Corneal infiltrates and extended-wear contact lenses

Corneal infiltrates are a relatively rare but potentially serious complication of extended-wear contact lenses. Clinical experience with a large population of extended-wear patients suggested that these infiltrates have a characteristic location and appearance which may aid in diagnosis and management. The records of 51 patients (54 eyes) with extended-wear contact lenses and corneal infiltrates were reviewed. Nearly all the infiltrates were in the peripheral cornea and 67% were located superiorly, beneath the upper lid. No permanent visual loss resulted and all patients resumed extended-wear of contact lenses following a period of appropriate management. The clinical features, management, and possible etiologies are discussed. The sample reported herein is the largest, to date, of any reported in the ophthalmic literature.

Central and peripheral corneal swelling accompanying soft lens extended wear

Central and peripheral corneal thickness changes were measured after 3 hr of eye closure with and without contact lens wear. Spun cast and lathe cut hydrogel extended wear lenses of -1.25, -6.00, and -9.00 D were used. Each of these conditions produced 25 to 50% less swelling in the peripheral than in the central cornea. Central swelling was greater with higher minus spun cast lenses, but not related to the power of the lathe cut lenses. Higher minus lens powers of both lens types produced greater peripheral swelling. Differences between central and peripheral swelling were smaller with the higher minus lenses, indicating little, if any, averaging of tear oxygen tension under the lens when the eyes are closed. The mechanism resulting in less peripheral corneal swelling is likely to be caused by an anatomical "clamping" at the corneal limbus.

Long-term effects of extended wear lenses: changes in refraction, corneal curvature, and visual acuity

Extended wear lenses (Scanlens 75) +4.25 to -10.00 D were worn monocularly by 19 patients for an average of 5.4 years. The other eye of each patient was either emmetropic or amblyopic and no lens was worn. Both eyes were tested after lens removal and again 2 days and 7 days later. No significant differences in refraction, keratometry, or visual acuity were found between the experimental and control eyes. The amount of changes in both groups was not clinically significant: refractive changes averaged less than 0.37 D, keratometric changes averaged an equivalent 0.25 D, astigmatism increases were less than 0.25 D, and visual acuity was fully correctible to previous best visual acuity with spectacles in all cases.

Critical oxygen levels to avoid corneal edema for daily and extended wear contact lenses

The relationship between corneal edema and hydrogel lens oxygen transmissibility was examined for both daily and extended contact lens wear by measuring the corneal swelling response induced by a variety of contact lenses over a 36-hr wearing period. The relationships derived enable average edema levels that occur with daily and extended wear in a population of normal young adults to be predicted to within +/- 1.0%. The critical lens oxygen transmissibilities required to avoid edema, for the group as a whole, for daily and extended contact lens wear were obtained from the derived curves. It was found under daily wear conditions that lenses having an oxygen transmissibility of at least 24.1 +/- 2.7 X 10(-9) (cm X ml O2)/(sec X ml X mmHg), an Equivalent Oxygen Percentage (EOP) of 9.9%, did not induce corneal edema. This level of oxygen transmissibility can be achieved (1) in standard, low water content, poly-HEMA lenses by using an average lens thickness of 33 microns or less, or (2) in a higher water content material, such as Duragel 75, by using an average thickness of 166 microns or less. The critical hydrogel lens oxygen transmissibility needed to limit overnight corneal edema to 4% (the level experienced without a contact lens in place) was found to be 87.0 +/- 3.3 X 10(-9) (cm X ml O2)/(sec X ml X mmHg)--an EOP of 17.9%. This ideal level of oxygen transmissibility cannot, at present, be provided with hydrogel materials.(ABSTRACT TRUNCATED AT 250 WORDS)

Complications of continuous-wear soft contact lenses in a nonreferral population

Serious corneal complications occurred in an otherwise successful experience with continuous-wear soft contact lenses (SCLs) for aphakic correction. One hundred twenty eyes were fit, and 92% attained visual acuity of 20/40 or better. Severe corneal complications were observed in 13 eyes, including bacterial ulcers (six), apical erosions (three), and severe superficial vascularization (four). Corneal ulcers occurred in nondiabetic as well as diabetic subjects. Continuous-wear SCLs are not innocuous; as for any other drug or device, continuous, long-term medical supervision is necessary to minimize potentially severe complications and visual loss.

