Scleral expansion surgery for presbyopia
2001; Elsevier BV; Volume: 108; Issue: 12 Linguagem: Inglês
10.1016/s0161-6420(01)00909-5
ISSN1549-4713
Autores Tópico(s)Corneal surgery and disorders
ResumoThe mechanism of human accommodation or disaccommodation, the ability of the eye to focus from far to near and near to far, respectively, has been debated with surprising passion for nearly two centuries. The pathophysiology of presbyopia, the loss of the ability to change the eye’s focus from far to near, has aroused similar passion. Considering that presbyopia, although the most common of all ocular afflictions, is a nonblinding condition, the intensity of the dialogue is truly surprising, even to this author who has been an active ophthalmic practitioner and researcher for three decades.The discussion, although intense, has been limited to a rather small group of ocular physiologists and physiologic optics researchers—until recently. Now, dramatic improvements in cataract surgical technique, artificial lens replacements for cataractous lenses, refractive surgery, declining government and insurance payments for cataract surgery and other “standard” ophthalmic procedures, and the public demand for real and perceived quality of life, preservation of youthful appearance, and device-free vision have all combined to create a larger interest—and market—for presbyopia correction. Where a perceived and/or real market exists, technology attempts to follow for both intellectual and pecuniary reasons.In the case of accommodation and presbyopia, this has taken two major forms. First are the attempts to create accommodating intraocular lens implants so as to restore the near-far focusing function along with clear vision, typically in elderly patients already undergoing cataract removal and intraocular lens implantation.1Parel J.M. Gelender H. Trefers W.F. Norton E.W. Phaco-Ersatz cataract surgery designed to preserve accommodation.Graefes Arch Clin Exp Ophthalmol. 1986; 224: 165-173Crossref PubMed Scopus (131) Google Scholar, 2Nishi O. Nakai Y. Yamada Y. Mizumoto Y. Amplitudes of accommodation of primate lenses refilled with two types of inflatable endocapsular balloons.Arch Ophthalmol. 1993; 111: 1677-1684Crossref PubMed Scopus (77) Google Scholar, 3Nishi O. Nishi K. Accommodation amplitude after lens refilling with injectable silicone by sealing the capsule with a plug in primates.Arch Ophthalmol. 1998; 116: 1358-1361Crossref PubMed Scopus (85) Google Scholar In essence, the goal is to restore both the visual clarity and range of the young eye, with surgery that is only modestly more complex and risky than current cataract/fixed-focus lens implant surgery—one of the least risky and most successful organ-invading surgeries in all of clinical medicine. The second and more problematic approach has been the attempt to surgically restore accommodation to the middle-aged eye, while leaving the still clear crystalline lens in place.A currently prominent—and controversial—approach in this latter category is so-called scleral expansion surgery, based on the theory of accommodation promulgated by Schachar and associates.4Schachar R.A. Cause and treatment of presbyopia with a method for increasing the amplitude of accommodation.Ann Ophthalmol. 1992; 24 (452): 445-447PubMed Google Scholar, 5Schachar R.A. Tello C. Cudmore D.P. et al.In vivo increase of the human lens equatorial diameter during accommodation.Am J Physiol. 1996; 271: R670-R676PubMed Google Scholar, 6Schachar R.A. Anderson D.A. The mechanism of ciliary muscle function.Ann Ophthalmol. 1995; 27: 126-132Google Scholar, 7Schachar R.A. Cudmore D.P. Black T.D. Experimental support for Schachar’s hypothesis of accommodation.Arch Ophthalmol. 1993; 25: 404-409Google Scholar, 8Schachar R.A. Black T.D. Kash R.L. et al.The mechanism of accommodation and presbyopia in the primate.Ann Ophthalmol. 1995; 27: 58-67Google Scholar, 9Schachar R.A. Zonular function a new hypothesis with clinical implications.Arch Ophthalmol. 