Abstract: The invention features improvements in PRK procedures that relate to preventing non-uniform removal of material from the corneal surface. It has been realized that photoablation by-products resulting during the PRK procedure can affect the accuracy and the predictability of the procedure. Under certain conditions, the plume of photoablation by-products that have left the corneal surface can non-uniformly redeposit onto the ablation area and thus affect the uniformity of subsequent material removal. The plume of photoablation by-products, in the space above the corneal surface, can also non-uniformly affect the escape of further photoablation products from the surface. In addition to the plume effects, it has been realized that the hydration level of the corneal tissue during the PRK procedure can vary over the ablation area and likewise non-uniformly affect the PRK procedure.

Abstract: Methods and apparatus are disclosed for removal of biological tissue slices or layers, preferably in the form of lamellar sections of predetermined shape and thickness employing a reference member that engages a target tissue site and cooperates with a cutter in order to remove the tissue segment or lamella. The cutter can include a flexible cutting element such as a wire or band element that is brought into physical contact with a guiding edge integrated with, or otherwise coupled to, the reference member. Alternatively, the cutter can include a stiff rigid blade element that is maintained in contact with the guiding edge. The cutter is drawn along a path defined by the guide edge through the tissue to sever, at least partially, a tissue section. In one particularly useful aspect of the invention, devices for keratectomy are disclosed employing an ocular reference member that engages the upper central region of the cornea and cooperates with a cutter to remove a lamellar segment from the cornea.

Abstract: Methods and apparatus for corneal reprofiling are disclosed in which a beam-swapping assembly is employed to redirect rays of ablative radiation passing through the assembly. Essentially, the beam-swapping assembly turns the beam profile "inside out" redirecting the inner most rays to the periphery of the beam while redirecting the outer rays at the same time to the center of the beam. The beam-swapping assembly can be used in conjunction with a beam-shaper, such as an adjustable iris or other beam-shaping device, to create convoluted annular ablation patterns of variable depth and, thereby, perform hyperopia and/or astigmatism correcting procedures.

Abstract: A beam profiler comprising: an intensity modifier constructed and arranged to separately modify the intensity profile of different subbeam portions of an initial beam to thereby create respective subbeams each having a respective predetermined modification; and a subbeam-directing optical system constructed and arranged to direct the multiple subbeams along respective subbeam beam paths that substantially overlap in an overlap plane, whereby, a resulting beam of radiation is created at the overlap plane that has an intensity profile equal to the optical incoherent summation of the predetermined intensity profiles of said overlapping subbeams. The intensity modifier preferably comprises an array of intensity-modifying profiling elements disposed across the initial beam each producing a corresponding subbeam.

Abstract: Methods and apparatus are disclosed for removal of biological tissue slices or layers, preferably in the form of lamellar sections of predetermined shape and thickness employing a reference member that engages a target tissue site and cooperates with a cutter in order to remove the tissue segment or lamella. The cutter preferably includes a flexible cutting element such as a wire or band element that is brought into physical contact with a guiding edge of the reference member and then draw along a path defined by the guide edge through the tissue to sever, at least partially, a tissue section. In one particularly useful aspect of the invention, methods and apparatus for keratectomy are disclosed employing an ocular reference member that engages the upper central region of the cornea and cooperates with a cutter to remove a lamellar segment from the cornea.

Abstract: A method and system are described for performing photorefractive keratectomy procedure employing pulses of photoablative radiation to selectively ablate corneal tissue of a patient's eye in an ablation zone on the anterior corneal surface to produce a desired refractive correction in the corneal tissue. The method and system employ control of the effect of ocular fluid at the corneal surface so as to reduce the disturbance of such fluid on the desired ablation process while maintaining hydration of the corneal tissue.

Abstract: A calibration apparatus is disclosed for measuring the properties of a laser beam. The apparatus includes a photoreactive element having a composition which reacts with laser radiation in a manner proportional to the intensity or intensity profile of the laser beam and an alignment means for disposing the photoreactive element in the path of a laser beam, such that the beam can be activate to impinge upon the photoreactive element and the properties of the beam are recorded by changes in the state of the calibration element. The calibration element may also be used to provide corrective feedback for modifying or controlling the properties of the laser beam.

Abstract: Apparatus and methods to modify the intensity distribution of a beam of radiation, such as a laser, and for eroding surfaces with predetermined shapes. A rotatable mask is formed with one or more apertures that have a geometric spiral shape originating substantially the center of rotation on the mask. The mask is insert to the beam for modification of the intensity of that beam, and additionally to form the desired etch pattern on a target surface. In a preferred embodiment, the invention is useful for performing kerotoplasty or keratomileusis.

Abstract: Methods and systems are disclosed for corneal reprofiling employing an annular beam of ablative radiation to correct refractive errors in vision, and/or create "blend zones" in order to reduce any surface discontinuities on the cornea following hyperopia-correcting or astigmatism-correcting procedures. Preferably, the methods and systems of the present invention also operate to change the intensity distribution of the light beam, such that the annulus of radiation has a varying intensity as a function of radius and, thereby, achieves a blending or other desired effect with the least number of pulses.

Abstract: The invention is a system and method of measuring the shape of a surface. The corneal topographer specifically shown comprises a rigid reference member having a reference surface of a predetermined shape applied to the surface of the eye. The shape of the reference surface is correlated with the measured information to determine the shape of the corneal surface. Several specific designs are shown that use optical, acoustic, acousto-optic or capacitive techniques to determine a distance between the reference surface and the corneal surface over a multiplicity of data points sufficient in number and spacing to represent the local topography of the surface of the eye.

