Measurement and analysis of the vitreous biochemical data in diabetes mellitus patients

Abstract

Purpose : We previously reported that regardless of the presence or absence of diabetes, no change in pH was observed in both the vitreous and venous blood (2017 ARVO Annual Meeting). Here we analyzed biochemical data and investigated whether the values change depending on the stage of diabetic retinopathy, and whether simultaneously there were the differences between vitreous and venous blood.

Methods : This cross-sectional study involved 30 cases [18 without diabetes mellitus (DM) (DM- Group) and 12 with DM (DM+ Group)] with no previous history of ophthalmologic surgery who underwent vitreous surgery at the Department of Ophthalmology, Kyoto Prefectural University of Medicine Hospital, Kyoto, Japan. In the DM+ Group, there were 6 proliferative diabetic retinopathy (PDR) cases and 6 non-PDR (NPDR) cases. In the DM- Group, we recruited patients with macular hole (MH) or idiopathic epiretinal membrane (ERM). In the DM+ Group, cases not only with MH or idiopathic ERM, but also diabetic macular edema, were included, while cases with obvious vitreous hemorrhage were excluded. A blood gas analyzer (ABL800 FLEX; Radiometer) was used to measure the vitreous and venous blood samples. Blood samples were collected immediately before surgery. Between the DM- and DM+ groups, K⁺, Na⁺, Ca²⁺, Cl^-, glucose, and lactate (i.e., 6 items) were compared. In the items that showed significant differences between DM- and DM+, we also compared the values between PDR and NPDR. Differences between the vitreous and venous blood samples were also investigated.

Results : In the vitreous biochemical data, Ca²⁺ significantly reduced and lactate and glucose significantly increased in DM+ compared to DM-. Thus, we compared Ca²⁺, lactate, and glucose between NPDR and PDR. Although glucose did not significantly change, Ca²⁺ significantly decreased and lactate significantly increased in PDR. In the venous biochemical data, only glucose significantly increased in DM+ compared to DM-. In all 6 items, significant differences were found between the vitreous and venous samples.

Conclusions : Lactate increased and Ca²⁺ decreased in the vitreous body of DM+ group patients, especially those with PDR, probably due to increased lactic acid production. We theorized that the Ca²⁺ decrease might be due to Ca²⁺ binding with the elevated lactic acid.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.