Retinal Function in Diabetic Patients Without Retinopathy

Assessment of Retinal Functional Abnormalities in Diabetic Patients Without Retinopathy

The primary purpose was to assess, in diabetic patients without diabetic retinopathy and control subjects, color vision, contrast sensitivity, electroretinography, and flicker-induced vasodilatation using the Dynamic Vessel Analyzer, in order to specify the earliest impaired retinal cells in diabetes, and gain more insight into diabetic retinopathy pathogenesis.

Type 1 and type 2 diabetic patients with no diabetic retinopathy and no hypertension were compared with sex and age-matched control subjects. Color vision was tested with the desaturated LANTHONY 15-Hue test. Contrast sensitivity was assessed with the Pelli-Robson contrast sensitivity test. Pattern-electroretinogram, Ganzfeld full-field electroretinogram and multifocal electroretinogram were recorded according to the International Society for Clinical Electrophysiology of Vision (ISCEV). Flicker-induced vasodilatation in retinal arteries and veins was assessed using the Dynamic Vessel Analyzer.

Inclusion Criteria:

• For diabetic patients :

  • age between 20 and 55
  • type 1 or type 2 diabetes mellitus
  • diabetes duration of more than 5 years
  • no diabetic retinopathy on fundus examination or fundus photographs

• For control subjects :

  • sex and age matching with the diabetic patients
  • no diabetes, no familial or personal history of elevated blood sugar

Exclusion Criteria:

*For both diabetic patients and control subjects :

• presence of cataract or history of cataract surgery
• intraocular pressure of more than 21 mmHg
• abnormal score on the Ishihara test
• other ocular disease
• ametropia more than 3 diopters, anisometropia more than 1 diopter, astigmatism more than 1 diopter
• systemic hypertension (defined as systolic blood pressure > 140 mmHg, diastolic blood pressure > 90 mmHg)
• treatment with vasoactive drugs
• tobacco consumption of more than 20 cigarettes a day