Cornea

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Karamichos D, Hutcheon AEK, Rich CB, Trinkaus-Randall V, Asara JM, Zieske JD. In vitro model suggests oxidative stress involved in keratoconus disease. Sci Rep 2014;4:4608.Abstract
Keratoconus (KC) affects 1:2000 people and is a disorder where cornea thins and assumes a conical shape. Advanced KC requires surgery to maintain vision. The role of oxidative stress in KC remains unclear. We aimed to identify oxidative stress levels between human corneal keratocytes (HCKs), fibroblasts (HCFs) and keratoconus cells (HKCs). Cells were cultured in 2D and 3D systems. Vitamin C (VitC) and TGF-β3 (T3) were used for 4 weeks to stimulate self-assembled extracellular matrix (ECM). No T3 used as controls. Samples were analyzed using qRT-PCR and metabolomics. qRT-PCR data showed low levels of collagen I and V, as well as keratocan for HKCs, indicating differentiation to a myofibroblast phenotype. Collagen type III, a marker for fibrosis, was up regulated in HKCs. We robustly detected more than 150 metabolites of the targeted 250 by LC-MS/MS per condition and among those metabolites several were related to oxidative stress. Lactate levels, lactate/malate and lactate/pyruvate ratios were elevated in HKCs, while arginine and glutathione/oxidized glutathione ratio were reduced. Similar patterns found in both 2D and 3D. Our data shows that fibroblasts exhibit enhanced oxidative stress compared to keratocytes. Furthermore the HKC cells exhibit the greatest level suggesting they may have a myofibroblast phenotype.
Karamichos D, Zieske JD, Sejersen H, Sarker-Nag A, Asara JM, Hjortdal J. Tear metabolite changes in keratoconus. Exp Eye Res 2015;132:1-8.Abstract

While efforts have been made over the years, the exact cause of keratoconus (KC) remains unknown. The aim of this study was to identify alterations in endogenous metabolites in the tears of KC patients compared with age-matched healthy subjects. Three groups were tested: 1) Age-matched controls with no eye disease (N = 15), 2) KC - patients wearing Rigid Gas permeable lenses (N = 16), and 3) KC - No Correction (N = 14). All samples were processed for metabolomics analysis using LC-MS/MS. We identified a total of 296 different metabolites of which >40 were significantly regulated between groups. Glycolysis and gluconeogenesis had significant changes, such as 3-phosphoglycerate and 1,3 diphosphateglycerate. As a result the citric acid cycle (TCA) was also affected with notable changes in Isocitrate, aconitate, malate, and acetylphosphate, up regulated in Group 2 and/or 3. Urea cycle was also affected, especially in Group 3 where ornithine and aspartate were up-regulated by at least 3 fold. The oxidation state was also severely affected. Groups 2 and 3 were under severe oxidative stress causing multiple metabolites to be regulated when compared to Group 1. Group 2 and 3, both showed significant down regulation in GSH-to-GSSG ratio when compared to Group 1. Another indicator of oxidative stress, the ratio of lactate - pyruvate was also affected with Groups 2 and 3 showing at least a 2-fold up regulation. Overall, our data indicate that levels of metabolites related to urea cycle, TCA cycle and oxidative stress are highly altered in KC patients.