1994; 26: 36-38Google Scholar, 10Schachar R.A. Bax A.J. Mechanism of accommodation.Int Ophthalmol Clin. 2001; 41: 17-32Crossref PubMed Scopus (13) Google Scholar, 11Schachar R.A. The correction of presbyopia.Int Ophthalmol Clin. 2001; 41 ([review]): 53-70Crossref PubMed Scopus (19) Google Scholar Schachar envisions that accommodation occurs when ciliary muscle contraction tenses, rather than relaxes, the anterior zonulae, most especially the equatorial zonular fibers. The lens would then be stretched equatorially or coronally (i.e., the lens edge moves toward the sclera), but the biomechanical properties of the lens are such that the central part of the lens rounds up and moves anteriorly, increasing its refracting power. This contradicts the classical Helmholtz mechanism, in which ciliary muscle contraction is thought to relax the zonule, allowing the centripetal elasticity of the lens capsule to sphericize the lens (i.e., the equatorial or coronal diameter of the lens decreases, the equatorial edge of the lens recedes from the sclera, and the lens as a whole rounds up).12von Helmholz H. Handbuch der Physiologishen Optik.in: Southall J.P.C. Helmholtz’s Treatise on Physiological Optics. Dover, New York1962: 143-172Google Scholar, 13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar According to Schachar’s theory, presbyopia results from growth in the equatorial diameter of the lens, such that the perilenticular space is reduced, and ciliary muscle contraction can no longer tense the zonule and expand the lens coronally. By implanting plastic bands intrasclerally to expand the scleral ring (i.e., the opposite of encircling bands for scleral buckling surgery to treat rhegmatogenous retinal detachment)11Schachar R.A. The correction of presbyopia.Int Ophthalmol Clin. 2001; 41 ([review]): 53-70Crossref PubMed Scopus (19) Google Scholar or by making radial relaxing incisions in the sclera (analogous to radial keratotomy, but more posterior;11Schachar R.A. The correction of presbyopia.Int Ophthalmol Clin. 2001; 41 ([review]): 53-70Crossref PubMed Scopus (19) Google Scholar and Thornton S, presented at ASCRS, Seattle, WA, 1999]), mechanical advantage to ciliary muscle contraction is postulated to be restored, and with it accommodation.One can debate the clinical wisdom of implanting bands of or making incisions in the sclera should the need arise later in life for glaucoma filtration or retinal detachment surgery. However, this editorial will focus (pardon the pun) on the theory underlying this approach to presbyopia therapy, the data thus far presented in support of the theory, and the clinical data on patients who have undergone scleral expansion surgery.Schachar11Schachar R.A. The correction of presbyopia.Int Ophthalmol Clin. 2001; 41 ([review]): 53-70Crossref PubMed Scopus (19) Google Scholar has criticized the data from experiments on living primates that contradict his theory and support the Helmholtz theory of accommodation.13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar However, the myriad of different approaches and analytical strategies used13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar negate the minor uncertainties that Schachar highlights and leave little doubt that the Schachar theory is quite simply incorrect. That is not to say that his analysis of the optical consequences of lenticular deformability is in error—the Schachar theory may well be correct on that point—but rather that the anatomic origin, nature, and direction of the forces on the lens that he envisions simply do not occur in the living nonhuman primate, and probably not in the living human either. Furthermore, to this author’s knowledge, restoration of accommodation has never been objectively demonstrated in even a single patient after scleral expansion surgery. Some patients experience subjectively improved near vision without a change in resting distance refraction.11Schachar R.A. The correction of presbyopia.Int Ophthalmol Clin. 2001; 41 ([review]): 53-70Crossref PubMed Scopus (19) Google Scholar However, improved near vision does not prove restoration of dynamic accommodation; for instance, expanding the scleral ring and stretching the lens equatorially could induce static multifocality.13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar, 14Mathews S. Scleral expansion surgery does not restore accommodation in human presbyopia.Ophthalmology. 