Extended-wear Soft Contact Research Articles

Corneal Ulcers Associated with Cosmetic Extended Wear Soft Contact Lenses

In 52 patients with a history of using cosmetic extended wear soft contact lenses, corneal ulcers developed requiring admission to Wills Eye Hospital between January 1, 1982, and June 30, 1986. A retrospective study was conducted to determine the contact lens history, clinical presentation, culture and sensitivity results, and final visual acuity of these patients. Pseudomonas organisms were isolated in 75% of culture-positive cases. The final visual acuity was 6/60 or less in 12% of all cases and 25% of the Pseudomonas ulcers. Patients and practitioners must be aware of this vision-threatening problem in patients wearing cosmetic extended wear lenses. The pathogenesis of corneal ulcers in contact lens patients has not been established. There may be an inherent increased risk in the use of extended wear, compared to daily wear, soft contact lenses for cosmetic purposes.

Corneal Endothelial Changes Associated with Contact Lens Wear

Contact lenses may induce short- and long-term corneal endothelial changes. The endothelial bleb response is a short-term, reversible change noted with contact lens wear. Long-term endothelial changes such as polymegethism (increased variation in cell size) and pleomorphism (a decrease in the frequency of hexagonal cells) have also been detected in polymethylmethacrylate, rigid gas permeable, and daily and extended wear soft contact lens patients. These morphometric changes have also been seen in myopes, aphakes, and corneal transplant recipients. Differences in endothelial morphometry between the central and mid-peripheral regions of the cornea have also been noted in hard lens wearers. The long-term significance of these findings is discussed.

Severe Corneal Infections Associated with Contact Lens Wear

An analysis of acute contact lens-related complications, with particular emphasis on severe microbial keratitis, was undertaken at the Department of Ophthalmology, Sahlgren's Hospital in Gothenburg. A total of 224 contact lens wearers presented with acute complications over a 2-year period (1981-1982). The lowest incidence of acute complications was found with hard contact lens wear. Similar numbers of daily wear and extended wear soft contact lens wearers presented with acute complications. The highest incidence of severe microbial keratitis was found in patients wearing soft contact lenses on an extended-wear basis. Inappropriate topical steroid therapy was implicated as a major factor contributing to the severity of these cases. Less severe sequelae of contact lens-related complications were also over-represented in the extended lens wear group. These findings emphasize the need for a conservative approach to the use of an extended wear regimen with soft contact lenses.

Epithelial Microcysts and Vacuoles Associated with Extended-Wear Soft Contact Lenses

Epithelial Microcysts and Vacuoles Associated with Extended-Wear Soft Contact Lenses

A Proposed Mechanism for Increased Tear-Film Osmolarity in Contact Lens Wearers

Contact lenses decrease corneal sensitivity and increase tear-film osmolarity. To determine whether the decrease in corneal sensitivity is responsible for the increase in tear-film osmolarity, we studied tear-film osmolarity in normal rabbits and rabbits with surgically induced keratoconjunctivitis sicca before and after the instillation of 0.5% proparacaine. Instillation of proparacaine resulted in a significant increase in tear-film osmolarity. Decreased corneal sensitivity, with a resultant decrease in tear secretory rates, is the most likely cause for increased tear-film osmolarity in wearers of hard contact and extended-wear soft contact lenses.

Morphology and ultrastructure of fungi in extended-wear soft contact lenses.

Filamentous fungi of the genera Acremonium, Aspergillus, Alternaria, Cladosporium, Curvularia, and Fusarium penetrated the matrix of soft contact lenses both during normal usage and in laboratory studies. Growth of the fungi within the lens matrix increased with increasing water content of the lens. Hyphae within the lens were coiled. Some species penetrated completely through the lens within 96 h. More frequent cleaning and disinfection of extended-wear soft contact lenses is recommended.

Meibomian gland evaluation in patients with extended wear soft contact lens deposits.

Etude des glandes de Meibomius par biomicroscopie transillumination et photographie infrarouge. Les resultats suggerent qu'un trouble de la fonction des glandes de Meibomius s'associerait au developpement de depots (lipides) sur les lentilles souples

Association of Fungi with Extended-Wear Soft Contact Lenses

Fungi were isolated from 11 extended-wear soft contact lenses. In two cases, fungi had penetrated through the contact lens and the same fungus was cultured from corneal ulcers. In four cases, fungal growth on and in the soft contact lens matrix was associated with conjunctivitis and punctate fluorescein staining of the corneal epithelium.

The Effects of Continuous Soft Contact Lens Wear After Radial Keratotomy in Cats

ABSTRACT: Radial keratotomy utilizing the American technique was performed on seven cat eyes. After six weeks both eyes were fitted with CSI extended wear soft contact lenses and corneal thickness and corneal vascularization analyzed. While the results of mean central corneal thickness were not significant, all experimental eyes showed some degree of vascularization (except those fitted three months after surgery). This complication following contact lens use must be closely monitored in patients with poor uncorrected visual acuity following radial keratotomy.