Karamichos D, Funderburgh ML, Hutcheon AEK, Zieske JD, Du Y, Wu J, Funderburgh JL. A role for topographic cues in the organization of collagenous matrix by corneal fibroblasts and stem cells. PLoS One 2014;9(1):e86260.Abstract
Human corneal fibroblasts (HCF) and corneal stromal stem cells (CSSC) each secrete and organize a thick stroma-like extracellular matrix in response to different substrata, but neither cell type organizes matrix on tissue-culture polystyrene. This study compared cell differentiation and extracellular matrix secreted by these two cell types when they were cultured on identical substrata, polycarbonate Transwell filters. After 4 weeks in culture, both cell types upregulated expression of genes marking differentiated keratocytes (KERA, CHST6, AQP1, B3GNT7). Absolute expression levels of these genes and secretion of keratan sulfate proteoglycans were significantly greater in CSSC than HCF. Both cultures produced extensive extracellular matrix of aligned collagen fibrils types I and V, exhibiting cornea-like lamellar structure. Unlike HCF, CSSC produced little matrix in the presence of serum. Construct thickness and collagen organization was enhanced by TGF-ß3. Scanning electron microscopic examination of the polycarbonate membrane revealed shallow parallel grooves with spacing of 200-300 nm, similar to the topography of aligned nanofiber substratum which we previously showed to induce matrix organization by CSSC. These results demonstrate that both corneal fibroblasts and stromal stem cells respond to a specific pattern of topographical cues by secreting highly organized extracellular matrix typical of corneal stroma. The data also suggest that the potential for matrix secretion and organization may not be directly related to the expression of molecular markers used to identify differentiated keratocytes.
Karamichos D, Rich CB, Zareian R, Hutcheon AEK, Ruberti JW, Trinkaus-Randall V, Zieske JD. TGF-β3 stimulates stromal matrix assembly by human corneal keratocyte-like cells. Invest Ophthalmol Vis Sci 2013;54(10):6612-9.Abstract
PURPOSE: We have previously shown that TGF-β3 (T3) stimulates extracellular matrix (ECM) assembly while maintaining antifibrotic characteristics in a model using human corneal fibroblasts (HCFs). This model, however, requires non-physiological levels of serum. In the current study, we tested whether T3 could stimulate human corneal keratocytes (HCKs) in vitro to assemble a functional ECM, while maintaining their characteristics. METHODS: Human corneal keratocytes and HCFs were isolated and cultured using 1% or 10% serum, respectively ±T3. The constructs were processed for indirect immunofluorescence (IF), transmission electron microscopy (TEM), and qRT-PCR, analyzing for keratocyte marker, keratocan, and ECM components, collagen (col) types I, III, and V. RESULTS: Quantitative reverse transcriptase PCR data showed that keratocan, col I, and V were all upregulated in HCKs compared with HCFs, whereas col III was expressed at low levels in HCKs. Transforming growth factor beta 3 stimulation further enhanced the level of change. Without T3, HCK constructs were very thin, approximately 5 μm; however, as with HCFs, upon stimulation with T3, HCK constructs increased in thickness by approximately 5-fold. Cell counts and ECM production revealed that HCKs assembled more ECM per unit area compared with HCFs, and IF revealed downregulation of fibrotic markers, col III, and thrombospondin-1, with T3 stimulation. Transmission electron microscopy data revealed aligned ECM with long fibrils for all conditions except HCK Controls. Human corneal keratocytes+T3 also showed denser collagen fibrils with more consistent fibril diameter. CONCLUSIONS: Overall, the data suggests that it is possible to stimulate matrix secretion and assembly by HCKs in vitro by using a single growth factor, T3.
Katikireddy KR, Schmedt T, Price MO, Price FW, Jurkunas UV. Existence of Neural Crest-Derived Progenitor Cells in Normal and Fuchs Endothelial Dystrophy Corneal Endothelium. Am J Pathol 2016;186(10):2736-50.Abstract

Human corneal endothelial cells are derived from neural crest and because of postmitotic arrest lack competence to repair cell loss from trauma, aging, and degenerative disorders such as Fuchs endothelial corneal dystrophy (FECD). Herein, we identified a rapidly proliferating subpopulation of cells from the corneal endothelium of adult normal and FECD donors that exhibited features of neural crest-derived progenitor (NCDP) cells by showing absence of senescence with passaging, propensity to form spheres, and increased colony forming efficacy compared with the primary cells. The collective expression of stem cell-related genes SOX2, OCT4, LGR5, TP63 (p63), as well as neural crest marker genes PSIP1 (p75(NTR)), PAX3, SOX9, AP2B1 (AP-2β), and NES, generated a phenotypic footprint of endothelial NCDPs. NCDPs displayed multipotency by differentiating into microtubule-associated protein 2, β-III tubulin, and glial fibrillary acidic protein positive neurons and into p75(NTR)-positive human corneal endothelial cells that exhibited transendothelial resistance of functional endothelium. In conclusion, we found that mitotically incompetent ocular tissue cells contain adult NCDPs that exhibit a profile of transcription factors regulating multipotency and neural crest progenitor characteristics. Identification of normal NCDPs in FECD-affected endothelium holds promise for potential autologous cell therapies.