1999; 106: 873-877Abstract Full Text Full Text PDF PubMed Scopus (92) Google ScholarThe study by Malecaze and associates in the current issue of Ophthalmology15Malecaze F.L. Gazagne C.S. Tarroux M.C. Gorrand J.M. Scleral expansion bands for presbyopia.Ophthalmology. 2001; 108: 2165-2171Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar reinforces other reports (e.g.,14Mathews S. Scleral expansion surgery does not restore accommodation in human presbyopia.Ophthalmology. 1999; 106: 873-877Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar) that improved near vision by whatever mechanism is by no means universal or long lasting after scleral expansion surgery and adds to the appropriately cautious view of this procedure. However, from the standpoint of clinical usefulness, the mechanism by which near vision is restored may not matter. If the procedure is low risk and uniformly effective, and if patients are satisfied, the issue of static multifocality vs. dynamic accommodative range becomes an academic/physiologic one. Nonetheless, the current report15Malecaze F.L. Gazagne C.S. Tarroux M.C. Gorrand J.M. Scleral expansion bands for presbyopia.Ophthalmology. 2001; 108: 2165-2171Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar and others14Mathews S. Scleral expansion surgery does not restore accommodation in human presbyopia.Ophthalmology. 1999; 106: 873-877Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar add to the great weight of evidence13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar against restoration of physiologic accommodation by scleral expansion procedures.A very simple and objective method is available to answer this important question definitively. Refractometers exist that can objectively measure the refractive error of the eye through a pupil as small as 2 mm. One could instill a drop of phenylephrine to dilate the pupil without paralyzing the ciliary muscle, then refract the eye, then instill a drop of 6% to 8% pilocarpine to maximally contract the ciliary muscle. The pupil will remain wide enough to permit further objective refraction 30 to 90 minutes later during maximum drug action.16Croft M.A. Oyen M.J. Gange S.J. et al.Aging effects on accommodation and outflow facility responses to pilocarpine in humans.Arch Ophthalmol. 1996; 114: 586-592Crossref PubMed Scopus (50) Google Scholar If Schachar’s theory is correct, and if scleral expansion surgery restores dynamic accommodation, the axial refractive measurement will change accordingly—with no response required by the patient, or encouragement or target manipulation by the examiner. Concurrent A-scan17Bito L.Z. DeRousseau C.J. Kaufman P.L. Bito J.W. Age-dependent loss of accommodative amplitude in rhesus monkeys an animal model for presbyopia.Invest Ophthalmol Vis Sci. 1982; 23: 23-31PubMed Google Scholar and high-resolution B-scan13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar ultrasonography measurements and Scheimpflug photography18Koretz J.F. Kaufman P.L. Neider M.W. Goeckner P.A. Accommodation and presbyopia in the human eye. I. Evaluation of in vivo measurement techniques.Appl Opti. 1989; 28: 1097-1102Crossref PubMed Scopus (46) Google Scholar, 19Koretz J.F. Cook C.A. Kaufman P.L. Accommodation and presbyopia in the human eye. Changes in the anterior segment and crystalline lens with focus.Invest Ophthalmol Vis Sci. 1997; 38: 569-578PubMed Google Scholar or videography20Croft M.A. Kaufman P.L. Crawford K.S. et al.Accommodation dynamics in aging rhesus monkeys.Am J Physiol. 1998; 275: R1885-R1897PubMed Google Scholar would provide additional objective measurements of lens axial and equatorial position and movement. The author of this editorial and other interested clinicians and scientists have offered to perform such studies on patients who have undergone scleral expansion surgery and experienced subjective improvement. To this author’s knowledge, these offers have been repeatedly declined by Dr. Schachar and at least some of his associates. Perhaps as more surgeons undertake the procedure, whether in or outside the United States, some will be inquisitive and objective enough to want to learn what they are really doing to their patients’ eyes. Such individuals know how to find this author and other clinician-scientists who would be pleased to participate in such scientific studies of