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A Rotating Slit Delivery System for Excimer Laser Refractive Keratoplasty
474
AMERICAN JOURNAL OF OPHTHALMOLOGY
A Rotating Slit Delivery System for Excimer Laser Refractive Keratoplasty
March, 1987
0.48 mm thick was excised and held on a con cave suction punch block, and was exposed to the laser for five minutes. The rotating slit excimer laser beam in the first eye ablated a well-defined circular zone, Khalil Hanna, M . D . , which progressively covered the central cor J. C. Chastang, nea. The central cornea was sculpted as a crater Yves Pouliquen, M . D . , with sloping sides. Transmission electron mi G i l l e s Renard, M . D . , croscopy showed that the epithelial cells were Louis Asfar, cut cleanly, as were Bowman's layer and the and George O. Waring III, M . D . stroma. A thin, electron-dense, discontinuous layer approximately 0.05 u.m thick covered Department of Ophthalmology, Hotel-Dieu Hospital (K.H., Y.P., and G.R.), IBM Scientific Center (K.H., most of the surface. J.C.C., and L.A.), and the Department of Ophthal Scanning electron microscopy demonstrated mology, Emory Eye Center (G.O.W.). that the superficial portion of the epithelial Inquiries to Khalil Hanna, M.D., Hotel-Dieu Hospital, cells had disappeared and the more resistant Department of Ophthalmology, 1 Place du Paris Notre nuclei appeared in relief. The cut surfaces of Dame, 75004 Paris, France. Bowman's layer had a granular, fine fibrillar Recent use of lasers to reshape the cornea for structure. The collagen fibrils of the stroma refractive keratoplasty 1,2 has defined three were not visible. The striated and the homoge major problems that must be solved before neous layers of Descemet's membrane were these systems can be used clinically: (1) identi apparent. fication of a safe and effective laser, (2) design In order to perform excimer laser refractive of a workable delivery system, and (3) develop keratoplasty, we designed a simple rotating slit ment of a mechanism for optically or mechani delivery system that would accomplish photocally coupling the laser to the eye. We describe ablative etching of the corneal surface in situ or here a rotating slit delivery system for use with on excised lenticules^By changing the shape of a 193-nm excimer laser. the slit and the rate of rotation, a profile of We used an excimer laser to produce 193-nm tissue can be resected to correct myopia, hyperradiation. The beam illuminated a rotating ra metropia, and astigmatism. dial slit whose shape created an ablation pro Morphologically, we observed effects similar file, deeper in the center of the cornea to correct to those previously noted by Marshall and myopia. A 45-degree mirror and a spherical associates 1 and Puliafito and associates. 3 2 lens created a 2.25-mm slit image on the cor nea, which was viewed through an operating microscope. References The total output of the laser was 167 mj per pulse. The energy delivered to the cornea was about 4.5 mj per pulse, with the fluence at 1. Marshall, J., Trokel, S., Rothery, S., and Krueger, R. R.: Photoablative reprofiling of the cor the level of the cornea about 200 mj/cm2. The nea using an excimer laser. Photorefractive kerateclaser was operated at 20 Hz. The slit rotated at tomy. Lasers Ophthalmol. 1:21, 1986. 0.0333 Hz. Because each laser pulse lasted 2. Seiler, T., Marshall, J., Rothery, S., and about 23 nsec, the slit was effectively stationary Wollensak, J.: The potential of an infrared hydrogen during each pulse. A helium-neon laser was fluoride (HF) laser (3.0 (wrt) for corneal surgery. used for centering. Lasers Ophthalmol. 1:4, 1986. We tested this system on two freshly enucle 3. Puliafito, C. S., Steinert, R. F., Deutsch, T. F., ated human eyes. The anterior surface of one Hillenkamp, F., Dehm, E. J., and Adler, C. M.: cornea was exposed until corneal perforation Excimer laser ablation of the cornea and lens. Experi occurred at the center (30 min). Using a micromental studies. Ophthalmology 92:741, 1985. keratome, a disk about 8.5 mm in diameter and
