Tomographic Assessment of Some Neural Elements Affection in Type I Diabetic Patients

Abstract
Background: Diabetic Retinopathy (DR) is the most common cause of blindness, affecting 1.9% of patients with DM. Furthermore, 2.64% of diabetic patients have visual Sight-Threatening Diabetic Retinopathy (STDR). The major cause of visual impairment in DM patients is Diabetic Macular Edema (DME) [1]. Although the long-term effects of D.M on vascular tissues are very well known, its effect on retinal neurons isn't very clear [2].
Aim of Study: To detect early neurodegenerative retinal changes preceding the microvasculopathy in patients with type 1 Diabetes Millets (DM) with no Diabetic Retinopathy (DR).
Patients and Methods: We measured mean Nerve Fiber Layer (NFL) and Ganglion Cell Layer (GCL) thickness by Optical Coherence Tomography (OCT) 8 ETDRS map zones, the inner circle (pericentral) and the outer circle (peripheral) area of the macula in sixty-three patients with type 1 DM with no DR underwent full ophthalmic examination and OCT compared to 36 healthy controls.
Results: We found insignificant mean thickness difference of NFL and GCL of each ETDRS zone of patients and controls, main effect of group, F=2.952, p=.090 by slip-plot (mixed design) ANOVA. There was insignificant interaction between group and zones of ETDRS, F=.821, p=.548. By independent samples Student's t-test there were no significant difference between diabetic patients and healthy controls except in temporal zone of inner circle in the left eye was statistically significant thinning in diabetic patient by only 2.02μm which is clinically insignificant.
Conclusion: Nerve Fiber Layer (NFL) and Ganglion Cell Layer (GCL) were not affected in early type 1 diabetic patient without minimal DR in the absence of macular edema. The theory of early neurodegenerative changes preceding the microvasculopathy in DM type 1 patient is not supported. Therefore, there is no advantage in performing OCT routinely in patients with type 1 diabetes without minimal DR.