Year: 2016
Type: dissertation
Abstract: Diabetic Retinopathy (DR) and Diabetic Macular Edema (DME) represent ocular complications of diabetes and DME is the leading cause of severe vision loss. This work investigated morphology, function, and circulation in patients with newly diagnosed DME in order to elucidate fundamental steps of the pathogenesis of DME development and resolution following laser treatment. Using the Canon Laser Blood Flowmeter, we investigated parameters of retinal blood flow (RBF) (diameter, velocity, and blood flow) in patients with newly diagnosed DME and compared with a control (non - diabetic) group. We assessed RBF parameters in patients with DME undergoing focal/grid laser photocoagulation. Using Spectral â Domain Optical Coherence Tomography (SD-OCT), we investigated and compared values of choroidal thickness (ChT) using enhanced depth imaging (EDI) and regular imaging (RI) acquisition approaches. Also, using SD-OCT, we examined morphological retinal changes induced by focal / grid laser photocoagulation. The correlation analysis revealed moderate agreement between EDI and RI at the temporal and nasal areas and poor agreement in the central choroidal area. There was a tendency for ChT values to be higher using RI approach than EDI. There was a trend for retinal blood velocity to be higher in patients with DME compared to controls but this difference was not significant. We demonstrated that there was no significant change in RBF parameters following the three, seven and thirty days post focal / grid laser photocoagulation. These results are the first to show simultaneous measurements of RBF parameters in patients with DME following laser and provided initial values for sample size calculation for the future studies. We found a significant reduction of total retinal volume and retinal thickness in the section of most edema between the 3 and 30 days of follow-up. The evaluation of histological retinal details revealed restoration of the external limiting membrane/photoreceptor complex which suggests mechanisms of retinal healing and reorganization. Future studies are needed to further elucidate the evidence in support of these theories on structural and vascular development of DME and post laser treatment.
Source: TSpace (University of Toronto)
Author: Elena Leontieva
Language: English
Subfield: Ophthalmology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2682135480