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COMPLICATIONS ASSOCIATED WITH EXTENDED WEAR OF SOFT CONTACT LENSES PERRY S. BINDER, MD SAN DIEGO, CALIFORNIA
The major complications with extended wear lenses are due to hypoxia and lens deposits. Certain patients tend to deposit proteins and lipids on the lens surface with daily wear and at a greater frequency during prolonged wear. A build-up of these deposits can be associated with decreased vision, conjunctival irritation, and giant papillary conjunctivitis. Frequent lens cleaning and the frequent use of concomitant topical artificial tears will hopefully reduce the incidence of lens deposits and their complications. Superficial circumlimbal vascularization occurs in a large percentage of patients who have worn lenses for weeks at a time. Corneal edema, ocular irritation, and decreased vision are also the hallmarks of a decreased oxygen supply to the cornea. A thin, loose-fitting lens will increase the percentage of patients who are able to successfully use extended wear lenses by increasing the amount of oxygen available to the cornea. Cessation or reduction in duration of lens wear will decrease the' frequency and severity of this complication. Conjunctival and corneal infections are real risks; lens loss, breakage, deformation, or discoloration also occur during extended wear.
Submitted for publication Oct 24, 1978. From the Ophthalmology Section, University of California, San Diego. 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 3350 La Jolla Village Dr (112G), San Diego, CA 92161.
INTRODUCTION FOR almost a decade, ophthalmologists have been treating patients with continuously worn therapeutic soft contact lenses to protect the front surface of the eye. Experience revealed many potential complications associated with this mode of therapy.1-3 Soon investigators began to fit aphakic patients with a continuously worn soft contact lens in hopes of improving the reported poor results in aphakic hard and soft contact lens wearers,4,5 and the results of extended wear in this group of patients have been encouraging. 6-15 The use of a continuously worn soft contact lens for the correction of monocular aphakia appears warranted and is a suitable alternative to intraocular lens implantation, as the risk to the eye is less-should a complication arise, the lenses can be removed without difficulty without subjecting the eye to further damage. More recently, investigations have turned to the possibility of a continuously worn soft contact lens for the treatment of refractive errors other than aphakia. 7,16.17
Although complications with continuously worn therapeutic soft contact lenses have been well documented, it was not known if these complications were associated with the disease being treated or with the wearing of the contact lens itself. It is now established that
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patients who wear soft contact lenses for periods greater than 24 hours at a time are subject to increased risks and potential complications compared with patients wearing the same lens on a daily basis. 5 . 13 The problems that occur are lens deposits, lens loss or displacement, lens intolerance, corneal neovascularization, anterior segment inflammation and infection, and a host of others (Table 1). TABLE 1
COMPLICATIONS ASSOCIATED WITH THE EXTENDED WEAR OF SOFT LENSES
I. Lens problems A. Deposits B. Loss C. Displacement D. Breakage, " degeneration ," rigidity changes
II. Lens intolerance (anoxia, "overwear") III . Conjunctival changes A. "Conjunctivitis," injection B. Folliculosis, follicular conjunctivitis C. Giant papillary conjunctivitis IV. Corneal changes (Table 3) A. Tear film defects B. Superficial corneal changes C. Deep corneal changes D. Neovascularization V. Refractive error changes A. Myopia B. Astigmatism
LENS DEPOSITS
One of the major problems facing successful extended wear is the deposits that occur on the contact lenses 18 (Fig 1). These deposits have been histochemically demonstrated to be lipid,1 8 calcium,19,2o protein,21 and lysozyme 22 (Table 2).
Fig I.-Protein deposits on cosmetic soft contact lens that had been worn continuously for five weeks. Paracentral deposits did not interfere with visual acuity.
The incidence of these deposits in therapeutic soft contact lens wear has been reported as 6.8%2 to 20%17 (Table 2). In early clinical trials with extended wear lenses, deposits were noticed in as many as 82% of the cases, appearing as early as four weeks after start of wear.16 The deposits do not necessarily interfere with vision in every case, but when they are present, patients complain of more ocular irritation and their eyes are more injected. The deposits can be easily removed by enzymatic cleaning with papaine 21 (Fig 2). There are numerous reports of patients discovering an "allergy" to their contact lenses, and it was proposed that tear protein adsorption on these contact lenses might be a possible cause. 22,23 Proteins easily adsorb on hydrogel surfaces, but no one has been able to propose a cause for the adsorption. Analysis of contact lens wearers' tear film and serum has failed to produce a correlation with lens deposits. 20 Deposits may develop more rapidly and more profusely in one patient than another l2 . 17 but a patient prone to deposits cannot be recognized clin-
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TABLE 2 INCIDENCE AND TYPE OF LENS DEPOSITS IN EXTENDED WEAR
INCIDENCE 7% 18% 20% 33% 37% 50% 82%
TYPE Protein/Lipid Calcium Protein/Lipid Protein/Lipid Protein/Lipid Protein/Lipid Protein/Lipid
Fig 2.-Example of efficiency of enzymatic clean· ing. This cosmetic lens became diffusely cloudy with superficial deposits after two months of con· tinuous wear. Left half was treated with standard chemical disinfection and right half was treated with enzymatic cleaning.
