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Los Angeles, CA, United States

Tan J.C.,Doheny Eye Institute
Investigative ophthalmology & visual science | Year: 2012

To characterize the three-dimensional (3-D) structure of the human trabecular meshwork (TM) by two-photon excited (TPEF) autofluorescence (AF) and optical sectioning without conventional histologic embedding and sectioning. Viable human ex vivo explants of the anterior chamber angle containing the aqueous humor drainage tissue in situ were imaged by TPEF to localize AF and Hoechst 33342 nuclear fluorescence. An autofluorescent marker in Schlemm's Canal (SC) aided SC situ visualization. En face and orthogonal views of the TM were generated. In the innermost uveal TM, AF signals outlined an intricate 3-D network of fine branching beams with large openings between the beams. In the adjacent corneoscleral TM, beams were thicker and coalesced as plate-like structures with pore-like openings. Linear and coiled AF fibers were visible on the background AF of beams. Deeper, in the external TM, this organization changed to fine fiber arrays orientated in the tissue's longitudinal axis, reminiscent of the cribriform plexus of the juxtacanalicular TM (JCT). In the outermost JCT, AF of fine fibers was sparse, then undetectable as optical sections approached the inner wall of SC. Cell nuclei were closely associated with the TM structural extracellular matrix. We have used TPEF and optical sectioning to exploit AF as a useful method to visualize the structure of the human conventional aqueous drainage pathway in situ. Ancillary nuclear staining allowed cell association with the AF structures to be seen. This approach revealed a unique 3-D perspective of the TM that is consistent with known TM structural characteristics. Source

Hu Z.,Doheny Eye Institute
Investigative ophthalmology & visual science | Year: 2013

Geographic atrophy (GA) is the atrophic late-stage manifestation of age-related macular degeneration (AMD), which may result in severe vision loss and blindness. The purpose of this study was to develop a reliable, effective approach for GA segmentation in both spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) images using a level set-based approach and to compare the segmentation performance in the two modalities. To identify GA regions in SD-OCT images, three retinal surfaces were first segmented in volumetric SD-OCT images using a double-surface graph search scheme. A two-dimensional (2-D) partial OCT projection image was created from the segmented choroid layer. A level set approach was applied to segment the GA in the partial OCT projection image. In addition, the algorithm was applied to FAF images for the GA segmentation. Twenty randomly chosen macular SD-OCT (Zeiss Cirrus) volumes and 20 corresponding FAF (Heidelberg Spectralis) images were obtained from 20 subjects with GA. The algorithm-defined GA region was compared with consensus manual delineation performed by certified graders. The mean Dice similarity coefficients (DSC) between the algorithm- and manually defined GA regions were 0.87 ± 0.09 in partial OCT projection images and 0.89 ± 0.07 in registered FAF images. The area correlations between them were 0.93 (P < 0.001) in partial OCT projection images and 0.99 (P < 0.001) in FAF images. The mean DSC between the algorithm-defined GA regions in the partial OCT projection and registered FAF images was 0.79 ± 0.12, and the area correlation was 0.96 (P < 0.001). A level set approach was developed to segment GA regions in both SD-OCT and FAF images. This approach demonstrated good agreement between the algorithm- and manually defined GA regions within each single modality. The GA segmentation in FAF images performed better than in partial OCT projection images. Across the two modalities, the GA segmentation presented reasonable agreement. Source

Liang D.,Doheny Eye Institute
Investigative ophthalmology & visual science | Year: 2013

We determined the mechanism by which all-trans retinoic acid (ATRA) inhibits experimental autoimmune uveitis (EAU) and determined the role of γδ T cells in this autoimmune disease. C57BL/6 (B6) mice were immunized with the uveitogenic, interphotoreceptor retinoid-binding protein1-20 peptide (IRBP1-20) in complete Freund's adjuvant (CFA), with or without a preceding ATRA treatment. Responses and pathogenic activity of Th1- and Th17-autoreactive T cells were compared, and the effects of ATRA on γδ T cells and CD25(+) dendritic cell (DC) subset were determined. Interactions among uveitogenic T cells, DC subsets, and γδ T cells were investigated. Administration of ATRA to B6 mice in which EAU was induced suppressed the response of Th17 autoreactive T cells, which was associated with decreased generation of the CD25(+) DC subset and suppressed activation of γδ T cells. Adoptively transferred γδ T cells isolated from ATRA-treated mice showed a diminished ability to promote the activation of Th17 autoreactive T cells in vitro and in vivo compared to γδ T cells from untreated donors. ATRA inhibits the expansion of CD25(+) DCs and γδ T-cell activation, thereby restraining the Th17 autoreactive T-cell response. Source

Hwang J.C.,Doheny Eye Institute
American Journal of Ophthalmology | Year: 2012

Purpose: To determine if there are variations in regional practice patterns for retinal detachment repair in the United States. Design: Retrospective, noninterventional, cross-sectional study. Methods: Year 2009 Medicare fee-for-service claims for retinal detachment repair were aggregated in 4 geographic regions and evaluated. The relative preference for retinal detachment repair by pars plana vitrectomy, scleral buckling, and pneumatic retinopexy was analyzed. Results: The Midwest demonstrated a greater preference for scleral buckling compared to all other regions (P <.01) and lower preference for pars plana vitrectomy relative to the South and West (P ≤.02). The Northeast demonstrated a greater preference for pneumatic retinopexy when compared to all other regions (P <.01). The Northeast also revealed a trend toward a lower preference for pars plana vitrectomy compared to the West and South (P ≤.08). Conclusion: There are statistically significant variations in regional practice patterns for retinal detachment repair. The West, despite its historical association with pneumatic retinopexy, did not demonstrate a greater preference for the surgical technique. © 2012 Elsevier Inc. All rights reserved. Source

Caprioli J.,Jules Stein Eye Institute | Varma R.,Doheny Eye Institute
American Journal of Ophthalmology | Year: 2011

Purpose: To review the role of intervisit intraocular pressure (IOP) fluctuation as an independent risk factor for glaucoma. Design: Perspective after literature review. Methods: Analysis of pertinent publications in the peer-reviewed literature. Results: Disparate findings regarding the role of intervisit IOP variation have been published. IOP variation was a significant risk factor in the Advanced Glaucoma Intervention Study (AGIS), the Collaborative Initial Glaucoma Treatment Study, and other smaller studies. These studies have in common low IOPs (often after surgery) and moderately advanced disease. In the AGIS, when patients were stratified by mean IOP, only those patients with low IOPs showed the detrimental effects of IOP variation. IOP variation was not a significant risk factor in the Early Manifest Glaucoma Treatment Trial, and in 2 separate studies of ocular hypertensives. These studies have in common generally higher IOPs and an earlier stage of glaucoma (or no glaucoma at all). We believe these results are complementary rather than contradictory: existing data suggest that the effects of IOP variation depend on the characteristics of the patient, the baseline IOP, their stage of damage, the type of glaucoma, and other as-yet unknown factors. Conclusions: Practitioners should consider whether patients who are progressing at low mean IOP may benefit from having IOP variation reduced. Single elevated measures of IOP may not be an anomaly or may not be related to compliance, but may identify patients who are at high risk for progressive glaucomatous damage, and thus should be monitored more carefully and potentially treated more aggressively. © 2011 Elsevier Inc. Source

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