OCT Central Macular Thickness in Type 2 Diabetes Asian and Caucasian patients: Is there a difference and do we care?

Abstract

Purpose : Diabetic macular edema (DME) affects 750,000 US adults over age 40. Asians are the fastest growing ethnic group in the US and are at an increasing risk of developing Type 2 Diabetes Mellitus (T2DM); thus, there is a need for more knowledge about comparing DME between Asians v Caucasians. OCT central macular thickness is used for clinical diagnosis and follow-up for diabetic macular edema. 16.1% of 959,945 anti-VEGF injections were for Diabetic retinopathy(2006-2015)¹, costing $200 million annually².

Methods : A retrospective chart review (2017-2019) using ICD 10 code “E11.3213” to find Asian and Caucasian patients with diabetes and macular edema, examining central macular thickness (CMT) using optical coherence tomography within ± 3 months of their HbA1c lab test. BCVA was taken using Snellen chart for each eye.
Inclusion criteria: Best corrected visual acuity 20/15 - 20/50, received optical coherence tomography for central macular thickness within ± 3 months of their HbA1c lab test. For T2DM patients, HbA1c value ≧ 6.0% and a diagnosis from a primary care physician (PCP). For Control patients, HbA1c value ≦ 6.0% and no diagnosis of T2DM from a PCP.
Exclusion criteria: Age under 18 or over 90 years.
Two-way ANOVA was used to analyze the difference between the four groups: T2DM Asians (ADM), T2DM Caucasian (CDM), Control Asian (CA), and Control Caucasian (CC). Another two-way ANOVA was conducted while separating right and left eye apart between the four groups: ADM, CDM, CA, and CC. Post-hoc test using Tukey’s HSD was used for p-values ≦ 0.05.

Results : 93 patients were included in the study with 23 patients in each group. T2DM Caucasian CMT is 14.84 μM thicker than those of T2DM Asian eyes (Tukey's HSD, p=0.0128). Control Caucasian CMT is 18.61 μM thicker than those of Control Asian eyes (Tukey's HSD, p = 0.000848). See table.

Conclusions : Asian Diabetic maculas are thinner in comparison to Caucasian Diabetic maculas in Diabetic patients. This small study suggests that ethnic differences may be important as we make clinical decisions for possible anti-VEGF treatment based on the central macular thickness in diabetic patients. More work needs to be done to further evaluate possible ethnic differences in the diabetic macula.

References:
1. Parikh R et al. Ophthalmology 2017;124:352.
2.Patel S. Ophthalmology Retina 2018;2(8):785.

This is a 2020 ARVO Annual Meeting abstract.