Abstract
Purpose::
Severe hyperglycemia and its correction with insulin therapy frequently have been associated with blurred vision. Generally this symptom was explained by osmotic changes in crystalline, but this theory actually has no evidence. Experimental studies have demonstrated that insulin increase vascular permeability in retina but there are no human studies about changes in retina in the introduction of insulin therapy. The aim of this work is a prospective evaluation of retinal changes, visual acuity and refraction after introduction of insulin therapy in patients with severe hyperglycemia
Methods::
10 consecutive patients (19 eyes), with a debutant hyperglycemia that require hospital assistance (4 type Diabetic 1, 6 type Diabetic 2). In days 1, 3, 7 and 21 after beginning the insulin therapy, we measured best corrected visual acuity, refraction with cycloplegics, macular thickness and volume with optic coherence tomography (OCT).
Results::
50% of patients referred blurred vision at the beginning of the study. Age and glucose levels at admission were higher in patients with blurred vision comparing with patients without this symptom (45+- 12 vs 30+- 7 years; p=0.04) (524+-192 vs 336+-88 mg/dl; p=0.09). Macular volume at baseline was similar in both groups (7.024+-0.42 vs 6.945+-0.41 mm3: p>0.05). In patients with blurred vision macular volume increased at the third day (Day 1, 7.024+-0.42 vs day 3, 7.242+- 0.43; p=0.013). At seventh day macular volume return to baseline values ( Day 1, 7.024+-0.42 vs Day 7, 7.045+-0.46 mm3; p=0.57). In the other hand in the group without blurred vision there was no change in macular volume (Day 1, 6.945+-0.41, day 3, 6.870+-38, day 7, 6.943+-0.42, day 21 6.899+-0.47; p>0.05)
Conclusions::
Patients with severe hyperglycemia treated with insulin may suffer changes in macular volume, especially those with blurred vision. Changes in macular volume doesn’t seem to be clinically significant and doesn’t justify refractive changes in those patients but, for the first time in human, introduction of insulin therapy has demonstrated changes in retina, this find open the door to other studies and questions about the paper of insulin in macular changes.
Keywords: diabetes • macula/fovea • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)