Corneal ulcers associated with contact lens wear

We reviewed the experience with ulcerative keratitis associated with contact lens wear at Wills Eye Hospital, Philadelphia, from Jan 1, 1978 through July 1, 1983. Of the 322 cases of ulcerative keratitis, 56 cases (17%) were associated with the use of contact lenses. Twenty-nine (52%) of the 56 cases of contact lens-associated ulcers were culture positive. Pseudomonas was the most common isolate, occurring in 13 (23%) of the 56 cases. Staphylococcus species were the second most common, occurring in 11 (20%) of the 56 cases. In this series, contact lens-associated ulcers were seen frequently in those wearing soft lenses (48/56 cases or 86%) and in those wearing aphakic lenses (32/56 cases or 57%). Contact lens use is an increasingly important risk factor for the development of corneal ulcers. Prompt, appropriate, and intensive treatment is necessary to prevent visual loss.

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.

Haemophilus influenzae corneal ulcer in a therapeutic contact lens wearer

Haemophilus influenzae is an unusual corneal pathogen and an unusual cause of corneal ulcers in Western society. In previous reports corneal complications from H. influenzae have been secondary to a conjunctivitis. The first case of a primary H. influenzae corneal ulcer as a complication of therapeutic contact lens wear is presented. Since other uncommon bacteria have been reported as causes of contact lens related corneal ulcers, the bacteriology of contact lens related corneal ulcers is reviewed. Ophthalmologists need to be aware that H. influenzae infections in adults are becoming more frequent.

Gram-negative corneal ulcers in elderly aphakic eyes with extended-wear lenses

We report 13 cases of corneal ulcers caused by gram-negative bacteria. These cases occurred in aphakic eyes wearing hydrophilic contact lenses on an extended-wear basis. The risks for infection in the elderly aphakic eye with extended-wear hydrophilic lenses are increased by delay in removal of the lens. Caution in the use of these lenses is urged. The ability of either the patient or an attendant to remove the lens as soon as redness, diminished vision, or pain presents itself is essential in minimizing the risks for serious infection.

Use of hyper-thin, low water content hydrophilic lenses for extended wear

A study was conducted to determine the efficacy of low water content, hyper-thin lenses for extended wear by myopic patients. Patients selected had from 1 to 7 D of simple myopia or myopia with up to 2 D of astigmatism. Patients were either first time wearers or previously successful soft lens wearers. All patients were fitted with Bausch & Lomb O3 or O4 series lenses and were evaluated for 6 months. Either heat or a chemical disinfection system was used. The study shows that Bausch & Lomb O Series lenses may be used successfully for up to 1 week of continuous wear. Visual acuity, patient comfort, lens life, and physiological tolerance compared favorably with those achieved when the currently available high water content lenses were used for extended wear.

Kinetic visual disturbances with contact lenses

Kinetic (variable) visual disturbances in contact lens wearers may be generated optically or mechanically. These disturbances are categorized in two groups: 1) those affecting both phakic and aphakic contact lens wearers; and 2) those peculiar to aphakic patients. Within each category disturbances vary with the types of lens used. In this review, the optical and mechanical bases for the various problems are discussed, as are possible solutions. It is emphasized that the ophthalmologist prescribing contact lenses should be aware of the patient's work hazards and requirements, and weigh the advantages and disadvantages of contact lenses. For example, is the patient exposed to high temperatures, heavy or fast-moving equipment, altered barometric conditions, etc.? Is physical exertion required? Employers and fellow workers should be aware of the contact lens wearers in their work force.