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ABSTRACT: Dimensional changes in the Barraquer cryolathe , resulting from contraction due to refrigeration, can exert a considerable effect on the dimensions of the lathed lenticule . We have devised a simple technique for re- zeroing the cryolathe after freezing. This procedure negates the effects of the dimensional changes and thereby improves the accuracy of shaping the lenticules .
Ophthalmic surgery 05/1984; 15(4):306-9.
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ABSTRACT: Two primate corneas were analyzed histologically 22 and 25 months after epikeratophakia surgery. Keratocytes had migrated from the host cornea into the lenticule through the surgical disruption of the host Bowman's membrane; the lenticule with the wider connection to the host cornea appeared to have more complete keratocyte repopulation. The lenticule stroma and host Bowman's membrane were continuously apposed along the interface, with a basement membrane-like material composed of collagen fibrils and amorphous matrix filling the interstices.
Ophthalmic surgery 04/1984; 15(3):230-5.
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ABSTRACT: New forms of refractive surgery result in corneas that are nearly doubled in thickness. To test the reliability of standard instrumentation for the measurement of intraocular pressure in such eyes, the MacKay-Marg tonometer was used on eye bank eyes with and without epikeratophakia lenticules and/or bandage contact lenses. The Goldmann applanation prism in the hand-held Perkins portable tonometer and the MacKay-Marg tonometer were used to measure IOP in vivo in a primate eye with an epikeratophakia graft. Measurements were compared with actual intraocular readings from a transducer. The MacKay-Marg tonometer was reliable at pressures above 20 mm Hg; the extra thickness of the graft and/or the rigidity of the contact lens impaired the accuracy below 20 mm Hg. The Goldman tonometer was accurate over the entire range of pressures.
Archives of Ophthalmology 08/1983; 101(7):1111-2. · 3.71 Impact Factor
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ABSTRACT: The shaping of swollen, abnormally hydrated donor corneal tissue on the cryolathe for use in keratorefractive surgery yields lenticules of insufficiently predictable dioptric powers. The irregular nature of this abnormal hydration precludes the use of mathematical compensating factors. To improve control over the shape of the lenticule, we have developed a cornea press which restores normal hydration and dimensions to the donor tissue by mechanical dehydration.
Ophthalmic surgery 05/1983; 14(4):327-31.
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ABSTRACT: Epikeratophakia grafts used to rehabilitate vision in adult monocular aphakic patients intolerate of contact lens correction or not candidates for IOLs were studied prospectively. Thirty-two patients who entered this study between its inception in February 1980 through February 1981 were followed for at least eight months. Patients with normal visual potential before surgery had average visual acuities with spectacle overcorrection of 20/50 at four months, 20/40 at eight months, and 20/30 at one year. Few long-term complications were seen. Empirical modification of the lathing process has decreased the undercorrection from the 5.5 diopters seen in the early patients to the 1.0 diopter seen in the more recent patients. Problems with predictability are related to the behavior of preserved corneal tissue during the lathing and the healing of these lamellar grafts. This procedure is intended for aphakic patients of whom IOL and contact lens correction is not possible.
Ophthalmology 09/1982; 89(8):916-20. · 5.45 Impact Factor
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ABSTRACT: Five patients required secondary surgical procedures after receiving epikeratophakia grafts. A neonate underwent epikeratophakia in combination with extracapsular cataract extraction, followed one week later by peripheral iridectomy and nine months later by strabismus surgery. A 53-year-old male had surgery to correct retinal detachment 4-1/2 months after epikeratophakia surgery for the correction of aphakia. A five-year-old male had epikeratophakia after removal of a traumatic cataract; five weeks later, retinal detachment necessitated vitrectomy, 360 degrees buckle, and cyclocryotherapy. A 4-1/2-year-old female had epikeratophakia for aphakia, followed nine months later by strabismus surgery. A 38-year-old female with keratoconus received a plano epikeratophakia graft, in combination with an extracapsular cataract extraction and anterior vitrectomy, followed two weeks later by an Ocutome vitrectomy. In all cases, the epikeratophakia grafts and interfaces remained clear, and in four of the five patients in whom secondary procedures were successful, vision continued to improve with time.
Ophthalmic surgery 08/1982; 13(7):555-7.
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ABSTRACT: The results of a prospective clinical study of hyperopic epikeratophakia grafts for the visual rehabilitation of aphakic patients are presented. Visual acuity data are given for 21 aphakic patients who have been followed for up to six months postoperatively. With spectacle overrefraction, on the average, patients were within three lines of their preoperative potential vision at three months postoperative and within two lines at six months postoperative. Three months postoperatively, two patients achieved visual acuities of 20/20, and 57% had 20/40 or better with spectacle overcorrection. Six months postoperatively, three patients achieved best-corrected visual acuities of 20/20, and 80% had best-corrected visual acuities of 20/40 or better.
Ophthalmology 12/1981; 88(11):1137-40. · 5.45 Impact Factor
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ABSTRACT: Epikeratophakia is a newly developed, investigational form of refractive corneal surgery for the correction of aphakic vision. The procedure involves the removal of the corneal epithelium from the recipient eye and the suturing of a prelathed lamellar donor corneal graft onto the surface of the recipient cornea. We initiated a prospective clinical trial of epikeratophakia in comparison with keratomileusis; however, only 14 patients were randomized between the two procedures, after which the protocol was modified to eliminate the keratomileusis procedure. subsequently, all patients who entered into the study underwent epikeratophakia. The limited comparative study showed that epikeratophakia was at least as effective as keratomileusis in terms of visual potential and visual recovery. The major problem encountered was undercorrection, which was largely eliminated by the use of donor tissue larger in diamter than the recipient bed. Three months postoperatively, five of seven patients undergoing epikeratophakia had 20/50 or better visual acuity with spectacle overcorrection.
