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.

Size does matter: what is the corneo-limbal diameter?

This review surveys available literature for corneal and limbal dimensions. With modern scleral lenses, these measures have become central to determining the overall size of a lens for satisfactory fitting. In general, published values are not based on a definition of what is being measured.

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.

Complications and fitting challenges associated with scleral contact lenses: A review.

Introduction: The modern scleral contact lens (ScCL) has evolved from the very first contact lens fitted 128 years ago. Originally manufactured in glass and oxygen impermeable plastics, these lenses are available today in high Dk gas permeable materials that allow permeation of oxygen, reducing many of the complications that were seen with older generation ScCL. However, as with any new contact lens modality, the modern ScCL brings with it a new set of complications and fitting limitations.

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.

Ultrastructure of UVR-B-induced cataract and repair visualized with electron microscopy.

Purpose: The aim of the study is to investigate and visualize the ultrastructure of cataract morphology and repair, after in vivo exposure to double threshold dose UVR-B in the C57BL/6 mouse lens.

Methods: Twenty-six-week-old C57BL/6 mice received in vivo double threshold dose (6.4 kJ/m2) UVR-B for 15 min.

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.

An explanation for the central to peripheral thickness variation in the mouse cornea.

Background: The mouse corneal stroma varies in thickness across its diameter. The purpose of the present study was to explain this variation and to advance our understanding of stromal lamellar architecture in the mammalian cornea.

Methods: Eight C57BL/6 mice were killed, eyes enucleated, immersed in 2% glutaraldehyde fixative, processed and sectioned transversely for light and transmission electron microscopy.

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.