ically at the time of fitting. Since it has been suggested that patients with decreased tear production are more subject to deposits, low viscosity or hypoosmotic tears may be used to change the characteristics of the tear film in hopes of reducing the deposits. Strict lid margin hygiene with baby shampoo and frequent lens cleaning are recommended for the patient who continues to form deposits. Other changes that occur during continuous wear include fungal growth on a lens,24 lens loss or displacement, spontaneous breakage, and degenerative changes such as
AUTHOR Dohlman et aF Gasset et alI 0 Freeman 7 Kersle y 9 Stein and Slatt" Dahl and Brocks l2 Binder and Worthen lfi
cracks and chips in the lens surface and edge. 2o .25 In time, lenses may discolor to a diffuse gray without any apparent cause, or they may become discolored owing to associated topical medications such as fluorescein or epinephrine. 26 .27 Clinically, the extended wear of a soft contact lens tends to produce a slightly more rigid (steeper-fitting) contact lens. In one report, a severe change in the rigidity of a lens was associated with spontaneous scleral perforation. 28 The frequency of lens loss during continuous wear is not well determined, but in one study, the lens was replaced or blinked out of an eye an average of 2.1 times per patient over a 12-week period,!7 and in another study, the lens was replaced 1.7 times per patient over six months of wear. 9 The incidence of lens loss in daily wear has been reported to vary between 6% and 14% in adults 1o .29 and as high as 34% in children. 30 The incidence of lens ripping or chipping is difficult to determine, but it has been reported to occur in as high as 20% during daily wear 29 and in 28% during extended wear.l0 When dispensing an extended wear contact lens, it is prudent to
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give the patient a sealed bottle of fresh solution to place in the refrigerator so that a lens that falls out of the eye may be placed in the bottle immediately. Patients should be requested to return for fitting as soon as convenient. It is not recommended that a patient refit an extended wear soft contact lens themselves. LENS INTOLERANCE
Soft contact lens intolerance is a syndrome tha t occurs primarily during extended wear but has occurred with daily wear. Patients who are apparently successfully fitted and have stable vision when leaving the office return hours to days later with symptoms of pain, photophobia, ocular injection, swollen eyelids, increased corneal thickness with or without folds in Descemet's membrane, corneal abrasions, ciliary flush, anterior chamber flare, decreased vision, and frequently, an apparently tight-fitting contact lens with perilimbal conjunctival edema (Fig 3). This syndrome of lens intolerance or "overwear" is apparently caused by a decrease in the oxygen supply to the cornea (anoxia).31 The earliest sign of this complication is an increase in central corneal thickness that can only be detected by the use of a pachometer. Liebowitz and co-workers l6 were among the first to evaluate the change in corneal thickness during hydrophilic lens wear. In ten normal volunteers, the corneal thicknesses increased up to 30% during the first day of ten days' continuous wear,16 but these changes did not interfere with vision and the corneas tended to stabilize at the new thickness without producing a
Fig 3.-Left eye of m yopic patient who had s cu· cessfully worn a contact l en s for one month . With· in two da ys sh e h ad symptoms of a noxia and a n increa sed corneal thickness, perilimbal injection , mild flare in an terior ch amber, and loss of oneline of vision.
change in visual acuity. Ruben and co-workers 32 found no increase in corneal thickness in five patients wearing lenses for 24 hours. Mobilia and co-workers 33 fitted 30 volunteer subjects with normal corneas with five different hydration levels of contact lenses and measured their corneal thicknesses during 24 hours of continuous wear. Twenty-one of the 30 subjects were able to wear the lens for 24 hours, but seven had to remove the lenses after one to ten hours because of discomfort. Sixteen of the 21 successful patients had to wear two or more lenses in order to complete the full 24 hours. Nine patients had a decrease in vision between one and five lines, associated with increased corneal thickness. The corneal thicknesses increased as much as 0.16 mm over the prefitting thickness. These changes tended to occur with thicker lenses. 33 In a different study,I7 eight of 17 patients who wore a thin hydrophilic lens for 12 weeks had increases in corneal thickness greater than 0.04 to 0.10 mm over base line, but in only four of these patients was there a change in vision of one to three lines. Gasset and co-workers Il described a slight
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but insignificant increase in central corneal thickness in ten aphakic eyes with permanent wear lenses worn from one week to five years. Most hydrogel lenses are highly permeable to oxygen in vitro, but it appears that most of the presently available hydrogel lenses do not allow significant transmission of oxygen through the center of the lenses in vivo. Consequently, the source of oxygen to the cornea must be from the tear film. It has been calculated that an ideal soft contact lens would contain 85% water and would measure less than 0.1 mm in thickness to allow adequate oxygen diffusion to meet the metabolic needs of the cornea through the closed eyelids. 34 In order to get around this problem, extended wear lenses have been fitted somewhat more loosely (more flat) to allow greater tear exchange and yet provide the most stable visual acuity. The use of frequent artificial tears to continually float the lens surface off the cornea and an increased frequency of blinking increase the amount of oxygen available to the corneal surface. When patients are examined during extended wear, the visual acuity, cen tral corneal thickness, and degree of lens movement should be recorded. If an increase in corneal thickness is greater than 0.05 mm, it is a significant increase35 and, in most instances, the lens should be removed. A flatter lens or a more highly hydrophilic lens may be fitted at a later date to increase the oxygen supply to the cornea. This anoxic complication usually develops within the first 48 hours of extended wear13 ; consequently, all patients should be reexamined within that time. Patients who are unable to
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tolerate an extended wear lens may do well with daily wear. CONJUNCTIVAL COMPLICATIONS
Conjunctival changes have been noted with daily wear soft contact lenses; these include "conjunctivitis,"7 follicular conjunctivitis, conjunctival injection, perilimbal conjunctival edema, and giant papillary conjunctivitis. 36 With therapeutic continuous wear, more frequent conjunctival changes have been noted, including a severe mucus-producing conjunctivitis 37 and other keratoconjunctivitises.2.38-4o With the advent of extended wear, these same changes have been noted-specifically, conjunctival hyperemia 38 and conjunctivitis. l1 In normal patients, a continuously worn hydrophilic lens apparently does not affect the normal conjunctival flora. 41 This is also true with therapeutic lenses. 4o The source of the infection is probably the patient, as the incidence of conjunctival infection between groups of patients who boiled their lenses daily and those who boiled their lenses twice a week was the same. Many ophthalmologists believe that patients with dry eyes and eyelid infections, patients with poor personal hygiene, and retarded patients have a greater risk of infection. Conjunctival changes appear to be related to changes within the lens surface itself and concomitant infections of the conjunctiva and cornea. Tight-fitting contact lenses, especially in patients with anoxic lens intolerance, produce conjunctival hyperemia and perilimbal edema, and in time, the superficial epithelium will stain with fluorescein.