an important issue. The mechanism of human accommodation or disaccommodation, the ability of the eye to focus from far to near and near to far, respectively, has been debated with surprising passion for nearly two centuries. The pathophysiology of presbyopia, the loss of the ability to change the eye’s focus from far to near, has aroused similar passion. Considering that presbyopia, although the most common of all ocular afflictions, is a nonblinding condition, the intensity of the dialogue is truly surprising, even to this author who has been an active ophthalmic practitioner and researcher for three decades. The discussion, although intense, has been limited to a rather small group of ocular physiologists and physiologic optics researchers—until recently. Now, dramatic improvements in cataract surgical technique, artificial lens replacements for cataractous lenses, refractive surgery, declining government and insurance payments for cataract surgery and other “standard” ophthalmic procedures, and the public demand for real and perceived quality of life, preservation of youthful appearance, and device-free vision have all combined to create a larger interest—and market—for presbyopia correction. Where a perceived and/or real market exists, technology attempts to follow for both intellectual and pecuniary reasons. In the case of accommodation and presbyopia, this has taken two major forms. First are the attempts to create accommodating intraocular lens implants so as to restore the near-far focusing function along with clear vision, typically in elderly patients already undergoing cataract removal and intraocular lens implantation.1Parel J.M. Gelender H. Trefers W.F. Norton E.W. Phaco-Ersatz cataract surgery designed to preserve accommodation.Graefes Arch Clin Exp Ophthalmol. 1986; 224: 165-173Crossref PubMed Scopus (131) Google Scholar, 2Nishi O. Nakai Y. Yamada Y. Mizumoto Y. Amplitudes of accommodation of primate lenses refilled with two types of inflatable endocapsular balloons.Arch Ophthalmol. 1993; 111: 1677-1684Crossref PubMed Scopus (77) Google Scholar, 3Nishi O. Nishi K. Accommodation amplitude after lens refilling with injectable silicone by sealing the capsule with a plug in primates.Arch Ophthalmol. 1998; 116: 1358-1361Crossref PubMed Scopus (85) Google Scholar In essence, the goal is to restore both the visual clarity and range of the young eye, with surgery that is only modestly more complex and risky than current cataract/fixed-focus lens implant surgery—one of the least risky and most successful organ-invading surgeries in all of clinical medicine. The second and more problematic approach has been the attempt to surgically restore accommodation to the middle-aged eye, while leaving the still clear crystalline lens in place. A currently prominent—and controversial—approach in this latter category is so-called scleral expansion surgery, based on the theory of accommodation promulgated by Schachar and associates.4Schachar R.A. Cause and treatment of presbyopia with a method for increasing the amplitude of accommodation.Ann Ophthalmol. 1992; 24 (452): 445-447PubMed Google Scholar, 5Schachar R.A. Tello C. Cudmore D.P. et al.In vivo increase of the human lens equatorial diameter during accommodation.Am J Physiol. 1996; 271: R670-R676PubMed Google Scholar, 6Schachar R.A. Anderson D.A. The mechanism of ciliary muscle function.Ann Ophthalmol. 1995; 27: 126-132Google Scholar, 7Schachar R.A. Cudmore D.P. Black T.D. Experimental support for Schachar’s hypothesis of accommodation.Arch Ophthalmol. 1993; 25: 404-409Google Scholar, 8Schachar R.A. Black T.D. Kash R.L. et al.The mechanism of accommodation and presbyopia in the primate.Ann Ophthalmol. 1995; 27: 58-67Google Scholar, 9Schachar R.A. Zonular function a new hypothesis with clinical implications.Arch Ophthalmol. 