Katikireddy KR, White TL, Miyajima T, Vasanth S, Raoof D, Chen Y, Price MO, Price FW, Jurkunas UV. NQO1 downregulation potentiates menadione-induced endothelial-mesenchymal transition during rosette formation in Fuchs endothelial corneal dystrophy. Free Radic Biol Med 2018;116:19-30.Abstract
Fuchs endothelial corneal dystrophy (FECD) is a genetic and oxidative stress disorder of post-mitotic human corneal endothelial cells (HCEnCs), which normally exhibit hexagonal shape and form a compact monolayer compatible with normal corneal functioning and clear vision. FECD is associated with increased DNA damage, which in turn leads to HCEnC loss, resulting in the formation rosettes and aberrant extracellular matrix (ECM) deposition in the form of pro-fibrotic guttae. Since the mechanism of ECM deposition in FECD is currently unknown, we aimed to investigate the role of endothelial-mesenchymal transition (EMT) in FECD using a previously established cellular in vitro model that recapitulates the characteristic rosette formation, by employing menadione (MN)-induced oxidative stress. We demonstrate that MN treatment alone, or a combination of MN and TGF-β1 induces reactive oxygen species (ROS), cell death, and EMT in HCEnCs during rosette formation, resulting in upregulation of EMT- and FECD-associated markers such as Snail1, N-cadherin, ZEB1, and transforming growth factor-beta-induced (TGFβI), respectively. Additionally, FECD ex vivo specimens displayed a loss of organized junctional staining of plasma membrane-bound N-cadherin, with corresponding increase in fibronectin and Snail1 compared to ex vivo controls. Addition of N-acetylcysteine (NAC) downregulated all EMT markers and abolished rosette formation. Loss of NQO1, a metabolizing enzyme of MN, led to greater increase in intracellular ROS levels as well as a significant upregulation of Snail1, fibronectin, and N-cadherin compared to normal cells, indicating that NQO1 regulates Snail1-mediated EMT. This study provides first line evidence that MN-induced oxidative stress leads to EMT in corneal endothelial cells, and the effect of which is further potentiated when redox cycling activity of MN is enhanced by the absence of NQO1. Given that NAC inhibits Snail-mediated EMT, this may be a potential therapeutic intervention for FECD.
Katikireddy KR, Jurkunas UV. Limbal Stromal Tissue Specific Stem Cells and Their Differentiation Potential to Corneal Epithelial Cells. Methods Mol Biol 2016;1341:437-44.Abstract

From the derivation of the first human embryonic stem (hES) cell line to the development of induced pluripotent stem (iPS) cells; it has become evident that tissue specific stem cells are able to differentiate into a specific somatic cell types. The understanding of key processes such as the signaling pathways and the role of the microenvironment in epidermal/epithelial development has provided important clues for the derivation of specific epithelial cell types.Various differentiation protocols/methods were used to attain specific epithelial cell types. Here, we describe in detail the procedure to follow for isolation of tissue specific stem cells, mimicking their microenvironment to attain stem cell characteristics, and their potential differentiation to corneal epithelial cells.

