Lifetime Corneal Edema Load Model.

Purpose: To highlight the potential benefits for long-term use of silicone hydrogels daily disposable (DD) contact lenses, particularly with patients who are noncompliant, sleeping or napping while wearing their lenses, or those who have higher oxygen demands and wear this modality for decades.

Methods: Published data for corneal swelling with lenses and no lens wear were used to develop a nonlinear least squares model. The edema load experienced with a range of oxygen transmissibilities (Dk/t) and wear compliance (sleep and napping) was determined.

Interpreting the corneal response to oxygen: Is there a basis for re-evaluating data from gas-goggle studies?

When anoxia (0% oxygen) is created within a gas-tight goggle, ocular physiological responses, including corneal swelling, limbal hyperaemia and pH change, are known to vary, depending on the presence or absence of a low, oxygen transmissibility contact lens. A new theory is proposed to account for this discrepancy based on the concept of lid derived oxygen, whereby oxygen originating from the vascular plexus of the palpebral conjunctiva supplements that available to the ocular surface in an open, normally blinking eye, even when the surrounding gaseous atmosphere is anoxic. The effect of a lid derived contribution to corneal oxygenation was assessed by using existing experimental data to model open-eye, corneal swelling behavior as a function of atmospheric oxygen content, both with and without the presence of a contact lens.

Contributions of ocular surface components to matrix-metalloproteinases (MMP)-2 and MMP-9 in feline tears following corneal epithelial wounding.

Purpose: This study investigated ocular surface components that contribute to matrix-metalloproteinase (MMP)-2 and MMP-9 found in tears following corneal epithelial wounding.

Methods: Laboratory short-haired cats underwent corneal epithelial debridement in one randomly chosen eye (n = 18). Eye-flush tears were collected at baseline and during various healing stages.

Tear film stability: a review.

Tear film stability can be assessed via a number of tools designed for clinical as well as research purposes. These techniques can give us insights into the tear film, and allow assessment of conditions that can lead to dry eye symptoms, and in severe cases, to significant ocular surface damage and deterioration of vision. Understanding what drives tear film instability and its assessment is also crucial for evaluating existing and new therapies.

Have silicone hydrogel lenses eliminated hypoxia?

Objective: The purpose of this article is to review the literature to date to determine if silicone hydrogel lenses have eliminated corneal hypoxia.

Methods: Results from clinical studies, including short-term laboratory studies and retrospective and prospective clinical trials that have assessed the cornea's response to silicone hydrogels, will be evaluated.

Results: Silicone hydrogels have eliminated the physiologic signs associated with lens-induced hypoxia including ocular and limbal redness, neovascularization, epithelial microcysts, and endothelial responses.

A preliminary study of changes in tear film proteins in the feline eye following nictitating membrane removal.

Objective: To investigate the influence of nictitating membrane (third eyelid) removal on selected proteins in feline tears.

Animal Studied: Domestic short-haired cats (7-17 months; 2.6-5.

The influence of surface topography of a porous perfluoropolyether polymer on corneal epithelial tissue growth and adhesion.

Design principles for corneal implants are challenging and include permeability which inherently involves pore openings on the polymer surface. These topographical cues can be significant to a successful clinical outcome where a stratified epithelium is needed over the device surface, such as with a corneal onlay or corneal repair material. The impact of polymer surface topography on the growth and adhesion of corneal epithelial tissue was assessed using porous perfluoropolyether membranes with a range of surface topography.

A perfluoropolyether corneal inlay for the correction of refractive error.

This study assessed the long-term biological response of a perfluoropolyether-based polymer developed as a corneal inlay to correct refractive error. The polymer formulation met chemical and physical specifications and was non-cytotoxic when tested using standard in vitro techniques. It was cast into small microporous membranes that were implanted as inlays into corneas of rabbits (n = 5) and unsighted humans (n = 5 + 1 surgical control) which were monitored for up to 23 and 48 months respectively.

A comparison of basal and eye-flush tears for the analysis of cat tear proteins.

Purpose: To identify a rapid and effective tear collection method providing sufficient tear volume and total protein content (TPC) for analysis of individual proteins in cats.

Methods: Domestic adult short-haired cats (12-37 months; 2.7-6.

Clinical observations of biofouling on PEO coated silicone hydrogel contact lenses.

Silicone hydrogel contact lenses, which have been a major advance in the field of vision correction, require surface modification or coatings for comfort and biocompatibility. While current coatings show adequate clinical performance, advanced coatings may improve the biocompatibility of contact lenses further by reducing biofouling and related adverse clinical events. Here, we have produced coatings on Lotrafilcon A contact lenses by deposition of a thin film of allylamine plasma polymer (ALAPP) as a reactive interlayer for the high density grafting of poly(ethylene oxide) dialdehyde (PEO(ALD)(2)), which had previously shown complete resistance to protein adsorption in vitro.

Are inflammatory events a marker for an increased risk of microbial keratitis?

Purpose: To consider whether inflammatory events, such as contact lens-induced peripheral ulcers, contact lens-induced acute red eye, and infiltrative keratitis are a marker for an increased risk for the occurrence of microbial keratitis.

Methods: A review of relevant studies was undertaken with the view to answering two questions: 1) Do inflammatory events associated with contact lens wear progress to infection or microbial keratitis; and 2) Do episodes of inflammatory events predispose a patient to having an event of microbial keratitis?

Results: The large body of laboratory work, along with the epidemiologic data on incidence rates and clinical data with regard to differences between the nature of inflammatory events and infection, supports the supposition that inflammatory events are not a marker for increased risk of microbial keratitis.

Conclusions: Inflammatory events are not a marker for increased risk of microbial keratitis, nor will they progress to infection because they are separate disease entities.

