Cornea

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.
Greiner JV. A single LipiFlow® Thermal Pulsation System treatment improves meibomian gland function and reduces dry eye symptoms for 9 months. Curr Eye Res 2012;37(4):272-8.Abstract
PURPOSE: To evaluate the effect of a single treatment with the LipiFlow(®) Thermal Pulsation System on signs of meibomian gland dysfunction (MGD) and dry eye symptoms over a 9-month period. METHODS: Patients (n = 42 eyes, 21 subjects) diagnosed with MGD and dry eye symptoms were recruited for a non-significant risk, prospective, open-label, 1-month clinical trial. Patients received a single 12-minute treatment using the LipiFlow(®) Thermal Pulsation System on each eye. The LipiFlow(®) device applies heat to the conjunctival surfaces of the upper and lower inner eyelids while simultaneously applying pulsatile pressure to the outer eyelid surfaces to express the meibomian glands. Patient symptoms were evaluated using the Ocular Surface Disease Index (OSDI) and Standard Patient Evaluation for Eye Dryness (SPEED) dry eye questionnaires; tear break-up time was measured with the dry eye test (DET™); and meibomian gland function was evaluated using a standardized diagnostic expression technique. Data are presented for patient's pre-treatment (baseline) and at 1-month and 9-month post-treatment. RESULTS: Meibomian gland secretion scores improved significantly from baseline (4.4 ± 4.0) to 1-month post-treatment (11.3 ± 6.2; p < 0.0001) and this improvement was maintained with no significant regression at 9 months (11.7 ± 5.9). Similarly, baseline tear break-up time (4.8 ± 3.2) was significantly increased at 1 month (9.6 ± 7.6; p < 0.001) and this increase was maintained with no significant regression at 9 months (7.1 ± 5.6). Symptom scores on both OSDI and SPEED questionnaires improved significantly at 1 month (p < 0.0001) and this improvement was maintained at 9 months. CONCLUSION: With such prolonged improvement in signs and symptoms of dry eye disease, the LipiFlow(®) Thermal Pulsation System offers a technological advancement for the treatment of dry eye disease secondary to meibomian gland dysfunction. A single 12-minute LipiFlow(®) treatment results in up to 9 months of sustained improvement of meibomian gland function, tear break-up time and dry eye symptoms that are unparalleled with current dry eye treatments.
Shazly TA, Latina MA, Dagianis JJ, Chitturi S. Effect of central corneal thickness on the long-term outcome of selective laser trabeculoplasty as primary treatment for ocular hypertension and primary open-angle glaucoma. Cornea 2012;31(8):883-6.Abstract
PURPOSE: To determine if central corneal thickness (CCT) impacts the intraocular pressure (IOP)-lowering effect of selective laser trabeculoplasty (SLT) in patients with ocular hypertension (OHT) and primary open-angle glaucoma (POAG). METHODS: A retrospective chart review of consecutive patients, who underwent SLT as primary treatment for OHT and POAG, between 2002 and 2005, was performed. Partial correlation analysis was performed to correlate the CCT to the percentage of IOP reduction at 3 to 30 months after SLT. Independent samples t test was performed to compare mean percentage of IOP reduction in eyes with CCT less than 555 μm versus CCT 555 μm or greater. RESULTS: Eighty eyes of 47 patients were identified. The partial correlation coefficient value between the CCT and percentage of IOP reduction after SLT at 3 months was -0.253 (P = 0.025), at 12 months it was -0.22 (P = 0.049), and at 30 months it was 0.301 (P = 0.007). Independent samples t test showed that the mean percentage of IOP reduction in eyes with thinner corneas (CCT < 555 μm) was greater than that in thicker corneas (CCT ≥ 555 μm) at 3-, 6-, 9-, 12-, and 30-month post-SLT (P < 0.05). CONCLUSIONS: In patients with POAG and OHT, percentage of IOP reduction after SLT was significantly greater in eyes with thinner corneas (CCT < 555 μm). These findings indicate that patients treated with SLT as primary therapy who had thinner corneas demonstrated better IOP control for at least 30 months after SLT.
Stevenson W, Chauhan SK, Dana R. Dry eye disease: an immune-mediated ocular surface disorder. Arch Ophthalmol 2012;130(1):90-100.Abstract
Dry eye disease is a multifactorial disorder of the tears and ocular surface characterized by symptoms of dryness and irritation. Although the pathogenesis of dry eye disease is not fully understood, it is recognized that inflammation has a prominent role in the development and propagation of this debilitating condition. Factors that adversely affect tear film stability and osmolarity can induce ocular surface damage and initiate an inflammatory cascade that generates innate and adaptive immune responses. These immunoinflammatory responses lead to further ocular surface damage and the development of a self-perpetuating inflammatory cycle. Herein, we review the fundamental links between inflammation and dry eye disease and discuss the clinical implications of inflammation in disease management.
