Central versus peripheral thickness in the human cornea explained.

Purpose: The human cornea is thicker in the periphery than the center and it has been suggested that this must be due to greater numbers of lamellae in the peripheral corneal stroma. The purpose of this study was to use high-resolution ultrastructural imaging to determine if the greater thickness of the peripheral cornea is due to the presence of more lamellae or if there is some other anatomical explanation.

Methods: In this study, full thickness corneas from three human donors were processed for light microscopy (LM) and transmission electron microscopy (TEM).

CLEAR - Anatomy and physiology of the anterior eye.

A key element of contact lens practice involves clinical evaluation of anterior eye health, including the cornea and limbus, conjunctiva and sclera, eyelids and eyelashes, lacrimal system and tear film. This report reviews the fundamental anatomy and physiology of these structures, including the vascular supply, venous drainage, lymphatic drainage, sensory innervation, physiology and function. This is the foundation for considering the potential interactions with, and effects of, contact lens wear on the anterior eye.

A measure of tear inflow in habitual scleral lens wearers with and without midday fogging.

Purpose: The purpose of this pilot study was to evaluate tear inflow in a scleral lens system using fluorophotometry, and indirectly assess the exchange of the tear reservoir in habitual scleral lens wearers with the presence or absence of midday fogging (MDF).

Methods: Habitual scleral lens wearers (n=23) and normal scleral lens neophytes (n=10) were recruited. Of the 23 habitual wearers, 11 of them experienced MDF and 12 did not have a diagnosis of MDF.

Assessing Scleral Contact Lens Satisfaction in a Keratoconus Population.

Purpose: To assess perceived comfort and related experiences of adapted keratoconic scleral contact lens (17-18.2 mm) wearers with a history of wearing other contact lens modalities and to compare these subjective clinical effects with previous experiences.

Methods: Twenty-four keratocones were recruited, signed an informed consent approved by the University Internal Review Board, and were asked to complete a survey and a dry eye questionnaire.

Lamellar changes in the keratoconic cornea.

Purpose: The purpose of this study was to identify ultrastructural changes associated with ectasia and to determine the association between lamellar count and corneal thinning.

Methods: Five surgically removed keratoconic corneal buttons and four, non-keratoconic, normal eye bank control corneas were processed for transmission electron microscopy using an established protocol, ensuring minimal tissue distortion. A sequence of overlapping digital images, spanning the full apical cone corneal thickness, was assembled.

Contact lens care solution killing efficacy against Acanthamoeba castellanii by in vitro testing and live-imaging.

In the past decade there has been an increased incidence of Acanthamoeba keratitis, particularly in contact lens wearers. The aim of this study was to utilize in vitro killing assays and to establish a novel, time-lapse, live-cell imaging methodology to demonstrate the efficacy of contact lens care solutions in eradicating Acanthamoeba castellanii (A. castellanii) trophozoites and cysts.

Recurrence or re-emergence of keratoconus--what is the evidence telling us? Literature review and two case reports.

Keratoconus may recur following penetrating or lamellar keratoplasty, but latency is considerably longer in the former. Since keratoplasty involves only partial excision of the cornea, and recent research strongly indicates the presence of the pathology in the peripheral host cornea, the reappearance of the pathology after a latency period is most likely due to migration of the disease from host to donor cornea. This notion is further corroborated by the shorter latency period in partial thickness keratoplasty, where more of the diseased host cornea remains in place.

Patient ocular conditions and clinical outcomes using a PROSE scleral device.

Purpose: To determine the type and distribution of ocular conditions cared for in a clinic dedicated to scleral devices and to report the clinical outcomes afforded by this approach.

Methods: Fifty-one charts of patients fitted unilaterally or bilaterally with a scleral device (Prosthetic Replacement of the Ocular Surface Ecosystem - PROSE) in a two year period were retrospectively reviewed. Patient demographics, ocular diagnoses, associated systemic conditions, best corrected visual acuity (BCVA) before and after fitting, Visual Function Questionnaire score (VFQ-25), and ocular surface disease index (OSDI) score were collected.

Morphologic alterations of the palpebral conjunctival epithelium in a dry eye model.

Purpose: To investigate the normal palpebral conjunctival histology in C57BL/6 mice and the structural changes that occur in a dry eye model.

Methods: Twenty-four male and female C57BL/6 mice, 8 untreated and 16 exposed to experimental ocular surface desiccating stress (DS). Ocular dryness was induced by administration of scopolamine hydrobromide (0.

Central and peripheral corneal thinning in keratoconus.

Purpose: Recent data regarding the mid-peripheral portion of the removed corneal button in transplant surgery indicate histopathologically that keratoconus was present also in the peripheral portion of the button. The intent of this study was therefore to investigate if peripheral changes could also be detected clinically by measuring the central and peripheral corneal thickness of KC patients.

Methods: Corneal pachymetry was measured with the Visante optical coherence tomography and Orbscan II.

