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Flowering plants must attract birds or insects to help disperse their pollen. The attraction, of course, is usually nectar, but this must be advertised with bright colours and/or scent. The [...]

Copepods ('oar-footed') are the most numerous of the metazoa and play an enormously important part in the food chain. In the colder waters closer the poles their biomass is so [...]

Competing Interests: None

Purpose: To perform in vivo evaluation of the structural morphology and vascular plexuses of the neurosensory retina and choroid across vertebrate species using swept-source optical coherence tomography (SS-OCT) and SS-OCT angiography (SS-OCTA) imaging., Methods: A custom-built SS-OCT system with an incorporated flexible imaging arm was used to acquire the three-dimensional (3D) retinal OCT and vascular OCTA data of five different vertebrates: a mouse (C57BL/6J), a rat (Long Evans), a gray short-tailed opossum (Monodelphis domestica), a white sturgeon (Acipenser transmontanus), and a great horned owl (Bubo virginianus)., Results: In vivo structural morphology of the retina and choroid, as well as en face OCTA images of retinal and choroidal vasculature of all species were generated. The retinal morphology and vascular plexuses were similar between rat and mouse, whereas distinct choroidal and paired superficial vessels were observed in the opossum retina. The retinal and vascular structure of the sturgeon, as well as the pecten oculi and overlying the avascular and choroidal vasculature in the owl retina are reported in vivo., Conclusions: A high-quality two-dimensional and 3D in vivo visualization of the retinal structures and en face visualization of the retina and choroidal vascular plexus of vertebrates was possible. Our studies affirm that SS-OCT and SS-OCTA are viable methods for evaluating the in vivo retinal and choroidal structure across terrestrial, aquatic, and aerial vertebrates., Translational Relevance: In vivo characterization of retinal morphology and vasculature plexus of multiple species using SS-OCT and SS-OCTA imaging can increase the pool of species available as models of human retinal diseases.

Purpose/objectives: to evaluate new onset uveitis or reactivated uveitis by biologic agents and characterize their features., Materials and Methods: This is a multicenter, retrospective case series. Patients under biologic therapy were included if they developed uveitis for the first time or experienced intraocular inflammation which was different in location or laterality to previous inflammation., Results: Sixteen patients were identified. The underlying disorders included ankylosing spondylitis, juvenile idiopathic arthritis, rheumatoid arthritis, and Behçet's Disease. The biologic agents associated with a first episode of uveitis (n = 11) or with a new recurrence of uveitis (n = 5) were etanercept, adalimumab, abatacept, infliximab, and golimumab. Sarcoidosis based on bihilar lymphadenopathy, other computer tomography-findings, or biopsy was diagnosed in five patients under therapy with etanercep, adalimumab, and abatacept. Additionally, seven patients developed clinical changes in their uveitis pattern, suggesting sarcoid uveitis., Conclusions: Biologic treatment-induced uveitis often presents as granulomatous disease.