Shatos MA, Haugaard-Kedstrom L, Hodges RR, Dartt DA. Isolation and characterization of progenitor cells in uninjured, adult rat lacrimal gland. Invest Ophthalmol Vis Sci 2012;53(6):2749-59.Abstract
PURPOSE: The purpose of this study was to investigate the presence of progenitor cells in the uninjured, adult rat lacrimal gland (LG). METHODS: The presence of progenitor cells was examined in LG sections from male rats using antibodies against selected stem cell markers and α-smooth muscle actin (SMA), which marks myoepithelial cells (MECs), by immunofluorescence microscopy (IF). Small, immature cells were isolated after digestion of LG with collagenase and culture in RPMI 1640 for 2 weeks. Immature cells were examined for expression of stem cell markers by IF. Immature cell were grown in neuronal, epithelial, and myoepithelial cell media, and examined by light morphology and IF using antibodies to markers of different cell lineages. RESULTS: In the intact LGs, MECs expressed the stem cell markers nestin, Musashi 1, ABCG2, Pax6, Chx 10, ΔN p63, and Sox 2. All markers colocalized with SMA. Isolated immature cells contained Ki-67, nestin, Musashi 1, Pax 6, and CHX 10. In neuronal media, immature cells differentiated and assumed a neuronal cell morphology expressing neurofilament 200. In media for human corneal endothelial cells, immature cells differentiated, assumed cobblestone morphology, and labeled with the epithelial marker AE1/AE3. In RPMI media immature cells differentiated into cells with MEC-like morphology, and expressed the MEC markers SMA, α-actinin, adenylate cyclase II, and vimentin. CONCLUSIONS: We conclude that uninjured, adult LG contains progenitor cells that may be MECs, which can be isolated and differentiated into multiple lineages.
Shukla AN, Cruzat A, Hamrah P. Confocal microscopy of corneal dystrophies. Semin Ophthalmol 2012;27(5-6):107-16.Abstract
In vivo confocal microscopy (IVCM) of the cornea is becoming an indispensable tool in the cellular study of corneal physiology and disease. This technique offers non-invasive imaging of the living cornea with images comparable to that of ex vivo histology. The ability to provide high-resolution images of all layers in the living cornea has resulted in new discoveries of corneal pathology at the cellular level. The IVCM analysis of corneal dystrophies is of importance to clinicians, as current methods of diagnosis involve slit-lamp characteristics, genetic analysis, and invasive biopsy. IVCM is helpful in evaluating the morphological characteristics of corneal dystrophies at the histological level and may be helpful in diagnosis, determination of progression, and understanding the pathophysiology of disease. The purpose of this review is to describe the principles, applications, and clinical correlation of IVCM in the study of corneal dystrophies.
Sullivan DA, Hammitt KM, Schaumberg DA, Sullivan BD, Begley CG, Gjorstrup P, Garrigue J-S, Nakamura M, Quentric Y, Barabino S, Dalton M, Novack GD. Report of the TFOS/ARVO Symposium on global treatments for dry eye disease: an unmet need. Ocul Surf 2012;10(2):108-16.Abstract
In September 2010, a Symposium in Florence, Italy, was held to address the unmet need for global treatments for dry eye disease (DED). It was sponsored by The Tear Film & Ocular Surface Society (TFOS; www.TearFilm.org) and co-sponsored by the Association for Research in Vision & Ophthalmology (www.arvo.org). The Symposium objectives were two-fold: first, to discuss accepted and emerging clinical endpoints of DED with regulatory experts from around the world; and second, to consider how to improve clinical trials of treatments for DED. The Symposium focused on the personal and collective burden of DED, as well as the developmental and regulatory challenges associated with generating new DED therapeutics. This article provides a synopsis of many of the presentations, discussions and recommendations of this Symposium.