Morphology of contact lens-induced conjunctival epithelial flaps: a pilot study.

Purpose: Conjunctival epithelial flap (CEF) is a conjunctival condition most commonly seen in silicone hydrogel contact lens wearers. This study utilized impression cytology to investigate the cellular composition and health of CEFs.

Methods: Nine (9) subjects were enrolled - 3 non-lens wearers, 3 contact lens wearers without CEF, and 3 contact lens wearers with CEFs wearing 8.

Does the eye benefit from wearing ultraviolet-blocking contact lenses?

Objectives: The human eye is exposed to toxic ultraviolet radiation (UVR) from sunlight and artificial sources. The UVR-induced damage occurs in ocular tissues from the corneal surface to the retina. Although the cornea and crystalline lens provide inherent UVR protection, the anterior ocular surface and the limbus, which contains stem cells, receive toxic levels of UVR from relatively short solar exposures.

Quantified histopathology of the keratoconic cornea.

Purpose: This study systematically investigated and quantified histopathological changes in a series of keratoconic (Kc) corneas using a physiologically formulated fixative to not further distort the already distorted diseased corneas.

Methods: Twelve surgically removed Kc corneal buttons were immediately preserved and processed for light and transmission electron microscopy using an established corneal protocol. Measurements were taken from the central cone and peripheral regions of the host button.

In vitro effects of medium tonicity, nutrient concentration, and free chlorine content on Acanthamoeba.

Background: The environment preferred by Acanthamoeba trophozoites and the mechanism by which the amebae enters the cornea are not yet fully understood. A better understanding of the pathogenesis of this disease may help with prevention and treatment.

Purpose: To define the preferred environments for Acanthamoeba survival and proliferation in vitro by examining the effect of tonicity, nutrient concentration, and free chlorine content on Acanthamoeba.

Entrapment of conjunctival goblet cells by desiccation-induced cornification.

Purpose: To evaluate the effects of desiccating stress on conjunctival goblet cell density and morphology and the expression of cornified envelope precursors by the ocular surface epithelia.

Methods: Experimental dry eye (EDE) was created in C57BL/6 mice. Real-time PCR evaluated the expression of cornified envelope (CE) precursor proteins (involucrin and small proline-rich [Sprr] -1a, -1b, -2a, -2b, -2f, and -2g proteins), the cross-linking transglutaminase 1 enzyme (Tg-1) and Muc5AC mRNA transcripts by the ocular surface epithelia.

Current silicone hydrogel UVR blocking lenses and their associated protection factors.

Purpose: Ultraviolet radiation (UVR) blocking contact lenses provides ocular protection factors (PF) that vary with lens thickness and the nature of the polymer dopant. This study measured the UVR PF of silicone hydrogel lenses outdoors and compares this to known methods for determining PF mathematically.

Methods: Ambient measurements were taken using an UVA-B radiometer, adapted to hold the test lenses over its sensor to quantify their UVR blocking capabilities.

Ultraviolet radiation transmittance of the mouse eye and its individual media components.

Recently, the mouse has become the preferred animal model in ophthalmic research. Therefore, there is a need for enhanced understanding of the mouse eye to validate its use in different experimental setting. The purpose of this study was to determine the ocular transmittance of the whole mouse eye, the cornea and the crystalline lens, particularly in the ultraviolet radiation (UVR) wavebands.

Dimensions and morphology of the cornea in three strains of mice.

Purpose: To use a histologic approach to obtain dimensional and morphologic information on the cornea in three commonly used strains of mice.

Methods: Adult mice (three each of 129/SVJ, C57BL/6, and BALB/c) were euthanatized, and the eyes were enucleated, immersed in 2% glutaraldehyde fixative, and prepared for light and transmission electron microscopy. The full corneal, epithelial, stromal, and posterior limiting lamina (PLL) with endothelium thicknesses were measured at the same location centrally and peripherally.

Corneal and conjunctival epithelial staining in hydrogel contact lens wearers.

Objectives: The purpose of this study was to investigate the prevalence of conjunctival and corneal epithelial staining in soft contact lens wearers and to see if staining could be associated with factors such as type of lens worn, wearing time, care system, age, and sex.

Methods: The records of 338 adapted hydrogel contact lens wearers were examined retrospectively.

Results: Conjunctival staining was found to be present in 32.

Fine structure of the interface between the anterior limiting lamina and the anterior stromal fibrils of the human cornea.

Purpose: To use transmission electron microscopy (TEM) to investigate further the ultrastructural details of the collagen fibrils linking the anterior limiting lamina (ALL; Bowman's membrane) of the human cornea to the anterior stromal lamellae.

Methods: Six disease-free corneas from donors aged 42 to 82 years were fixed (2% glutaraldehyde in 80 mM sodium cacodylate) and processed for TEM within 72 hours postmortem. A series of overlapping images, at 10,204x magnification, of the central corneal ALL-stroma interface were assembled.