The New Zealand White rabbit has been widely used as a model of limbal stem cell deficiency (LSCD). Current techniques for experimental induction of LSCD utilize caustic chemicals, or organic solvents applied in conjunction with a surgical limbectomy. While generally successful in depleting epithelial progenitors, the depth and severity of injury is difficult to control using chemical-based methods. Moreover, the anterior chamber can be easily perforated while surgically excising the corneal limbus. In the interest of creating a safer and more defined LSCD model, we have therefore evaluated a mechanical debridement technique based upon use of the AlgerBrush II rotating burr. An initial comparison of debridement techniques was conducted in situ using 24 eyes in freshly acquired New Zealand White rabbit cadavers. Techniques for comparison (4 eyes each) included: (1) non-wounded control, (2) surgical limbectomy followed by treatment with 100% (v/v) n-heptanol to remove the corneal epithelium (1-2 min), (3) treatment of both limbus and cornea with n-heptanol alone, (4) treatment of both limbus and cornea with 20% (v/v) ethanol (2-3 min), (5) a 2.5-mm rounded burr applied to both the limbus and cornea, and (6) a 1-mm pointed burr applied to the limbus, followed by the 2.5-mm rounded burr applied to the cornea. All corneas were excised and processed for histology immediately following debridement. A panel of four assessors subsequently scored the degree of epithelial debridement within the cornea and limbus using masked slides. The 2.5-mm burr most consistently removed the corneal and limbal epithelia. Islands of limbal epithelial cells were occasionally retained following surgical limbectomy/heptanol treatment, or use of the 1-mm burr. Limbal epithelial cells were consistently retained following treatment with either ethanol or n-heptanol alone, with ethanol being the least effective treatment overall. The 2.5-mm burr method was subsequently evaluated in the right eye of 3 live rabbits by weekly clinical assessments (photography and slit lamp examination) for up to 5 weeks, followed by histological analyses (hematoxylin & eosin stain, periodic acid-Schiff stain and immunohistochemistry for keratin 3 and 13). All 3 eyes that had been completely debrided using the 2.5-mm burr displayed symptoms of ocular surface failure as defined by retention of a prominent epithelial defect (∼40% of corneal surface at 5 weeks), corneal neovascularization (2-3 quadrants), reduced corneal transparency and conjunctivalization of the corneal surface (demonstrated by the presence of goblet cells and/or staining for keratin 13). In conclusion, our findings indicate that the AlgerBrush II rotating burr is an effective method for the establishment of ocular surface failure in New Zealand White rabbits. In particular, we recommend use of the 2.5-mm rotating burr for improved efficiency of epithelial debridement and safety compared to surgical limbectomy., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objective: To describe using spectral domain optical coherence tomography (SD-OCT), digital slit-lamp biomicroscopy, and external photography, changes in the ophidian cuticle, spectacle, and cornea during ecdysis., Animals Studied: Four normal royal pythons (Python regius)., Procedures: Snakes were assessed once daily throughout a complete shed cycle using nasal, axial, and temporal SD-OCT images, digital slit-lamp biomicroscopy, and external photography., Results: Spectral domain optical coherence tomography (SD-OCT) images reliably showed the spectacular cuticle and stroma, subcuticular space (SCS), cornea, anterior chamber, iris, and Schlemm's canal. When visible, the subspectacular space (SSS) was more distended peripherally than axially. Ocular surface changes throughout ecdysis were relatively conserved among snakes at all three regions imaged. From baseline (7 days following completion of a full cycle), the spectacle gradually thickened before separating into superficial cuticular and deep, hyper-reflective stromal components, thereby creating the SCS. During spectacular separation, the stroma regained original reflectivity, and multiple hyper-reflective foci (likely fragments from the cuticular-stromal interface) were noted within the SCS. The cornea was relatively unchanged in character or thickness throughout all stages of ecdysis. Slit-lamp images did not permit observation of these changes., Conclusions: Spectral domain optical coherence tomography (SD-OCT) provided excellent high-resolution images of the snake anterior segment, and especially the cuticle, spectacle, and cornea of manually restrained normal snakes at all stages of ecdysis and warrants investigation in snakes with anterior segment disease. The peripheral spectacle may be the preferred entry point for diagnostic or therapeutic injections into the SSS and for initiating spectacular surgery., (© 2014 American College of Veterinary Ophthalmologists.)

Ocular surface disorders, such as dry eye disease, ocular rosacea, and allergic conjunctivitis, are a heterogeneous group of diseases that require an interdisciplinary approach to establish underlying causes and develop effective therapeutic strategies. These diverse disorders share a common thread in that they involve direct changes in ocular surface chemistry as well as the rheological properties of the tear film and topographical attributes of the cellular elements of the ocular surface. Knowledge of these properties is crucial to understand the formation and stability of the preocular tear film. The study of interfacial phenomena of the ocular surface flourished during the 1970s and 1980s, but after a series of lively debates in the literature concerning distinctions between the epithelial and the glandular origin of ocular surface disorders during the 1990s, research into this important topic has declined. In the meantime, new tools and techniques for the characterization and functionalization of biological surfaces have been developed. This review summarizes the available literature regarding the physicochemical attributes of the ocular surface, analyzes the role of interfacial phenomena in the pathobiology of ocular surface disease, identifies critical knowledge gaps concerning interfacial phenomena of the ocular surface, and discusses the opportunities for the exploitation of these phenomena to develop improved therapeutics for the treatment of ocular surface disorders., (Copyright © 2014 Elsevier Inc. All rights reserved.)

