Ocular structure and function in an aged monkey with spontaneous diabetes mellitus

Area of Science:

• Ophthalmology
• Diabetology
• Vascular Biology

Background:

• Spontaneous type 2 diabetes in obese rhesus monkeys offers a model for studying co-morbidities and end-organ damage.
• This study focuses on ocular changes in a diabetic monkey with hypertension and dyslipidemia.

Purpose of the Study:

• To investigate the structural and functional changes in the eyes of a spontaneously diabetic rhesus monkey.
• To correlate vascular dysfunction with visual function loss in a diabetic, hypertensive model.

Main Methods:

• High-resolution, enzyme histochemical, and histopathological analyses of retina and choroid.
• In vivo functional assessments including Indo-cyanin green (ICG) angiography and multifocal electroretinogram (ERG).
• Color duplex Doppler ultrasound to assess blood flow in posterior ciliary arteries.

Main Results:

• The diabetic monkey exhibited intraretinal hemorrhages, retinal capillary nonperfusion, and choriocapillaris loss.
• Evidence of basal laminar deposits and drusen on Bruch's membrane adjacent to avascular areas.
• Significant loss of photoreceptors and retinal ganglion cells, correlating with ERG findings and indicating both diabetic and glaucomatous damage.

Conclusions:

• Vascular dysfunction in both large and small choroidal vessels is linked to vision loss in diabetic hypertensive monkeys.
• The observed changes include age-related macular degeneration-like alterations in Bruch's membrane and photoreceptor degeneration.
• This model highlights the critical relationship between vascular health and visual function in diabetes.