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Discussion of Presentation By Dr George Edward Garcia
DISCUSSION OF PRESENTATION BY DR GEORGE EDWARD GARCIA ANTHONY B. NESBURN, MD LOS ANGELES, CALIFORNIA GEORGE E. Garcia, MD, presented encouraging data for those physicians seeking better means of coping with aphakic visual correction. In spite of the increasing use of intraocular lenses (IOL), there will always be aphakic patients who would be best handled by prolonged wear of contact lenses. That group would include patients who have contraindications for either primary or secondary IOL implantation and those who cannot tolerate aphakic spectacles or daily wear contact lenses. At present, many other aphakic patients would elect prolonged wear of contact lenses if a safe, comfortable, and practical method was available. Dr Garcia's paper shows an approximate success rate of 80% for extended wear of cellulose acetate butyrate (CAB) lenses. This study included 135 eyes followed for 3 to 60 months with an average followup of 24.75 months. Complications were minor. Years ago, Welsh 1 reported a similar success rate with minimal complications, fitting small, thin, polymethyl methacrylate (PMMA) lenses on a prolonged wear basis in aphakic patients.
Submitted for publication Oct 22, 1978. From the Estelle Doheny Eye Foundation and the University of Southern California School of Medi· cine, Los Angeles. Presented at the 1978 Annual Meeting of the American Academy of Ophthalmology, Kansas City, Mo, Oct 22-26. Reprint requests to Estelle Doheny Eye Foundation, 1355 San Pablo St, Los Angeles, CA 90033.
However, this fitting technique did not gain wide acceptance. In recent months, several other ophthalmologists, including Halberg and Boyd, have had similar encouraging results using CAB lenses for prolonged wear (Minihighlights of Ophthalmology, vol 4, No. 11, 1976). The results of these independent trials parallel Dr Garcia's. The author's experience with this lens for prolonged wear is limited, but successful. Failures were caused by lens intolerance, dry eyes, and variable visual acuity caused by coated lenses. Patients with dry eyes do not tolerate this or any other contact lens well for prolonged wear. The oily coating of the contact lens necessitates frequent cleaning. Cellulose acetate butyrate lenses are untinted and, therefore, are difficult to find when displaced from the cornea or if they come out of the eye. This problem may be solved if a safe dye can be found that does not interfere with the gas permeability of the lens. Cellulose acetate butyrate lenses offer several theoretic and practical advantages over customary hard lenses. Improved wetting ability and faster heat dissipation account for some of the improved comfort of CAB over PMMA, but no hard contact lens can match the comfort of a soft contact lens in a sensitive patient. Increased gas permeability is a definite advantage. However, the 02 transmissivity of CAB lenses is not particularly great and depends on lens thickness. The vital
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central part of an aphakic lens barely passes any oxygen at all, but the thinner peripheral parts do. The overall effect is to allow the fitting of larger lenses for better vision and, if necessary, tighter lenses for better centering with less anoxia and edema than would be possible with PMMA. For those patients who develop edema with CAB lenses, the suggestion by Steven Kelly, MD (oral communication, January 1978) of fenestrating the lens has been helpful. The lack of serious lens-related complications in Dr Garcia's series was impressive; no neovascularization or corneal infections occurred. In the author's series of 59 aphakic eyes fitted with Bausch & Lomb and Softcon hydrogel lenses, not specifically designed for prolonged wear, four minor corneal infections were encountered in the four-year course of the study; these were easily treated without visual loss. However, in almost all the patients some superficial