Summit Technology, Inc.

Alex C Sacharoff

Peter J Klopotek

David F Muller

Richard G Caro

Troy Harmon

Mike D'Agati

Marc Friedman

Evan Sherr

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.

Photo-refractive keratectomy

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. Controlling the average repetition rate of the radiation pulses applied to the corneal surface so as to reduce intrapulse fluid accumulation at the corneal surface without dehydrating the corneal tissue, selecting an increased fluence level of the pulse applied to the corneal surface to reduce the effect of fluid accumulation at the corneal surface, and applying evaporative energy to the site of incidence of a pulse of an ablative beam prior to incidence of said pulse at said site are shown as ways to effect this control. Application of the new method and system to wide area ablation techniques and to scanning techniques are described Reduction of irregularities when ablating large areas, e.g., grater than 5.5 cm is made possible in either case.

Control of photorefractive keratectomy

The invention is a system and method for modifying the corneal curvature by irradiating the cornea to deliver thermal energy to the stroma. The system includes multiple irradiation ports for introducing electromagnetic radiation of a wavelength suitable for absorption in the stroma; positioning means, such as a hemi-spherical dome with several tracks for positioning the irradiation ports, respectively, at locations of a preselected geometric pattern relative to the pretreated cornea, the geometric pattern being selected to correspond to a desired modified shape of the cornea; transmission means adapted to deliver controlled amounts of the radiation from a radiation source to each of the irradiation ports; and the irradiation ports, positioned at the locations of the geometric pattern, constructed to introduce the radiation to treatment volumes of the stroma in a cooperative manner to induce desired shrinkage of the collagenous stromal tissue and cause change in the corneal curvature. Each treatment volume, formed by a radiation pattern emanating from one irradiation port or by intersection of radiation patterns emanating from multiple irradiation ports, is created in a controllable manner to have a desired volume and energy profile. The transmission means that includes fiber optic waveguides are connected to distribution means for dispensing controlled amounts of the radiation to each of the fiber optic waveguides. The system also includes inspection means for observing and evaluating the shrinkage of collagenous tissue.

Method and system for laser thermokeratoplasty of the cornea

Methods and apparatus for determining the depth of excision generated by a material removal process, for determining the thickness of unablated material below the excision or incision, and for providing endpoint control of a material removal process utilize acoustic transducers for measuring the time delay between a first acoustic pulse resulting from material removal and a second acoustic pulse reflected from a distal surface or boundary layer of the material. The time delay between the two pulses detected by the transducer provides a measure of excision depth and of the depth of material below the excision. Endpoint control is provided by terminating material removal when a selected excision depth is detected. The invention can be used, for example, as a real-time monitor of excision depth and residual lamella thickness under the excision during laser corneal surgery.

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Framingham, MA, United States of America

Alex C Sacharoff