To some extent, fewer treatments with anti-VEGF agents may account for why patients with foot ulcers have more eye complications, Ramsey added. “Additional research needs to be done to further dissect the cause and the effect, but it’s a very important finding that we need to increase awareness about,” he said.

Ramsey and Zhu reported no relevant financial relationships.

Association for Research in Vision and Ophthalmology (ARVO) 2023 annual meeting. Presented on demand.

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