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CORNEAL COMPLICATIONS
The corneal changes noted with the continuous wear of soft contact lenses include those found with daily and therapeutic wear (Table 3), but the incidence of these complications is presently undetermined. The superficial changes in the cornea have been described by Ruben. 38 These superficial changes are not serious and resolve with cessation of wear. Contact lens fitters have noted subepithelial opacities and corneal stromal opacities associated with a red eye, and although these deposits are culture negative, they have been treated as infections. In most instances, these opacities do not result in visual morbidity. TABLE
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continually.2,13,40, 44 Infectious keratitis in continuous wear patients has recently been reported in seven patients (Fig 4).10,45 The causes of the infectious ulcers in these seven cases were Pseudomonas aeruginosa, Serratia liquefaciens, Staphylococcus aureus, and Escherichia coli.
3
CORNEAL COMPLICATIONS WITH EXTENDED WEAR
I. Precorneal tear film defects
II . Superficial corneal changes A. Punctate epithelial keratitis B. Decreased corneal sensation C. Corneal microcysts D. Filamentary keratitis E. Epithelial hypertrophy F. Subepithelial opacification III . Deep corneal changes A. Corneal edema B. Noninfectious corneal opacities C. Bacterial ulcers D. Fungal ulcers IV. Corneal neovascularization
Infectious keratitis with cosmetic soft lens wear has been reported by F . S. Brightbill (oral communication, March, 1977), Krachmer and Purcell,42 and others43; it has also been described in patients wearing therapeutic contact lenses
Fig 4.-Right eye of 17-year-old myopic patient who had successfully worn a lens for two months. A red, painful eye developed, and a white "spot" was n oted o n cornea (arrows). Gram stain demonstra ted Gram positive cocci that failed t o grow on culture. Patient was treated with freq uent topical antibiotics, and lesion cleared without affecting visua l acuity.
Corneal neovascularization occurs rarely with the daily wear of soft contact lenses but has been reported with therapeutic soft lens wear2,46,47 and in aphakic extended wear 5,lO. 11,13 (Fig 5). The corneal vascularization tends to remain stable or even regress if the lenses are removed, but it will not respond to the addition of topical corticosteroids that may predispose the patient to infection. It is not known at this time if the replacement of a moderately hydrophilic lens with a more hydrophilic lens will decrease the degree and incidence of neovascularization. 5 If neovascularization occurs, it is best to discontinue extended wear for at least one week and reevaluate the extent of the
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Fig 5.-Superficial corneal vascularization anterior to Bowman's membra ne in aphakic patient who had successfully worn a soft contact l ens for three months. The vessels did not recede following cessation of lens wear.
vascularization. If it regresses, extended wear may be restarted. If it persists, a switch to daily wear or a schedule of on 24, off 24 hours is recommended. REFRACTIVE ERROR CHANGES
Refractive error changes with hard contact lenses are well documented. Less commonly, refractive error changes also occur with cosmetic soft contact lenses. 48 These changes may be caused by an increase in corneal thickness producing a decrease in visual acuity,16 or they may1 3,17 or may not5 be associated with a change in the corneal curvature. These changes revert to normal when lens wear IS stopped. CONCLUSION
The major complications occurring with extended wear appear to be deposits on the lenses and lens intolerance (overwear syndrome). Other lens problems, such as chipped, broken, degenerated, or lost lenses, also produce many of the problems
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associated with extended wear but do not permanently affect vision. The problems secondary to lens deposits such as "conjunctivitis" and giant papillary conjunctivitis are a nuisance but do not permanently affect vision. The reversible superficial corneal changes that occur are easily corrected by cessation of wear and the addition of lubricants. The major complications of deposits and lens changes make it necessary to replace lenses an average of almost twice within six months. The major problem with extended wear that affects visual acuity is infectious keratitis, and the incidence of this complication can be decreased by carefully choosing patients who understand the importance of extended wear, patients who are mentally capable of seeking help, patients with a good personal hygiene, and patients without signs of anterior segment infection or eyelid disease. The addition of concomitant prophylactic antibiotics is not warranted, as the use of artificial tears appears to do just as well. In order to minimize complications, patients should be examined within 48 hours of their initial fit, at one week, at three weeks after fit, and then monthly thereafter, with visual acuity, corneal thickness, and the condition of the conjunctiva and the lens determined at each visit. A recent review summarizes many of the problems facing the future of successful continuous wear.49
REFERENCES 1. Kaufman HE, Uotila MH, Gasset AR, et al: The medical uses of soft contact lenses. Trans Am Acad Ophthalmol Otolaryngol 75:361-373, 1971.
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2. Dohlman CH, Boruchoff SA, Mobilia EF: Complications in use of soft contact lenses in corneal disease. Arch Ophthalmol 90:367-371, 1973. 3. Gasset AR, Lobo L: Simplified soft contact lens treatment in corneal diseases. Ann Ophthalmol 9:843-848, 1977. 4. Kratz RP: Surgical techniques of in· traocular lens implantation, in Worthen DM, Binder PS, (eds): The Intraocular Lens in Perspective. New York, Stratton Inter· continental Medical Book Corp, 1976, pp 39-45.
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17. Binder PS, Worthen DM: Clinical evaluation of continuous-wear hydrophilic lenses. Am J Ophthalmol 83:549-553, 1977. 18. Doughman DJ, Mobilia E, Drago D, et al: The nature of "spots" on soft lenses. Ann Ophthalmol 7:345-353, 1975. 19. Klintworth GK, Reed JW, Hawkins HK, et al: Calcification of soft contact lenses in patient with dry eye and elevated calcium concentration in tears. Invest Ophthalmol Vis Sci 16:158-161, 1977.
5. Stein HA, Slatt BJ: Extended wear of soft contact lenses in perspective. Int Contact Lens Clin 14:35-40, 1977.
20. Ruben M, Tripathi RC, Winder AF: Calcium deposition as a cause of spoiliation of hydrophilic soft contact lenses. Br J Ophthalmol 59:141-148, 1975.