An otherwise healthy 62-year-old woman developed necrotizing scleritis 23 years following pterygium excision with adjunctive beta-radiation. Surgically induced necrotizing scleritis (SINS) was diagnosed, but the scleritis progressed despite anti-inflammatory therapy, and 10 weeks after presentation the patient developed a hypopyon and decreased vision. After cultures revealed no growth at 72 hours, immunosuppressive therapy was escalated, with a subsequent deterioration in the patient's clinical course. Scedosporium superinfection was eventually cultured and found on histological examination of the enucleated globe. In reported cases, infectious scleral necrosis occurs most commonly following pterygium (71.4%) and scleral buckling (97.2%) surgery. Hypopyon is uncommon (10.0%) in patients with postoperative scleral necrosis, but when present is a strong predictor of infection (odds ratio, 21.2; 95% confidence interval, 2.9-157.5). Rates of underlying autoimmune disease are generally low (0.0-12.5%) except following cataract and lens procedures, where the occurence of SINS heralds systemic illness in 42.9% of cases., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objective: Troglomorphic fishes provide excellent comparative models for studying eye evolution. We describe the gross and microscopic anatomy of ocular structures of the depigmented, blind cichlid, Lamprologus lethops, and its putative sister species, Lamprologus tigripictilis collected from the lower Congo River in the Democratic Republic of Congo., Procedures: Both species were fixed, paraffin-sectioned and stained. Immunohistochemical staining for rhodopsin markers was also performed., Results: The globe in L. lethops is smaller than its sighted congener and recessed beneath bone and skin. The scleral profile maintains a wrinkled spherical shape, and the choroid is occupied by adipose tissue containing no rete mirabilis. The globe in L. lethops is foreshortened in the anterior-posterior dimension and deviated dorsally toward the midline with no extraocular muscles. At the posterior pole of the globe, there is an open periocular space containing no cell bodies. In L. tigripictilis, no choroidal adipose tissue is seen and a rete mirabilis is present. The retina of L. lethops is thinner compared with L. tigripictilis. Both species have scleral cartilage and fully developed lenses. Rhodopsin is present in the inner and outer segments of both species., Conclusions: Ocular adaptations evolve over time as a response to a life in darkness. Combining ocular anatomy, developmental data, and genetics will lead to insights about evolution in these fishes and contribute to understanding how ocular evolution works in other vertebrates., (© 2012 American College of Veterinary Ophthalmologists.)

Objectives: To characterize the clinical presentations, features, and outcomes of eyelash alopecia areata., Design: Retrospective chart review of patients evaluated for eyelash loss and found to have eyelash alopecia areata. A 3-year follow-up was required., Participants: The study involved 15 patients., Methods: Patients who presented at a tertiary care eye clinic for evaluation of eyelash loss and were found to have eyelash alopecia areata were reviewed. Demographic considerations were categorized; they included age at presentation, areas of other hair loss, other relevant history, and treatment responses., Results: Patients were young (mean age 18 years) and had a large female predominance (female-to-male ratio, 14:1). Concurrent scalp and brow involvement, either in isolation (20% and 13%, respectively) or together (13%), were seen in half of the patients (46%). Upper eyelid involvement was more common and severe than lower eyelid involvement, and 40% of patients experienced complete regrowth of lashes, with a mean time to regrowth of 28 months (range, 6 to 60 months). Of these, 13% experienced partial regrowth. Younger age at presentation was associated with regrowth, whereas presence or absence of other involved sites, personal or family histories of atopy, family history of alopecia, other autoimmune diseases, or the use of topical steroids did not appear to affect prognosis., Conclusions: Eyelash alopecia areata is a unique entity, although it remains potentially underdiagnosed. The key differential diagnosis is trichotillomania, which is commonly associated with obsessive-compulsive disorders. The presence of exclamation-mark hairs in alopecia areata plays an important role in differentiating the 2 diagnoses., (Copyright © 2012 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate a silk fibroin (SF) biomaterial as a substrate for corneal epithelial cell proliferation, differentiation, and stratification in vitro compared with denuded human amniotic membrane (AM)., Methods: Primary human and rabbit corneal epithelial cells and immortalized human corneal limbal epithelial cells were cultured on the SF and denuded AM, respectively. The biological cell behavior, including the morphology, proliferation, differentiation, and stratification, on the two substrates was compared and analyzed., Results: Corneal epithelial cells can adhere and proliferate on the SF and denuded AM with a cobblestone appearance, abundant microvilli on the surface, and wide connection with the adjacent cells. MTT assay showed that cell proliferation on denuded AM was statistically higher than that on SF at 24 and 72 hours after plating (P = 0.001 and 0.0005, respectively). Expression of ΔNp63a and keratin 3/12 was detected in primary cell cultures on the two substrates with no statistical difference. When cultured at the air-liquid interface for 7 days, cells on SF could form a comparable stratified graft with a 2- to 3-cell layering, which compared similarly to AM cultures., Conclusions: SF, a novel biomaterial, could support corneal epithelial cells to proliferate, differentiate, and stratify, retaining the normal characteristic epithelium phenotype. Compared with AM, its unique features, including the transparency, ease of handling, and transfer, and inherent freedom from disease transmission, make it a promising substrate for corneal wound repair and tissue-engineering purposes.

