Contrast Increment and Decrement Processing in Individuals With and Without Diabetes.

Area of Science:

• Ophthalmology
• Neuroscience
• Endocrinology

Background:

• Diabetic insult may disproportionately affect ON retinal ganglion cells (RGCs) compared to OFF RGCs.
• Psychophysical tasks can infer the functional status of ON and OFF RGCs in early diabetes mellitus (DM).

Purpose of the Study:

• To investigate whether early diabetes mellitus (DM) preferentially impacts functional responses to contrast increments over decrements.
• To infer the functional status of ON and OFF retinal ganglion cells (RGCs) in individuals with DM.

Main Methods:

• Fifty-two individuals with DM and 48 age-matched controls participated.
• Three psychophysical tasks were employed: contrast sensitivity to increments and decrements, a response time (RT) task, and a temporal order judgment task.
• Data collected included contrast sensitivity, RT, and accuracy at various visual field locations.

Main Results:

• The DM group exhibited reduced contrast sensitivity to both increments and decrements, particularly in the central visual field.
• Individuals with DM showed slower RTs and lower response accuracies for both increments and decrements.
• No significant differences were found in temporal order judgment thresholds between groups.

Conclusions:

• Early diabetes mellitus (DM) causes nonselective functional deficits in retinal neurons, impacting both ON and OFF RGC pathways.
• These functional changes are particularly evident in foveal testing.
• Further research is needed to determine if these increment-decrement functional indices predict diabetic retinopathy (DR) progression or visual prognosis.