Quantitative analysis of optical coherence tomography angiography metrics in diabetic retinopathy.

PURPOSE: To evaluate the correlation of the visual acuity and diabetic retinopathy stage using optical coherence tomography and optical coherence tomography angiography metrics. METHODS: In this prospective study, optical coherence tomography and optical coherence tomography angiography images of patients with different stages of diabetic retinopathy were obtained. In optical coherence tomography angiography images, the size of foveal avascular zone, central macular thickness, and vessel density at superficial and deep capillary layers of the macula were measured. In optical coherence tomography images, the presence of intraretinal cyst, disorganization of retinal inner layer, and ellipsoid zone and external limiting membrane disruption were evaluated. The associations between the variables with visual acuity and diabetic retinopathy stage were analyzed. RESULTS: In total, 68 eyes of 38 patients with a mean age of 58.96 ± 10.59 years were included. In total, 34 eyes were categorized as non-proliferative diabetic retinopathy, 14 as active, and 20 as regressed proliferative diabetic retinopathy. Univariate analysis showed deep parafoveal vessel density, central macular thickness, ellipsoid zone disruption, disorganization of retinal inner layer, and external limiting membrane disruption had a significant relationship with visual acuity. However, in multivariate analysis, only central macular thickness and ellipsoid zone disruption had significant association with visual acuity (p = 0.02 and p = 0.01, respectively). There was a significant difference in deep parafoveal vessel density (p = 0.04), but not in foveal avascular zone area, between different stages of diabetic retinopathy. CONCLUSION: In this study, the foveal avascular zone area did not correlate with visual acuity and different stages of diabetic retinopathy. Structural abnormalities on optical coherence tomography images with especial focus on outer retinal disruption provided more reliable predictors for visual acuity outcomes in patients with diabetic retinopathy.

Effect of segmentation error correction on optical coherence tomography angiography measurements in healthy subjects and diabetic macular oedema.

PURPOSE: To evaluate the impact of segmentation error on vessel density measurements in healthy eyes and eyes with diabetic macular oedema (DMO). METHODS: In this prospective, comparative, non-interventional study, enface optical coherence tomography angiography (OCTA) images of the macula from healthy eyes and eyes with DMO were acquired. Two expert graders assessed and corrected the segmentation error. The rate of segmentation error and the changes in vessel density and inner retinal thickness after correction of the segmentation error were recorded and compared between the two groups. RESULTS: 20 eyes with DMO and 24 healthy eyes were evaluated. Intergrader agreement was excellent (intraclass correlation coefficient ≥0.9) for all parameters in both groups. The rate of segmentation error was 33% and 100% in healthy and diabetic eyes, respectively (p<0.001). Nine healthy eyes (37.5%) and all eyes with DMO (100%) were noted to exhibit a change in at least one of the foveal or parafoveal vessel density measurements. The rate of any change in foveal and parafoveal vessel densities in both the superficial and deep capillary plexus was statistically significantly higher in the diabetic group (all p<0.001). No statistically significant change was observed in mean vessel density (superficial and deep capillary plexuses) after correction of the segmentation error in healthy and DMO eyes (All p>0.05). However, the mean absolute change in the vessel density measurements was statistically significantly higher in the diabetic group (all p<0.05). The mean absolute change in superficial and deep inner retinal thickness was statistically significantly higher in DMO (p=0.02 and p=0.002, respectively). CONCLUSIONS: In this study, misidentification of retinal layers and consequent vessel density measurement error occurred in all eyes with DMO and in one-third of healthy eyes. The segmentation error should be checked and manually corrected in the OCTA vessel density measurements, especially in the presence of macular oedema.

Optical coherence tomography angiography features of optic nerve head drusen and nonarteritic anterior ischemic optic neuropathy.