AMERICAN JOURNAL OF OPHTHALMOLOGY
A Rotating Slit Delivery System for Excimer Laser Refractive Keratoplasty
March, 1987
0.48 mm thick was excised and held on a con cave suction punch block, and was exposed to the laser for five minutes. The rotating slit excimer laser beam in the first eye ablated a well-defined circular zone, Khalil Hanna, M . D . , which progressively covered the central cor J. C. Chastang, nea. The central cornea was sculpted as a crater Yves Pouliquen, M . D . , with sloping sides. Transmission electron mi G i l l e s Renard, M . D . , croscopy showed that the epithelial cells were Louis Asfar, cut cleanly, as were Bowman's layer and the and George O. Waring III, M . D . stroma. A thin, electron-dense, discontinuous layer approximately 0.05 u.m thick covered Department of Ophthalmology, Hotel-Dieu Hospital (K.H., Y.P., and G.R.), IBM Scientific Center (K.H., most of the surface. J.C.C., and L.A.), and the Department of Ophthal Scanning electron microscopy demonstrated mology, Emory Eye Center (G.O.W.). that the superficial portion of the epithelial Inquiries to Khalil Hanna, M.D., Hotel-Dieu Hospital, cells had disappeared and the more resistant Department of Ophthalmology, 1 Place du Paris Notre nuclei appeared in relief. The cut surfaces of Dame, 75004 Paris, France. Bowman's layer had a granular, fine fibrillar Recent use of lasers to reshape the cornea for structure. The collagen fibrils of the stroma refractive keratoplasty 1,2 has defined three were not visible. The striated and the homoge major problems that must be solved before neous layers of Descemet's membrane were these systems can be used clinically: (1) identi apparent. fication of a safe and effective laser, (2) design In order to perform excimer laser refractive of a workable delivery system, and (3) develop keratoplasty, we designed a simple rotating slit ment of a mechanism for optically or mechani delivery system that would accomplish photocally coupling the laser to the eye. We describe ablative etching of the corneal surface in situ or here a rotating slit delivery system for use with on excised lenticules^By changing the shape of a 193-nm excimer laser. the slit and the rate of rotation, a profile of We used an excimer laser to produce 193-nm tissue can be resected to correct myopia, hyperradiation. The beam illuminated a rotating ra metropia, and astigmatism. dial slit whose shape created an ablation pro Morphologically, we observed effects similar file, deeper in the center of the cornea to correct to those previously noted by Marshall and myopia. A 45-degree mirror and a spherical associates 1 and Puliafito and associates. 3 2 lens created a 2.25-mm slit image on the cor nea, which was viewed through an operating microscope. References The total output of the laser was 167 mj per pulse. The energy delivered to the cornea was about 4.5 mj per pulse, with the fluence at 1. Marshall, J., Trokel, S., Rothery, S., and Krueger, R. R.: Photoablative reprofiling of the cor the level of the cornea about 200 mj/cm2. The nea using an excimer laser. Photorefractive kerateclaser was operated at 20 Hz. The slit rotated at tomy. Lasers Ophthalmol. 1:21, 1986. 0.0333 Hz. Because each laser pulse lasted 2. Seiler, T., Marshall, J., Rothery, S., and about 23 nsec, the slit was effectively stationary Wollensak, J.: The potential of an infrared hydrogen during each pulse. A helium-neon laser was fluoride (HF) laser (3.0 (wrt) for corneal surgery. used for centering. Lasers Ophthalmol. 1:4, 1986. We tested this system on two freshly enucle 3. Puliafito, C. S., Steinert, R. F., Deutsch, T. F., ated human eyes. The anterior surface of one Hillenkamp, F., Dehm, E. J., and Adler, C. M.: cornea was exposed until corneal perforation Excimer laser ablation of the cornea and lens. Experi occurred at the center (30 min). Using a micromental studies. Ophthalmology 92:741, 1985. keratome, a disk about 8.5 mm in diameter and