Diseases of the periocular hair range from localized disease to systemic processes and may present challenging diagnostic questions. We present a comprehensive clinical guide to the evaluation and diagnosis of these disorders. Deficiencies in growth, excess production, changes in pigmentation, aberrant position, or abnormalities in form may affect this region's hair. These range from benign to sight-, and even life-, threatening pathologies., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The purpose of this study is to identify evolutionary origin and fate of anatomic features of the duck-billed platypus eye. Eyes from the duck-billed platypus and four key evolutionary basal vertebrates (Pacific hagfish, north hemisphere sea lamprey, and Australian and South American lungfishes) were prepared for light microscopy. In addition to a standard panel of stains, tissues were immunostained against a variety of rod and cone opsins. Finally, published opsin sequences of platypus and several other vertebrate species were aligned and compared with immunohistochemical results. A complete scleral cartilage similar to that seen in birds, reptiles and amphibians encloses the platypus eye. This feature is present in sharks and rays, and in extant relatives of tetrapods, the lungfishes. The choroid lacks a tapetum. The retina is largely avascular and is rod-dominated, with a minority of red- and blue- cone immunoreactive photoreceptors. Like marsupials and many nonmammalian vertebrates, cones contain clear inner segment droplets. Double cones were present, a feature not found in eutherian mammals or marsupials. Evaluation of opsins indicates that red and blue immunoreactive cone opsins, but not rhodopsin, are present in the most basal of the extant species examined, the Pacific hagfish. Rhodopsin appears in the Australian and South American lungfishes, establishing emergence of this pigment in an extant relative of tetrapods. Unlike eyes of eutherian mammals, the platypus eye has retained morphologic features present in early tetrapods such as amphibians and their evolutionarily basal sister group, the lungfishes. These include scleral cartilage, double cones and cone droplets. In the platypus, as in other mammals, rod rhodopsin is the predominant photoreceptor pigment, at expense of the cone system., (Copyright © 2011 Wiley-Liss, Inc.)

The corneal epithelium generates a significant trans-epithelial potential (TEP) which aids in maintaining cornea water balance and transparency. Injury to the cornea causes a short circuit of the TEP at the wound. The TEP in the intact epithelium around the wound acts like a battery, powering significant ion flux and electric current at the wound. These circulating endogenous currents generate an electric field orientated towards the wound, with the wound the cathode. Many cell types, including human corneal epithelial cells and keratinocytes, migrate to the cathode at physiological electric field strengths. Indeed, the electric signal is a powerful stimulator of cell migration, which appears to override other cues such as chemotaxis and wound void. These wound fields also have a dynamic timecourse of change after wounding. It has been assumed that wound electric fields are produced by passive leakage of ions from damaged cells and tissue. Could these fields be actively maintained and regulated as an active wound response? What are the molecular, ionic and cellular mechanisms underlying the wound electric currents?