OBJECTIVE: To evaluate the optic disc microvasculature in optic nerve head drusen (ONHD) vasculature in comparison to acute nonarteritic anterior ischemic optic neuropathy (NAION) and normal eyes using optical coherence tomography angiography (OCT-A). METHODS: Ten eyes with ONHD, 10 eyes with acute NAION, and 10 healthy eyes were included in this prospective, comparative, observational case series. OCT-A imaging was performed on the optic discs. Qualitative grading was performed for dilation and tortuosity of the peripapillary vessels by 3 graders. Quantitative comparison was performed for peripapillary and inside disc vessel densities in nerve head (NH) and retinal peripapillary capillary (RPC) slabs. RESULTS: The intergrader agreement for dilation and tortuosity of the peripapillary vessels was poor (0.313 and 0.182 for vascular dilation in nerve head and radial peripapillary capillary enface images, respectively, and 0.478 and 0.490 for vascular tortuosity in nerve head and radial peripapillary capillary enface images, respectively). In NH en face images, the vessel density measurements were statistically significantly different between the 3 groups (all p < 0.05). In RPC en face images, the vessel density measurements were statistically significantly different between the 3 groups (all p < 0.05) except for nasal peripapillary sector (0.08). CONCLUSION: Despite poor intergrader agreement in qualitative analysis, quantitative OCT-A evaluation may differentiate optic disc edema due to NAION from pseudodisc edema due to ONHD.

Correlation of optic disc morphometry and optic disc microvasculature assessed with optical coherence tomography angiography.

OBJECTIVE: To compare optic disc microvasculature measurements to the disc morphometrics in normal eyes. DESIGN: Cross-sectional study. PARTICIPANTS: Fifty-eight healthy subjects. METHODS: Enface 4.5x4.5 mm optical coherence tomography angiography images were obtained from the optic disc of healthy individuals. The radial peripapillary capillary (RPC) and the nerve head (NH) en face images were obtained. Also, spectral domain OCT measurements of the peripapillary nerve fibre layer (NFL) thickness were recorded. Correlations of the vessel density and NFL measurements with optic disc morphometrics were analyzed. RESULTS: Fifty-eight eyes of 58 patients were included. Mean peripapillary NFL thickness was 99.77 ± 8.47 µm. The mean disc area was 2.15 ± 0.34 mm2 (range, 1.48-3.02 mm2) with an average cup/disc area ratio of 0.27 ± 0.14 (range, 0.0-0.6). On the RPC en face image, the mean vessel density of the whole image, peripapillary, and inside disc was 55.52 ± 2.90, 62.42 ± 3.30, and 45.77 ± 9.24%, respectively. On the NH en face images, the mean vessel density of the whole image, peripapillary, and inside disc was 55.69 ± 3.04, 60.15 ± 2.79, and 52.69 ± 5.31%, respectively. The NH vessel density in the inside disc area correlated with the cup/disc area ratio (R = -0.44, p < 0.001). The association of RPC vessel density in the inside disc area with the cup/disc area ratio was significant (R= -0.88, p < 0.001). The RPC vessel density in the peripapillary area correlated with the cup/disc area ratio (R = 0.37, p = 0.004). Also, the RPC vessel density in the whole image was associated with the peripapillary NFL thickness (R = 0.32, p = 0.01). CONCLUSION: We observed a significant negative correlation between inside disc vessel density and cup/disc area ratio, but not to the disc area in normal eyes. In addition, the whole image RPC vessel density was revealed to be weakly correlated with the average RNFL thickness.

Foveal Avascular Zone and Vessel Density in Healthy Subjects: An Optical Coherence Tomography Angiography Study.

PURPOSE: To report the normal characteristics and correlations of the foveal microvascular networks using optical coherence tomography angiography (OCTA) in a healthy Iranian population. METHODS: Enface 3x3 OCTA images were obtained using the RTVue Avanti spectral-domain optical coherence tomography with AngioVue software (Optovue, Fremont, CA, USA). Foveal avascular zone (FAZ) area, central foveal point thickness and inner retinal thickness at the foveal center and the vascular density of the superficial retinal capillary plexus (SCP) and deep retinal capillary plexus (DCP) in the fovea were recorded. RESULTS: Seventy normal eyes of 70 subjects (range, 9 to 71 years) were studied. Mean FAZ area was 0.32 ± 0.11 (range, 0.13-0.67) mm2 in SCP and 0.50 ± 0.13 (range, 0.19-0.94) mm2 in DCP. Mean SCP vessel density was 29.6 ± 4.7 (range, 16.3-40.3) % in the fovea. Mean DCP vessel density was 27.0 ± 5.9 (range, 15.0-45.2) % in the fovea. The FAZ area at SCP level was negatively correlated to the central subfield thickness (P < 0.001). The FAZ area at DCP level correlated negatively to the central subfield thickness and was significantly associated to age (both P < 0.001). The foveal SCP vessel density significantly correlated with foveal thickness and the foveal DCP vessel density correlated significantly with central foveal subfield thickness and was inversely related to age (all P < 0.05). CONCLUSION: In this study, central foveal subfield thickness was a major determinant of the FAZ size and foveal vessel density. Age was a determinant for FAZ area and whole image vessel density in DCP.