1994; 26: 36-38Google Scholar, 10Schachar R.A. Bax A.J. Mechanism of accommodation.Int Ophthalmol Clin. 2001; 41: 17-32Crossref PubMed Scopus (13) Google Scholar, 11Schachar R.A. The correction of presbyopia.Int Ophthalmol Clin. 2001; 41 ([review]): 53-70Crossref PubMed Scopus (19) Google Scholar Schachar envisions that accommodation occurs when ciliary muscle contraction tenses, rather than relaxes, the anterior zonulae, most especially the equatorial zonular fibers. The lens would then be stretched equatorially or coronally (i.e., the lens edge moves toward the sclera), but the biomechanical properties of the lens are such that the central part of the lens rounds up and moves anteriorly, increasing its refracting power. This contradicts the classical Helmholtz mechanism, in which ciliary muscle contraction is thought to relax the zonule, allowing the centripetal elasticity of the lens capsule to sphericize the lens (i.e., the equatorial or coronal diameter of the lens decreases, the equatorial edge of the lens recedes from the sclera, and the lens as a whole rounds up).12von Helmholz H. Handbuch der Physiologishen Optik.in: Southall J.P.C. Helmholtz’s Treatise on Physiological Optics. Dover, New York1962: 143-172Google Scholar, 13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar According to Schachar’s theory, presbyopia results from growth in the equatorial diameter of the lens, such that the perilenticular space is reduced, and ciliary muscle contraction can no longer tense the zonule and expand the lens coronally. By implanting plastic bands intrasclerally to expand the scleral ring (i.e., the opposite of encircling bands for scleral buckling surgery to treat rhegmatogenous retinal detachment)11Schachar R.A. The correction of presbyopia.Int Ophthalmol Clin. 2001; 41 ([review]): 53-70Crossref PubMed Scopus (19) Google Scholar or by making radial relaxing incisions in the sclera (analogous to radial keratotomy, but more posterior;11Schachar R.A. The correction of presbyopia.Int Ophthalmol Clin. 2001; 41 ([review]): 53-70Crossref PubMed Scopus (19) Google Scholar and Thornton S, presented at ASCRS, Seattle, WA, 1999]), mechanical advantage to ciliary muscle contraction is postulated to be restored, and with it accommodation. One can debate the clinical wisdom of implanting bands of or making incisions in the sclera should the need arise later in life for glaucoma filtration or retinal detachment surgery. However, this editorial will focus (pardon the pun) on the theory underlying this approach to presbyopia therapy, the data thus far presented in support of the theory, and the clinical data on patients who have undergone scleral expansion surgery. Schachar11Schachar R.A. The correction of presbyopia.Int Ophthalmol Clin. 2001; 41 ([review]): 53-70Crossref PubMed Scopus (19) Google Scholar has criticized the data from experiments on living primates that contradict his theory and support the Helmholtz theory of accommodation.13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar However, the myriad of different approaches and analytical strategies used13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar negate the minor uncertainties that Schachar highlights and leave little doubt that the Schachar theory is quite simply incorrect. That is not to say that his analysis of the optical consequences of lenticular deformability is in error—the Schachar theory may well be correct on that point—but rather that the anatomic origin, nature, and direction of the forces on the lens that he envisions simply do not occur in the living nonhuman primate, and probably not in the living human either. Furthermore, to this author’s knowledge, restoration of accommodation has never been objectively demonstrated in even a single patient after scleral expansion surgery. Some patients experience subjectively improved near vision without a change in resting distance refraction.11Schachar R.A. The correction of presbyopia.Int Ophthalmol Clin. 2001; 41 ([review]): 53-70Crossref PubMed Scopus (19) Google Scholar However, improved near vision does not prove restoration of dynamic accommodation; for instance, expanding the scleral ring and stretching the lens equatorially could induce static multifocality.13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar, 14Mathews S. Scleral expansion surgery does not restore accommodation in human presbyopia.Ophthalmology. 1999; 106: 873-877Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar The study by Malecaze and associates in the current issue of Ophthalmology15Malecaze F.L. Gazagne C.S. Tarroux M.C. Gorrand J.M. Scleral expansion bands for presbyopia.Ophthalmology. 