peripheral neovascularization developed, but none serious enough to warrant discontinuation of wear of soft contact lenses. If one compares CAB lenses for prolonged wear with these hydrogel lenses, it appears that the CAB lenses are associated with fewer complications; however, many of our patients could not have tolerated CAB lenses. Ruben 2 has documented that contact lens wear, both soft and hard, produces many minor and a few serious complications. The CAB lenses, gas-permeable hard or soft lenses, or, indeed, any contact lens will be associated with a finite number of complications. Obviously, the safety of devices to correct aphakia is relative and must be judged in light of accept-
OPHTH AAO
able alternatives for visual correction in each patient. With the mounting momentum toward IOL implantation, two pertinent notes in regard to contact lens correction of aphakia should be mentioned. First, Schecter3 shows that a calculated overplussed contact lens and a correcting lowpower spectacle can reduce aniseikonia from the 7% of aphakic contact lenses to less than 0.2%. The aniseikonia produced by IOLs in monocular aphakic patients is about 2%. If practical, this system of prescribing could eliminate one of the most annoying problems of contact lenses in monocular aphakic patients. Second, interim reports to the FDA on new contact lenses undergoing investigation for prolonged wear reveal an approximate patient acceptance rate of 80%. No serious complications have been reported in the course of the official investigations; however, these studies are being carried out under ideal circumstances. There are individual reports from smaller, perhaps less carefully monitored series (not involving CAB lenses), which indicate that infections and other complications do occur. Some of the new lenses have higher oxygen permeability and appear to be more comfortable than aphakic CAB lenses. These are lenses made of silicone, PMMA plus silicone, ultra-thin hydroxyethyl methyl methacrylate (HEMA), and high water content hydrogels. Some may prove to be better than CAB for prolonged aphakic wear. However, present information would seem to vindicate the careful trial of CAB lenses in patients who need prolonged wear contact lenses for aphakic correction. It should be
VOLUME 86 FEBRUARY 1979
DISCUSSION
pointed out that, as yet, manufacturers of CAB lenses have not officially applied for or received FDA permission to test their lenses for prolonged wear. Practitioners who decide to use CAB lenses for extended wear should obtain appropriate informed consent from their patients. The precautions of proper patient selection, meticulous fitting, and careful follow-up must be observed. As pointed out by Dr Garcia, the long-term effects of extended wear gas-permeable contact lenses are not known. The carefully planned FDA protocols for testing prolonged wear contact lenses will yield important safety information. However, the essentially safe contact lens wear over the last 30 years and several small studies .of prolonged
339
wear suggest that such an extended wear schedule will not be found particularly harmful. The continuing technologic advances in contact lenses, IOLs, and keratophakia will expand the modalities available to us as practitioners in trying to help our patients.
REFERENCES 1. Welsh RC: Continuous use of tiny hard
corneal lenses for aphakia (200 cases). Ann Ophthalmol 5:1003-1004, 1973.
2. Ruben M: Acute eye disease secondary to contact-lens wear. Lancet 1 (7951):138-140, 1976. 3. Schecter RJ: Elimination of aniseikonia in monocular aphakia with a contact lensspectacle correction. Surv Ophthalmol 23: 57-61, 1978.
Submitted for publication Oct 22, 1978. From the Estelle Doheny Eye Foundation and the University of Southern California School of Medi· cine, Los Angeles. Presented at the 1978 Annual Meeting of the American Academy of Ophthalmology, Kansas City, Mo, Oct 22-26. Reprint requests to Estelle Doheny Eye Foundation, 1355 San Pablo St, Los Angeles, CA 90033.