Kaufman AR, Cruzat A, Colby KA. Clinical Outcomes Using Oversized Back Plates in Type I Boston Keratoprosthesis. Eye Contact Lens 2018;44(6):399-404.Abstract
OBJECTIVES: To examine clinical outcomes of oversized titanium back plates in type I Boston keratoprosthesis (KPro) implantation. METHODS: Retrospective study of 22 sequential eyes (20 patients) undergoing type I KPro implantation with an oversized titanium back plate (larger than trephined wound diameter by 1.0 mm or more), performed by a single surgeon (K.A.C.) from June 2010 to November 2014. Data were collected regarding preoperative eye characteristics, surgical details, and postoperative clinical outcomes. RESULTS: Mean follow-up time per eye was 24.1±14.9 months. All eyes had improved vision after surgery; 13 eyes (59.1%) maintained visual acuity improvement at last follow-up. Initial KPro's were retained in 19 eyes (86.4%); one eye required KPro replacement. Primary retroprosthetic membrane (RPM) developed in three eyes (13.6%), with similar occurrence in aniridic (14.3%) and nonaniridic eyes (13.3%). Secondary RPM's developed in two eyes (9.1%) after vitritis (one eye) and retinal and choroidal detachment (one eye). Glaucoma was a common comorbidity: 2 of 14 eyes (14.3%) with preoperative glaucoma had glaucoma progression, and 4 of 8 eyes (50.0%) without preoperative glaucoma developed glaucoma postoperatively. Other postoperative complications included retinal detachment (5 eyes, 22.7%) and idiopathic vitritis (3 eyes, 13.6%). CONCLUSIONS: Oversized titanium KPro back plates are associated with a low rate of primary RPM formation and may have particular utility in reducing primary RPM formation in aniridic eyes. Glaucoma remains a challenge in postoperative KPro management. Complex eyes, at increased risk of postoperative complications, require careful management.
Kaye R, Botten N, Lippestad M, Li D, Hodges RR, Utheim TP, Serhan CN, Dartt DA. Resolvin D1, but not resolvin E1, transactivates the epidermal growth factor receptor to increase intracellular calcium and glycoconjugate secretion in rat and human conjunctival goblet cells. Exp Eye Res 2019;180:53-62.Abstract
PURPOSE: To identify interactions of the epidermal growth factor receptor (EGFR) with the pro-resolving mediator receptors for RvD1 and RvE1 to stimulate an increase in intracellular [Ca] ([Ca]) and mucin secretion from cultured human and rat conjunctival goblet cells. METHODS: Goblet cells from human and rat conjunctiva were grown in culture using RPMI media. Cultured goblet cells were pre-incubated with inhibitors, and then stimulated with RvD1, RvE1, EGF or the cholinergic agonist carbachol (Cch). Increase in [Ca] was measured using fura-2/AM. Goblet cell secretion was measured using an enzyme-linked lectin assay with UEA-1. Western blot analysis was performed with antibodies against AKT and ERK 1/2. RESULTS: In cultured human conjunctival goblet cells RvE1 -stimulated an increase in [Ca]. RvD1-, but not the RvE1-, stimulated increase in [Ca] and mucin secretion was blocked by the EGFR inhibitor AG1478 and siRNA for the EGFR. RvD1-, but not RvE1-stimulated an increase in [Ca] that was also inhibited by TAPI-1, an inhibitor of the matrix metalloprotease ADAM 17. Inhibition of the EGFR also blocked RvD1-stimulated increase in AKT activity and both RvD1-and RvE1-stimulated increase in ERK 1/2 activity. Pretreatment with either RvD1 or RvE1 did not block the EGFR-stimulated increase in [Ca]. CONCLUSIONS: We conclude that in cultured rat and human conjunctival goblet cells, RvD1 activates the EGFR, increases [Ca], activates AKT and ERK1/2 to stimulate mucin secretion. RvE1 does not transactivate the EGFR to increase [Ca] and stimulate mucin secretion, but does interact with the receptor to increase ERK 1/2 activity.
Keating A, Pineda R. Trichosporon asahii keratitis in a patient with a type I Boston keratoprosthesis and contact lens. Eye Contact Lens 2012;38(2):130-2.Abstract
PURPOSE: The aim of the study was to report a case of Trichosporon asahii in a patient with a type I Boston keratoprosthesis and contact lens with review of the literature. METHODS: A case report and literature review are provided. RESULTS: A 70-year-old monocular South Asian man with light perception vision and dense corneal scarring from previously failed amniotic membrane grafting and one failed corneal transplant was evaluated for a keratoprosthesis for visual rehabilitation. Three months after undergoing uneventful implantation of a type I Boston keratoprosthesis and placement of a therapeutic contact lens, he was found on routine follow-up to have a corneal infiltrate that was culture positive for T. asahii. The fungal keratitis was successfully treated with topical amphotericin B and oral ketoconazole. CONCLUSIONS: Contact lens wear is a known risk factor for fungal keratitis. Trichosporon is an uncommon agent of fungal keratitis. We report the first known case of fungal keratitis caused by T.asahii in a patient with a keratoprosthesis and contact lens.
Kemp PS, Shah AS, Elliott AT, Wan MJ. Removal of a barbed fish hook from the cornea of an 8-year-old boy. J AAPOS 2017;
Khalil IA, Saleh B, Ibrahim DM, Jumelle C, Yung A, Dana R, Annabi N. Ciprofloxacin-loaded bioadhesive hydrogels for ocular applications. Biomater Sci 2020;8(18):5196-5209.Abstract
The management of corneal infections often requires complex therapeutic regimens involving the prolonged and high-frequency application of antibiotics that provide many challenges to patients and impact compliance with the therapeutic regimens. In the context of severe injuries that lead to tissue defects (e.g. corneal lacerations) topical drug regimens are inadequate and suturing is often indicated. There is thus an unmet need for interventions that can provide tissue closure while concurrently preventing or treating infection. In this study, we describe the development of an antibacterial bioadhesive hydrogel loaded with micelles containing ciprofloxacin (CPX) for the management of corneal injuries at risk of infection. The in vitro release profile showed that the hydrogel system can release CPX, a broad-spectrum antibacterial drug, for up to 24 h. Moreover, the developed CPX-loaded hydrogels exhibited excellent antibacterial properties against Staphylococcus aureus and Pseudomonas aeruginosa, two bacterial strains responsible for the most ocular infections. Physical characterization, as well as adhesion and cytocompatibility tests, were performed to assess the effect of CPX loading in the developed hydrogel. Results showed that CPX loading did not affect stiffness, adhesive properties, or cytocompatibility of hydrogels. The efficiency of the antibacterial hydrogel was assessed using an ex vivo model of infectious pig corneal injury. Corneal tissues treated with the antibacterial hydrogel showed a significant decrease in bacterial colony-forming units (CFU) and a higher corneal epithelial viability after 24 h as compared to non-treated corneas and corneas treated with hydrogel without CPX. These results suggest that the developed adhesive hydrogel system presents a promising suture-free solution to seal corneal wounds while preventing infection.