Synthetic corneal inlays.

This review is based on the activities of the Vision Cooperative Research Centre (previously Cooperative Research Centre for Eye Research and Technology) Corneal Implant team from 1991 to 2007. The development of a synthetic polymer of perfluoropolyether (PFPE), meeting essential physical and biological requirements, for use as a corneal inlay is presented. Each inlay was placed in a corneal flap created with a microkeratome and monitored over a two-year period in a rabbit model.

Accommodative facility in eyes with and without myopia.

Purpose: To compare accommodative facility in eyes with myopia to that in eyes with emmetropia or hyperopia and to determine whether accommodative facility can be used to predict an association with myopia.

Methods: In the Sydney Myopia Study, year-1 school children (6.7 +/- 0.

Silicone hydrogel contact lenses and the ocular surface.

For 30 years, contact lens research focused on the need for highly oxygen-permeable (Dk) soft lens materials. High Dk silicone hydrogel contact lenses, made available in 1999, met this need. The purpose of this review is to examine how silicone hydrogel lens wear affects the ocular surfaces and to highlight areas in which further research is needed to improve biocompatibility.

The Max Schapero Memorial Award Lecture 2004: contact lenses on and in the cornea, what the eye needs.

Purpose: The aim of this study is to review the advances made in understanding the needs of the cornea and the way in which it responds to contact lens wear and corneal implants.

Methods: The review is based on personal knowledge and involvement of the author and colleagues from the 1970s to 2005.

Results: Development of silicone hydrogel contact lenses is presented as well as development of synthetic materials for implantation on the corneal surface (corneal onlay).

Two presentations of contact lens-induced papillary conjunctivitis (CLPC) in hydrogel lens wear: local and general.

Purpose: The purpose of this study was to confirm that two distinct clinical presentations of contact lens-induced papillary conjunctivitis (CLPC), local and general, occur in hydrogel lens wear.

Methods: Retrospective analyses of 124 CLPC events were identified. The classification of CLPC was based on location and extent of papillae.

Two-year preclinical testing of perfluoropolyether polymer as a corneal inlay.

Purpose: To assess the long-term biocompatibility and optical clarity of a perfluoropolyether (PFPE) polymer as a corneal inlay.

Methods: A 4-mm-diameter PFPE inlay was implanted under a microkeratome flap in the corneas of rabbits (n = 16) and maintained for predetermined time points of 6, 12, or 24 months. These were compared with normal (n = 3) and time-matched sham-wounded rabbit corneas (n = 8).

Microbial keratitis in prospective studies of extended wear with disposable hydrogel contact lenses.

Purpose: To report the annualized incidence of microbial keratitis with extended wear of low oxygen transmissible (Dk/t) disposable soft contact lenses from prospective postmarket clinical trials.

Methods: Seven hundred ninety subjects were enrolled at the L.V.

Comparison of the performance of 6- or 30-night extended wear schedules with silicone hydrogel lenses over 3 years.

Aim: To compare the clinical performance of silicone hydrogel lenses worn for 6- or 30-nights, with monthly replacement, for 3 years.

Methods: In this 3-year prospective clinical trial, 161 subjects were enrolled and 154 commenced extended wear. Clinical performance was assessed by comparing discontinuations and lens surface characteristics (front surface deposits, lens wettability, number of mucin balls), lens fitting performance (primary gaze movement, lens tightness), and physiologic parameters (limbal and bulbar redness, corneal and conjunctival staining, microcysts) and subjective parameters (ratings of comfort and vision) between groups.

Comparison of adverse events with daily disposable hydrogels and spectacle wear: results from a 12-month prospective clinical trial.

Objective: To evaluate the type and incidence of adverse events seen with daily disposable hydrogel contact lens wear compared with a control (spectacle) group over 12 months.

Design: Prospective, randomized, observer-masked, comparative clinical trial.

Participants: Two hundred eighty-one myopes with no prior contact lens wear experience were enrolled from August to December 1996.

Corneal hypoxia secondary to contact lenses: the effect of high-Dk lenses.

Contact lenses made from materials of low-oxygen permeability (Dk) do not meet the oxygen requirements of the cornea for overnight wear. Long-term extended wear of these lenses results in chronic changes to all layers of the cornea, many of which are associated with hypoxia. High-Dk silicone hydrogel and gas permeable lenses are now available for 30-night continuous wear.

A comparison of biological coatings for the promotion of corneal epithelialization of synthetic surface in vivo.

Purpose: To investigate the effect of a range of biological coatings on corneal epithelialization of a synthetic polymer surface in vivo.

Methods: Eight diverse biological factors (collagen I, collagen III, collagen IV, laminin, fibronectin, endothelial extracellular matrix, hyaluronic acid, and chondroitin sulfate) were coated individually onto the surface of polycarbonate membranes with a pore size of 0.1 micro m.

Altered conjunctival response after contact lens-related corneal inflammation.

Purpose: Corneal inflammation in overnight contact lens (CL) wear is not fully understood. We designed a masked study to examine the impact of overnight CL wear on clinical variables in subjects who had previously experienced corneal inflammatory disease.

Methods: Forty-four subjects were entered into the study: Nine subjects who had previously experienced CL-associated acute red eye (CLARE) and nine controls; 13 subjects who had previously experienced CL-induced peripheral ulceration (CLPU) and 13 controls, respectively.

Clinical characterization of corneal infiltrative events observed with soft contact lens wear.

Purpose: Corneal infiltrates are commonly observed during adverse reactions associated with contact lens wear. Broad ranges of presentations are encountered, and there is no well-established classification system. The aim of this paper is to categorize corneal infiltrates associated with soft lens wear and present the typical clinical characteristics associated with each type of event.