Analysis of Contact Lens Complications

Contact lens complications and their frequency of occurrence have been the subject of many published reports; the most important ones are listed in Table 34. Estimates of frequency vary markedly across the international literature because of the lack of uniform standards of definition or assessment. Some authors report complication rates as high as 30%, depending on the variety of lens, lens care system, and mode of wear, while others report complication rates well under 1%. Any such figure should be viewed critically, as most reports fail to state either the composition of the patient population or the length of wearing time.

It is clear, however, that an accurate quantitative estimate of risk would be of great use to manufacturers, fitters, and, above all, patients. In our analysis, we divide contact lens complications into two groups, as shown in Tables 35 and 36: those that occur in the first year of wear, and those that typically occur only after 10 or more years of wear. These two types of complication show very different statistical behavior.

Distinguishing in this way between initial and long-term contact lens complications provides useful information for the development of new lens materials and lens care products and the improvement of those already in use. Once contact lenses have been worn successfully for 1 year, the likelihood of a complication becomes much lower, as the patient’s handling of the lenses improves with experience and allergic reactions have usually been eliminated by the end of the first year by a change of lens material or lens care products, if necessary. On the other hand, any intractable problems of handling or allergy that may arise usually result in a reversion to spectacles or other visual aids within the first year. Interestingly, patients who wear contact lenses for medical reasons and have no viable therapeutic alternative to them seem to tolerate their lenses much better than those who wear them for refractive correction, who can always fall back on spectacles if desired.

Many problems and complications of contact lens wear can be prevented by the identification of possible hindrances and risk factors before the lenses are fitted (see p. 160). All too frequently, contraindications to contact lens wear are overlooked or disregarded at the fitting stage, and later, when the patient has begun to wear the lenses. The resulting difficulties may later cause not only frustration for the fitter and the patient, but also severe, irreversible eye damage. Problems of this type are the most common cause of malpractice suits against contact lens fitters.

The potential risk factors that must be taken into account are numerous and by no means limited to ocular pathology; systemic problems such as an allergic predisposition, immune deficiency, or metabolic disease often complicate contact lens wear. Medication use, too, including the use of oral contraceptives, may complicate contact lens wear by an effect on the composition of the tear fluid. Low patient intelligence or generally negligent personal grooming are predictors of faulty lens handling and hygiene. Even the suspicion of poor patient compliance with the recommendations for proper lens care is a sufficient contraindication for contact lens fitting. Problems of this nature are, of course, not restricted to the wearing of contact lenses, but are found in all fields of medicine.

The most common causes of contact lens complications, and their frequencies, are listed in Table 37. As can be seen from the table, approximately three-quarters of all complications are due to poor patient compliance. This underscores the fitter’s vital responsibility to provide the patient with clear, thorough, and, when necessary, repeated instruction and counseling on proper lens care. Proper patient education cannot be assured if contact lenses are acquired by mail order or over the Internet.