Los cambios de densidad parafoveal no se han caracterizado en diabéticos tipo 2 sin retinopatía. Objetivo: Comparar la densidad capilar parafoveal entre sujetos sanos y diabéticos con y sin retinopatía. Método: Estudio observacional, prospectivo, transversal y comparativo. Se incluyeron sujetos sin diabetes (grupo 1), diabéticos tipo 2 sin y con retinopatía (grupos 2 y 3), y con edema macular (grupo 4), sin isquemia macular. La variable de estudio fue la densidad capilar parafoveal, y las variables predictoras fueron las mediciones de la ZAF, el grosor retiniano y el grupo. Se compararon las diferencias entre grupos mediante las pruebas de Kruskal-Wallis y Rho de Spearman. Resultados: 144 ojos; la densidad capilar parafoveal del grupo 1 superó la de los restantes (p < 0.05). El área, el perímetro y el diámetro de la ZAF fueron mayores en el grupo 3. Existió correlación positiva entre la densidad capilar parafoveal y el grosor del campo central en los grupos 1, 2, y 3. Conclusiones: La densidad capilar parafoveal disminuye conforme avanza el daño por diabetes tipo 2; puede existir una reducción en sujetos con diabetes sin retinopatía, con grosor retiniano y ZAF normales. El impacto clínico de este hallazgo requiere evaluación adicional.
Photocoagulation may still be a therapeutic choice for center-sparing diabetic macular edema. We compared the visual evolution after photocoagulation, in eyes with focal diabetic macular edema, stratified per the location of thickening with optical coherence tomography. We evaluated people with type 2 diabetes and focal diabetic macular edema, before and three weeks after focal photocoagulation. We divided the sample by edema location: central (group1); paracentral (group 2) and pericentral (group 3) and compared the proportions of eyes with baseline visual impairment, visual improvement, and visual deterioration between groups; central edema was evaluated with logistic regression, as an explaining variable of baseline visual impairment and visual improvement. The study included 160 eyes: 77 in group 1, 20 in group 2, 63 in group 3; baseline visual impairment was more frequent in groups 1 and 2 (52.6%) than in group 3 (28.6%, p = 0.002, OR 2.77) and as common in groups 1 (51.9%) and 2 (55.0%, p = 0.8). The proportions of visual improvement and visual deterioration did not differ between groups (p > 0.05). The outcome after focal photocoagulation was similar in paracentral (considered center-sparing) and central macular edema; the definition of center involvement, which needs intravitreal antiangiogenics, should expand to include paracentral thickening.
Diabetic retinal neuropathy is a disorder that can appear before clinical signs of diabetic retinopathy; the evidence of neuronal damage has been reported in histologic and experimental studies in subjects with diabetic retinopathy. Signs of early dysfunction can be identified using functional tests such as retinal sensitivity, contrast sensitivity, color vision and electroretinogram, all of which show changes in diabetic subjects without retinopathy compared with non-diabetic subjects. Optical coherence tomography has identified a thinning of the ganglion cell layer in diabetic subjects without retinopathy, which has been considered a surrogate of early neuronal damage, and has been proposed to develop before retinal vascular damage. Optical coherence tomography angiography is now able to identify vascular density and perfusion, which also appear before retinopathy in diabetic subjects. Diabetic retinal neuropathy could again be linked to vascular impairment, and the evaluation of the retinal neurovascular unit will require simultaneous measurement of parafoveal density and functional tests to identify the early interactions of microvascular and neuronal retinal damage.
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