Sahin A, Hamrah P. Clinically relevant biometry. Curr Opin Ophthalmol 2012;23(1):47-53.Abstract
PURPOSE OF REVIEW: Obtaining precise postoperative target refraction is of utmost importance in today's modern cataract and refractive surgery. Given the growing number of patients undergoing premium intraocular lens (IOL) implantations, patient expectation continues to rise. In order to meet heightened patient expectations, it is crucial to pay utmost attention to patient selection, accurate keratometry and biometry readings, as well as to the application of correct IOL power formula with optimized lens constants. This article reviews recent advances in the field of clinical biometry and IOL power calculations. RECENT FINDINGS: Recently developed low-coherence reflectometry optical biometry is comparable to older ultrasonic biometric and keratometric techniques. In addition, the new IOLMaster software upgrade has improved reproducibility and enhanced signal acquisition. Further, the modern lens power formulas currently determine the effective lens position and the shape of the intraocular lens power prediction curve more accurately. SUMMARY: In order to reach target refraction, precise biometric measurements are imperative. Understanding the strengths and limitations of the currently available biometry devices allows prevention of high variability and inaccuracy, ultimately determining the refractive outcomes.
Sayegh RR, Pineda R. Practical applications of anterior segment optical coherence tomography imaging following corneal surgery. Semin Ophthalmol 2012;27(5-6):125-32.Abstract
Anterior segment optical coherence tomography (AS-OCT) has recently emerged as an important modality for imaging of the cornea. Since its introduction less than a decade ago, it has been clinically used for the diagnosis and management of an expanding number of corneal conditions. In this review, we will discuss the applications of anterior segment optical coherence tomography after corneal surgery, focusing on penetrating and lamellar keratoplasty, keratoprosthesis, intracorneal ring segments, collagen cross-linking and refractive surgery. Anterior segment optical coherence tomography is useful in evaluating outcomes, detecting adverse events, determining prognosis, guiding management decisions, and surgical planning.
Kurbanyan K, Hoesl LM, Schrems WA, Hamrah P. Corneal nerve alterations in acute Acanthamoeba and fungal keratitis: an in vivo confocal microscopy study. Eye (Lond) 2012;26(1):126-32.Abstract
PURPOSE: To study sub-basal corneal nerve alterations in patients with acute Acanthamoeba keratitis (AK) and fungal keratitis (FK), using laser in vivo confocal microscopy (IVCM). METHODS: A retrospective analysis of IVCM (Heidelberg Retina Tomograph 3/Rostock Cornea Module) images of 10 AK corneas and 4 FK corneas was performed, and the results compared with those of 10 normal and 12 acute herpetic keratitis (HK) corneas. Sub-basal corneal nerves were analyzed with respect to total number of nerves, main nerve trunks, branching pattern and total length of nerves per image, as well as tortuosity. For each variable, results for three frames were averaged and analyzed using analysis of variance. RESULTS: Total corneal nerve length was significantly (P < 0.0001) reduced in patients with AK (193.4 ± 124.5 μm) and FK (268.6 ± 257.4 μm) when compared with normal controls (3811.84 ± 911.4 μm). Total nerve counts in patients with AK (3.9 ± 1.2) and FK (3.6 ± 3.2) were significantly (P < 0.0001) decreased in comparison with normal controls (24.7 ± 5.5). The number of main nerve trunks and nerve branching was found to be significantly lower in AK and FK corneas, when compared with controls. There was a statistically significant decrease in the above parameters when compared with HK controls. CONCLUSIONS: The sub-basal corneal nerve plexus is significantly diminished in eyes with AK and FK, as demonstrated by IVCM. These results are more profound than previously reported findings of a diminished nerve plexus in HK.
Li D, Carozza RB, Shatos MA, Hodges RR, Dartt DA. Effect of histamine on Ca(2+)-dependent signaling pathways in rat conjunctival goblet cells. Invest Ophthalmol Vis Sci 2012;53(11):6928-38.Abstract
PURPOSE: The purpose of this study was to determine the Ca(2+)-dependent cellular signaling pathways used by histamine to stimulate conjunctival goblet cell secretion. METHODS: Cultured rat goblet cells were grown in RPMI 1640. Goblet cell secretion of high molecular weight glycoconjugates was measured by an enzyme-linked lectin assay. Intracellular [Ca(2+)] ([Ca(2+)](i)) was measured by loading cultured cells with the Ca(2+) sensitive dye fura-2. The level of [Ca(2+)](i) was measured using fluorescence microscopy. Extracellular regulated kinase (ERK) 2 was depleted using small interfering RNA (siRNA). RESULTS: Histamine-stimulated conjunctival goblet cell secretion of high molecular weight glycoproteins was blocked by removal of extracellular Ca(2+) and depletion of ERK2 by siRNA. Histamine increase in [Ca(2+)](i) was desensitized by repeated addition of agonist and blocked by a phospholipase C antagonist. Histamine at higher doses increased [Ca(2+)](i) by stimulating influx of extracellular Ca(2+), but at a lower dose released Ca(2+) from intracellular stores. Activation of each histamine receptor subtype (H(1)-H(4)) increased [Ca(2+)](i) and histamine stimulation was blocked by antagonists of each receptor subtype. The H(2) receptor subtype increase in [Ca(2+)](i) was cAMP dependent. CONCLUSIONS: We conclude that histamine activates phospholipase C to release intracellular Ca(2+) that induces the influx of extracellular Ca(2+) and activates ERK1/2 to stimulate conjunctival goblet cell mucous secretion, and that activation of all four histamine receptor subtypes can increase [Ca(2+)](i).