Intravitreal triamcinolone as an adjunct to standard laser therapy in coexisting high-risk proliferative diabetic retinopathy and clinically significant macular edema.

PURPOSE: To evaluate the efficacy and safety of combined intravitreal triamcinolone acetonide (IVTA) injection plus panretinal photocoagulation (PRP) and macular photocoagulation (MPC) in comparison with PRP and MPC in eyes with coexisting high-risk proliferative diabetic retinopathy (PDR) and clinically significant macular edema (CSME). METHODS: Twenty-three patients diagnosed with both high-risk PDR and CSME were enrolled in our prospective, randomized clinical trial study. One eye of each patient was selected to undergo IVTA injection one week before initial PRP and MPC (IVTA eye), and the other eye was treated with PRP and MPC (control eye) based on block randomization. Panretinal photocoagulation was performed in 3 sessions at 1 week intervals. Baseline characteristics included best-corrected visual acuity (BCVA) using Snellen charts, intraocular pressure and patients were observed at 1, 4, and 6 months of treatment. Main outcome measures included change in central macular thickness (CMT) as measured by optical coherence tomography (OCT), logarithm of the minimum angle of resolution BCVA (logMAR), and complications occurring within the follow-up period. RESULTS: Of 23 enrolled patients, 5 patients did not complete follow-up visits due to dense vitreous hemorrhage, tractional retinal detachment and loss of future follow-up. Mean baseline logMAR BCVA was 0.46 +/- 0.29 and 0.56 +/- 0.27 in IVTA eyes and controls. Final mean logMAR BCVA was 0.39 +/- 0.29 (IVTA eyes) and 0.55 +/- 0.33 (control eyes), which was not significantly different (P = 0.08). Mean baseline CMT was 319.2 +/- 79.1 microm (IVTA eyes) and 345.9 +/- 100.6 microm (control eyes). Significant reduction of CMT in IVTA eyes was observed at 1 month (P = 0.024), which had not remained stable after 6 months showing no significant difference as compared with baseline CMT (P = 0.06). In control eyes, CMT was not significantly reduced at 1 and 6 months of treatment. The standardized change in macular thickening (SCMT) was 29.4 +/- 52.2 (IVTA group) versus 5.66 +/- 31.5 (control group) (P = 0.12) at 1 month. At 6 months, SCMT was 16.8 +/- 55.8 (IVTA group) versus 5.03 +/- 47.4 (control group) (P = 0.51). CONCLUSION: Combined IVTA plus PRP and MPC in coexisting high-risk PDR and CSME eyes do not have a significant beneficial effect on BCVA improvement and CMT reduction compared with standard treatment.

Living related conjunctival limbal allograft and amniotic membrane transplantation for limbal stem cell deficiency in chemically injured eyes / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To evaluate the clinical success of living related conjunctival limbal and amniotic membrane transplantation for treatment of chemical injury induced limbal stem cell deficiency.METHODS: From July 2005 to December 2007, 10 eyes of 9 male patients with chemical injury induced limbal stem cell deficiency were included in the study. All subjects underwent living related conjunctival limbal and amniotic membrane transplantation. Blepharorrhaphy was performed in two cases. Systemic immunosuppression with cyclosporine and prednisolone was initiated.RESULTS: Complete corneal epithelialization was observed in 3 eyes (30%). In one of the patients immunologic rejection and corneal melting led to perforation 1.5 months after surgery. The increasing dose of systemic immunosuppression was used to control it. Three eyes were described as primary failure because graft could not re-epithelialize the corneal surface. The remained four eyes showed partial re-epithelialization, but failed to cover the entire corneal surface with epithelium. Best corrected visual acuity ranged from hand movement to counting finger at 1 meter before the surgery and after the surgery was light perception to 20/80. Five eyes had visual improvement without any additional procedure. Dry eye and persistent inflammation were known as main causes of failure.CONCLUSION: Living related conjunctival limbal allograft and amniotic membrane transplantation can be a good option in the management of limbal stem cell deficiency in selected cases in which tear production and control of ocular inflammation are adequate.