6. Lumbroso P, Fourny A, Maussan M: Lentilles souples ii forte hydrophilie. Arch Ophtalmol 35:341-346, 1975.
21. Eriksen S: Cleaning hydrophilic contact lenses: An overview. Ann Ophthalmol 7:1223-1232, 1975.
7. Benson C: Continuous use of contact lenses. Aust J Ophthalmol 4:99-103, 1976.
22. Karageozian HL: Use of the amino acid analyzer to illustrate the efficacy of an enzyme preparation for cleaning hydrophilic lenses. Contacto 20:5, 1976.
8. Freeman MI: Continuous wear of contact lens after cataract surgery. Bull Mason Clin 30:145-151, 1976-1977. 9. Pierse D, Kersley HJ: Fitting "continuous wear" soft contact lenses at the time of cataract extraction. Trans Ophthalmol Soc UK 96:11-12, 1976. 10. Kersley HJ, Kerr C, Pierse D: Hydrophilic lenses for "continuous" wear in aphakia: Definitive fitting and the problems that occur. Br J Ophthalmol 61:38-42, 1977. 11. Gasset AR, Lobo L, Houde W: Permanent wear of soft contact lenses in aphakic eyes. Am J Ophthalmol 83:115-120, 1977. 12. Dahl AA, Brocks ER: The use of con· tinuous-wear silicone contact lenses in the optical correction of aphakia. Am J Ophthalmol 85:454-461, 1978.
23. Refojo MF, Holly FJ: Tear protein adsorption on hydrogels: A possible cause of contact lens allergy. Contact and Intraocular Lens Med J 3:23-35, 1977. 24. Palmer E, Ferry AP, Safir A: Furlgal invasion of a soft (Griffin Bionite) contact lens. Arch Ophthalmol 93:278-280, 1974. 25. Tripathi RC, Ruben M: Degenerative changes in a soft hydrophilic contact lens. Ophthalmic Res 4:185-192, 1973. 26. Sugar J: Adrenochrome pigmentation of hydrophilic lenses. Arch Ophthalmol 91: 11-12, 1974. 27. Miller D, Brooks SM, Mobilia E: Adrenochrome staining of soft contact lenses. Ann Ophthalmol 8:65-67, 1976.
13. Binder PS: Extended wear of three soft contact lenses. Contact Intraocular Lens Med J 5:45-53, 1979.
28. Brown SI, Rosen J: Scleral perforation: A complication of the, soft contact lens. Arch Ophthalmol 93:1047-1048, 1975.
14. Aquavella JV, Jackson GK, Guy LF: Therapeutic effects of bionite lenses:. Mechanisms of action. Ann Ophthalmol 3:13411350, 1971.
29. Koetting RA: Frequency of hydrogel lens replacement. Contacto 19:11-14, 1975.
15. Pierse D, Kersley HJ: Hydrophilic lenses for "continuous" wear in aphakia: Fitting at operation. Br J OphthalmoI61:3437, 1977. 16. Liebowitz HM, Laing RA, Sandstrom M: Continuous wear of hydrophilic contact lenses. Arch Ophthalmol 89:306-310, 1973.
30. Yamamoto M, Tabuchi A: Experience in the use of contact lenses in children. Contact Intraocular Lens Med J 2:8-14, 1976. 31. PoIse KA, Mandel RB: Etiology of corneal striae accompanying hydrogel lens wear. Invest Ophthalmol 15:553-556, 1976. 32. Ruben M, Brown N, Lobascher D, et al: Clinical manifestations secondary to
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soft contact lens wear. Br J Ophthalmol 60:529-531, 1976.
ical antibiotics. Arch Ophthalmol 94:21092111, 1976.
33. Mobilia EF, Dohlman CH, Holly FJ: A comparison of various soft contact lenses for therapeutic purposes. Contact Intraocular Lens Med J 3:9-15, 1977.
42. Krachmer JH, Purcell JJ Jr: Bacterial corneal ulcers in cosmetic soft contact lens wearers. Arch Ophthalmol 96:57-61, 1978.
34. Holly FJ, Refojo MF: Oxygen permeability of hydrogel contact lenses. J Am Optom Assoc 43:1173-1180, 1972. 35. Binder PS, Kohler JA, Rorabaugh DA: Evaluation of an electronic corneal pachometer. Invest Ophthalmol Vis Sci 16:855858, 1977. 36. Allansmith MR, Korb DR, Greiner JV, et al: Giant papillary conjunctivitis in contact lens wearers. Am J Ophthalmol 83: 697-708, 1977. 37. Johnson DG: Keratoconjunctivitis associated with wearing hydrophilic contact lenses. Can J Ophthalmol 8:92-96, 1973. 38. Ruben M: Acute eye disease secondary to contact lens wear. Lancet 1:138-140, 1976. 39. Lemp MA: An unusual keratoconjunctivitis occurring after long-time wearing of AO Softcon hydrophilic contact lens. Ann Ophthalmol 7:97-106, 1975. 40. Brown SI, Bloomfield S, Pearce DB, et al: Infections with the therapeutic soft lens. Arch Ophthalmol 91:275-277, 1974. 41. Binder PS, Worthen DM: A continuous-wear hydrophilic lens. Prophylactic top-
43. Nakajima A, Kanai A, Yamaguchi T: Eitrige hornhautgeschwure und kontaktlinsen. Klin Monatsbl Augenheilkd 170:366373, 1970. 44. Olson RJ: Bilateral hemophilus corneal ulcers in a patient with bandage contact lenses. Contact Intraocular Lens Med J 4:95-99, 1978. 45. Cooper RL, Constable IJ: Infective keratitis in soft contact lens wearers. Br J Ophthalmol 61:25()'254, 1977. 46. Schecter DR, Emery JM, Soper JW: Corneal vascularization in therapeutic softlens wear. Contact Intraocular Lens Med J 1:141-145, 1975. 47. Weinberg RJ: Deep corneal vascularization caused by aphakic soft contact lens wear. Am J Ophthalmol 83:121-122, 1977. 48. Baldone J A: Corneal curvature changes secondary to the wearing of hydrophilic gel contact lenses. Contact Intraocular Lens Med J 1:175-176, 1975. 49. Nesburn AB: Prolonged-wear contact lenses in aphakia. Ophthalmology 85:73-79, 1978.
