Extended-wear Contact Research Articles

Corneal thickness changes associated with daily and extended contact lens wear.

Human corneal thickness was measured during daily wear of hydrogel contact lenses and then during the initial 2 weeks extended wear of hyper-thin (0.035 mm), low water content (38.6%), hydrogel lenses (polymacon). Results show that subjects wearing standard thickness (0.12 mm) and ultra-thin (0.07 mm) hydrogel lenses of low water content for daily wear will exhibit a diurnal swelling of the cornea. Subjects wearing hyper-thin (0.035 mm) low minus power hydrogel contact lenses of low water content for extended wear will exhibit overnight (closed eye) swelling of the cornea followed by a deswelling throughout the day (open eye). The degree of swelling and deswelling can vary greatly among individual subjects.

Current Management in Ophthalmology

As stated in the preface, this book by 17 authors is intended to bring practical information up to date on procedures for and diagnosis and treatment of a timely selection of 18 ocular conditions. These include ocular herpes, abnormalities of the tear film, fungal keratitis, conjunctival transplantation for corneal epithelial abnormalities, the use of extendedwear contact lenses, pharmacologic treatment of glaucoma, infantile glaucoma, cyclopexy for hypotony due to traumatic cyclodialysis, orbital lesions in children, the posterior fixation suture in limitations of extraocular movements, intraocular lens implantation in children, posterior ocular injury, complications of pars plana vitrectomy, toxoplasmosis, basal cell carcinoma of the lids, entropion and ectropion surgical failures, thyroid ophthalmopathy, and migraine. These presentations are definitely review papers, representing the personal views of the authors and supported by a considerable number of references. The value of each paper varies considerably, and much of the material presented is elementary and well-known

Extended Wear Contact Lenses for Myopes: A Follow-up Study of 400 Cases

The long-term effects of extended wear contact lenses (Perfilcon A [Permalens]) for myopia have been studied among 400 patients in a private clinic from December 1977 to September 1982. The drawbacks and possible complications were evaluated. With the exception of one case, no permanent modification of the cornea or ocular adnexa was found. The high rate of success among well-selected patients (without significant astigmatism or chronic infection of the eyelids) far outweighs the risks of radial keratotomy as it is known today. By and large patients opt for this method of optical correction once they are aware of its availability and remain with it despite the necessary frequent replacement of the lenses.

Aphakic Extended-Wear Contact Lenses after Penetrating Keratoplasty

Fifteen aphakic eyes in 15 selected patients who underwent penetrating keratoplasty were successfully fitted with extended-wear contact lenses three to 42 months postoperatively. After an average follow-up of 17 months, there was no graft edema, no microbial corneal ulcers, and no episode of graft rejection. Three eyes developed minor (1 to 2 mm) graft neovascularization; the neovascularization was stable and did not require discontinuation of the contact lenses. Fourteen of the 15 patients had postoperative visual acuities of 20/70 or better; the one patient whose visual acuity was worse than 20/70 had a clear graft but also had senile macular degeneration.

Book Reviews

Book reviewed in this article: EXTENDED WEAR CONTACT LENSES FOR APHAKIA AND MYOPIA:Jack Hartsiein, MD, NEURO‐OPHTHALMOLOGY FOCUS 1982:Edited by J. Lawton Smith, MD, MANUAL OF OPHTHALMIC TERMINOLOGY:H. A. Stein, B. J. Slatt, THE DEVELOPMENT OF VISION:P. A. Gardiner

Visual System Screening in Infants and Young Children

Many abnormalities of the visual system in infants and young children respond to treatment when instituted at an early age. Ocular abnormalities that require early recognition and therapy include congenital cataracts, congenital glaucoma, intraocular tumors, intraocular inflammation, large errors of refraction, strabismus, and corneal opacities (Figs 1 to 6). The visual prognosis for children with these problems is often directly related to early detection and treatment of the visual disorder. Visual deprivation of young laboratory animals can permanently damage their developing central nervous system. Diseases once believed hopeless, such as monocular congenital cataracts, can now be treated.1 Technologic advances, such as extended-wear contact lenses which are useful for infants who have had cataract surgery during the first few weeks of life, have facilitated visual rehabilitation of young eyes. Corneal opacities, complete ptosis, prolonged patching, and eyelid or orbit abnormalities such as large hemangiomas can cause amblyopia if the vision is obstructed. Even brief occlusion can result in irreversible amblyopia during the early months of life.2 Unilateral disruptions of vision are generally more damaging to the eye than are bilateral ocular abnormalities. Each of the young child's eyes must enjoy a clear, focused retinal image for visual development to progress normally. Early diagnosis and treatment of congenital glaucoma is important so that intraocular pressure can be lowered, thereby, avoiding irreversible anatomic damage to the eye.