Khandelwal P, Liu S, Sullivan DA. Androgen regulation of gene expression in human meibomian gland and conjunctival epithelial cells. Mol Vis 2012;18:1055-67.Abstract
PURPOSE: Androgens exert a significant influence on the structure, function and/or pathophysiology of the meibomian gland and conjunctiva. We sought to determine whether this hormone action involves the regulation of epithelial cell gene expression in these tissues. METHODS: Immortalized human meibomian gland and conjunctival epithelial cells were treated with placebo or dihydrotestosterone (DHT) and processed for molecular biologic procedures. Gene expression was evaluated with BeadChips and data were analyzed with bioinformatic and statistical software. RESULTS: Androgen treatment significantly influenced the expression of approximately 3,000 genes in immortalized human meibomian gland and conjunctival epithelial cells. The nature of DHT action on gene activity was predominantly cell-specific. Similarly, DHT exerted a significant, but primarily cell-specific, influence on many gene ontologies and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. These included groups of genes related, for example, to lipid dynamics, innate immunity, cell cycle, Janus kinase (JAK)-signal transducer and activator of transcription (stat) cascades, oxidative phosphorylation, the proteasome, and mammalian target of rapamycin (mTOR), Wnt, and peroxisome proliferator-activated receptor (PPAR) signaling. CONCLUSIONS: Our findings support our hypothesis that androgens regulate gene expression in human meibomian gland and conjunctival epithelial cells. Our ongoing studies are designed to determine whether many of these genes are translated and play a role in the health and well being of the eye.
Kheirkhah A, Crnej A, Ren A, Mullins A, Satitpitakul V, Hamrah P, Schaumberg D, Dana R. Patients' Perceived Treatment Effectiveness in Dry Eye Disease. Cornea 2017;36(8):893-897.Abstract
PURPOSE: Patients' perceptions of the effectiveness of a treatment, or perceived treatment effectiveness (PTE), play an important role in medicine. This study aimed to evaluate patients' PTE in dry eye disease (DED) and investigate factors contributing to these patients' perceptions. METHODS: This cross-sectional study included 66 patients with DED. At enrollment, all patients had comprehensive ophthalmic assessment. In addition, to evaluate the patient's PTE, they were asked to use a 10-point scale ranging from "strongly disagree (score 1)" to "strongly agree (score 10)" to score their views on whether their DED treatments had been effective. Changes in clinical parameters of DED over time during their care were also evaluated retrospectively and correlated with the patients' PTE. RESULTS: The mean age of patients was 55.7 years; 79% were women. Regarding patients' PTE, 36.4% strongly (score 10) and 53.0% moderately (scores 6-9) believed that their DED treatment had been effective. However, 10.6% thought that their treatment had not been effective (scores 1-5). Less favorable PTE for the DED treatment was significantly associated with a younger age (P < 0.001), current use of antidepressant medications (P = 0.01), and a higher Ocular Surface Disease Index score (P = 0.01) at enrollment. CONCLUSIONS: A majority of patients with DED have positive perceptions regarding the effectiveness of their treatments. Less favorable perceptions are associated with more severe ocular symptoms and nonocular parameters such as younger age and current antidepressant use. In DED management, assessing patients' PTE should be considered as an important part of clinical practice.
Kheirkhah A, Syed ZA, Satitpitakul V, Goyal S, Müller R, Tu EY, Dana R. Sensitivity and Specificity of Laser-Scanning In Vivo Confocal Microscopy for Filamentous Fungal Keratitis: Role of Observer Experience. Am J Ophthalmol 2017;179:81-89.Abstract
PURPOSE: To determine sensitivity and specificity of laser-scanning in vivo confocal microscopy (LS-IVCM) for detection of filamentous fungi in patients with microbial keratitis and to evaluate the effect of observer's imaging experience on these parameters. DESIGN: Retrospective reliability study. METHODS: This study included 21 patients with filamentous fungal keratitis and 24 patients with bacterial keratitis (as controls). The etiology of infection was confirmed based on the response to specific therapy regardless of culture results. All patients had undergone full-thickness corneal imaging by a LS-IVCM (Heidelberg Retina Tomograph 3 with Rostock Cornea Module; Heidelberg Engineering, Heidelberg, Germany). The images were evaluated for the presence of fungal filaments by 2 experienced observers and 2 inexperienced observers. All observers were masked to the clinical and microbiologic data. RESULTS: The mean number of images obtained per eye was 917 ± 353. The average sensitivity of LS-IVCM for detecting fungal filaments was 71.4% ± 0% for the experienced observers and 42.9% ± 6.7% for the inexperienced observers. The average specificity was 89.6% ± 3.0% and 87.5% ± 17.7% for these 2 groups of observers, respectively. Although there was a good agreement between the 2 experienced observers (κ = 0.77), the inexperienced observers showed only a moderate interobserver agreement (κ = 0.51). The LS-IVCM sensitivity was higher in patients with fungal infections who had positive culture or longer duration of the disease. CONCLUSIONS: Although LS-IVCM has a high specificity for diagnosing filamentous fungal keratitis, its sensitivity is moderate and highly dependent on the level of the observer's experience and training with this imaging modality.
Kheirkhah A, Muller R, Mikolajczak J, Ren A, Kadas EM, Zimmermann H, Pruess H, Paul F, Brandt AU, Hamrah P. Comparison of Standard Versus Wide-Field Composite Images of the Corneal Subbasal Layer by In Vivo Confocal Microscopy. Invest Ophthalmol Vis Sci 2015;56(10):5801-7.Abstract

