Correlación del déficit funcional visual y alteraciones microvasculares en la retinopatía diabética 
mediante microperimetría 
y angiografía por tomografía de coherencia óptica

Resum

Abstract PURPOSE: The main purpose of this doctoral thesis has been to study the relationship between the vessel density (VD) measured with angiography by optical coherence tomography (OCTA) and the retinal sensitivity (SR), measured by microperimetry, in diabetic retinopathy voluntaries and healthy controls in the whole macula and by smaller sectors. In this study we have assessed variables that measure the vascular structure of the macula and its visual function and how they are related. METHODS: A prospective and observational cross-sectional study was design including a group of diabetic subjects and a control group with healthy subjects. They were examined with the OCTA device, with the microperimeter and they underwent a complete ophthalmological examination in the Ophthalmology Service of the University Hospital of La Candelaria. Correlations between the variables of VD in the retinal plexus, area, perimeter and circularity of the foveal avascular zone (FAZ), and macular perfusion with the variables of RS and central fixation were analysed. RESULTS: One-hundred-twenty-two eyes from 83 subjects with diabetes and 88 eyes from 54 control subjects were recruited. The mean vascular density in the superficial vascular plexus was 14.25 % (+/- 3.75) in diabetics and 18.27% (+/- 2.46) in healthy patients, with statistically significant difference between groups (p <0.05). In deep plexus, the mean density was 20.65% (+/- 3.29) in diabetics and 23.47% (+/- 3.01) in healthy subjects (p <0.05). The area of the FAZ was 0.38 mm2 (+/- 0.21) in the diabetic group and 0.30 mm2 (+/- 0.13) in the healthy group (p <0.05). The mean RS was 27.56 (+/- 3.22) dB in diabetics and 31.57 (+/-1.31) dB in healthy subjects (p <0.05). No differences were detected between groups in central fixation within the ring of 2 and 4 central degrees. A force of correlation r = 0.48 and r = 0.46 is established between the densities of the superficial and deep vascular plexuses, respectively, and the RS (p <0.05) in the group of diabetics, while this force is r = 0.29 and r = 0.24 in the healthy group (p <0.05). This relationship can also be observed by smaller sectors in 7 and 8 of 9 sectors in diabetics and 2 and 0 of 9 sectors in healthy subjects. A relationship is found between the parameters of the FAZ, especially the area with the mean, central RS and visual acuity, which is not found in healthy subjects. We did not find a relationship between the parameters of the FAZ and the central fixation (p> 0.05) in both diabetics and healthy subjects. The VD in the superficial plexus decreases with age in healthy subjects (r = -0.26; p <0.05) but does not present a significant relationship in diabetics. RS decreases with age in healthy subjects (r = -0.55; p <0.05) and in the diabetic group (r = 0.28; p <0.05) with less force. The degree of severity of DR is inversely and significantly related to VD in the superficial and deep retinal plexuses (p <0.05). SR also decreases when the severity of DR increases (p <0.05). CONCLUSIONS: Vessel density measured by OCTA in diabetic retinopathy subjects is decreased compared to healthy subjects and is related to a decrease in retinal sensitivity overall, although there are other factors that could modify this relationship. Microperimetry is more sensitive than visual acuity to determine the functional damage of FAZ. Central retinal fixation is a function that remains stable until advanced stages of the disease.