Visual System Screening in Infants and Young Children

Many abnormalities of the visual system in infants and young children respond to treatment when instituted at an early age. Ocular abnormalities that require early recognition and therapy include congenital cataracts, congenital glaucoma, intraocular tumors, intraocular inflammation, large errors of refraction, strabismus, and corneal opacities (Figs 1 to 6). The visual prognosis for children with these problems is often directly related to early detection and treatment of the visual disorder.Visual deprivation of young laboratory animals can permanently damage their developing central nervous system. Diseases once believed hopeless, such as monocular congenital cataracts, can now be treated.1 Technologic advances, such as extended-wear contact lenses which are useful for infants who have had cataract surgery during the first few weeks of life, have facilitated visual rehabilitation of young eyes.Corneal opacities, complete ptosis, prolonged patching, and eyelid or orbit abnormalities such as large hemangiomas can cause amblyopia if the vision is obstructed. Even brief occlusion can result in irreversible amblyopia during the early months of life.2 Unilateral disruptions of vision are generally more damaging to the eye than are bilateral ocular abnormalities. Each of the young child's eyes must enjoy a clear, focused retinal image for visual development to progress normally.Early diagnosis and treatment of congenital glaucoma is important so that intraocular pressure can be lowered, thereby, avoiding irreversible anatomic damage to the eye.

OXYGEN MEASUREMENTS

Equivalent oxygen percentage (E.O.P.) responses, using a mammalian corneal model, were measured for open-and closed-eye conditions with the presence of a Permalens contact lens. Under open-eye conditions, the E.O.P. responses agreed with those measured or predicted by other investigators. However, under closed-eye conditions, the E.O.P. responses were significantly different from those measured or predicted by other investigators. This discrepancy is discussed in terms of its clinical significance for extended wear contact lens patients.

Extended-Wear Contact Lenses in Patients with Corneal Grafts and Aphakia

Extended-wear contact lenses (EWCL) were fitted successfully on 61 aphakic eyes with penetrating corneal grafts. In two- to 32-months follow-up there were 26 eyes that had varying amounts of superficial neovascularization of the grafts and one Staphylococcus epidermidis corneal graft ulcer. There were five homograft rejections, all occurring in severely diseased eyes. Variable vision and visual acuity less than that with hard contact lenses or aphakic spectacles were the most frequent problems. Both were due to the high corneal astigmatism present in many patients. The results indicate that EWCLs may be used safely by patients with penetrating corneal grafts and aphakia, particularly if there is no host corneal edema, scarring, or vascularization, if there are no synechias to the graft wound, and if the astigmatism is less than 3.0 diopters.

Flurbiprofen in the Treatment of Corneal Neovascularization Induced by Contact Lenses

Cellulose acetate butyrate extended-wear contact lenses were fitted bilaterally on ten New Zealand albino rabbits. We administered flurbiprofen 0.03% solution topically to the experimental eyes and vehicle solution to the contralateral control eyes four times a day in a random, masked fashion beginning 24 hours before the contact lens was fitted. Corneal neovascularization, which developed in all eyes by the 25th day of contact lens wear, was significantly suppressed by flurbiprofen treatment (mean vessel length was 1.5 +/- 0.4 mm for the treated eyes and 3.0 +/- 0.3 mm for the control eyes; P less than .005). Topical administration of a noncorticosteroidal anti-inflammatory agent may be an effective treatment for corneal neovascularization induced by contact lenses.

Extended-wear contact lenses for myopic correction.

The long-term effects of an extended-wear contact lens (perfilcon A [Permalens]) for myopia were evaluated in 106 patients who had successfully worn the lens for four to eight years (median, 4.94 years). Visual acuity was 6/12 (20/40) or better in 95% of the 207 eyes fitted. Corneal neovascularization, when encountered (8.7%), was mild and did not reduce visual acuity. There were no cases of infectious corneal ulcer or scarring or of permanent visual loss from use of the lens. In selected patients, use of extended-wear lenses seems to be a reasonable form of optical correction of myopia, and they deserve further study. The use of these lenses is discussed as an alternative to the experimental procedure of radial keratotomy.