Abstract: Methods and apparatus as disclosed for shaping the cornea of a patient's eye such that the epithelial tissue of the patient's cornea is shaped into a preliminary shape, corresponding to a desired final stromal shape, using photoablative radiation, and then the preliminary shape of the epithelial tissue is transferred into the stromal tissue of the cornea using photoablative radiation, thereby shaping the cornea into the desired final stromal shape. The epithelium may be shaped using an erodible mask with a predefined profile of resistance to erosion, or by a graded intensity filter, or by selectively varying the dimension of an aperture that controls the area of the epithelial surface irradiated by the photoablative laser radiation or by other mechanisms that selectively expose regions of the epithelium, or by a scanning laser beam. The epithelium may also be shaped, without using an aperture or a mask, by using a beam of photoablative radiation with substantially uniform intensity distribution.

Abstract: The invention is a system and method of measuring the shape of a surface. The corneal topographer specifically shown comprises a transparent rigid reference member having a reference surface of a predetermined shape, a conformable substance capable of assuming the conformation of surfaces being pressed against, a light source for irradiating the conformable substance pressed between the reference surface and the corneal surface, and a detection system for detecting light propagating from the reference member and carrying information about the thickness. Two specific designs are shown, both based on differential topography. The first design uses a fluorescent conformable substance which fills the space between the reference surface and the corneal surface. The local intensity of fluorescent radiation detected by the detection system is correlated to the local thickness of the fluorescent conformable substance.

Abstract: Laser surface ablation methods and apparatus are disclosed reprofiling surfaces astigmatically. An optical system includes cylindrically-powered elements to form an elliptical laser irradiation pattern on a target surface. By successively altering the area of the elliptical irradiation, an astigmatic, bi-powered ablation profile is achieved. Preferably, the invention is used with an excimer laser for excimer laser keratoplasty, keratomileusis or other ablative eye surgeries.

Abstract: A method and system for reshaping Bowman's membrane, which lies directly below the anterior epithelial surface of the cornea, to provide correction of refractive errors in the eye by photoablation of selective regions of the Bowman's membrane without substantial penetration into the stroma of the eye is disclosed including a laser and a beam-shaping mask, disposed between the laser and the surface of the cornea, which imposes a defined ablation profile upon the Bowman's membrane by laser radiation. The system can also include a feedback control for measuring the effectiveness of the laser during operation and for controlling the laser such that the reprofiling operation is substantially confined to the Bowman's membrane throughout the procedure. The beam-shaping mask can include either an aperture e.g.

Abstract: Apparatus and methods are disclosed for astigmatically ablating surfaces in order to impart new profiles and curvatures to such surfaces. A laser means, e.g., a rapidly pulsed laser radiation source, is aligned with a surface to provide photoablative pulses of energy along an optical path to a target region on the surface. A light restricting means, such as an adjustable iris or profiled mask, is disposed within the optical path to spatially control the extent of the laser radiation striking the target surface. The light restricting means is adapted to permit orientation (e.g., tilting) in various planes relative to the optical path in order to modify the symmetry of the laser beam, e.g., from a circular shape to an elliptical shape, and thereby provide astigmatic ablation of the surface in a single step.

Abstract: Methods and apparatus are disclosed for the correction of presbyopia by reprofiling the cornea to create at least one region having a different focal point, and thereby assist the eye in accommodating for close-viewing conditions. According to the invention, at least one region of different curvature is created by photoablation of the cornea to permit the eye to accommodate for near objects. This "add" region is preferably located near the center of the optical zone and preferably within Bowman's membrane or the adjacent upper portions of the stroma, which lies directly below Bowman's membrane. Apparatus is disclosed, including a laser means and a beam-shaping means, disposed between the laser means and the surface of the cornea, which imposes a defined ablation profile upon the cornea. The system can also include a feedback control means for measuring the effectiveness of the laser during operation and for controlling the laser. The beam-shaping means can include either an aperture e.g.

Abstract: Systems and methods are disclosed for aligning and confining laser beam exposure to a defined target region of biological tissue during laser surgery by employing a floating lens which is mechanically coupled to a reference element, such as a target tissue securing assembly, in order to compensate for movements of the target during surgical procedures. The floating lens forms part of the imaging optics and, by its design, direct the laser beam to follow the movements of the target tissue regardless of translational movements of the target.

Abstract: Methods and apparatus for correction of optical defects in vision, employing an infrared radiation source and a focusing element, for changing the curvature of the eye by application of focused infrared radiation into the collagenous tissue of the cornea in a controlled manner.

Abstract: A laser system for reprofiling a surface, such as the corneal surface of an eye, comprising a laser and a photoreactive mask disposed between the laser means and the surface for providing a predefined profile of resistance to laser radiation, such that, upon irradiation of the mask, a portion of the laser radiation is selectively absorbed and another portion is transmitted to the surface, in accordance with the mask profile, to selectively erode the surface. The mask can be connected to the support structure and disposed in optical alignment with the laser means and the surface. The mask can be directly integrated with support structure attached to the surface or spatially separated from the surface and imaged onto the surface. In one preferred embodiment, the mask includes a transparent matrix and light-absorbing dispersoids selectively distributed within the matrix, such that the dispersed elements are progressively bleached by exposure to the laser radiation.

Abstract: A method and device for lifting the epithelium from a selected area of the eye using an incision instrument for cutting the epithelium to define an area of the epithelium to be removed, and a fluid jet assembly for separating the selected area of the epithelium from the underlying layer. The incision instrument shown has a series of incision elements distributed about a peripheral pattern, arranged to cut the epithelium in the direction of its thickness without disturbing the underlying layer, to create a tear line. The jet assembly directs through the tear line a fluid jet in the manner that the fluid progresses inwardly from the tear line and effectively wedges the epithelium from the underlying layer. The device shown also has an epithelium support structure for engaging the exterior surface of the delineated area of the epithelium in order to support and maintain the structural integrity of the lifted epithelium.