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COMPLICATIONS ASSOCIATED WITH EXTENDED WEAR OF SOFT CONTACT LENSES PERRY S. BINDER, MD SAN DIEGO, CALIFORNIA
The major complications with extended wear lenses are due to hypoxia and lens deposits. Certain patients tend to deposit proteins and lipids on the lens surface with daily wear and at a greater frequency during prolonged wear. A build-up of these deposits can be associated with decreased vision, conjunctival irritation, and giant papillary conjunctivitis. Frequent lens cleaning and the frequent use of concomitant topical artificial tears will hopefully reduce the incidence of lens deposits and their complications. Superficial circumlimbal vascularization occurs in a large percentage of patients who have worn lenses for weeks at a time. Corneal edema, ocular irritation, and decreased vision are also the hallmarks of a decreased oxygen supply to the cornea. A thin, loose-fitting lens will increase the percentage of patients who are able to successfully use extended wear lenses by increasing the amount of oxygen available to the cornea. Cessation or reduction in duration of lens wear will decrease the' frequency and severity of this complication. Conjunctival and corneal infections are real risks; lens loss, breakage, deformation, or discoloration also occur during extended wear.
Submitted for publication Oct 24, 1978. From the Ophthalmology Section, University of California, San Diego. 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 3350 La Jolla Village Dr (112G), San Diego, CA 92161.
INTRODUCTION FOR almost a decade, ophthalmologists have been treating patients with continuously worn therapeutic soft contact lenses to protect the front surface of the eye. Experience revealed many potential complications associated with this mode of therapy.1-3 Soon investigators began to fit aphakic patients with a continuously worn soft contact lens in hopes of improving the reported poor results in aphakic hard and soft contact lens wearers,4,5 and the results of extended wear in this group of patients have been encouraging. 6-15 The use of a continuously worn soft contact lens for the correction of monocular aphakia appears warranted and is a suitable alternative to intraocular lens implantation, as the risk to the eye is less-should a complication arise, the lenses can be removed without difficulty without subjecting the eye to further damage. More recently, investigations have turned to the possibility of a continuously worn soft contact lens for the treatment of refractive errors other than aphakia. 7,16.17
Although complications with continuously worn therapeutic soft contact lenses have been well documented, it was not known if these complications were associated with the disease being treated or with the wearing of the contact lens itself. It is now established that
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patients who wear soft contact lenses for periods greater than 24 hours at a time are subject to increased risks and potential complications compared with patients wearing the same lens on a daily basis. 5 . 13 The problems that occur are lens deposits, lens loss or displacement, lens intolerance, corneal neovascularization, anterior segment inflammation and infection, and a host of others (Table 1). TABLE 1
COMPLICATIONS ASSOCIATED WITH THE EXTENDED WEAR OF SOFT LENSES
I. Lens problems A. Deposits B. Loss C. Displacement D. Breakage, " degeneration ," rigidity changes
II. Lens intolerance (anoxia, "overwear") III . Conjunctival changes A. "Conjunctivitis," injection B. Folliculosis, follicular conjunctivitis C. Giant papillary conjunctivitis IV. Corneal changes (Table 3) A. Tear film defects B. Superficial corneal changes C. Deep corneal changes D. Neovascularization V. Refractive error changes A. Myopia B. Astigmatism
LENS DEPOSITS
One of the major problems facing successful extended wear is the deposits that occur on the contact lenses 18 (Fig 1). These deposits have been histochemically demonstrated to be lipid,1 8 calcium,19,2o protein,21 and lysozyme 22 (Table 2).
Fig I.-Protein deposits on cosmetic soft contact lens that had been worn continuously for five weeks. Paracentral deposits did not interfere with visual acuity.
The incidence of these deposits in therapeutic soft contact lens wear has been reported as 6.8%2 to 20%17 (Table 2). In early clinical trials with extended wear lenses, deposits were noticed in as many as 82% of the cases, appearing as early as four weeks after start of wear.16 The deposits do not necessarily interfere with vision in every case, but when they are present, patients complain of more ocular irritation and their eyes are more injected. The deposits can be easily removed by enzymatic cleaning with papaine 21 (Fig 2). There are numerous reports of patients discovering an "allergy" to their contact lenses, and it was proposed that tear protein adsorption on these contact lenses might be a possible cause. 22,23 Proteins easily adsorb on hydrogel surfaces, but no one has been able to propose a cause for the adsorption. Analysis of contact lens wearers' tear film and serum has failed to produce a correlation with lens deposits. 20 Deposits may develop more rapidly and more profusely in one patient than another l2 . 17 but a patient prone to deposits cannot be recognized clin-
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TABLE 2 INCIDENCE AND TYPE OF LENS DEPOSITS IN EXTENDED WEAR
INCIDENCE 7% 18% 20% 33% 37% 50% 82%
TYPE Protein/Lipid Calcium Protein/Lipid Protein/Lipid Protein/Lipid Protein/Lipid Protein/Lipid
Fig 2.-Example of efficiency of enzymatic clean· ing. This cosmetic lens became diffusely cloudy with superficial deposits after two months of con· tinuous wear. Left half was treated with standard chemical disinfection and right half was treated with enzymatic cleaning.