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.

Extended wear contact lenses for aphakia.

The current modality for correcting unilateral aphakia is by the use of daily wear hard and soft contact lenses and by the use of intraocular lens implants. The use of the Cooper Permalens soft contact lens as an extended wear lens for correction of aphakia was investigated in 177 eyes. The relative merits of the extended wear lens are discussed with emphasis on fit, visual function, and contact lens-related problems.

Fungal Growth in Aphakic Soft Contact Lenses

Fungal growth was detected in two aphakic hydrophilic contact lenses. Aspergillus species was cultured from the extended-wear contact lens and Dermatophilus congolensis was identified by specific antibody staining of the daily-wear contact lens. As in the 16 previously described cases of fungal contact lens growth, our patients had no evidence of ocular infection but did experience irritation which cleared up when contact lens wear was discontinued. Although only a small percentage of contact lenses are prescribed because of aphakia, these thicker contact lenses may be more susceptible to fungal growth and should be monitored carefully.

Corneal thickness changes with extended contact lens wear.

Eight myopic patients wearing Permalens contact lenses continuously for 18 months were monitored for corneal thickness changes. The averaged results showed maximum corneal swelling after 1 week of wear with the cornea gradually returning to near prefitting thickness levels. However, great individual variation in corneal thickness response was noted with some patients showing chronic corneal thickening and some showing corneal thinning after the 18-month wearing period.

Symposium on Medical and Surgical Diseases of the Cornea

Like so many of the previous transactions of the New Orleans Academy of Ophthalmology, the most recent volume dealing with the cornea and external diseases of the eye is an excellent compendium of current concepts. In 26 chapters plus a series of round-table discussions, the nine contributing authors cover a broad spectrum of topics ranging from the pathogeneses of recurrent herpes simplex to orthokeratology. The central 13 chapters of this book are devoted largely to keratoplasty, including specialized techniques and management of complications. Several of these chapters are noteworthy for their practical approach to surgical problems. In addition to the surgical material, medical therapeutics is well represented, and the reader will be updated on the recent advances in antiviral therapy and extended-wear contact lenses. Particularly outstanding are the chapters on the management of microbial keratitis and stromal herpes. If this volume suffers any major criticisms, they are related to its

Micro-epithelial cysts and extendedcontact lens wear

Micro-epithelial cysts and extendedcontact lens wear

The Correction of Aphakia: Xxxvi Edward Jackson Memorial Lecture

Major advances in the correction of aphakia have been made in the past few years. Extended-wear contact lenses constitute one advance, if not a perfect one. Intraocular lenses are now safer to use, and new research is seeking ways to improve their safety through protection of the corneal endothelium during surgery and stimulation of endothelial healing where damage does occur. Altering the refractive power of the cornea offers another possible approach to the correction of aphakia. Modifications of Barraquer's keratomileusis procedure using preserved, preground corneas may have definite indications for certain types of aphakia, such as monocular aphakia in children and in individuals who would otherwise require secondary implants. We have experimented with a "living contact lens" of shaped donor tissue attached to the de-epithelialized surface of the eye. Such a lens of preground, preserved cornea tissue can be sutured to the patient's cornea with its central Bowman's membrane intact. A peripheral trephine mark is made, but the central cornea is untouched and the attachment of the living lens is simple. The procedure is apparently safe, and should be usable by any competent ophthalmic surgeon if the long-term results continue to be as encouraging as our early experience now suggests.

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

Extended-Wear Contact Lenses in 525 Aphakic Eyes

Extended-wear contact lenses were fitted to 225 patients with monocular aphakia and 150 with bilateral aphakia. They were observed from three months to three years. Eighty-eight of the 195 eyes fitted with a Softcon lens became red and painful within 14 days during extended wear. The Hydrocurve lens was better tolerated in 55, but many patients had acute congestion, pain, and tearing. Deposits accumulated rapidly on the Sauflon-PW lens. Some 90% of all patients can be fitted successfully with the cellulose acetate butyrate lens or the silicone lens. The silicone coating of the silicone lens is lost or damaged in about 20% of the patients because of excess mucous accumulation.