Functional and Structural Reliability of Optic Nerve Head Measurements in Healthy Eyes by Means of Optical Coherence Tomography Angiography.

Background and Objectives: the aim of the study was to evaluate the repeatability and reproducibility of optical microangiography (OMAG)-based optical coherence tomography angiography (OCTA) in the optic nerve head (ONH) and radial peripapillary capillary (RPC) perfusion assessment of healthy eyes. Materials and Methods: in this observational study, a total of 40 healthy subjects underwent ONH evaluation, using an OMAG-based OCTA system at baseline (T0), after 30 min (T1), and after 7 days (T2). The main outcome measures were the vessel density (VD) and flux index (FI) of the RPCs, as well as peri-papillary retinal nerve fibre layer (pRNFL) thickness. The analysis was performed by two observers independently. The coefficient of repeatability (CR), within the subject coefficient of variation (CVw) and intrasession correlation coefficient (ICC), to evaluate intrasession repeatability of measurements was calculated for each observer. Results: the high intrasession and intersession repeatability and reproducibility were assessed in the two observers for all three outcome measures. Of note, the CRs for the first and the second observer were 0.011 (95% confidence interval (CI) 0.009-0.014) and 0.016 (95% CI 0.013-0.020) for FI, 0.016 (95% CI 0.013-0.021) and 0.017 (95% CI 0.014-0.021) for VD, and 2.400 (95% CI 1.948-3.092) and 3.732 (95% CI 3.064-4.775) for pRNFL thickness, respectively. The agreement between them was excellent for pRNFL assessment and very good for FI and VD. Conclusion: OCTA has a great potential in the accurate assessment of ONH and peri-papillary microcirculation. It allows for repeated and reproducible measurements without multiple scans-related bias, thus guaranteeing an independent operator analysis with good reproducibility and repeatability.

Angiographic biomarkers of filtering bleb function after XEN gel implantation for glaucoma: an optical coherence tomography-angiography study.

PURPOSE: To evaluate, using optical coherence tomography-angiography (OCT-A), the vascular features of good bleb function after XEN gel implantation (XGI) for uncontrolled glaucoma. METHODS: Forty-three patients (43 eyes), who underwent XGI, were enrolled. According to the intraocular pressure (IOP) reduction, patients were classified into Group 1 (21 eyes; success) and Group 2 (22 eyes; failure). Optical coherence tomography-angiography (OCT-A) was performed to image the vascularization of the conjunctival bleb-wall. The main outcomes were as follows: vessel displacement areas (VDAs), major vessel displacement area (MVDA; mm2 ), non-flow whole area (NFWA; mm2 ) and bleb-wall vessel density (BVD; %). Co-registered B-scans were also considered to evaluate the bleb-wall cyst-like structure density and area (BCSD, cysts/mm2 ; BCSA, mm2 ), and the bleb-wall thickness (BT, µm). RESULTS: Mean postoperative follow-up was 7.5 ± 0.14 months; Group 1 and 2 IOP were 14.0 ± 2.5 and 25.3 ± 2.1 mmHg, respectively (p < 0.001). Greater VDA (p < 0.001), MVDA (p = 0.046) and NFWA (p = 0.001) values, and lower BVD (p < 0.001) was found in Group 1 compared to Group 2. Group 1 showed higher BSCD, BSCA and BT values compared to Group 2 (p < 0.001). Postoperative IOP positively correlated with BVD (r = 0.567; p = 0.003), but negatively with VDAs, MVDA (r = -0.581, p = 0.002; r = -0.619, p = 0.001, respectively), BCSD, BCSA (r = -0.580; p = 0.002; r = -0.664; p < 0.001) and BT (r = -0.627, p = 0.001). CONCLUSION: Successful filtration blebs after XGI present numerous and large areas of vessel displacement within the bleb-wall, along with a rarefied vascular network. These OCT-A features can be considered angiographic biomarkers of a good aqueous humour percolation through the bleb-wall layers.

Multilayer amniotic membrane transplantation for bacterial keratitis with corneal perforation after hyperopic photorefractive keratectomy: case report and literature review.