Corneal Ulcers Associated with Extended-Wear Soft Contact Lenses

We treated nine myopic and nine aphakic eyes in patients who developed corneal ulcers while wearing extended-wear soft contact lenses. Bacteria were recovered from the corneal ulcers of 13 of 18 patients with Pseudomonas aeruginosa being the pathogen most frequently isolated. Chemical disinfection was used by seven of the nine patients with myopia and eight of the nine with aphakia. Two of nine patients in the myopic group had visual loss to 20/200 and hand movements; five of nine patients in the aphakic group had visual loss to 20/50 or worse. Invasion of the corneal stroma by bacteria may occur after breakdown of the epithelial barrier by contact lens manipulation or after chronic overnight anoxic stress. Thus, the use of soft contact lenses on an extended-wear basis may be complicated by the development of corneal ulcers. Both aphakic and myopic eyes are at risk.

EXTENDED WEAR SOFT CONTACT LENSES IN THE TREATMENT OF STRABISMIC AMBLYOPIA

17 amblyopic children between 4 and 9 years were fitted with high power plus extended wear soft contact lenses (Scanlens 24 h, Duragel 75) for optical occlusion of strabismic amblyopia. Amblyopia and eccentric fixation responded quickly to treatment between 2 to 13 weeks. Only one patient failed to reach 6/9, and 11 patients achieved equal visual acuity. Out of 10 patients with eccentric fixation only two remained eccentric after treatment. The contact lenses were tolerated by the children. Among the problems, concerning the use of extended wear soft contact lenses, should be mentioned fitting problems, deposits, loss of lenses (1 child needed 4 lenses) and occurrence of conjunctivitis (5 eyes). No major infections were seen. A one year follow-up showed that almost all the children needed renewed occlusion treatment. It is therefore recommended to continue with contact lens occlusion for at total period of 3 months.

The osmotic component of swelling under extended wear soft contact lenses.

Swelling of the cornea during sleep when wearing an extended wear contact lens has a osmotic and hypoxic component. The normal swelling of the cornea during sleep, caused by the change from hypertonic tears of the open eye to the isotonic tears of the closed eye, is about 3%. Under an extended-wear contact lens, there is an additional 6 to 8% swelling of the cornea in the closed eye because the cornea under the contact lens is at an oxygen tension substantially below that present in the palpebral conjunctiva. Data on human subjects wearing extended wear contact lenses are consistent with this allocation of the 8 to 12% total corneal swelling observed upon awakening.

Complications with Therapeutic Extended Wear Soft Contact Lenses*

Complications with Therapeutic Extended Wear Soft Contact Lenses*

Complications with Therapeutic Extended Wear Soft Contact Lenses*

Complications with Therapeutic Extended Wear Soft Contact Lenses*

The Physiologic Effects of Extended Wear Soft Contact Lenses

The major physiologic effect to the eyes of soft contact lenses in general and continuously worn hydrogel lenses in particular is a decrease in the amount of oxygen normally available to the cornea. This reduction in oxygen supply produces changes as minimal as clinically undetectable epithelial edema and as severe as the anoxic overwear syndrome that produces pain and decreased vision. Induced corneal edema can produce refractive error changes and endothelial cell changes. On a long-term basis the lenses produce physical trauma to the anterior surface of the cornea as well as certain metabolic changes and have been associated with a significant degree of corneal neovascularization. Because hydrogel lenses require a different type of care than standard, hard PMMA lenses, new complications are being described, such as giant papillary conjunctivitis, lens deposits, and acute red eye syndromes that may be associated with allergic or toxic reactions to preservatives used in the cleaning processes. Research is underway to develop hydrogel materials that will allow more oxygen to reach the corneal surface and prevent surface deposits from forming.

What about extended-wear soft contact lenses?

A group from The Johns Hopkins University School of Medicine, Baltimore, has tested use of both the artificial intraocular lens and the soft contact lens after cataract removal. Basically, said Walter J. Stark, MD, director of the corneal service at the university's Wilmer Ophthalmological Institute, the resulting vision with the soft contact lenses was as good as with the intraocular lenses. Furthermore, Stark told a Research to Prevent Blindness seminar, increased incidence of inflammation has been seen recently after intraocular lens insertion. He suggests this may be due to the current method of lens sterilization in this country, involving use of ethylene oxide rather than sodium hydroxide. Additional information came from H. Dwight Cavanagh, MD, PhD, professor and chairman, Department of Ophthalmology, Emory University School of Medicine, Atlanta. He said that, for the first time, "a newly developed third generation of soft contact lenses represents a safe, reliable, and effective

What about extended-wear soft contact lenses?

What about extended-wear soft contact lenses?

Extended-Wear Contact Lenses and Intraocular Lenses for Aphakic Correction

We evaluated extended-wear soft contact lens use in 128 aphakic eyes of 113 patients, 44 of whom had been unable to wear conventional contact lenses; 116 eyes (91%) have been successfully fitted and have worn the extended-wear lenses without significant complication. Eleven patients were unable to wear the lens or had to be discontinued for transient lens-related problems. In 103 eyes successfully fitted the lens is removed for cleaning less often than monthly. Ninety six of the 116 eyes fitted have visual acuity as good as, or better than, with aphakic correcting spectacles. The results obtained with the extended-wear soft contact lens are similar to those obtained with intraocular lenses, except for the recent high incidence of inflammation seen after intraocular lens insertion when using ethylene-oxide-sterilized lenses.