Remarkable improvements in optical coherence tomography (OCT) technology have resulted in highly sophisticated, noninvasive machines allowing detailed and advanced morphological evaluation of all retinal and choroidal layers. Postproduction semiautomated imaging analysis with dedicated public-domain software allows precise quantitative analysis of binarized OCT images. In this regard, the choroidal vascularity index (CVI) is emerging as a new imaging tool for the measurement and analysis of the choroidal vascular system by quantifying both luminal and stromal choroidal components. Numerous reports have been published so far regarding CVI and its potential applications in healthy eyes as well as in the evaluation and management of several chorioretinal diseases. Current literature suggests that CVI has a lesser variability and is influenced by fewer physiologic factors as compared to choroidal thickness. It can be considered a relatively stable parameter for evaluating the changes in the choroidal vasculature. In this review, the principles and the applications of this advanced imaging modality for studying and understanding the contributing role of choroid in retinal and optic nerve diseases are discussed. Potential advances that may allow the widespread adoption of this tool in the routine clinical practice are also presented.

The cornea is the most commonly transplanted tissue in medicine. The main cause of corneal graft failure is allograft rejection. The incidence of graft rejection depends on the presence of high-risk characteristics, most notably corneal neovascularization. Although corneal graft has high success rates in the absence of these risk factors, high-risk keratoplasty is associated with low success rates due to a high incidence of immune-mediated graft rejection. To improve the survival of high-risk corneal transplantation, various preoperative, intraoperative, and postoperative measures can be considered. However, the key step in the management of these grafts is the long-term use of local and/or systemic immunosuppressive agents. Although a number of immunosuppressive agents have been employed for this purpose, the results vary significantly across different studies. This is partly due to the lack of an optimized method for their use as well as the lack of a precise stratification of the degree of risk in each individual patient. New targeted biologic treatments as well as tolerance-inducing methods show promising horizons in the management of high-risk corneal transplantation in near future.

Pediatric corneal transplantation is a critical tool for visual restoration and development in young patients with corneal opacities, particularly during the critical period of visual development. Successful management of the significant challenges associated with pediatric keratoplasty requires customized clinical and surgical management of each patient with particular attention paid to proper post-operative rehabilitation.

Regulatory T cells (Tregs) are crucial for allograft survival. Tregs can be divided into thymus-derived natural Tregs (tTregs) and peripherally-derived induced Tregs (pTregs). Here, we determine whether the suppressive function of Treg subsets is hampered in hosts who are at high risk for rejecting their graft. To induce graft beds that promote high risk of transplant rejection, intrastromal corneal sutures were placed two weeks prior to the transplant procedure in mice. We demonstrate that in high-risk recipients the frequencies and function of pTregs (but not tTregs) are suppressed. Reduced function of pTregs correlated with decreased expression of CTLA-4, interleukin-10, and transforming growth factor-β. Adoptive transfer of pTregs from mice at low risk of subsequent graft rejection is able to rescue graft survival in recipients that are at high risk of rejecting their grafts. Our data suggest that impaired function of pTregs, but not tTregs, mediates the loss of immune tolerance and promotes allograft rejection.

Purpose To delineate and compare the kinetics of corneal angiogenesis after high-risk (HR) versus low-risk (LR) corneal transplantation. Methods In mice intrastromal sutures were placed in the recipient graft bed two weeks before allogeneic transplantation to induce angiogenesis and amplify the risk for graft rejection. Control (LR) graft recipients did not undergo suture placement, and thus the host bed remained avascular at the time of transplantation. Graft hemangiogenesis and opacity scores were evaluated for 8 weeks by slit-lamp biomicroscopy. Immunohistochemistry was used to measure CD31hi (blood vessels) and LYVE-1hi (lymphatic vessels) cells. Results A biphasic kinetics was observed for hemangiogenesis in both HR and LR transplant recipients using clinical and immunohistochemical assessments. The biphasic kinetics was composed of a rise-fall (phase 1) followed by a second rise (phase 2) in the degree of vessels. Compared to LR recipients, HR recipients showed higher hemangiogenesis (whole cornea and graft) throughout 8 weeks. Analyzing grafts revealed sustained presence of lymphatic vessels in HR recipients; however, lymphatic neovessels regressed in LR recipients two weeks post-transplantation. In contrast to HR host beds, the LR host bed microenvironment cannot sustain the growth of lymphatic neovessels in allografts while it can sustain continued hemangiogenesis. Conclusion The sustained presence of lymphatic vessels in the HR host beds can facilitate host immunity against allografts and is likely associated with ongoing higher risk of rejection of these grafts in long-term, suggesting that therapeutic interventions targeting inflammation and lymphatic vessels need to be sustained long-term in the HR corneal transplant setting.