The silk structural protein fibroin displays potential for use in tissue engineering. We present here our opinion of its value as a biomaterial for reconstructing tissues of clinical significance within the human eye. We review the strengths and weaknesses of using fibroin in those parts of the eye that we believe are most amenable to cellular reconstruction, namely the corneoscleral limbus, corneal stroma, corneal endothelium and outer blood-retinal barrier (Ruysch's complex). In these areas we find that by employing the range of manufacturing products afforded by fibroin, relevant structural assemblies can be made for cells expanded ex vivo. Significant questions now need to be answered concerning the effect of this biomaterial on the phenotype of key cell types and the biocompatibility of fibroin within the eye. We conclude that fibroin's strength, structural versatility and potential for modification, combined with the relative simplicity of associated manufacturing processes, make fibroin a worthy candidate for further exploration., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Background: Endogenous electric fields and currents occur naturally at wounds and are a strong signal guiding cell migration into the wound to promote healing. Many cells involved in wound healing respond to small physiological electric fields in vitro. It has long been assumed that wound electric fields are produced by passive ion leakage from damaged tissue. Could these fields be actively maintained and regulated as an active wound response? What are the molecular, ionic and cellular mechanisms underlying the wound electric currents?, Methodology/principal Findings: Using rat cornea wounds as a model, we measured the dynamic timecourses of individual ion fluxes with ion-selective probes. We also examined chloride channel expression before and after wounding. After wounding, Ca(2+) efflux increased steadily whereas K(+) showed an initial large efflux which rapidly decreased. Surprisingly, Na(+) flux at wounds was inward. A most significant observation was a persistent large influx of Cl(-), which had a time course similar to the net wound electric currents we have measured previously. Fixation of the tissues abolished ion fluxes. Pharmacological agents which stimulate ion transport significantly increased flux of Cl(-), Na(+) and K(+). Injury to the cornea caused significant changes in distribution and expression of Cl(-) channel CLC2., Conclusions/significance: These data suggest that the outward electric currents occurring naturally at corneal wounds are carried mainly by a large influx of chloride ions, and in part by effluxes of calcium and potassium ions. Ca(2+) and Cl(-) fluxes appear to be mainly actively regulated, while K(+) flux appears to be largely due to leakage. The dynamic changes of electric currents and specific ion fluxes after wounding suggest that electrical signaling is an active response to injury and offers potential novel approaches to modulate wound healing, for example eye-drops targeting ion transport to aid in the challenging management of non-healing corneal ulcers.

The current study investigates potential differences in fibroblast phenotype across the anterior segment of the human eye with the aim to understanding factors that support the regenerative function of human limbal epithelial progenitor cells (LEPs) during wound healing. Separate cultures of fibroblasts were established from the cornea, limbus and sclera by growth in serum-supplemented medium. The resulting cultures were examined for potential differences in morphology and growth rate, as well as expression of CD34, CD45, CD90, CD141, CD271, vimentin and α-smooth muscle actin (α-sma). Finally, cultures were examined for their ability to support the growth of LEPs. While all cultures grew at a similar rate, scleral cultures often contained larger and more irregularly shaped cells which stained positive for α-sma. Western blotting confirmed a gradient of α-sma expression with lowest levels in corneal cultures. All three cultures stained positively for CD90 and vimentin, and were negative for CD34, CD45, CD141 and CD271. Only limbal or corneal irradiated fibroblasts supported the establishment of LEP cultures. While LEP colony forming efficiency and prominent expression of ABCG2, C/EBPδ and p63 was similar with either limbal or corneal fibroblasts, limbal fibroblasts supported significantly better growth. These results indicate that scleral fibroblasts have an increased capacity for myofibroblast formation which appears to negatively impact on their ability to support LEP growth. Superior growth of LEPs in the presence of limbal fibroblasts indicates a role for limbal fibroblasts in promoting the proliferation of limbal epithelium during wound healing., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Purpose: To evaluate the transfer of heterologous genes carrying a Green Fluorescent Protein (GFP) reporter cassette to primary corneal epithelial cells ex vivo., Methods: Freshly enucleated rabbit corneoscleral tissue was used to obtain corneal epithelial cell suspension via enzymatic digestion. Cells were plated at a density of 5×10³ cells/cm² and allowed to grow for 5 days (to 70-80% confluency) prior to transduction. Gene transfer was monitored using fluorescence microscopy and fluorescence activated cell sorter (FACS). We evaluated the transduction efficiency (TE) over time and the dose-response effect of different lentiviral particles. One set of cells were dual sorted by fluorescence activated cell sorter for green fluorescent protein expression as well as Hoechst dye exclusion to evaluate the transduction of potentially corneal epithelial stem cells (side-population phenotypic cells)., Results: Green fluorescent protein expressing lentiviral vectors were able to effectively transduce rabbit primary epithelial cells cultured ex vivo. Live cell imaging post-transduction demonstrated GFP-positive cells with normal epithelial cell morphology and growth. The transduction efficiency over time was higher at the 5(th) post-transduction day (14.1%) and tended to stabilize after the 8(th) day. The number of transduced cells was dose-dependent, and at the highest lentivirus concentrations approached 7%. When double sorted by fluorescence activated cell sorter to isolate both green fluorescent protein positive and side population cells, transduced side population cells were identified., Conclusions: Lentiviral vectors can effectively transfer heterologous genes to primary corneal epithelial cells expanded ex vivo. Genes were stably expressed over time, transferred in a dose-dependence fashion, and could be transferred to mature corneal cells as well as presumable putative stem cells.

