Optical coherence tomography indices for diagnosis of chronic glaucoma in patients with diabetes mellitus: a pilot study.

PURPOSE: To evaluate optical coherence tomography (OCT) parameters in patients with concomitant type-2 diabetes mellitus (DM) and primary open angle glaucoma (POAG) compared with patients with either of these diseases. METHODS: Sixty eyes (52 patients) were divided into three groups. The first group included nonglaucomatous diabetic patients, the second included patients with POAG without DM, and the third included patients with both POAG and DM. Spectral domain OCT evaluation of the retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), and optic disc parameters was performed. Visual field (VF) was measured for structural and functional correlation. RESULTS: Significant differences were found in average RNFL, inferior RNFL, average GCC, inferior GCC, rim area, focal loss volume (FLV%), and global loss volume (GLV%) (P = 0.014, 0.001, 0.027, 0.006, 0.009, 0.043, and 0.001, respectively). The concomitant presence of DM and glaucoma was a risk factor for decreased average RNFL, inferior RNFL, rim area, and inferior GCC, and for increased GLV% (P = 0.034, 0.002, 0.014, 0.015, and 0.003, respectively). The inferior RNFL thickness had the largest significant area under the curve (P = 0.726; 90% sensitivity) at a specificity greater than 80% with a cutoff value of 105.38 µm (P = 0.005) compared with average RNFL, inferior GCC, rim area, and GLV% (P = 0.073, 0.25, 0.23, and 0.1, respectively). VF demonstrated the predominance of nasal scotomata in the diabetic group and arcuate scotoma in the glaucoma group (P < 0.001 and 0.03, respectively). CONCLUSIONS: OCT could be a valuable tool for the detection and follow-up of POAG in diabetic patients. The inferior RNFL thickness could be a sensitive and a specific predictor for glaucoma diagnosis and progression in diabetic patients without retinopathy.

Review on Recent Trials Evaluating the Effect of Intravitreal Injections of Anti-VEGF Agents on the Macular Perfusion of Diabetic Patients with Diabetic Macular Edema.

BACKGROUND: Diabetic macular edema (DME) is a major cause of vision loss in diabetics worldwide. Anti-vascular endothelial growth factor (anti-VEGF) agents have become the mainstay of treatment of vision loss due to DME. Long-term effects of these agents on the macular perfusion (MP) are a current concern. OBJECTIVE: To review recently published studies that evaluated the effect of intravitreal injection of anti-VEGF agents on the MP of diabetics with DME. METHODS: Different databases were searched including PubMed, Medline, Ovid, Science Direct, and Google Scholar for relevant studies published between 2010 and 2019. All studies found were compared regarding methodology and results and included in this review. Some studies relating to retinal perfusion in general and not strictly MP were also included for comprehensiveness. RESULTS: Several studies utilizing different anti-VEGF agents were identified. All the large randomized controlled clinical trials identified utilized primarily fluorescein angiography (FA) and human graders and found generally no worsening of MP associated with anti-VEGF agents use in diabetic patients with DME. Some of these studies, however, depended on post-hoc analysis. Several more recent, but smaller case series, have utilized the relatively new and non-invasive optical coherence tomography angiography (OCTA) in this evaluation and found more conflicting results. CONCLUSION: The large clinical trials recently performed depended mainly on FA in the analysis of MP changes following injections and generally found no worsening of MP. More recently, smaller case series have utilized OCTA in this analysis, yielding more conflicting results. Large randomized controlled trials using OCTA are thus needed.

Evaluation of Changes in Macular Perfusion Detected by Optical Coherence Tomography Angiography following 3 Intravitreal Monthly Bevacizumab Injections for Diabetic Macular Edema in the IMPACT Study.

OBJECTIVE: To evaluate macular perfusion changes following intravitreal bevacizumab injections for diabetic macular edema (DME) using spectral domain optical coherence tomography angiography (SD-OCTA). METHODS: This study was a prospective noncomparative interventional case series. Treatment naïve patients with DME underwent full ophthalmological examination and SD-OCTA scanning at baseline and after 3 intravitreal bevacizumab injections. Both the 6 × 6 and 3 × 3 mm macular scan protocols were used. Pretreatment and posttreatment OCTA images were automatically aligned using a commercially available retina alignment software (i2k Align Retina software); then the fractal dimension (FD), vascular density (VD), and skeleton VD changes were obtained at the full retinal thickness (Full) and superficial (SCP) and deep (DCP) capillary plexuses after processing images using a semiautomated program. The foveal avascular zone (FAZ) was manually measured and FD was calculated using the FracLac plugin of ImageJ. RESULTS: Forty eyes of 26 patients were included. Following injections, there were an 8.1% increase in FAZ, 1.3% decrease in FD-Full and FD-SCP, 1.9% decrease in FD-DCP, 8% decrease in VD-Full, 9.1% decrease in VD-SCP, 10.6% decrease in VD-DCP, 13.3% decrease in skeleton VD-Full, 12.5% decrease in skeleton VD-SCP, and 16.3% decrease in skeleton VD-DCP in the 6 × 6 mm macular area and a 2.6% decrease in FD-Full, 3.4% decrease in FD-SCP, 11.5% decrease in VD-Full, 14.3% decrease in VD-SCP, and 25.1% decrease in skeleton VD-SCP in the 3 × 3 mm macular area which were all statistically significant (p < 0.05). Using univariate and multivariate analysis, the pretreatment FD, VD, and skeleton VD at each capillary layer significantly negatively correlated with the change in FD, VD, and skeleton VD at the corresponding capillary layer, respectively (p < 0.05). CONCLUSION: OCTA is a useful noninvasive tool for quantitative evaluation of macular perfusion changes following DME treatment. This trial is registered with NCT03246152.

Evaluation of the Effect of Repeated Intravitreal Bevacizumab Injections on the Macular Microvasculature of a Diabetic Patient Using Optical Coherence Tomography Angiography.

A 53-year-old female patient with center-involving diabetic macular edema affecting the left eye was imaged using optical coherence tomography angiography (OCTA) in both eyes. She underwent three monthly intravitreal bevacizumab injections in the left eye only and OCTA was repeated in both eyes one month following the last injection and showed decreased vascular density (VD) in the treated left eye but not in the untreated right eye compared to baseline. No further injections were required in either eye, and OCTA was done in both eyes 4 months following the last injection which showed improved VD of the left eye with stable VD in the right. Three monthly intravitreal bevacizumab injections were then required in both eyes; then OCTA was repeated following the last injection and revealed decreased VD in both eyes compared to previous scan. OCTA could be a useful tool for detecting VD changes following bevacizumab injections in diabetics.