Archives of Ophthalmology 12/1981; 99(11):1957-60. · 3.71 Impact Factor
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ABSTRACT: Thirteen keratophakia patients were followed for 13 to 35 months. Eighteen cases of hyperopic keratomileusis or hyperopic keratomileusis using preserved corneal tissue were followed for 2 to 30 months. All 13 patients who underwent keratophakia achieved 20/50 or better acuity. All seven patients having hyperopic keratomileusis achieved 20/60 or better acuity. Eight of the 11 patients who had hyperopic keratomileusis using donor corneal tissue achieved 20/60 or better acuity. The preservation of lenticules after lathing did not adversely affect the correlation between predicted and observed dioptric corrections. There was a statistically significant correlation between predicted and observed dioptric corrections. There was a statistically significant correlation between predicted and observed dioptric correction measured at the corneal surface when the lenticule was lathed from fresh tissue (hyperopic keratomileusis) or from relatively fresh tissue (keratophakia). However, we found that there was poor correlation between the predicted and observed corrections when the lenticule was lathed from donor tissue that had been cryopreserved for long periods of time (hyperopic keratomileusis with preserved corneal tissue).
Ophthalmology 09/1981; 88(8):716-20. · 5.45 Impact Factor
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Metabolic and pediatric ophthalmology 02/1981; 5(1):13-5.
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ABSTRACT: Epikeratophakia is a newly developed form of refractive corneal surgery for the correction of hyperopia. In this procedure, a piece of donor corneal tissue is lathed to a specific dioptric power. The epithelial cells are removed from the recipient cornea, and the donor tissue is sutured to the front of the eye. The resulting change in corneal curvature provides the visual correction, as, for instance, in the correction of aphakia. We describe here the computational analysis used to lathe human donor corneal tissue for use as epikeratophakia grafts. With these equations, the precision of the observed thickness of the lathed lenticule was +/- 0.05 mm and the precision of the observed diameter was +/- 0.25 mm. We found that, in a graft of a given diameter, the smaller the optical zone, the greater the maximal dioptric power of the graft, limited only by the central thickness of the donor cornea and the mechanical limitations of the cryolathe. In our case, the highest theoretical correction obtainable was 37 diopters.
Current Eye Research 02/1981; 1(3):123-9. · 1.28 Impact Factor
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ABSTRACT: We have developed a new form of refractive surgery, epikeratophakia, in which a disc of donor corneal tissue is lathed to a specific dioptric power and sutured on top of the recipient's cornea after the recipient epithelium has been removed. The optical correction obtained with epikeratophakia should be similar in quality to that of a contact lens, but would be permanent and would require no maintenance. A non-human primate model was used to test the predictability, stability, and clarity of epikeratophakia grafts. After surgery, the grafts did not always re-epithelialize readily; this problem has been solved with the use of a small, steep, soft bandage contact lens. For the nine month period of this study, the epikeratophakia grafts have remained clear and the curvatures of the anterior surfaces have remained constant. However, the actual visual potential of these grafts can be evaluated only by a controlled clinical study in humans.
Current Eye Research 02/1981; 1(3):131-7. · 1.28 Impact Factor
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ABSTRACT: Using cats as an experimental model, we compared the clarity of fresh, glycerine-preserved and nitrogen-preserved lenticules (corneal stromal implants) in keratophakia. No difference in final clarity was observed and the change in corneal curvature was maintained. In six patients freshly cut lenticules were used; in nine patients liquid nitrogen-preserved lenticules were used. Again, no difference in final clarity or correction was noted. The use of preserved, precut tissue in keratophakia will make this technique available to the general ophthalmic surgeon.
Ophthalmology 08/1980; 87(7):687-92. · 5.45 Impact Factor
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ABSTRACT: In order to develop a surgical technique as an alternate method for the treatment of myopia, we have adapted the epikeratophakia corneal graft procedure. The procedure is not burdened with some of the side effects associated with radial keratotomy and a wide range of predictable correction can be obtained. Preliminary trails in a non-human primate model have indicated that myopia up to -27 diopters can be corrected accurately with these grafts. In this paper we present the mathematical model for the lathing of epikeratophakia grafts for the correlation of myopia, and preliminary results in the non-human primate model.
Current Eye Research 1(10):591-7. · 1.28 Impact Factor
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ABSTRACT: Epikeratophakia is a form of refractive surgery in which the recipient's epithelium is removed and a pre-shaped donor lenticule is sutured to the patient's cornea. Seventeen patients ranging in age from two months to 6.6 years received 19 epikeratophakia grafts for the correction of aphakic vision. The correction provided by the graft in combination with vigorous amblyopia therapy has yielded some improvement in vision in the 12 patients with successful grafts. This procedure may be particularly suitable for pediatric aphakic patients because it is extraocular and reversible and may be employed as a secondary procedure or in conjunction with cataract extraction. Only with longer follow-up of these and additional patients can these preliminary results be validated and the risk/benefit ratio of this procedure be assessed.
Journal of Pediatric Ophthalmology & Strabismus 18(6):23-9. · 0.63 Impact Factor