Pterygium is an ocular surface disease of humans attributed to chronic ultraviolet-B exposure. Clinically, the condition involves invasive centripetal growth with associated inflammation and neovascularisation. Previous clinical studies focused primarily on the clinical characteristics and surgical management of pterygia and, because of this, the pathogenesis of pterygia remains incompletely understood. However, considerable progress in this area has been achieved, providing additional insight into this complex disease. This recent evidence implicates antiapoptotic mechanisms, immunological mechanisms, cytokines, growth factors, extracellular matrix modulators, genetic factors, viral infections and other possible causative factors. Limited investigation regarding differences in pathogenesis of primary and recurrent pterygia has been performed. We summarise many of these recent discoveries concerning the pathogenesis of pterygia and describe reported differences between primary and recurrent pterygia.

Purpose: To describe the characteristic, clinical, and epidemiological features of Salzmann nodular degeneration., Methods: Retrospective review of cases. All patients with diagnosis of Salzmann nodular degeneration examined on the Cornea and External Disease Service in the Department of Ophthalmology and Vision Science at the University of California, Davis, were included in this review. Demographic features, clinical characteristics, treatment regimens, surgical procedures, and outcomes were recorded. Descriptive statistics, correlation statistics in bilateral cases, and simple regression models were constructed to assess the effect of potential indicators of severity., Results: One hundred eighty eyes of 108 patients were included in this review. Seventy-nine patients (72.2%) were female and 29 (27.8%) were male. Seventy-two patients had bilateral disease. The mean age for all patients was 60.8 (13-92) years, and the mean follow-up time was 61.2 months (0-357 months). 76.1% of all eyes were from White. Mean logarithm of the minimum angle of resolution best-corrected visual acuity was 0.24 (Snellen equivalent 20/35, range -0.12 to 2.60, SD 0.44). Decreased visual acuity was the most common symptom in 30.6% of patients. The visual axis was affected in 30% of the cases. Meibomian gland dysfunction was the most common coexistent condition, identified in 41.7% of the cases. For bilateral cases, Spearman correlations for best-corrected visual acuity, magnitude of astigmatism, spherical equivalent, and disease extension were statistically significant (P = 0.001). The number of quadrants affected was found to be a significant predictor for astigmatism (P = 0.01). Surgery was indicated in 41 eyes of 30 patients. Decreased visual acuity was the most common indication for superficial keratectomy. Patients with more than 1 quadrant of the cornea affected or those in which the central visual axis was involved were more likely to require surgery (P = 0.015 and 0.0001, respectively). The surgical outcome was satisfactory in 90.2% of the cases; 9 eyes (21.9%) developed recurrences., Conclusions: Salzmann nodular degeneration is a disease of uncertain etiology in which inflammation of the ocular surface may play a role. It predominantly affects women in the sixth decade of life. Management with conservative therapy is generally adequate, and in cases that require surgical intervention, simple nodulectomy is usually effective.

We provide a historical perspective on the rainbow, with a review of early research and observations regarding the rainbow's origin and a discussion of some of the major contributors to our current understanding of what the rainbow represents. An overview of the various types of rainbows is undertaken. We conclude with a discussion of the rainbow's link to refraction, light, the visual system, and perception.

