Alteration of timing of secretion of vascular endothelial growth factors is responsible for progression of diabetic retinopathy.

Diabetic retinopathy is one of the most common complications in diabetes mellitus due to persistent hyperglycaemia. Various biochemical mechanisms have been suggested to cause this complication. The authors' present study which included 100 patients of type-2 diabetes mellitus with different stages of diabetic retinopathy and without retinopathy shows that initiation of diabetic retinopathy is associated with increased anaerobic glycolysis and accelerated oxidative stress. Progression of this complication is guided by increased secretion of vascular endothelial growth factors. It is our assumption that increased secretion of vascular endothelial growth factors in early part of this disease e.g. before occurrence of morphological abnormality may modify this complication.

Relation between increased anaerobic glycolysis and visual acuity in long-standing type 2 diabetes mellitus without retinopathy.

In long-standing diabetes mellitus, blood flow to essential organs including the retina is reduced owing to macrovascular and/or microvascular changes. Poor glycolytic pathway of glucose metabolism owing to tissue hypoxia caused by ischemia at capillary bed of essential organs produces excessive lactic acid and less of adenosine triphosphate, which lead to poor cellular function. The purpose of the study was to evaluate the relationship between increased anaerobic glycolysis and visual acuity in type 2 diabetes mellitus without retinopathy. Fifty patients of type 2 diabetes mellitus of 10-12 years duration, without retinopathy, constituted the study group. The controls were 50 age-matched healthy persons without diabetes mellitus. Blood lactate level and best-corrected visual acuity (BCVA) were measured in both the groups. The mean blood lactate level was 1.05 mM/l in the control group and 2.32 mM/l in the study group. BCVA of 20/20 (log MAR 0) was seen in 48 (96%) patients of the control group and in 27 (54%) patients of the study group. BCVA of 20/30 (log MAR 0.2) was seen in 23 (46%) patients in the study group and 2 (4%) in the control group. Association of higher blood lactate level with decreased BCVA in the study group was statistically significant (P< 0.001).

Eye health and adolescence.

Complete development of eyes occurs between 8 and 11 years, though longitudinal growth of axial length may occur up to 13 years (approximately). Except a few, most of the eye diseases affecting adolescence age group are similar to adult type. Diseases like myopia, keratoconus, vernal keratoconjunctivitis, juvenile diabetic retinopathy and injuries to eye are exclusively diseases of adolescence that are commonly encountered. Psychologically, impact of eye disease on adolescent mind may be profound, thinking they might lose their eyesight. Early detection of diseases, prevention of injuries, health education and frequent eye check-up are essential.

The efficacy of topical administration of brimonidine to reduce ischaemia in the very early stage of diabetic retinopathy in good controlled type-2 diabetes mellitus.

It is now proved that diabetic micro-angiopathy is caused by ischaemia at the capillary bed of retina due to reduced capillary blood flow in long standing type-2 diabetes mellitus. Deranged metabolic process due to chronic hypoxia at the tissue level produces visual and vascular dysfunction. Brimonidine tartrate, an alpha-2 agonist which is commonly used in glaucoma to protect retinal ganglion cells from pressure related ischaemia induced cell apoptosis, is administered in very early stage of non-proliferative diabetic retinopathy to reduce ischaemia at the capillary bed of retina. Improved visual acuity and decreased micro-aneurysm formation, which indicate elimination of ischaemic stimulus at the tissue level, are seen in long standing type-2 diabetes mellitus.