Dynamic changes to tear protein profiles occur with aging. Our study identifies the expression of IL-8, IL-6, RANTES, MMP-1, and MIP-3β as increasing with age. These select inflammatory and matrix remodeling factors may be relevant to the development of novel diagnostic tools and therapeutics in the context of age-related ocular surface disease.

Purpose To evaluate the safety and efficacy of topical tacrolimus 0.05% vs. topical methylprednisolone 0.5% in patients with ocular graft-versus-host disease (GVHD). Design Phase I/II, prospective, randomized, double-masked clinical trial. Subjects Eighty eyes from 40 patients diagnosed with chronic ocular GVHD were enrolled. Methods Forty patients with ocular GVHD were randomized; 24 patients were treated with topical tacrolimus 0.05% and 16 patients with topical methylprednisolone 0.5% twice a day for 10 weeks, in addition to continuing their baseline treatment regimen. Main Outcome Measures Safety was evaluated based on occurrence of adverse events. Tolerability was assessed based on subjects’ reports of discomfort after drop instillation. Intraocular pressure (IOP) was monitored. The main efficacy endpoints were: corneal fluorescein staining (CFS), tear break-up time (TBUT), Schirmer test, and expression of the ocular surface inflammatory markers human leukocyte antigen-DR (HLA-DR) and intercellular adhesion molecule-1 (ICAM-1). Symptoms were evaluated using the Ocular Surface Disease Index (OSDI). Results After 10 weeks of treatment, no major adverse events occurred in either treatment group, and there was no significant difference in the composite tolerability scores between the two groups (P=0.06). However, burning sensation was more pronounced with tacrolimus (P=0.002). Topical tacrolimus was more effective than methylprednisolone in reducing the CFS score at week 10 (55% vs. 23% reduction, respectively; P=0.01), and achieved significant improvement in TBUT when compared to baseline (P<0.001). OSDI score reduction achieved statistical significance with tacrolimus (27% reduction; P=0.02) but was marginal with methylprednisolone (32% reduction; P=0.06). ICAM-1 expression by ocular surface epithelium decreased significantly in both groups (tacrolimus P=0.003; methylprednisolone P=0.008), while HLA-DR expression significantly decreased only in the tacrolimus group (P=0.03). Schirmer test scores did not change significantly in either group during the study; IOP increased significantly with methylprednisolone at week 10 (P=0.04). Conclusions Topical tacrolimus 0.05% is safe, generally well tolerated and effective for the treatment of ocular GVHD, without the hypertensive effects of topical corticosteroids.

Corneal transplantation serves as a reproducible and simple surgical model to study mechanisms regulating immunity and angiogenesis. The simplicity of the model allows for systematic analysis of different mechanisms involved in immune and angiogenic privilege and their failures. This protocol describes how to induce neovessels and inflammation in an actively regulated avascular and immune-privileged site. This involves placing intra-stromal corneal sutures for two weeks, disrupting the privileges, and performing corneal transplantation subsequently. Privileged and non-privileged recipient responses to donor cornea can be compared to identify key immunological mechanisms that underlie angiogenesis and graft rejection. This protocol can also be adapted to the growing repertoire of genetic models available in the mouse, and is a valuable tool to elucidate molecular mechanisms mediating acceptance or failure of corneal graft. The model could be used to assess the potential of therapeutic molecules to enhance graft survival in vivo.