Symposium: Contact Lens and Spectacle Lens Correction of Aphakia

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PROBLEMS ASSOCIATED WITH PROLONGED WEAR SOFr CONTACT LENSES

HERBERT E. KAUFMAN, MD NEW ORLEANS, LOUISIANA

Complications of prolonged wearing of soft contact lenses are corneal in­fection, peripheral vascularization, giant papillary conjunctivitis and allergy, ster­ile ulcers, corneal warping, lens infec­tion, protein and calcium deposits, lens fragility, and problems with disinfec­ting solutions. Further long-term studies are needed to compare the safety of prolonged wear soft contact lenses with the safety of intraocular lenses, on which long-term studies are currently being done.

IN choosing a rational treatment for a patient, it must be decided with the patient whether the risks are worth the benefits, and whether, in fact, there are safer ways to accomplish the desired goals than those now being used. One of the primary purposes of prolonged wear of contact lenses is the correction of aphakia, and the risks and benefits of contact lenses must be balanced against those of intraocular lenses and spectacles, with regard to the problems spectacle wearers have with visual function.

Prolonged wear contact lenses will be considered in two different

Submitted for publication Oct 25, 1978.

From the Louisiana State University Medical Cen­ter, New Orleans.

Presented in combination with the Contact Lens Association of Ophthalmologists at the 1978 An­nual Meeting of the American Academy of Oph­thalmology, Kansas City, Mo, Oct 22-26.

Reprint requests to LSU Eye Center, 136 S Roman St, New Orleans, LA 70112 (Dr Kaufman) .

ways: complications of lens wear in relation to the eye and problems of the lens itself. In addition, there may be other problems if use be­comes widespread and nonmedical practitioners begin to dispense pro­longed wear lenses.

EYE PROBLEMS WITH PROLONGED WEAR SOFI'

LENSES

Infection

Infection is the most devastat­ing complication of contact lens wear. When a serious corneal ulcer occurs, it often means functional loss of vision in the eye (Fig 1 through 4). This complication is irreversible and cannot be helped simply by removing the lens.

Fig 1.-Ring shaped corneal ulcer caused by Ser­ratia marcescens in patient with prolonged wear lens.

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412 HERBERT E. KAUFMAN OPHTH AAO

Fig 2.-Pseudomonas ulcer in patient with pro· longed wear soft contact lens.

tion is likely to be more common when lenses are no longer under study and when hygiene is no longer as rigidly stressed as it was in the study. The risk of infection does not appear to decrease with time. On the contrary, the risk may increase as the lenses are worn over a period of years. This may be a function not only of sus­ceptibility of the eye to the lens but also of the normal decrease in tear flow with age, since there is no question that dry eyes in­crease the risk of infection.

In order to assess the magni­tude of this complication, it will be necessary to have good in­cidence figures-not just for a short term after the lenses are dispensed, b\lt over a period of five or ten years, since the risk does not ap­pear to decrease with time. It is essential to analyze these risks in order to compare them with the risks of intraocular lenses.

Fig 3.-Pseudomonas corneal ulcer in patient with Conjunctivitis and external ocular prolonged wear lens. mfections also occur with these

Fig 4.-Staphylococcus aureus ulcer in patient with prolonged wear lens.

The true incidence of infection with prolonged wear soft lenses is not known. Several points have been established, however. Infec-

lenses. During a period of intensive study it is likely that these infec­tions will be managed promptly and will not lead to serious eye damage; however, the risk of serious complications occurring after con­trol has been relaxed may well be much greater.

Vascularization

Virtually all patients who wear prolonged wear soft lenses have some peripheral vascularization with time (Fig 5). A certain percentage of people have more extensive vas­cularization and deep vasculariza­tion (Fig 6). This may be due to a relative degree of anoxia, but vas­cularization also is seen with daily

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wear of hard lenses. Although ves­sel ingrowth is rare with hard lenses compared with prolonged wear soft lenses, it has not been proven that lenses with greater oxygen perme­ability will eliminate vasculariza­tion of the cornea. It is not clear how the susceptibility to vasculari­zation varies in the population, but since some people vascularize ex­tensively and rapidly, this may not be predictable. Vascularization is not necessarily at its peak during the initial time of study, and this problem needs to be followed for many years, as do the complica­tions of intraocular lenses.

Fig 5.-Moderately heavy peripheral vasculariza­tion of cornea from prolonged lens wear.

Fig 6.-Heavy, rapidly developing central vascu­larization in patient with prolonged wear soft con­tact lens.

Vascularization is less of a prob­lem than infection, since vessels usually regress when lens wear is discontinued. This means, however, that the prolonged wear lenses can­not be used, and a disability such as monocular aphakia cannot be corrected.

Giant Papillary Conjunctivitis and Allergy

This complication, originally de­scribed by Spring1 and further elu­cidated by the studies of Allan­smith and others, 2 can be accom­panied by symptoms of such intense itching and burning that lens wear must be discontinued. Although permanent damage to the lids and cornea from this is not usually seen, the discomfort results in discon­tinuing use of the lens.

Part of the difficulty with giant papillary conjunctivitis is that the incidence of this complication that terminates lens wear appears to increase as a function of time. Some experienced lens fitters feel that a high proportion of patients will aquire this problem if soft lenses are worn long enough, and again, a prolonged experience over many years is required to accurately de­termine the risk.

