heat chemicals
hydrogen peroxide ultraviolet light exposure
The care system selected depends on the personal preference of the fitter and patient, the simplicity and convenience of use, cost, and possible allergies to solution components. Currently, multipurpose solutions are the most popular care systems in the United States.
The fitter should instruct the patient in the care of contact lenses. The following are important guidelines:
Clean and disinfect a lens whenever it is removed.
Follow the advice included with the lens-care system that is selected; do not “mix and match” solutions.
Do not use tap water for storing or cleaning lenses because it is not sterile. Do not use homemade salt solutions; they too are not sterile.
Do not use saliva to wet a lens.
Do not reuse contact lens–care solutions.
Do not allow the dropper tip to touch any surface; close the bottle tightly when not in use. Clean the contact lens case daily and replace it every 2–3 months; the case can be a source of contaminants.
Pay attention to labels on contact lens–care solutions because solution ingredients may change without warning to the consumer.
In addition to teaching appropriate contact lens and case care, the fitter should instruct the patient in proper lens insertion and removal techniques, determine a wear schedule (DW or EW), and decide if and when the lens should be disposed of or replaced. Insertion and handling vary significantly between soft and RGP lenses, and many manufacturers provide written information and videos to instruct professional staff and patients in appropriate insertion and removal techniques.
Chang DC, Grant GB, O’Donnell K, et al. Multistate outbreak of Fusarium keratitis associated with use of a contact lens solution. JAMA. 2006;296(8):953–963.
Contact Lens–Related Problems and Complications
Ocular problems related to contact lenses are uncommon but potentially serious. A wide spectrum of problems may arise secondary to contact lens wear, but they can be categorized as follows: infectious, hypoxic/metabolic, toxic, mechanical, inflammatory, and dry eye–related complications (Table 4-9).
Table 4-9
Infections
Corneal infections secondary to lens use are rare, but when they occur, they are potentially serious and vision threatening. To reduce risk, the clinician and patient should ensure that the contact lenses are fitted properly, contact lens–care systems are used regularly, and follow -up care is provided. In addition, patients should understand the signs and symptoms of serious eye problems and know when to seek medical assistance. With the increased use of disposable lenses, better patient education, more convenient care systems, and the availability of more-oxygen-permeable lens materials, serious eye infections from lens use have become uncommon. However, practitioners should be aware of unusual infections that can occur, such as Acanthamoeba keratitis. Diagnosis and treatment of corneal infections are covered in BCSC Section 8, External Disease and Cornea.
Hypoxic/Metabolic Problems
Metabolic epithelial damage
Contact lens overwear syndromes can be manifested in several forms. Central epithelial edema (Sattler veil) may present after many hours of wear, more commonly with hard contact lenses. This epithelial edema causes blurred vision that may persist for many hours or, in rare instances, progress to acute epithelial necrosis. Physiologic stress as a result of hypoxia, with lactate accumulation and impaired carbon dioxide efflux, is responsible for these complications.
Microcystic epitheliopathy, another condition caused by impaired metabolic activities in the corneal epithelium, shows fine epithelial cysts that are most easily observed with retroillumination. This condition is most common in patients who use EW soft contact lenses. The cysts may either be asymptomatic or cause recurrent brief episodes of pain and epiphora. It takes up to 6 weeks following discontinuation of contact lens wear for the cysts to resolve. In some cases, this epitheliopathy may have a dendritic appearance.
Corneal neovascularization
Corneal neovascularization is usually a sign of hypoxia. Refitting with lenses of higher-oxygen- permeability material or with a looser fit, requiring fewer hours of lens wear per day, or switching to disposable lenses can prevent further progression. If neovascularization is extensive, it can lead to corneal scarring and lipid deposition or intracorneal hemorrhage. Superficial pannus is rarely
associated with hard or RGP contact lens wear but is encountered more frequently in patients who use soft EW or nonfrequent disposable lenses. This type of neovascularization is probably caused by hypoxia and chronic trauma to the limbus, which lead to the release of angiogenic mediators. Other causes of pannus, such as staphylococcal and chlamydial keratoconjunctivitis, should be considered in the presence of the appropriate accompanying signs.
Deep stromal neovascularization has been associated with EW contact lenses, especially in aphakia. This condition is not usually symptomatic unless there is secondary lipid deposition. Deep neovascularization of the cornea is often irreversible and is best managed by discontinuing contact lens wear and resorting to spectacle correction or scleral-fixated intraocular lenses.
Toxicity
Punctate keratitis
A finding of punctate keratitis may be related to a poor lens fit, a toxic reaction to lens solutions, or dry eye.
Toxic conjunctivitis
Conjunctival injection, epithelial staining, punctate epithelial keratopathy, erosions, microcysts, and limbal stem cell deficiency are all potential signs of conjunctival or corneal toxicity arising from contact lens solutions. Any of the proteolytic enzymes or chemicals used for cleaning contact lenses, or the preservative-containing soaking solution, may be the culprit. Cleaning agents such as benzalkonium chloride, chlorhexidine, hydrogen peroxide, and other substances used for chemical sterilization, if not properly removed from contact lenses, can cause an immediate, severe epitheliopathy with accompanying pain.
Mechanical Problems
Corneal warpage
Change in corneal shape from contact lens use has been reported with both soft and RGP lenses, but it is more commonly associated with hard lenses. Most warpage resolves after the patient discontinues wearing the lens. To evaluate corneal shape on an ongoing basis, the clinician should include a standard evaluation by keratometry or corneal topography and manifest refraction as part of the contact lens follow -up examination, and the findings should be compared with previous measurements.
