Choroidal thickness and morphology analysed by optical coherence tomography as a method to approach diabetic ocular disease prognosis and progression

INTRODUCTION Clinical evidence of diabetic choroidopathy (DC) in-vivo has been difficult to demonstrate clinically due to the lack of means to visualize the choroid. Advances of Optical Coherence Tomography (OCT) technology allowed in-vivo visualization of the choroid. Controversial results in Diabetes for choroidal thickness (CT) and lack in the identification of morphologic changes makes DC identified with OCT still to be understood. PURPOSE To evaluate whether CT measurement alone is a reliable parameter to characterize DC, to characterize choroidal morphological findings using the OCT and correlation with CT and the diabetic retinopathy (DR). METHODS A cohort, prospective, longitudinal and observational study, where diabetic and healthy controls were followed in consecutive visits. Inclusion criteria were: healthy and Diabetic patients without or with any stage of DR, aged 18 or more, signed voluntarily informed consent. Exclusion criteria were: previous treatment of any kind for DR; previous or ongoing ocular disease or history of ocular surgery; relevant media opacities; refractive errors greater than ± 6 Diopters; systemic chronic steroid or immunosuppressive medication; any serious and uncontrolled systemic condition. Previous studies were performed to identify choroidal morphological findings on OCT to be used as classification method. Quantitative assessment of retinal and subfoveal choroidal thickness (SFCT), qualitative assessment of choroidal morphological findings, and correlation with the retinal diabetic disease state. Evaluation of progression and predictive relevancy. RESULTS One hundred and ninety-six diabetic eyes and seventy-eight healthy eyes were included. From choroidal morphologic analysis we found: on healthy 78% were normal, and abnormalities found were always on the great vessels layers with preserved choriocapillaris/Sattler (ChS) layers. Most of diabetic eyes with no abnormalities had no and initial stages of DR. Focal choroidal vascular changes were correlated with the subjacent retinal disease. Atrophy of the ChS layer or the great vessels layer was well corelated with more advanced stages of DR and maculopathy. Progression of choroidal morphologic changes was well evidenced and correlated with progression of retinal disease. From statistical analysis: SFCT showed huge variability with multifactorial dependence. Statistical significance of correlation with SFCT was found only for age for both groups and choroidal layers abnormalities for diabetics and systolic blood pressure for healthy. CONCLUSION SFCT showed to be dependent on multifactorial variables with a wide range of values showing not to be a reliable parameter alone for DC evaluation. With OCT images we can identify and classify as normal or abnormal choroidal morphologic findings. Abnormal choroidal findings are well correlated with suprajacent retinal diabetic disease and can be a marker of evolution or progression of the disease of treatment effect.