Sterile Corneal Ulcers

These ulcers, at one time thought to be pressure ulcers, occur in con­tact lens patients and are of uncer­tain cause. They may be small round focal ulcers in the center of the cornea or in the periphery. Sometimes ring ulcers, which are necrotizing and produce terrible corneal damage, are seen with soft contact lenses. The cause of these is not clear. If these ulcers are detected

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early, the lenses can be removed, and often damage to the cornea is minimized. Some, on the other hand, are so serious when first seen that permanent visual damage results. As lenses become more available and as patients are less closely followed and perhaps less closely screened in terms of patient selec­tion and reliability, complications resulting from sterile ulcers may increase.

Corneal Warping

Corneal warping with resultant induction of high astigmatism oc­curs in a small proportion of pro­longed wear users. It can result in permanently high astigmatism and refractive error.

Solutions

The available disinfecting solu­tions and boiling procedures bring with them their own set of prob­lems. A significant number of people who use solutions containing thi­merosal over a long period of time acquire severe medication intoler­ance. This is usually not signaled by the itching and contact dermati­tis seen with atropine, but rather with a burning discomfort that makes lenses intolerable. If it is recognized, discontinuation of fluid sterilization and a change of lenses may permit continued use of the lenses. Although this is less com­mon with prolonged wear soft lenses, which do not require frequent cleans­ing, it must nevertheless be con­sidered. Similarly, the mucous-bind­ing properties of solutions contain­ing chlorhexidine hydrochloride can make lenses hydrophobic and, by binding protein to the surface, per­haps increase the incidence of giant

papillary conjunctivitis and shorten the life and tolerability of the lens.

LENS PROBLEMS WITH PROLONGED WEAR

SOFI' LENSES

Lens Infection

The lenses themselves present one of the most serious problems with prolonged wear, lens infection. The lenses have a pore size that is generally too small for microbial organisms to enter. However, there are now a number of cases docu­mented in which organisms such as fungi attach to the surface of the lens (Fig 7 and 8) and digest the lens material while growing into it (Fig 9 and 10). Fungus infections can develop on the lens while the lens is in the patient's eye. This can sometimes happen without any damage to the eye at all. Neverthe­less, as prolonged wear lenses be­come more commonplace, the prob­lem may become magnified. Fun­gus infections may first appear as nondescript white deposits or as fluid. These deposits are much more

Fig 7.-Fungus deposit on prolonged wear lens.

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Fig 8.-Fungus deposits on surface of prolonged wear lens (x50).

likely to occur in prolonged wear lenses than in lenses that are cleaned daily.

Protein and Calcium Deposits

Protein 'deposits occur on contact lenses, and mucoproteins can ad­here to the surface, rendering the lenses unusable. Patients with cer­tain allergies appear more prone to this problem, but deposits generally occur in an unpredictable manner. Some patients can wear a lens only a few weeks before it becomes un-

usable owing to deposits. Sometimes these deposits can be removed by cleaning the lens, but those pa­tients with chronic deposit forma­tion cannot, in any practical way, wear lenses on a prolonged-wear basis.

Calcium as well as protein can accumulate on the lens surface. These are smaller, rounder, harder opacities, as a rule. The source of the calcium is not clear, but Uotila3

has demonstrated that there is cal­cium in tears, and the working hy­pothesis is that tear calcium precipi-

416 HERBERT E. KAUFMAN OPHTH AAO

Fig 9.-Fungus eating into soft contact lens.

tates on and in the lens substance. It is not known whether this is a function of the total amount of cal­cium produced or of the pH of the milieu; nevertheless, these deposits can render the lens unusable.

Certain kinds of lenses seem more prone to deposits than others. Al­though definitive data are not avail­able, silicone lenses appear to have a greater tendency to form deposits than do other hydrogel lenses.

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Fig 10.-Fungus in prolonged wear lens while lens is still being worn by patient.

Lens Fragility

The typical lens life remains un­certain and presumably varies from manufacturer to manufacturer. Pa­tients selected for initial studies are particularly suitable for lens wear and can handle lenses well. How­ever, the eventual necessity of re­moving lenses, even occasionally, may result in a shortened lens life, as has been documented in all soft contact lens studies thus far.

COMMENT

This discussion must be inter­preted with care. No attempt is being made to indicate that soft contact lenses are unduly hazardous or more hazardous than intraocular lenses or other types of refractive corrections.

Most modalities have both ad­vantages and disadvantages. The exact risks of prolonged soft con­tact lens wear have not been thor­oughly documented, and there seems to be an unjustified feeling that some modalities such as intraocular lenses are dangerous while soft contact lenses are safe. Soft contact lenses may be safer, but this has not yet been established. Only long­term follow-up, comparable to that required for intraocular lenses, will establish it. The potential impact of widespread dispensing and care by nonmedical practitioners must also be considered.

ACKNOWLEDGMENTS

Figures 8 and 9 were provided by Atsushi Kanai, MD, Department of Ophthalmology, Juntendo University, Tokyo.

REFERENCES

1. Spring TF: Reaction to hydrophilic lenses. Med J Aust 1:499-500, 1974.

2. Allansmith MR, Korb DR, Greiner JV, et al: Giant papillary conjunctivitis in con­tact lens wearers. Am J Ophthalmo/83:697-708 , 1977.

3. Uotila MH, sOble RE, Savory J : Mea­surement of tear calcium levels. Invest Oph­thalmol 11:258-259, 1972.