We report a case of corneal infection caused by Streptococcus pneumoniae after hyperopic photorefractive keratectomy (PRK) that produced severe corneal melting, ulceration, and multiple perforations. Treatment included antibiogram-based antibiotic topical therapy and multilayer amniotic membrane transplantation (AMT) performed to seal the perforations and restore the globe integrity. Clinical and anterior segment optical coherence tomography (Visante OCT, Carl Zeiss Meditec) examinations documented progressive integration of the amniotic membrane tissues within the cornea, stromal and epithelial healing, and recovery of a stable and regular anterior chamber. The cornea healed with an avascular leucoma; the best corrected visual acuity was reduced to 20/200. Severe pneumococcal ulcerative perforation is a potential complication of PRK. Penetrating keratoplasty, at high risk for failure in the acute settings of an infected and inflamed eye, can be delayed until the cornea is healed. Amniotic membrane transplantation may be an alternative surgical option to achieve this goal.

Photorefractive keratectomy with aspheric profile of ablation versus conventional photorefractive keratectomy for myopia correction: six-month controlled clinical trial.

PURPOSE: To analyze ocular wavefront error and corneal asphericity (Q) in patients treated with aspheric profile photorefractive keratectomy (PRK) compared with patients having conventional PRK to correct myopia and myopic astigmatism and to evaluate the effect of postoperative corneal shape on visual performance. SETTING: Eye Clinic, University G. d'Annunzio, Chieti-Pescara, Italy. METHODS: Fifty eyes were treated with aspheric profile PRK using the MEL 80 flying-spot excimer laser, and 24 eyes were treated with standard PRK using the MEL 70 flying-spot excimer laser. RESULTS: Postoperative wavefront error increased in both groups. Six months after surgery, there was a smaller increase in root mean square (RMS) of total higher-order aberrations and spherical aberration (59% and 106%, respectively) in the aspheric profile PRK group than in the conventional PRK group (94% and 136%, respectively) (P<.01). The aspheric profile PRK group showed more prolate corneal asphericities (mean Q of 0.15 +/- 0.26) than the conventional group (mean Q of 0.45 +/- 0.26) (P<.001), with increasing oblateness for higher attempted corrections. A higher percentage of patients with better low-contrast uncorrected visual acuity and best corrected visual acuity was observed in the aspheric PRK group than in the conventional PRK group (P<.05). CONCLUSIONS: Aspheric profile and conventional PRK were safe and efficient for the correction of myopia and myopic astigmatism. Moreover, aspheric profile PRK induced a smaller increment of total wavefront error, was related to a smaller increase in spherical aberration, and better maintained the physiology of the corneal surface than conventional treatment.

Reliability of nerve fiber layer thickness measurements using optical coherence tomography in normal and glaucomatous eyes.

OBJECTIVE: To evaluate the reliability of nerve fiber layer (NFL) thickness measurements by optical coherence tomography (OCT) in normal and glaucomatous eyes. DESIGN: Prospective, comparative, observational case series and instrument validation study. PARTICIPANTS: Twenty-four glaucomatous patients were compared with 24 gender- and age-matched normal subjects. METHODS: Each individual underwent OCT measurements of NFL thickness. Five repetitions of a series of scans on five separate occasions within a 0.5-month period were performed. Each eye was scanned at three different nerve head programs (1.5 radius [R], R = 1.73 mm, 2.0 R). For each option (1.5 R, R = 1.73 mm, and 2.0R) and region (superior, inferior, temporal, nasal, and overall mean), variance components and intraclass correlation coefficients were determined using repeated measures regression. In these models, NFL thickness, as measured by OCT, was assumed to have three variance components: intersubject, intervisit (within-subject between-dates), and intravisit (within-subject within-date). The intraclass correlation coefficient (intersubject variance/total variance) was used as a measure of reliability. MAIN OUTCOME MEASURES: Measurements of NFL thickness using OCT were performed. RESULTS: Reliability values, as measured by intraclass correlation coefficients, resulted as follows: 1.5 R, 0.54/0.52 (normal/glaucoma); R = 1.73 mm, 0.50/0.50; 2.0 R, 0.49/0.50. CONCLUSIONS: Our results indicate that the recent commercially available OCT provides reliable NFL thickness measurements in both healthy and glaucomatous eyes with each circle radius tested. The greatest amount of variability can be attributed to intersubject differences.