However, this fitting technique did not gain wide acceptance. In recent months, several other ophthalmologists, including Halberg and Boyd, have had similar encouraging results using CAB lenses for prolonged wear (Minihighlights of Ophthalmology, vol 4, No. 11, 1976). The results of these independent trials parallel Dr Garcia's. The author's experience with this lens for prolonged wear is limited, but successful. Failures were caused by lens intolerance, dry eyes, and variable visual acuity caused by coated lenses. Patients with dry eyes do not tolerate this or any other contact lens well for prolonged wear. The oily coating of the contact lens necessitates frequent cleaning. Cellulose acetate butyrate lenses are untinted and, therefore, are difficult to find when displaced from the cornea or if they come out of the eye. This problem may be solved if a safe dye can be found that does not interfere with the gas permeability of the lens. Cellulose acetate butyrate lenses offer several theoretic and practical advantages over customary hard lenses. Improved wetting ability and faster heat dissipation account for some of the improved comfort of CAB over PMMA, but no hard contact lens can match the comfort of a soft contact lens in a sensitive patient. Increased gas permeability is a definite advantage. However, the 02 transmissivity of CAB lenses is not particularly great and depends on lens thickness. The vital
337
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ANTHONY B. NESBURN
central part of an aphakic lens barely passes any oxygen at all, but the thinner peripheral parts do. The overall effect is to allow the fitting of larger lenses for better vision and, if necessary, tighter lenses for better centering with less anoxia and edema than would be possible with PMMA. For those patients who develop edema with CAB lenses, the suggestion by Steven Kelly, MD (oral communication, January 1978) of fenestrating the lens has been helpful. The lack of serious lens-related complications in Dr Garcia's series was impressive; no neovascularization or corneal infections occurred. In the author's series of 59 aphakic eyes fitted with Bausch & Lomb and Softcon hydrogel lenses, not specifically designed for prolonged wear, four minor corneal infections were encountered in the four-year course of the study; these were easily treated without visual loss. However, in almost all the patients some superficial peripheral neovascularization developed, but none serious enough to warrant discontinuation of wear of soft contact lenses. If one compares CAB lenses for prolonged wear with these hydrogel lenses, it appears that the CAB lenses are associated with fewer complications; however, many of our patients could not have tolerated CAB lenses. Ruben 2 has documented that contact lens wear, both soft and hard, produces many minor and a few serious complications. The CAB lenses, gas-permeable hard or soft lenses, or, indeed, any contact lens will be associated with a finite number of complications. Obviously, the safety of devices to correct aphakia is relative and must be judged in light of accept-
OPHTH AAO
able alternatives for visual correction in each patient. With the mounting momentum toward IOL implantation, two pertinent notes in regard to contact lens correction of aphakia should be mentioned. First, Schecter3 shows that a calculated overplussed contact lens and a correcting lowpower spectacle can reduce aniseikonia from the 7% of aphakic contact lenses to less than 0.2%. The aniseikonia produced by IOLs in monocular aphakic patients is about 2%. If practical, this system of prescribing could eliminate one of the most annoying problems of contact lenses in monocular aphakic patients. Second, interim reports to the FDA on new contact lenses undergoing investigation for prolonged wear reveal an approximate patient acceptance rate of 80%. No serious complications have been reported in the course of the official investigations; however, these studies are being carried out under ideal circumstances. There are individual reports from smaller, perhaps less carefully monitored series (not involving CAB lenses), which indicate that infections and other complications do occur. Some of the new lenses have higher oxygen permeability and appear to be more comfortable than aphakic CAB lenses. These are lenses made of silicone, PMMA plus silicone, ultra-thin hydroxyethyl methyl methacrylate (HEMA), and high water content hydrogels. Some may prove to be better than CAB for prolonged aphakic wear. However, present information would seem to vindicate the careful trial of CAB lenses in patients who need prolonged wear contact lenses for aphakic correction. It should be
VOLUME 86 FEBRUARY 1979
DISCUSSION
pointed out that, as yet, manufacturers of CAB lenses have not officially applied for or received FDA permission to test their lenses for prolonged wear. Practitioners who decide to use CAB lenses for extended wear should obtain appropriate informed consent from their patients. The precautions of proper patient selection, meticulous fitting, and careful follow-up must be observed. As pointed out by Dr Garcia, the long-term effects of extended wear gas-permeable contact lenses are not known. The carefully planned FDA protocols for testing prolonged wear contact lenses will yield important safety information. However, the essentially safe contact lens wear over the last 30 years and several small studies .of prolonged
339
wear suggest that such an extended wear schedule will not be found particularly harmful. The continuing technologic advances in contact lenses, IOLs, and keratophakia will expand the modalities available to us as practitioners in trying to help our patients.
REFERENCES 1. Welsh RC: Continuous use of tiny hard
corneal lenses for aphakia (200 cases). Ann Ophthalmol 5:1003-1004, 1973.
2. Ruben M: Acute eye disease secondary to contact-lens wear. Lancet 1 (7951):138-140, 1976. 3. Schecter RJ: Elimination of aniseikonia in monocular aphakia with a contact lensspectacle correction. Surv Ophthalmol 23: 57-61, 1978.