Assessment of the tear meniscus using optical coherence tomography in patients with type 2 diabetes mellitus

Purpose: To analyze tear meniscus dimensions with Fourier domain-optical coherence tomography (FD-OCT) in patients with type 2 diabetes mellitus. Methods: Patients with type 2 diabetes without diabetic retinopathy (DR) (n = 54), with nonproliferative DR (n = 45), with proliferative DR (PDR) (n = 25), and controls (n = 45) were enrolled. Hemoglobin A1c and Early Treatment Diabetic Retinopathy Study (ETDRS) stages of DR were evaluated. Schirmer test (ST), tear breakup time test, and fluorescein corneal staining were carried out. Tear meniscus height (TMH), tear meniscus depth (TMD), and tear meniscus area (TMA) were obtained by FD-OCT. Results: TMH, TMD, and TMA in the diabetes and control groups were 233 ± 79 mm, 148 ± 53 mm, and 0.026 ± 0.015 mm2, and 261 ± 67 mm, 167 ± 49 mm, and 0.032 ± 0.017 mm², respectively. All parameters were lower in diabetes (all P, 0.01). And the values in PDR were 185 ± 90 mm, 117 ± 50 mm, and 0.017 ± 0.010 mm² which were lower than those in control and nonproliferative DR (227 ± 71 mm, 144 ± 50 mm, and 0.023 ± 0.010 mm²) (all P < 0.01). TMH, TMD, and TMA correlated with ST (P < 0.01, P = 0.02, and P < 0.01, respectively) and the corneal staining score (all P < 0.01). Patients with longer diabetes duration and a history of panretinal photocoagulation showed significantly decreased TMH, TMD, and TMA (P < 0.01). Conclusions: OCT, along with tear breakup time and ST, is an effective way to assess tear function in type 2 diabetes. Patients with PDR and a history of panretinal photocoagulation showed lower tear meniscus parameters. The decrease in tear meniscus parameters was correlated with diabetes duration.