Cornea

Bauskar A, Mack WJ, Mauris J, Argüeso P, Heur M, Nagel BA, Kolar GR, Gleave ME, Nakamura T, Kinoshita S, Moradian-Oldak J, Panjwani N, Pflugfelder SC, Wilson MR, Fini EM, Jeong S. Clusterin Seals the Ocular Surface Barrier in Mouse Dry Eye. PLoS One 2015;10(9):e0138958.Abstract

Dry eye is a common disorder caused by inadequate hydration of the ocular surface that results in disruption of barrier function. The homeostatic protein clusterin (CLU) is prominent at fluid-tissue interfaces throughout the body. CLU levels are reduced at the ocular surface in human inflammatory disorders that manifest as severe dry eye, as well as in a preclinical mouse model for desiccating stress that mimics dry eye. Using this mouse model, we show here that CLU prevents and ameliorates ocular surface barrier disruption by a remarkable sealing mechanism dependent on attainment of a critical all-or-none concentration. When the CLU level drops below the critical all-or-none threshold, the barrier becomes vulnerable to desiccating stress. CLU binds selectively to the ocular surface subjected to desiccating stress in vivo, and in vitro to the galectin LGALS3, a key barrier component. Positioned in this way, CLU not only physically seals the ocular surface barrier, but it also protects the barrier cells and prevents further damage to barrier structure. These findings define a fundamentally new mechanism for ocular surface protection and suggest CLU as a biotherapeutic for dry eye.

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.

Veldman PB, Dye PK, Holiman JD, Mayko ZM, Sáles CS, Straiko MD, Stoeger CG, Terry MA. Stamping an S on DMEK Donor Tissue to Prevent Upside-Down Grafts: Laboratory Validation and Detailed Preparation Technique Description. Cornea 2015;34(9):1175-8.Abstract

PURPOSE: To report endothelial cell loss (ECL) caused by a novel S-stamp preparation technique for Descemet membrane endothelial keratoplasty (DMEK). METHODS: Six cadaveric human corneas were prepared for DMEK transplantation using a single standardized technique, including the application of a dry ink gentian violet S-stamp to the stromal side of Descemet membrane. Endothelial cell death was evaluated and quantified using computerized analysis of vital dye staining. RESULTS: ECL caused by the S-stamp was 0.6% (range 0.1%-1.0%), which comprised less than one-tenth of the total ECL caused by our preparation of the DMEK graft from the start to finish, including recovery, prestripping, S-stamping, and trephination (13.7% total ECL, range 9.9%-17.6%). CONCLUSIONS: Our novel S-stamp donor tissue preparation technique is intuitive to learn and holds the promise of preventing iatrogenic primary graft failure due to upside-down grafts without causing unacceptable increases in ECL.

Pal-Ghosh S, Pajoohesh-Ganji A, Tadvalkar G, Kyne BM, Guo X, Zieske JD, Stepp MA. Topical Mitomycin-C enhances subbasal nerve regeneration and reduces erosion frequency in the debridement wounded mouse cornea. Exp Eye Res 2015;Abstract

Corneal epithelial basement membrane dystrophies and superficial injuries caused by scratches can lead to recurrent corneal erosion syndrome (RCES). Patients and animals with reduced corneal sensory nerve innervation can also develop recurrent erosions. Multiple wild-type mouse strains will spontaneously develop recurrent corneal erosions after single 1.5 mm debridement wounds. Here we show that this wound is accompanied by an increase in corneal epithelial cell proliferation after wound closure but without a commensurate increase in corneal epithelial thickness. We investigated whether excess corneal epithelial cell proliferation contributes to erosion formation. We found that topical application of Mitomycin C (MMC), a drug used clinically to improve healing after glaucoma and refractive surgery, reduces erosion frequency, enhances subbasal axon density to levels seen in unwounded corneas, and prevents excess epithelial cell proliferation after debridement wounding. These results suggest that topically applied MMC, which successfully reduces corneal haze and scarring after PRK, may also function to enhance subbasal nerve regeneration and epithelial adhesion when used to treat RCES.