ically at the time of fitting. Since it has been suggested that patients with decreased tear production are more subject to deposits, low viscosity or hypoosmotic tears may be used to change the characteristics of the tear film in hopes of reducing the deposits. Strict lid margin hygiene with baby shampoo and frequent lens cleaning are recommended for the patient who continues to form deposits. Other changes that occur during continuous wear include fungal growth on a lens,24 lens loss or displacement, spontaneous breakage, and degenerative changes such as
AUTHOR Dohlman et aF Gasset et alI 0 Freeman 7 Kersle y 9 Stein and Slatt" Dahl and Brocks l2 Binder and Worthen lfi
cracks and chips in the lens surface and edge. 2o .25 In time, lenses may discolor to a diffuse gray without any apparent cause, or they may become discolored owing to associated topical medications such as fluorescein or epinephrine. 26 .27 Clinically, the extended wear of a soft contact lens tends to produce a slightly more rigid (steeper-fitting) contact lens. In one report, a severe change in the rigidity of a lens was associated with spontaneous scleral perforation. 28 The frequency of lens loss during continuous wear is not well determined, but in one study, the lens was replaced or blinked out of an eye an average of 2.1 times per patient over a 12-week period,!7 and in another study, the lens was replaced 1.7 times per patient over six months of wear. 9 The incidence of lens loss in daily wear has been reported to vary between 6% and 14% in adults 1o .29 and as high as 34% in children. 30 The incidence of lens ripping or chipping is difficult to determine, but it has been reported to occur in as high as 20% during daily wear 29 and in 28% during extended wear.l0 When dispensing an extended wear contact lens, it is prudent to
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give the patient a sealed bottle of fresh solution to place in the refrigerator so that a lens that falls out of the eye may be placed in the bottle immediately. Patients should be requested to return for fitting as soon as convenient. It is not recommended that a patient refit an extended wear soft contact lens themselves. LENS INTOLERANCE
Soft contact lens intolerance is a syndrome tha t occurs primarily during extended wear but has occurred with daily wear. Patients who are apparently successfully fitted and have stable vision when leaving the office return hours to days later with symptoms of pain, photophobia, ocular injection, swollen eyelids, increased corneal thickness with or without folds in Descemet's membrane, corneal abrasions, ciliary flush, anterior chamber flare, decreased vision, and frequently, an apparently tight-fitting contact lens with perilimbal conjunctival edema (Fig 3). This syndrome of lens intolerance or "overwear" is apparently caused by a decrease in the oxygen supply to the cornea (anoxia).31 The earliest sign of this complication is an increase in central corneal thickness that can only be detected by the use of a pachometer. Liebowitz and co-workers l6 were among the first to evaluate the change in corneal thickness during hydrophilic lens wear. In ten normal volunteers, the corneal thicknesses increased up to 30% during the first day of ten days' continuous wear,16 but these changes did not interfere with vision and the corneas tended to stabilize at the new thickness without producing a
Fig 3.-Left eye of m yopic patient who had s cu· cessfully worn a contact l en s for one month . With· in two da ys sh e h ad symptoms of a noxia and a n increa sed corneal thickness, perilimbal injection , mild flare in an terior ch amber, and loss of oneline of vision.
change in visual acuity. Ruben and co-workers 32 found no increase in corneal thickness in five patients wearing lenses for 24 hours. Mobilia and co-workers 33 fitted 30 volunteer subjects with normal corneas with five different hydration levels of contact lenses and measured their corneal thicknesses during 24 hours of continuous wear. Twenty-one of the 30 subjects were able to wear the lens for 24 hours, but seven had to remove the lenses after one to ten hours because of discomfort. Sixteen of the 21 successful patients had to wear two or more lenses in order to complete the full 24 hours. Nine patients had a decrease in vision between one and five lines, associated with increased corneal thickness. The corneal thicknesses increased as much as 0.16 mm over the prefitting thickness. These changes tended to occur with thicker lenses. 33 In a different study,I7 eight of 17 patients who wore a thin hydrophilic lens for 12 weeks had increases in corneal thickness greater than 0.04 to 0.10 mm over base line, but in only four of these patients was there a change in vision of one to three lines. Gasset and co-workers Il described a slight
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but insignificant increase in central corneal thickness in ten aphakic eyes with permanent wear lenses worn from one week to five years. Most hydrogel lenses are highly permeable to oxygen in vitro, but it appears that most of the presently available hydrogel lenses do not allow significant transmission of oxygen through the center of the lenses in vivo. Consequently, the source of oxygen to the cornea must be from the tear film. It has been calculated that an ideal soft contact lens would contain 85% water and would measure less than 0.1 mm in thickness to allow adequate oxygen diffusion to meet the metabolic needs of the cornea through the closed eyelids. 34 In order to get around this problem, extended wear lenses have been fitted somewhat more loosely (more flat) to allow greater tear exchange and yet provide the most stable visual acuity. The use of frequent artificial tears to continually float the lens surface off the cornea and an increased frequency of blinking increase the amount of oxygen available to the corneal surface. When patients are examined during extended wear, the visual acuity, cen tral corneal thickness, and degree of lens movement should be recorded. If an increase in corneal thickness is greater than 0.05 mm, it is a significant increase35 and, in most instances, the lens should be removed. A flatter lens or a more highly hydrophilic lens may be fitted at a later date to increase the oxygen supply to the cornea. This anoxic complication usually develops within the first 48 hours of extended wear13 ; consequently, all patients should be reexamined within that time. Patients who are unable to
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tolerate an extended wear lens may do well with daily wear. CONJUNCTIVAL COMPLICATIONS
Conjunctival changes have been noted with daily wear soft contact lenses; these include "conjunctivitis,"7 follicular conjunctivitis, conjunctival injection, perilimbal conjunctival edema, and giant papillary conjunctivitis. 36 With therapeutic continuous wear, more frequent conjunctival changes have been noted, including a severe mucus-producing conjunctivitis 37 and other keratoconjunctivitises.2.38-4o With the advent of extended wear, these same changes have been noted-specifically, conjunctival hyperemia 38 and conjunctivitis. l1 In normal patients, a continuously worn hydrophilic lens apparently does not affect the normal conjunctival flora. 41 This is also true with therapeutic lenses. 4o The source of the infection is probably the patient, as the incidence of conjunctival infection between groups of patients who boiled their lenses daily and those who boiled their lenses twice a week was the same. Many ophthalmologists believe that patients with dry eyes and eyelid infections, patients with poor personal hygiene, and retarded patients have a greater risk of infection. Conjunctival changes appear to be related to changes within the lens surface itself and concomitant infections of the conjunctiva and cornea. Tight-fitting contact lenses, especially in patients with anoxic lens intolerance, produce conjunctival hyperemia and perilimbal edema, and in time, the superficial epithelium will stain with fluorescein.
