Do Type 2 Diabetes and Prediabetes Associate With Macular Cone Dysfunction?

Fundus Oculi Examination
Photo Essay From The University Hospital Of Bordeaux. Cardiologic Hospital Of Haut Leveque. Department Of Diabetology. Nurse’s Aide ; Examination Of Retinography For The Screening Of Diabetic Retinopathy. (Photo By BSIP/UIG Via Getty Images)
The study demonstrates decreasing foveal thickness in patients with early diabetes and prediabetes.

This article is part of Optometry Advisor’s conference coverage from the 2021 meeting of the American Academy of Optometry, held in Boston from November 3 to 6, 2021. The team at Optometry Advisor will be reporting on a variety of the research presented by the primary eye care experts at the AAO. Check back for more from the AAO Optometry 2021 Meeting..

Cone dysfunction may be, in part, involved with N1 latency observed among patients who are prediabetic or have type 2 diabetes mellitus (T2DM). These findings were presented during Academy 2021 presented by the American Academy of Optometry held in Boston, November 3-6, 2021.

T2DM has previously been associated with changes to retinal structure. It remains clear, however, whether prediabetes or T2DM associates with changes to macular cone function.

This study, conducted by researchers from the University of Houston, evaluated 77 patients by multifocal electroretinogram (mfERG) and optical coherence tomography (OCT). All individuals had mfERG N1 latency and amplitude assessed in the foveal hexagon (central 2.4°) of their fully dilated right eye. The patients were stratified by glycated hemoglobin (HbA1C) into T2DM (HbA1C >6.4%; n=20), prediabetic (HbA1C 5.7%-6.4%; n=28), or control (HbA1C <5.7%; n=29) cohorts.

Study participants were aged between 28 and 69 years and the patients with T2DM had a mean HbA1C of 6.9%±0.68%.

The average N1 latency among controls was 15.57±1.38 ms which was significantly shorter than patients with prediabetes (16.62±1.14 ms; P =.001) or T2DM (16.60±0.94 ms; P <.001).

The study investigators did not observe a significant difference in N1 latency among the prediabetic or T2DM cohorts (P <.27).

Compared with all nondiabetic individuals, those who had a diagnosis of T2DM exhibited both delayed N1 latency (P <.007) and reduced foveal thickness (P <.010).

This study was limited by its small, unbalanced cohorts of patients and by the single-center design.

These findings suggested that in addition to retinal structure changes, patients who are prediabetic or have T2DM likely have macular cone dysfunction. This dysfunction may be responsible for the mfERG-detected N1 latency observed among these patient populations and the decreased foveal thickness observed among those with T2DM. Additional longitudinal studies are needed to better understand the effects of early diabetes disease progression on eye health.

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Echiverri A, Harrison W. Detection of differences in cone function as measured by mfERG (N1) in patients with prediabetes and type 2 diabetes. Poster presented at: American Academy of Optometry 2021; November 3-6, 2021; Boston. Board #95