Hu K, Harris DL, Yamaguchi T, von Andrian UH, Hamrah P. A Dual Role for Corneal Dendritic Cells in Herpes Simplex Keratitis: Local Suppression of Corneal Damage and Promotion of Systemic Viral Dissemination. PLoS One 2015;10(9):e0137123.Abstract

The cornea is the shield to the foreign world and thus, a primary site for peripheral infections. However, transparency and vision are incompatible with inflammation and scarring that may result from infections. Thus, the cornea is required to perform a delicate balance between fighting infections and preserving vision. To date, little is known about the specific role of antigen-presenting cells in viral keratitis. In this study, utilizing an established murine model of primary acute herpes simplex virus (HSV)-1 keratitis, we demonstrate that primary HSV keratitis results in increased conventional dendritic cells (cDCs) and macrophages within 24 hours after infection. Local depletion of cDCs in CD11c-DTR mice by subconjuntival diphtheria toxin injections, led to increased viral proliferation, and influx of inflammatory cells, resulting in increased scarring and clinical keratitis. In addition, while HSV infection resulted in significant corneal nerve destruction, local depletion of cDCs resulted in a much more severe loss of corneal nerves. Further, local cDC depletion resulted in decreased corneal nerve infection, and subsequently decreased and delayed systemic viral transmission in the trigeminal ganglion and draining lymph node, resulting in decreased mortality of mice. In contrast, sham depletion or depletion of macrophages through local injection of clodronate liposomes had neither a significant impact on the cornea, nor an effect on systemic viral transmission. In conclusion, we demonstrate that corneal cDCs may play a primary role in local corneal defense during viral keratitis and preserve vision, at the cost of inducing systemic viral dissemination, leading to increased mortality.

Singh G, Zhou X, Lee JY, Yousuf MA, Ramke M, Ismail AM, Lee JS, Robinson CM, Seto D, Dyer DW, Jones MS, Rajaiya J, Chodosh J. Recombination of the epsilon determinant and corneal tropism: Human adenovirus species D types 15, 29, 56, and 69. Virology 2015;485:452-9.Abstract

Viruses within human adenovirus species D (HAdV-D) infect epithelia at essentially every mucosal site. Hypervariable loops 1 and 2 of the hexon capsid protein contain epitopes that together form the epsilon determinant for serum neutralization. We report our analyses comparing HAdV-D15, 29, 56, and the recently identified type 69, each with highly similar hexons and the same serum neutralization profile, but otherwise disparate genomes. Of these, only HAdV-D type 56 is associated with epidemic keratoconjunctivitis (EKC), a severe infection of ocular surface epithelium and underlying corneal stroma. In the mouse adenovirus keratitis model, all four viruses induced inflammation. However, HAdV-D56 entry into human corneal epithelial cells and fibroblasts in vitro dramatically exceeded that of the other three viruses. We conclude that the hexon epsilon determinant is not a prime contributor to corneal tropism.

Lagali N, Poletti E, Patel DV, McGhee CNJ, Hamrah P, Kheirkhah A, Tavakoli M, Petropoulos IN, Malik RA, Utheim TP, Zhivov A, Stachs O, Falke K, Peschel S, Guthoff R, Chao C, Golebiowski B, Stapleton F, Ruggeri A. Focused Tortuosity Definitions Based on Expert Clinical Assessment of Corneal Subbasal Nerves. Invest Ophthalmol Vis Sci 2015;56(9):5102-9.Abstract