Sahin A, Hamrah P. Acute Herpetic Keratitis: What is the Role for Ganciclovir Ophthalmic Gel?. Ophthalmol Eye Dis 2012;4:23-34.Abstract
Herpes simplex keratitis (HSK) is a major cause of corneal blindness in the world. Following the primary infection, the virus enters into a latent phase. Recurrent infectious or immune keratitis cause structural damage to the cornea, scarring, and may lead to blindness. Several commercially available topical and oral antiviral drugs for HSK are currently available. However, toxicity and low patient compliance hamper their use in HSK. Further, oral antiviral drugs alone are not always effective in HSK. Thus, there had been a need for safe and effective topical antiviral agents against HSK. Systemic ganciclovir has been in use for the treatment of cytomegalovirus infections. Recently, topical ganciclovir has become available for use in patients with HSK. Ganciclovir 0.15% ophthalmic gel has been shown to be both safe and effective against viruses of the herpes family. Topical ganciclovir ophthalmic gel is well tolerated and does not cause significant toxic effects on the ocular surface. Several multicenter studies have revealed the potential role of ganciclovir ophthalmic gel in the treatment and prophylaxis of epithelial HSK. In this paper, we have reviewed the pharmacology, efficacy, side effects, and the role of ganciclovir ophthalmic gel 0.15% in the treatment of acute herpetic keratitis.
Kumar R, Dohlman CH, Chodosh J. Oral acetazolamide after Boston keratoprosthesis in Stevens-Johnson syndrome. BMC Res Notes 2012;5:205.Abstract
BACKGROUND: Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is a rare but severe and sometimes fatal condition associated with exposure to medications; sulfamethoxazole is among the most common causes. We sought to address the safety of acetazolamide, a chemically related compound, in patients with prior SJS/TEN and glaucoma. A retrospective case series is described of patients at the Massachusetts Eye and Ear Infirmary who underwent keratoprosthesis surgery for corneal blindness from SJS/TEN, and later required oral acetazolamide for elevated intraocular pressure. FINDINGS: Over the last 10 years, 17 patients with SJS/TEN received a Boston keratoprosthesis. Of these, 11 developed elevated intraocular pressure that required administration of oral acetazolamide. One of 11 developed a mild allergic reaction, but no patient experienced a recurrence of SJS/TEN or any severe adverse reaction. CONCLUSION: Although an increase in the rate of recurrent SJS/TEN due to oral acetazolamide would not necessarily be apparent after treating only 11 patients, in our series, acetazolamide administration was well tolerated without serious sequela.
Schmedt T, Chen Y, Nguyen TT, Li S, Bonanno JA, Jurkunas UV. Telomerase immortalization of human corneal endothelial cells yields functional hexagonal monolayers. PLoS One 2012;7(12):e51427.Abstract
Human corneal endothelial cells (HCEnCs) form a monolayer of hexagonal cells whose main function is to maintain corneal clarity by regulating corneal hydration. HCEnCs are derived from neural crest and are arrested in the post-mitotic state. Thus cell loss due to aging or corneal endothelial disorders leads to corneal edema and blindness-the leading indication for corneal transplantation. Here we show the existence of morphologically distinct subpopulations of HCEnCs that are interspersed among primary cells and exhibit enhanced self-renewal competence and lack of phenotypic signs of cellular senescence. Colonies of these uniform and hexagonal HCEnCs (HCEnC-21) were selectively isolated and demonstrated high proliferative potential that was dependent on endogenous upregulation of telomerase and cyclin D/CDK4. Further transduction of HCEnC-21 with telomerase yielded a highly proliferative corneal endothelial cell line (HCEnT-21T) that was devoid of oncogenic transformation and retained critical corneal endothelial cell characteristics and functionality. This study will significantly impact the fields of corneal cell biology and regenerative medicine.

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