Purpose: To compare the University of California Davis experience using the Boston keratoprosthesis with the Boston Keratoprosthesis Study Group's initial report., Design: Retrospective chart review., Participants: We analyzed 30 eyes of 28 patients who previously underwent Boston type 1 keratoprosthesis surgery at our institution between 2004 and 2008., Methods: Preoperative, intraoperative, and postoperative parameters were collected and analyzed., Main Outcome Measures: Visual acuity and keratoprosthesis stability., Results: Preoperative diagnoses were failed graft (26 eyes, 87%), chemical injury (3 eyes, 10%), and Stevens-Johnson syndrome (1 eye, 3%). Twenty eyes (66%) had preoperative glaucoma. Preoperative best-corrected visual acuity ranged from 20/150 to light perception and was <20/200 in 83% of eyes. At an average follow-up of 19 months (range, 1-48; SD, 13.8; and median, 13), postoperative vision improved to >or=20/200 in 77% of eyes. Among eyes at least 1 year after the operation (16 eyes), vision was >or=20/200 in 75% of eyes and >or=20/40 in 25% of eyes. At an average follow-up of 19 months, retention of the initial keratoprosthesis was 83.3%., Conclusions: The Boston type 1 keratoprosthesis is a viable option after multiple keratoplasty failures or in conditions with a poor prognosis for primary keratoplasty. Patients with autoimmune disease are at higher risk for complications. The University of California Davis experience seems equivalent to the initial report of the Boston Keratoprosthesis Study Group. With longer follow-up, additional surgical procedures may be required but good anatomic and functional outcomes can be maintained.

Membranes were prepared from fibroin, a protein isolated from the domesticated silkworm (Bombyx mori) silk, and evaluated as a potential substratum for corneal limbal epithelial cells. These membranes (i.e., B. mori silk fibroin [BMSF] membranes) were cast from dialyzed solutions of fibroin protein (4% w/v) dispensed into 35-mm-diameter culture dishes and dried at room temperature (23-24 degrees C). The resulting material was transparent, easy to handle, and supported levels of human limbal epithelial (HLE) cell growth comparable to that observed on tissue culture plastic. Remarkably, these results were obtained utilizing a commercial serum-free medium (CnT-20) designed for the ex vivo expansion of corneal epithelial progenitor cells. The potential benefits of serum proteins on this culture system were examined through addition of fetal bovine serum (FBS) either to fibroin stocks prior to membrane casting or by supplementation of the CnT-20 medium. Membranes cast in the presence of FBS displayed increasing opacity and induced little change in HLE growth. Supplementation of CnT-20 medium with FBS deterred cell growth on all substrata, including tissue culture plastic control substrata. The remarkable properties of BMSF membranes demonstrated under serum-free conditions warrant investigation of this material as a substratum in the creation of tissue-engineered constructs for the restoration of diseased or damaged ocular surface.

Objective: The Leatherback sea turtle is the largest extant reptile and the sole member of the family Dermochelyidae. Here, the eye of this critically endangered marine turtle was investigated to determine the anatomy, optics, and optical sensitivity., Animals Studied: Three Leatherback sea turtles, Dermochelys coriacea., Results: The eye is small in proportion to body size of the adult compared to other vertebrates, with prominence of the retractor bulbi and pyramidalis muscles. The nictitans shows extensive folding of the bulbar conjunctiva as an apparent mechanism to increase the surface area for mucus secretion. The intraocular anatomy is consistent with an eye adapted to aquatic vision with minimal curvature of the cornea, a near-spherical lens, deep ciliary cleft and highly vascularized ciliary body. The optical sensitivity, a measure of the sensitivity to light of a given optical system, is higher than in other marine turtles studied but lower than those found in teleost fish that share a habitat with the Leatherback sea turtle., Conclusions: The Leatherback sea turtle shows ocular features that are characteristic of Chelonians with similarities to aquatic mammals. The calculated optical sensitivity suggests that compared to pelagic fishes, for instance, the Leatherback sea turtle eye is not particularly well adapted for vision in dim light even though this species is known to venture into deep, dark waters, and might feed at night.

Investigations were undertaken to evaluate the unique choroidal vascular system of the Megachiroptera (fruit bats) and its possible significance for retinal nutrition. Fluorescein angiography was performed and documented on Pteropus poliocephalus. Vascular casts were made of the eye of Pteropus scapulatus. Histologic evaluation was performed on P. scapulatus. Results confirmed that each papilla has a vascular core, and a unique vascular system emanating from the optic disc. The histological appearance of the choroid and retina of P. scapulatus confirmed a vascular core to the papillae with a thin, but definite Bruch's membrane. Megachiroptera have a unique vascular system to supply nutrition to the retina consisting of capillary loops within a dense, uniform mosaic of choroidal projections or papillae, which permit the diffusion of metabolites to the retina and a heretofore undescribed vascular tuft emanating from the optic disc. We suggest that this vascular system provides nutrition by diffusion to a thick avascular retina, without any shadowing by vessels, and allows for nocturnal visual acuity and light-gathering capabilities.