PURPOSE: We examined agreement among experts in the assessment of corneal subbasal nerve tortuosity. METHODS: Images of corneal subbasal nerves were obtained from investigators at seven sites (Auckland, Boston, Linköping, Manchester, Oslo, Rostock, and Sydney) using laser-scanning in vivo confocal microscopy. A set of 30 images was assembled and ordered by increasing tortuosity by 10 expert graders from the seven sites. In a first experiment, graders assessed tortuosity without a specific definition and performed grading three times, with at least 1 week between sessions. In a second experiment, graders assessed the same image set using four focused tortuosity definitions. Intersession and intergrader repeatability for the experiments were determined using the Spearman rank correlation. RESULTS: Expert graders without a specific tortuosity definition had high intersession (Spearman correlation coefficient 0.80), but poor intergrader (0.62) repeatability. Specific definitions improved intergrader repeatability to 0.79. In particular, tortuosity defined by frequent small-amplitude directional changes (short range tortuosity) or by infrequent large-amplitude directional changes (long range tortuosity), indicated largely independent measures and resulted in improved repeatability across the graders. A further refinement, grading only the most tortuous nerve in a given image, improved the average correlation of a given grader's ordering of images with the group average to 0.86 to 0.90. CONCLUSIONS: Definitions of tortuosity specifying short or long-range tortuosity and considering only the most tortuous nerve in an image improved the agreement in tortuosity grading among a group of expert observers. These definitions could improve accuracy and consistency in quantifying subbasal nerve tortuosity in clinical studies.

Müller RT, Abedi F, Cruzat A, Witkin D, Baniasadi N, Cavalcanti BM, Jamali A, Chodosh J, Dana R, Pavan-Langston D, Hamrah P. Degeneration and Regeneration of Subbasal Corneal Nerves after Infectious Keratitis: A Longitudinal InVivo Confocal Microscopy Study. Ophthalmology 2015;122(11):2200-9.Abstract

PURPOSE: To investigate the longitudinal alterations of subbasal corneal nerves in patients with infectious keratitis (IK) during the acute phase, cessation of treatment, and the recovery phase by in vivo confocal microscopy (IVCM). DESIGN: Prospective, longitudinal, case-control, single-center study. PARTICIPANTS: Fifty-six eyes of 56 patients with the diagnosis of bacterial (n = 28), fungal (n = 15), or Acanthamoeba (n = 13) keratitis were included in the study. Thirty eyes of 30 normal volunteers constituted the control group. METHODS: Corneal sensation and serial IVCM of the central cornea were performed prospectively using the Heidelberg Retina Tomograph 3/Rostock Cornea Module (Heidelberg Engineering, Heidelberg, Germany). The IVCM images were assessed at 3 time points: at the acute phase (first visit to the cornea service), at cessation of antimicrobial treatment, and up to 6 months after the resolution of infection. MAIN OUTCOME MEASURES: Total nerve number and length, main nerve trunks, branching, and corneal sensation were assessed during the follow-up period. RESULTS: Corneal nerves were reduced significantly during the acute phase in eyes with IK compared with controls across all subgroups, with total nerve length of 5.47±0.69 mm/mm(2) versus 20.59±1.06 mm/mm(2) (P <0.0001). At the cessation of treatment, corneal nerves in patients with IK had regenerated, including total nerve length (8.49±0.94 mm/mm(2); P = 0.02) and nerve branch length (4.80±0.37 mm/mm(2); P = 0.005). During the recovery phase, after resolution of infection, corneal nerves regenerated further, including total nerve length (12.13±1.97 mm/mm(2); P = 0.005), main nerve trunk length (5.80±1.00 mm/mm(2); P = 0.01), and nerve branch length (6.33±0.76 mm/mm(2); P = 0.003) as compared with the acute phase, but were still significantly lower when compared with controls (P < 0.05 for all parameters). Corneal degeneration and regeneration correlated with corneal sensation (r = 0.47; P = 0.0009). CONCLUSIONS: Patients with IK who sustain profound loss of corneal nerves during the acute phase of infection demonstrate increased corneal nerve density during the first 6 months after the resolution of infection. However, despite significant nerve regeneration, corneal nerve density does not recover fully and remains low compared to controls. By providing an objective methodology to monitor corneal re-innervation, IVCM adds potentially important findings that may have implications for clinical management and surgical planning.