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CORNEAL COMPLICATIONS
The corneal changes noted with the continuous wear of soft contact lenses include those found with daily and therapeutic wear (Table 3), but the incidence of these complications is presently undetermined. The superficial changes in the cornea have been described by Ruben. 38 These superficial changes are not serious and resolve with cessation of wear. Contact lens fitters have noted subepithelial opacities and corneal stromal opacities associated with a red eye, and although these deposits are culture negative, they have been treated as infections. In most instances, these opacities do not result in visual morbidity. TABLE
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continually.2,13,40, 44 Infectious keratitis in continuous wear patients has recently been reported in seven patients (Fig 4).10,45 The causes of the infectious ulcers in these seven cases were Pseudomonas aeruginosa, Serratia liquefaciens, Staphylococcus aureus, and Escherichia coli.
3
CORNEAL COMPLICATIONS WITH EXTENDED WEAR
I. Precorneal tear film defects
II . Superficial corneal changes A. Punctate epithelial keratitis B. Decreased corneal sensation C. Corneal microcysts D. Filamentary keratitis E. Epithelial hypertrophy F. Subepithelial opacification III . Deep corneal changes A. Corneal edema B. Noninfectious corneal opacities C. Bacterial ulcers D. Fungal ulcers IV. Corneal neovascularization
Infectious keratitis with cosmetic soft lens wear has been reported by F . S. Brightbill (oral communication, March, 1977), Krachmer and Purcell,42 and others43; it has also been described in patients wearing therapeutic contact lenses
Fig 4.-Right eye of 17-year-old myopic patient who had successfully worn a lens for two months. A red, painful eye developed, and a white "spot" was n oted o n cornea (arrows). Gram stain demonstra ted Gram positive cocci that failed t o grow on culture. Patient was treated with freq uent topical antibiotics, and lesion cleared without affecting visua l acuity.
Corneal neovascularization occurs rarely with the daily wear of soft contact lenses but has been reported with therapeutic soft lens wear2,46,47 and in aphakic extended wear 5,lO. 11,13 (Fig 5). The corneal vascularization tends to remain stable or even regress if the lenses are removed, but it will not respond to the addition of topical corticosteroids that may predispose the patient to infection. It is not known at this time if the replacement of a moderately hydrophilic lens with a more hydrophilic lens will decrease the degree and incidence of neovascularization. 5 If neovascularization occurs, it is best to discontinue extended wear for at least one week and reevaluate the extent of the
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Fig 5.-Superficial corneal vascularization anterior to Bowman's membra ne in aphakic patient who had successfully worn a soft contact l ens for three months. The vessels did not recede following cessation of lens wear.
vascularization. If it regresses, extended wear may be restarted. If it persists, a switch to daily wear or a schedule of on 24, off 24 hours is recommended. REFRACTIVE ERROR CHANGES
Refractive error changes with hard contact lenses are well documented. Less commonly, refractive error changes also occur with cosmetic soft contact lenses. 48 These changes may be caused by an increase in corneal thickness producing a decrease in visual acuity,16 or they may1 3,17 or may not5 be associated with a change in the corneal curvature. These changes revert to normal when lens wear IS stopped. CONCLUSION
The major complications occurring with extended wear appear to be deposits on the lenses and lens intolerance (overwear syndrome). Other lens problems, such as chipped, broken, degenerated, or lost lenses, also produce many of the problems
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associated with extended wear but do not permanently affect vision. The problems secondary to lens deposits such as "conjunctivitis" and giant papillary conjunctivitis are a nuisance but do not permanently affect vision. The reversible superficial corneal changes that occur are easily corrected by cessation of wear and the addition of lubricants. The major complications of deposits and lens changes make it necessary to replace lenses an average of almost twice within six months. The major problem with extended wear that affects visual acuity is infectious keratitis, and the incidence of this complication can be decreased by carefully choosing patients who understand the importance of extended wear, patients who are mentally capable of seeking help, patients with a good personal hygiene, and patients without signs of anterior segment infection or eyelid disease. The addition of concomitant prophylactic antibiotics is not warranted, as the use of artificial tears appears to do just as well. In order to minimize complications, patients should be examined within 48 hours of their initial fit, at one week, at three weeks after fit, and then monthly thereafter, with visual acuity, corneal thickness, and the condition of the conjunctiva and the lens determined at each visit. A recent review summarizes many of the problems facing the future of successful continuous wear.49
REFERENCES 1. Kaufman HE, Uotila MH, Gasset AR, et al: The medical uses of soft contact lenses. Trans Am Acad Ophthalmol Otolaryngol 75:361-373, 1971.
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2. Dohlman CH, Boruchoff SA, Mobilia EF: Complications in use of soft contact lenses in corneal disease. Arch Ophthalmol 90:367-371, 1973. 3. Gasset AR, Lobo L: Simplified soft contact lens treatment in corneal diseases. Ann Ophthalmol 9:843-848, 1977. 4. Kratz RP: Surgical techniques of in· traocular lens implantation, in Worthen DM, Binder PS, (eds): The Intraocular Lens in Perspective. New York, Stratton Inter· continental Medical Book Corp, 1976, pp 39-45.
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17. Binder PS, Worthen DM: Clinical evaluation of continuous-wear hydrophilic lenses. Am J Ophthalmol 83:549-553, 1977. 18. Doughman DJ, Mobilia E, Drago D, et al: The nature of "spots" on soft lenses. Ann Ophthalmol 7:345-353, 1975. 19. Klintworth GK, Reed JW, Hawkins HK, et al: Calcification of soft contact lenses in patient with dry eye and elevated calcium concentration in tears. Invest Ophthalmol Vis Sci 16:158-161, 1977.
5. Stein HA, Slatt BJ: Extended wear of soft contact lenses in perspective. Int Contact Lens Clin 14:35-40, 1977.
20. Ruben M, Tripathi RC, Winder AF: Calcium deposition as a cause of spoiliation of hydrophilic soft contact lenses. Br J Ophthalmol 59:141-148, 1975.