2001; 108: 2165-2171Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar reinforces other reports (e.g.,14Mathews S. Scleral expansion surgery does not restore accommodation in human presbyopia.Ophthalmology. 1999; 106: 873-877Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar) that improved near vision by whatever mechanism is by no means universal or long lasting after scleral expansion surgery and adds to the appropriately cautious view of this procedure. However, from the standpoint of clinical usefulness, the mechanism by which near vision is restored may not matter. If the procedure is low risk and uniformly effective, and if patients are satisfied, the issue of static multifocality vs. dynamic accommodative range becomes an academic/physiologic one. Nonetheless, the current report15Malecaze F.L. Gazagne C.S. Tarroux M.C. Gorrand J.M. Scleral expansion bands for presbyopia.Ophthalmology. 2001; 108: 2165-2171Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar and others14Mathews S. Scleral expansion surgery does not restore accommodation in human presbyopia.Ophthalmology. 1999; 106: 873-877Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar add to the great weight of evidence13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar against restoration of physiologic accommodation by scleral expansion procedures. A very simple and objective method is available to answer this important question definitively. Refractometers exist that can objectively measure the refractive error of the eye through a pupil as small as 2 mm. One could instill a drop of phenylephrine to dilate the pupil without paralyzing the ciliary muscle, then refract the eye, then instill a drop of 6% to 8% pilocarpine to maximally contract the ciliary muscle. The pupil will remain wide enough to permit further objective refraction 30 to 90 minutes later during maximum drug action.16Croft M.A. Oyen M.J. Gange S.J. et al.Aging effects on accommodation and outflow facility responses to pilocarpine in humans.Arch Ophthalmol. 1996; 114: 586-592Crossref PubMed Scopus (50) Google Scholar If Schachar’s theory is correct, and if scleral expansion surgery restores dynamic accommodation, the axial refractive measurement will change accordingly—with no response required by the patient, or encouragement or target manipulation by the examiner. Concurrent A-scan17Bito L.Z. DeRousseau C.J. Kaufman P.L. Bito J.W. Age-dependent loss of accommodative amplitude in rhesus monkeys an animal model for presbyopia.Invest Ophthalmol Vis Sci. 1982; 23: 23-31PubMed Google Scholar and high-resolution B-scan13Glasser A. Kaufman P.L. The mechanism of accommodation in primates.Ophthalmology. 1999; 106: 863-872Abstract Full Text Full Text PDF PubMed Scopus (266) Google Scholar ultrasonography measurements and Scheimpflug photography18Koretz J.F. Kaufman P.L. Neider M.W. Goeckner P.A. Accommodation and presbyopia in the human eye. I. Evaluation of in vivo measurement techniques.Appl Opti. 1989; 28: 1097-1102Crossref PubMed Scopus (46) Google Scholar, 19Koretz J.F. Cook C.A. Kaufman P.L. Accommodation and presbyopia in the human eye. Changes in the anterior segment and crystalline lens with focus.Invest Ophthalmol Vis Sci. 1997; 38: 569-578PubMed Google Scholar or videography20Croft M.A. Kaufman P.L. Crawford K.S. et al.Accommodation dynamics in aging rhesus monkeys.Am J Physiol. 1998; 275: R1885-R1897PubMed Google Scholar would provide additional objective measurements of lens axial and equatorial position and movement. The author of this editorial and other interested clinicians and scientists have offered to perform such studies on patients who have undergone scleral expansion surgery and experienced subjective improvement. To this author’s knowledge, these offers have been repeatedly declined by Dr. Schachar and at least some of his associates. Perhaps as more surgeons undertake the procedure, whether in or outside the United States, some will be inquisitive and objective enough to want to learn what they are really doing to their patients’ eyes. Such individuals know how to find this author and other clinician-scientists who would be pleased to participate in such scientific studies of an important issue.
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