Theophanous C, Jacobs DS, Hamrah P. Corneal Neuralgia after LASIK. Optom Vis Sci 2015;92(9):e233-40.Abstract

PURPOSE: To illustrate that corneal neuralgia may be the basis for refractory dry eye syndrome after laser-assisted in situ keratomileusis (LASIK). METHODS: The methodology used is that of a retrospective medical record review of a small case series. RESULTS: Three male patients, aged 30 to 48 years, referred in 2012 for dry eye syndrome refractory to treatment within 1 year of LASIK or LASIK enhancement are reported. Each patient gave history of eye pain, light sensitivity, and difficulty with visual activities beginning within 2 months of LASIK or LASIK enhancement. Best-corrected visual acuity was 20/15 or 20/20 in each of the six eyes. Tear-centered models and metrics did not explain persistent symptoms, which was consistent with inadequate response to standard dry eye treatments used before referral and reported here. In vivo confocal microscopy was abnormal at presentation in each case and was followed over time. Treatments undertaken subsequent to referral included autologous serum tears (three cases), PROSE (Prosthetic Replacement of the Ocular Surface Ecosystem) treatment (two cases), and systemic agents for pain, anxiety, or depression (three cases). By the end of 2013, at a mean of 23 months after LASIK or LASIK enhancement, symptoms improved in all three patients. CONCLUSIONS: Patients with persistent dry eye symptoms out of proportion to clinical signs after LASIK have a syndrome that may best be classified as corneal neuralgia. In vivo confocal microscopy can be informative as to the neuropathic basis of this condition. In keeping with current understanding of complex regional pain syndrome, early multimodal treatment directed toward reducing peripheral nociceptive signaling is warranted to avoid subsequent centralization and persistence of pain. Distinguishing this syndrome from typical post-LASIK dry eye remains a challenge.

Grassi CM, Cruzat A, Taniguchi EV, Crnej A, Colby KA, Dohlman CH, Chodosh J. Periprosthetic Tissue Loss in Patients With Idiopathic Vitreous Inflammation After the Boston Keratoprosthesis. Cornea 2015;34(11):1378-82.Abstract

PURPOSE: Idiopathic vitritis is a poorly understood complication after Boston keratoprosthesis surgery with unclear etiology. We sought to determine whether an association exists between periprosthetic corneal tissue loss and the development of idiopathic vitritis in keratoprosthesis recipients. METHODS: Thirteen Boston type I keratoprosthesis recipient eyes with a history of idiopathic vitritis and 34 type I keratoprosthesis recipient eyes with no history of idiopathic vitritis underwent anterior segment optical coherence tomography (AS-OCT) at a median time postoperatively of 2.4 years versus 1.9 years (range, 0.5-14.2 vs. 0.1-13.6 years), respectively. Areas of corneal graft tissue loss ("gaps") around the keratoprosthesis stem were identified and analyzed by 2 masked observers. The difference in the presence, number, and size of gaps was compared between cases and controls. RESULTS: A periprosthetic gap was identified more commonly in idiopathic vitritis cases than in controls on AS-OCT (11/13, 86% vs. 11/34, 33.3%, P < 0.001). The number of gaps between cases and controls was also significantly different (2.6 ± 1.6 vs. 0.5 ± 0.8, P < 0.001), but not the estimated gap area (0.056 ± 0.049 mm vs. 0.039 ± 0.025 mm, P = 0.22). CONCLUSIONS: A significantly higher proportion of keratoprosthesis recipient eyes with idiopathic vitritis had corneal tissue loss around the keratoprosthesis stem than did controls. Tissue loss could serve as an entry point for debris or bacterial components, triggering idiopathic vitritis. Our study underscores the utility of AS-OCT imaging in the postoperative management of keratoprosthesis patients.