PURPOSE: To evaluate whether the densities of corneal subbasal nerves and epithelial immune dendritiform cells (DCs) are comparable between a set of three representative standard images of in vivo confocal microscopy (IVCM) and the wide-field mapped composite IVCM images. METHODS: This prospective, cross-sectional, and masked study included 110 eyes of 58 patients seen in a neurology clinic who underwent laser-scanning IVCM (Heidelberg Retina Tomograph 3) of the central cornea. Densities of subbasal corneal nerves and DCs were compared between the average of three representative standard images and the wide-field mapped composite images, which were reconstructed by automated mapping. RESULTS: There were no statistically significant differences between the average of three representative standard images (0.16 mm2 each) and the wide-field composite images (1.29 ± 0.64 mm2) in terms of mean subbasal nerve density (17.10 ± 6.10 vs. 17.17 ± 5.60 mm/mm2, respectively, P = 0.87) and mean subbasal DC density (53.2 ± 67.8 vs. 49.0 ± 54.3 cells/mm2, respectively, P = 0.43). However, there were notable differences in subbasal nerve and DC densities between these two methods in eyes with very low nerve density or very high DC density. CONCLUSIONS: There are no significant differences in the mean subbasal nerve and DC densities between the average values of three representative standard IVCM images and wide-field mapped composite images. Therefore, these standard images can be used in clinical studies to accurately measure cellular structures in the subbasal layer.