Spectacle blur
Corneal warpage and more temporary changes in corneal shape can change normal spectaclecorrected vision immediately after lens removal. If a patient reports symptoms of spectacle blur, the contact lens fit should be reevaluated and discontinuation of lens use for a period should be considered.
Ptosis
Ptosis is related not to corneal changes but possibly to dehiscence of the levator aponeurosis, which
is secondary to long-term use of RGP lenses.
Corneal abrasions
Corneal abrasions can result from foreign bodies under a lens, a poor insertion or removal technique, or a damaged contact lens. Therefore, contact lens use can increase the risk of infection. Most clinicians treat abrasions with antibiotic eyedrops and without patching.
3-o’clock and 9-o’clock staining
This specific superficial punctate keratitis staining pattern may be observed in RGP contact lens users and is probably related to poor wetting in the horizontal axis (Fig 4-16). Paralimbal staining is characteristic of low-riding lenses and is associated with an abortive reflex blink pattern, insufficient lens movement, inadequate tear meniscus, and a thick peripheral lens profile. Occasionally, refitting the lens and/or initiating regular use of wetting drops can decrease the finding.
Figure 4-16 Three-o’clock and 9-o’clock corneal staining. A, Inferior corneal desiccation of the tear film. B, Peripheral
corneal desiccation. (Part B courtesy of Perry Rosenthal, MD.)
Inflammation
Contact lens–induced keratoconjunctivitis
The pathogenesis of contact lens–induced keratoconjunctivitis (CLIK) is multifactorial (ie, can arise from allergies, dry eye, and infection). Patients with ocular prostheses and exposed monofilament sutures have shown reactions similar to those observed in patients with contact lens–induced conjunctivitis. A hypersensitivity reaction to the contact lens polymer itself (or to antigens or other foreign material adhering to it) has also been postulated but not formally demonstrated. Dry eye may be present in some cases. The histologic findings in contact lens–induced conjunctivitis are similar to those observed in vernal keratoconjunctivitis. An abnormal accumulation of mast cells, basophils, and eosinophils is observed in the epithelium and/or the substantia propria of the superior tarsus. Abnormally elevated concentrations of immunoglobulins—specifically IgE, IgG, and IgM—and
complement components have been found in the tears of affected patients. These findings suggest a combined mechanical and immune-mediated pathophysiology for this condition. Surface deposits on worn contact lenses are a known risk factor for the development and persistence of CLIK.
Allergic reactions
The preservative thimerosal can produce a type IV delayed hypersensitivity response, resulting in conjunctivitis, keratitis, and even coarse epithelial and subepithelial opacities. Thimerosal was implicated in contact lens–induced superior limbic keratoconjunctivitis. This condition has become less common, probably as a result of the replacement of thimerosal by other preservatives in contact lens solutions and the introduction of disposable contact lenses.
Giant papillary conjunctivitis
At the more severe end of the spectrum of contact lens–related inflammation is giant papillary conjunctivitis (GPC). GPC tends to develop earlier and more frequently in EW soft contact lens wearers in the setting of dry eye and meibomian gland dysfunction. It may also be induced by other irritants, such as loose sutures or prosthetics. Symptoms include contact lens intolerance, itching, excessive mucus discharge, and blurred vision from mucus coating of the contact lens; contact lens decentration; and conjunctival redness. In rare instances, bloody tears and ptosis secondary to inflammation of the superior tarsal conjunctiva may be observed.
The signs of GPC consist of hyperemia, thickening, and abnormally large papillae (diameter > 0.3 mm) on the superior tarsal conjunctiva due to disruption of the anchoring septae. The morphologic appearance of the superior tarsal papillae may be variable in GPC. In some cases, the giant papillae cover the entire central tarsus from the posterior eyelid margin to the upper border of the tarsal plate; involvement in other cases may be less extensive. Long-standing or involuted giant papillae on the superior tarsus may resemble follicles. The symptoms of GPC generally resolve when contact lens wear is discontinued. The tarsal conjunctival hyperemia and thickening may resolve in several weeks, but papillae or dome-shaped scars on the superior tarsus can persist for months to years.
If GPC persists, the clinician should consider changing the lens to a different polymer or to DW disposable lenses. Some patients prefer low-water-content lenses. Nevertheless, some patients continue to experience symptoms of GPC as a result of soft contact lens wear despite these measures. In these cases, consider fitting the patient with RGP contact lenses, which are associated with a lower incidence of GPC. In some patients, GPC recurs despite aggressive lens management and even RGP lens wear; these patients should be counseled about alternatives to contact lens wear.
Pharmacologic therapy can be helpful in managing patients with GPC. Many practitioners recommend discontinuing lens wear for 2–3 weeks while treatment is initiated. Mast-cell stabilizers, such as cromolyn sodium and dual-active agents with antihistamine and nonsteroidal activity, have been reported to improve early, mild GPC. However, once advanced cases of GPC have been brought under control, maintenance therapy with topical mast-cell inhibitors may prevent further exacerbations. Topical corticosteroids, though effective in GPC, generally are of limited use because of their potential side effects. Topical cyclosporine and tacrolimus may play a role in treatment.
Elhers WH, Donshik PC. Giant papillary conjunctivitis. Curr Opin Allergy Clin Immunol. 2008;8(5):445–449.
Sterile infiltrates
Typically, sterile infiltrates are observed in the peripheral cornea; often there is more than one spot,