Müller RT, Pourmirzaie R, Pavan-Langston D, Cavalcanti BM, Aggarwal S, Colón C, Jamali A, Cruzat A, Hamrah P. In Vivo Confocal Microscopy Demonstrates Bilateral Loss of Endothelial Cells in Unilateral Herpes Simplex Keratitis. Invest Ophthalmol Vis Sci 2015;56(8):4899-906.Abstract

PURPOSE: To report bilateral corneal endothelial cell density (ECD), as well as its correlation with subbasal nerve changes, in patients with unilateral herpes simplex keratitis (HSK). METHODS: Thirty-six eyes of 36 patients with corneal scarring caused by HSK, as well as their respective contralateral clinically unaffected eyes, were prospectively studied and compared with 26 eyes of 26 healthy volunteers. In vivo confocal microscopy and corneal sensation of the central cornea were performed bilaterally in all patients and in one random eye of controls. The ECD and subbasal corneal nerve density, including the lengths of total nerves, main trunks, and branches were evaluated and correlated to central corneal sensation. RESULTS: The ECD was significantly lower in eyes affected with HSK than in controls (2304 ± 578 vs. 2940 ± 370 cells/mm2, P < 0.0001). Surprisingly, lower ECD was also detected in contralateral clinically unaffected eyes (2548 ± 423), compared to controls (P = 0.02). Both affected and contralateral eyes showed decrease in total nerve length, compared to controls (10.0 ± 6.3 vs. 17.6 ± 6.3 vs. 21.9 ± 4.3 mm/mm2, respectively; P < 0.05 for all). The ECD correlated positively with total nerve length (r = 0.39, P = 0.0009) and with corneal sensation (r = 0.31, P = 0.009). CONCLUSIONS: In vivo confocal microscopy findings demonstrated alterations in corneal ECD in both affected and clinically unaffected contralateral eyes of patients with unilateral HSK. Moreover, the positive significant correlation between the ECD and the subbasal nerve density may suggest a potential link between corneal innervation and corneal endothelial cell homeostasis.

Aggarwal S, Kheirkhah A, Cavalcanti BM, Cruzat A, Colon C, Brown E, Borsook D, Prüss H, Hamrah P. Autologous Serum Tears for Treatment of Photoallodynia in Patients with Corneal Neuropathy: Efficacy and Evaluation with InVivo Confocal Microscopy. Ocul Surf 2015;13(3):250-62.Abstract

OBJECTIVE: Patients suffering from corneal neuropathy may present with photoallodynia; i.e., increased light sensitivity, frequently with a normal slit-lamp examination. This study aimed to evaluate the efficacy of autologous serum tears (AST) for treatment of severe photoallodynia in corneal neuropathy and to correlate clinical findings with corneal subbasal nerve alterations by in vivo confocal microscopy (IVCM). METHODS: Retrospective case control study with 16 patients with neuropathy-induced severe photoallodynia compared to 16 normal controls. Symptom severity, clinical examination and bilateral corneal IVCM scans were recorded. RESULTS: All patients suffered from extreme photoallodynia (8.8±1.1) with no concurrent ocular surface disease. Subbasal nerves were significantly decreased at baseline in patients compared to controls; total nerve length (9208±1264 vs 24714±1056 μm/mm(2); P<.0001) and total nerve number (9.6±1.4 vs 28.6±2.0; P<.0001), respectively. Morphologically, significantly increased reflectivity (2.9±0.2 vs 1.8±0.1; P<.0001), beading (in 93.7%), and neuromas (in 62.5%) were seen. AST (3.6±2.1 months) resulted in significantly decreased symptom severity (1.6±1.7; P=.02). IVCM demonstrated significantly improved nerve parameters (P<.005), total nerve length (15451±1595 μm/mm(2)), number (13.9±2.1), and reflectivity (1.9±0.1). Beading and neuromas were seen in only 56.2% and 7.6% of patients. CONCLUSION: Patients with corneal neuropathy-induced photoallodynia show profound alterations in corneal nerves. AST restores nerve topography through nerve regeneration, and this correlated with improvement in patient-reported photoallodynia. The data support the notion that corneal nerve damage results in alterations in afferent trigeminal pathways to produce photoallodynia.