Kheirkhah A, Saboo US, Marmalidou A, Dana R. Overestimation of Corneal Endothelial Cell Density in Smaller Frame Sizes in In Vivo Confocal Microscopy. Cornea 2016;35(3):363-9.Abstract

PURPOSE: To evaluate the effect of frame size on the calculated corneal endothelial cell density (CECD) in images of laser scanning in vivo confocal microscopy (IVCM). METHODS: Forty-nine corneal endothelial images acquired by laser scanning IVCM (Heidelberg Retina Tomograph 3 with Rostock Corneal Module) with different endothelial cell densities were analyzed. In each image (160,000 μm), the CECD was calculated using the fixed-frame method by counting cells in the following frame sizes: 80,000 μm, 40,000 μm, 20,000 μm, 10,000 μm, 5000 μm, and 2500 μm. The calculated CECD was then compared with that of the variable-frame method as the reference value. RESULTS: There was no significant difference in the calculated CECD between the variable-frame method (2004 ± 832 cells/mm), and the fixed-frame method using a 40,000-μm frame (2023 ± 810 cells/mm). On the other hand, the calculated CECD showed significant overestimations in frame sizes of 20,000 μm (2066 ± 820 cells/mm), 10,000 μm (2156 ± 785 cells/mm), 5000 μm (2352 ± 783 cells/mm), and 2500 μm (2715 ± 754 cells/mm), with P < 0.001 in all. This resulted in overestimations of 4.8 ± 9.8%, 11.9 ± 16.2%, 24.9 ± 23.1%, and 49.1 ± 38.8% for these frame sizes, respectively. Images with lower CECD demonstrated higher overestimations of cell density in smaller frame sizes. CONCLUSIONS: In laser scanning IVCM images, there is significant overestimation of CECD if the cells are counted in frames smaller than 25% of the image. Similar frame sizes should be used when monitoring CECD over time.

Kheirkhah A, Coco G, Satitpitakul V, Dana R. Subtarsal Fibrosis Is Associated With Ocular Surface Epitheliopathy in Graft-Versus-Host Disease. Am J Ophthalmol 2018;189:102-110.Abstract
PURPOSE: To evaluate occurrence of subtarsal fibrosis in patients with graft-vs-host disease (GVHD) and to determine its association with ocular surface epitheliopathy. DESIGN: Cross-sectional study. METHODS: We enrolled 40 patients with moderate or severe dry eye disease, including 20 patients with chronic ocular GVHD and 20 patients without (as the control group). All patients had a comprehensive ophthalmic assessment including evaluation for subtarsal fibrosis, corneal and conjunctival staining, tear break-up time (TBUT), and Schirmer test. Furthermore, meibomian gland drop-out area and densities of epithelial and stromal immune cells were measured using meibography and in vivo confocal microscopy, respectively. RESULTS: Subtarsal fibrosis was not seen in any eye of the non-GVHD group. However, 16 eyes (40%) of 10 patients (50%) in the GVHD group had subtarsal fibrosis (P < .001) with an average involvement of 28.9% ± 13.7% of the tarsal area. Fibrosis was more frequent in the upper lids (35%) than in the lower lids (5%). Regression analyses showed that corneal fluorescein staining was significantly associated with the extent of fibrosis (P < .001, β = 0.14) and TBUT (P < .001, β = -0.53) but not with other clinical or imaging parameters. Conjunctival lissamine green staining also had a statistically significant association with the extent of fibrosis (P = .04, β = 0.12) but not other clinical or imaging parameters. Eyes with subtarsal fibrosis had a more severe ocular surface epitheliopathy compared with eyes without fibrosis. CONCLUSIONS: Subtarsal fibrosis is present in a significant percentage of patients with chronic ocular GVHD, likely contributing to the ocular surface damage in these patients.
Kheirkhah A, Dohlman TH, Amparo F, Arnoldner MA, Jamali A, Hamrah P, Dana R. Effects of corneal nerve density on the response to treatment in dry eye disease. Ophthalmology 2015;122(4):662-8.Abstract