6. Lumbroso P, Fourny A, Maussan M: Lentilles souples ii forte hydrophilie. Arch Ophtalmol 35:341-346, 1975.
21. Eriksen S: Cleaning hydrophilic contact lenses: An overview. Ann Ophthalmol 7:1223-1232, 1975.
7. Benson C: Continuous use of contact lenses. Aust J Ophthalmol 4:99-103, 1976.
22. Karageozian HL: Use of the amino acid analyzer to illustrate the efficacy of an enzyme preparation for cleaning hydrophilic lenses. Contacto 20:5, 1976.
8. Freeman MI: Continuous wear of contact lens after cataract surgery. Bull Mason Clin 30:145-151, 1976-1977. 9. Pierse D, Kersley HJ: Fitting "continuous wear" soft contact lenses at the time of cataract extraction. Trans Ophthalmol Soc UK 96:11-12, 1976. 10. Kersley HJ, Kerr C, Pierse D: Hydrophilic lenses for "continuous" wear in aphakia: Definitive fitting and the problems that occur. Br J Ophthalmol 61:38-42, 1977. 11. Gasset AR, Lobo L, Houde W: Permanent wear of soft contact lenses in aphakic eyes. Am J Ophthalmol 83:115-120, 1977. 12. Dahl AA, Brocks ER: The use of con· tinuous-wear silicone contact lenses in the optical correction of aphakia. Am J Ophthalmol 85:454-461, 1978.
23. Refojo MF, Holly FJ: Tear protein adsorption on hydrogels: A possible cause of contact lens allergy. Contact and Intraocular Lens Med J 3:23-35, 1977. 24. Palmer E, Ferry AP, Safir A: Furlgal invasion of a soft (Griffin Bionite) contact lens. Arch Ophthalmol 93:278-280, 1974. 25. Tripathi RC, Ruben M: Degenerative changes in a soft hydrophilic contact lens. Ophthalmic Res 4:185-192, 1973. 26. Sugar J: Adrenochrome pigmentation of hydrophilic lenses. Arch Ophthalmol 91: 11-12, 1974. 27. Miller D, Brooks SM, Mobilia E: Adrenochrome staining of soft contact lenses. Ann Ophthalmol 8:65-67, 1976.
13. Binder PS: Extended wear of three soft contact lenses. Contact Intraocular Lens Med J 5:45-53, 1979.
28. Brown SI, Rosen J: Scleral perforation: A complication of the, soft contact lens. Arch Ophthalmol 93:1047-1048, 1975.
14. Aquavella JV, Jackson GK, Guy LF: Therapeutic effects of bionite lenses:. Mechanisms of action. Ann Ophthalmol 3:13411350, 1971.
29. Koetting RA: Frequency of hydrogel lens replacement. Contacto 19:11-14, 1975.
15. Pierse D, Kersley HJ: Hydrophilic lenses for "continuous" wear in aphakia: Fitting at operation. Br J OphthalmoI61:3437, 1977. 16. Liebowitz HM, Laing RA, Sandstrom M: Continuous wear of hydrophilic contact lenses. Arch Ophthalmol 89:306-310, 1973.
30. Yamamoto M, Tabuchi A: Experience in the use of contact lenses in children. Contact Intraocular Lens Med J 2:8-14, 1976. 31. PoIse KA, Mandel RB: Etiology of corneal striae accompanying hydrogel lens wear. Invest Ophthalmol 15:553-556, 1976. 32. Ruben M, Brown N, Lobascher D, et al: Clinical manifestations secondary to
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soft contact lens wear. Br J Ophthalmol 60:529-531, 1976.
ical antibiotics. Arch Ophthalmol 94:21092111, 1976.
33. Mobilia EF, Dohlman CH, Holly FJ: A comparison of various soft contact lenses for therapeutic purposes. Contact Intraocular Lens Med J 3:9-15, 1977.
42. Krachmer JH, Purcell JJ Jr: Bacterial corneal ulcers in cosmetic soft contact lens wearers. Arch Ophthalmol 96:57-61, 1978.
34. Holly FJ, Refojo MF: Oxygen permeability of hydrogel contact lenses. J Am Optom Assoc 43:1173-1180, 1972. 35. Binder PS, Kohler JA, Rorabaugh DA: Evaluation of an electronic corneal pachometer. Invest Ophthalmol Vis Sci 16:855858, 1977. 36. Allansmith MR, Korb DR, Greiner JV, et al: Giant papillary conjunctivitis in contact lens wearers. Am J Ophthalmol 83: 697-708, 1977. 37. Johnson DG: Keratoconjunctivitis associated with wearing hydrophilic contact lenses. Can J Ophthalmol 8:92-96, 1973. 38. Ruben M: Acute eye disease secondary to contact lens wear. Lancet 1:138-140, 1976. 39. Lemp MA: An unusual keratoconjunctivitis occurring after long-time wearing of AO Softcon hydrophilic contact lens. Ann Ophthalmol 7:97-106, 1975. 40. Brown SI, Bloomfield S, Pearce DB, et al: Infections with the therapeutic soft lens. Arch Ophthalmol 91:275-277, 1974. 41. Binder PS, Worthen DM: A continuous-wear hydrophilic lens. Prophylactic top-
43. Nakajima A, Kanai A, Yamaguchi T: Eitrige hornhautgeschwure und kontaktlinsen. Klin Monatsbl Augenheilkd 170:366373, 1970. 44. Olson RJ: Bilateral hemophilus corneal ulcers in a patient with bandage contact lenses. Contact Intraocular Lens Med J 4:95-99, 1978. 45. Cooper RL, Constable IJ: Infective keratitis in soft contact lens wearers. Br J Ophthalmol 61:25()'254, 1977. 46. Schecter DR, Emery JM, Soper JW: Corneal vascularization in therapeutic softlens wear. Contact Intraocular Lens Med J 1:141-145, 1975. 47. Weinberg RJ: Deep corneal vascularization caused by aphakic soft contact lens wear. Am J Ophthalmol 83:121-122, 1977. 48. Baldone J A: Corneal curvature changes secondary to the wearing of hydrophilic gel contact lenses. Contact Intraocular Lens Med J 1:175-176, 1975. 49. Nesburn AB: Prolonged-wear contact lenses in aphakia. Ophthalmology 85:73-79, 1978.