Hong J, Shi W, Liu Z, Pineda R, Cui X, Sun X, Xu J. Limitations of Keratoplasty in China: A Survey Analysis. PLoS One 2015;10(7):e0132268.Abstract

PURPOSE: Each year, over 8,000 corneal transplantation surgeries are performed in China. Unlike developed countries, which have established standard requirements for operative experience for corneal specialists, little information exists on surgical training for keratoplasty in China. The aim of this study was to assess the keratoplasty experience of Chinese corneal specialists and to characterize their surgical patterns. METHODS: One hundred and twenty-one corneal specialists in 16 provinces (65 cities) in China were invited to complete an anonymous survey at the 2014 Chinese Corneal Society annual meeting, which consisted of questions with single or multiple-choice answers. Demographics, the number and type of keratoplasties performed, and the perceived limiting factors for performing keratoplasties were analyzed. RESULTS: An overwhelming 89% response rate was achieved. Of the 108 respondents, 76% worked in tertiary centers, and only 23% held a medical doctorate degree. Furthermore, 69% of the participants had received corneal fellowship training of less than one year. Only 71% were capable of keratoplasties. Among those doing keratoplasty, 68% performed less than 50 keratoplasties each year. Of the same group of keratoplasty surgeons, 88% of corneal specialists capable of keratoplasties had performed penetrating keratoplasties, 87% had performed lamellar keratoplasties, 12% had performed deep anterior lamellar keratoplasties, and 5% had performed Descemet's stripping endothelial keratoplasties. When questioned on the reasons for the low number of keratoplasties performed in China, the respondents deemed the following factors most important: lack of surgical training (71%), a shortage of donor supply (52%), and a lack of curricula (42%). A multivariate logistic regression analysis showed that corneal transplantation capabilities are significantly associated with responders' education levels and training time. CONCLUSION: Keratoplasty surgery experience is suboptimal for Chinese corneal specialists. Penetrating and lamellar keratoplasties are the preferred surgical patterns. Our findings raise concerns about the adequacy of keratoplasty training in China.

Grob SR, Jakobiec FA, Stagner AM, Colby KA. Diffuse Epibulbar Complex Lacrimal-Cartilaginous Choristoma: Diagnostic Clues and Management. Cornea 2015;34(10):1321-3.Abstract

PURPOSE: To describe the clinical and histopathologic features distinguishing an extensive complex choristoma of the epibulbar surface and to address the management of such lesions. METHODS: Clinical history, diagnostic imaging studies, and histopathologic sections stained with hematoxylin and eosin were reviewed from a 2-year-old girl with a congenital conjunctival lesion of the right eye that was surgically excised. RESULTS: The patient clinically displayed an extensive, vascularized amelanotic conjunctival lesion located superotemporally with extension onto the cornea. Her visual acuity was reduced to 20/670. The clinical diagnosis was a large lacrimal gland choristoma with corneal involvement and resulting deprivation amblyopia. The patient underwent an excision of the lesion including the corneal portion, and the ocular surface was reconstructed with amniotic membrane. Histopathologic evaluation disclosed lobules of lacrimal tissue and cartilage plaques, smooth muscle, and nerves consistent with a complex choristoma. Six weeks postoperatively, the visual acuity had improved to 20/180. The patient returned to her local ophthalmologist for amblyopia management. CONCLUSIONS: We emphasize the importance of recognizing lesion-induced amblyopia and the timely performance of appropriate surgery for complex epibulbar choristomas. A differential diagnosis of other congenital epibulbar lesions is provided.

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