Transcutaneous oximetry but not arterial toe blood pressure or ankle-brachial index is related to macular thickness in patients with chronic diabetic foot ulcers

Abstract

Objectives: Diabetes related vascular complications of the lower extremity could be classified as micro- and macrovascular. Ankle-brachial index (ABI) and toe blood pressure (TBP) measurements evaluate macro-circulation, whereas transcutaneous oximetry (TcPO2) is considered to be a composite measure of vascular function, thereby also reflecting microcirculation. Microvascular disease in the eye involves abnormal capillary permeability and possibly thereby increased macular thickness. The aim of the present clinical study was to evaluate if microvascular disease in the eye was related to measures of foot ischemia in patients with diabetes mellitus. Methods: Twenty consecutive patients with diabetes and chronic full-thickness foot ulcers were included. Peripheral ischemia was diagnosed using TcPO2, TBP and ABI. Macular thickness was measured with optical coherence tomography technique. Results: Based on TcPO2, TBP and ABI measurements 14, 13 and 13 patients, respectively, were classified as ischemic. Patients with ischemic TcPO2 levels at the dorsum of the foot had significantly higher macular thicknesses. This was not the case in patients with ischemic TBP or ABI levels. Conclusion: TcPO2, unlike TBP and ABI, seems to be a clinically relevant measure of peripheral microvascular disease in patients with diabetes mellitus and may, if low, indicate an increased risk of macular edema.