Retinal Nerve Fiber Layer Damage Assessment in Glaucomatous Eyes Using Retinal Retardance Measured by Polarization-Sensitive Optical Coherence Tomography.

Purpose: To assess the diagnostic performance and structure-function association of retinal retardance (RR), a customized metric measured by a prototype polarization-sensitive optical coherence tomography (PS-OCT), across various stages of glaucoma. Methods: This cross-sectional pilot study analyzed 170 eyes from 49 healthy individuals and 68 patients with glaucoma. The patients underwent PS-OCT imaging and conventional spectral-domain optical coherence tomography (SD-OCT), as well as visual field (VF) tests. Parameters including RR and retinal nerve fiber layer thickness (RNFLT) were extracted from identical circumpapillary regions of the fundus. Glaucomatous eyes were categorized into early, moderate, or severe stages based on VF mean deviation (MD). The diagnostic performance of RR and RNFLT in discriminating glaucoma from controls was assessed using receiver operating characteristic (ROC) curves. Correlations among VF-MD, RR, and RNFLT were evaluated and compared within different groups of disease severity. Results: The diagnostic performance of both RR and RNFLT was comparable for glaucoma detection (RR AUC = 0.98, RNFLT AUC = 0.97; P = 0.553). RR showed better structure-function association with VF-MD than RNFLT (RR VF-MD = 0.68, RNFLT VF-MD = 0.58; z = 1.99; P = 0.047) in glaucoma cases, especially in severe glaucoma, where the correlation between VF-MD and RR (r = 0.73) was significantly stronger than with RNFLT (r = 0.43, z = 1.96, P = 0.050). In eyes with early and moderate glaucoma, the structure-function association was similar when using RNFLT and RR. Conclusions: RR and RNFLT have similar performance in glaucoma diagnosis. However, in patients with glaucoma especially severe glaucoma, RR showed a stronger correlation with VF test results. Further research is needed to validate RR as an indicator for severe glaucoma evaluation and to explore the benefits of using PS-OCT in clinical practice. Translational Relevance: We demonstrated that PS-OCT has the potential to evaluate the status of RNFL structural damage in eyes with severe glaucoma, which is currently challenging in clinics.

Comparison of a commercial spectral-domain OCT and swept-source OCT based on an angiography scan for measuring circumpapillary retinal nerve fibre layer thickness.

BACKGROUND/AIMS: To assess the agreement in measuring retinal nerve fibre layer (RNFL) thickness between spectral-domain (SD; Cirrus HD, Carl Zeiss Meditec, USA) optical coherence tomography (OCT) and swept-source (SS; Plex Elite 9000, Carl Zeiss Meditec) OCT using an OCT angiography (OCTA) scanning protocol. METHODS: 57 participants (12 glaucomatous, 8 ocular hypertensive and 74 normal eyes) were scanned with two OCT instruments by a single experienced operator on the same day. Circumpapillary RNFL thicknesses were automatically segmented for SD-OCT and manually segmented for SS-OCTA scans. Agreement of global RNFL thickness, as well as average thickness in four quadrants was assessed using intraclass correlation coefficients (ICCs). RESULTS: There was excellent agreement in the inferior and superior quadrants and the global (all ICC >0.90), followed by good agreement in the temporal (ICC=0.79) and nasal (ICC=0.73) quadrants. The ICC values were similar in the subgroups except within the ocular hypertension group, where the nasal quadrant was less agreeable (ICC=0.31). SS-OCTA-derived RNFL thickness was on average 3 µm thicker than SD-OCT, particularly in the nasal (69.7±11.5 µm vs 66.3±9.3 µm; p<0.001) and temporal (75.6±13.7 µm vs 67.9±12.3 µm; p<0.001) quadrants. CONCLUSIONS: RNFL measurements taken with SS-OCTA have good-to-excellent agreement with SD-OCT, which suggests that the RNFL thickness can be sufficiently extracted from wide-field OCTA scans.

Inhibition of Monocyte Chemoattractant Protein 1 Prevents Conjunctival Fibrosis in an Experimental Model of Glaucoma Filtration Surgery.

Purpose: To evaluate the effect of treatment with monocyte chemoattractant protein-1 receptor inhibitor (MCP-Ri) to maintain bleb survival and prevent fibrosis in an experimental model of glaucoma filtration surgery (GFS). Methods: GFS was performed on one eye of C57/Bl6 mice (n = 36) that was treated with MCP-Ri, mitomycin-C (MMC), or vehicle at the time of surgery. Real-time polymerase chain reaction was used to evaluate conjunctival expression of monocyte chemoattractant protein-1 (MCP-1), TGFB1, TGFB2, collagen 1a1 (Col1a1), sparc (Sparc), and fibronectin at 2 and 7 days following surgery. Anterior segment slit-lamp examination, optical coherence tomography, and confocal microscopy were performed in vivo at day 14. Eyes were processed for immunohistochemical staining of F4/80, a monocyte-macrophage marker, at day 2. In vitro experiments were also performed to compare the effect of MMC, MCP-Ri, and vehicle on the viability of mouse Tenon's fibroblasts. Results: Treatment with MCP-Ri results in a greater reduction in the percentage of F4/80-positive cells in conjunctival blebs and lesser MCP-1 gene expression following experimental GFS than MMC or control. Both MMC and MCP-Ri reduced Col1a1 and Sparc expression, but not fibronectin. TGFB1 decreased with MCP-Ri but not MMC; MMC but not MCP-Ri reduced TGFB2. MMC and MCP-Ri treatment resulted in the preservation of bleb height at day 14, as compared to control. MCP-Ri was less toxic to mouse Tenon's fibroblasts in comparison with MMC. Conclusions: Targeting MCP-1 results in prolonged bleb survival following experimental GFS with less cellular toxicity as compared to MMC. MCP inhibition could provide a safer alternative to conventional antifibrotic adjunctive treatments in GFS.