PURPOSE: To evaluate whether levels of corneal subbasal nerve fiber length (SNFL) in dry eye disease (DED) could prognosticate the level of improvement in signs and symptoms after treatment. DESIGN: Phase IV, double-masked, randomized clinical trial. PARTICIPANTS: Sixty patients with meibomian gland dysfunction-associated DED and 27 age-matched controls. METHODS: Patients with DED were randomized to receive topical artificial tears, loteprednol etabonate 0.5%, or loteprednol etabonate 0.5%/tobramycin 0.3% twice daily for 4 weeks. At baseline, in vivo confocal microscopy of central cornea was performed in both eyes. Patients with DED were divided into 2 subgroups: those with low baseline SNFL and those with near-normal baseline SNFL for this purpose (the cutoff point: the mean SNFL in controls minus 2 standard deviations). Clinical signs and symptoms at baseline and after 4 weeks of treatment were compared between the subgroups with low and near-normal SNFL for all therapeutic groups. MAIN OUTCOME MEASURES: Symptom questionnaires, corneal fluorescein staining (CFS), conjunctival staining with lissamine green, tear break-up time, Schirmer's test, and SNFL. RESULTS: In patients with DED, baseline SNFL (17.06±5.78 mm/mm(2)) was significantly lower than in controls (23.68±3.42 mm/mm(2), P = 0.001). In the artificial tear and loteprednol groups, although no significant improvement in any sign or symptom was noted in patients with low baseline SNFL (<16.84 mm/mm(2)), subjects with near-normal baseline SNFL (≥16.84 mm/mm(2)) showed significant improvement in both symptoms and CFS score (all P < 0.05). In the loteprednol/tobramycin group, no significant change was evident for any sign or symptom in either subgroup of low or near-normal baseline SNFL. CONCLUSIONS: Significant improvements in CFS and patient symptomatology after DED treatment were evident only in the subgroup with near-normal corneal SNFL. Consideration of SNFL may assist in explaining the variability of patients' response to DED therapy.

Kheirkhah A, Satitpitakul V, Hamrah P, Dana R. Patients With Dry Eye Disease and Low Subbasal Nerve Density Are at High Risk for Accelerated Corneal Endothelial Cell Loss. Cornea 2016;Abstract

PURPOSE: To evaluate changes in corneal endothelial cell density over time in patients with dry eye disease (DED) and to correlate endothelial cell loss with corneal subbasal nerve density. METHODS: This retrospective study included 40 eyes of 20 patients with DED. Laser in vivo confocal microscopy had been performed in the central cornea of both eyes at an initial visit and repeated after a mean follow-up of 33.2 ± 10.2 months. The densities of corneal endothelial cells and subbasal nerves were measured in both visits and compared with 13 eyes of 13 normal age-matched controls. RESULTS: At the initial visit, the DED group had lower densities of corneal endothelial cells (2620 ± 386 cells/mm) and subbasal nerves (17.8 ± 7.5 mm/mm) compared with the control group (2861 ± 292 cells/mm and 22.8 ± 3.0 mm/mm, with P = 0.08 and P = 0.01, respectively). At the end of follow-up, although there was no significant change in subbasal nerve density (16.7 ± 7.2 mm/mm, P = 0.43), the mean corneal endothelial cell density significantly decreased to 2465 ± 391 cells/mm (P = 0.01), with a mean corneal endothelial cell loss of 2.1 ± 3.6% per year. The endothelial cell loss showed a statistically significant negative correlation with the initial subbasal nerve density (Rs = -0.55, P = 0.02). CONCLUSIONS: Patients with DED have an accelerated corneal endothelial cell loss compared with that reported in the literature for normal aging. Those with lower subbasal nerve density, in particular, are at a higher risk for endothelial cell loss over time.

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