RU2113835C1 - Method for surgical correction of residual myopia after keratotomy - Google Patents

Abstract

FIELD: medicine, surgical ophthalmology. SUBSTANCE: method deals with evaporation of surface layers in central corneal area by an impact of ultraviolet laser radiation directed through myopic forming system by taking not higher than a half of keratotomic cicatrix against a center, at the same time the rest corneal thickness should be 300 mcm, not lower, an impact is conducted at 170-270 mJ/cm² beam energy density and 10 Hz frequency and 15 millisecond impulse duration in a central corneal area of 5-7 mm diameter. EFFECT: higher efficiency of the operation.

Description

 The invention relates to medicine, and more particularly to ophthalmology, and can be used for excimer correction of residual myopia after keratotomy.

 A known method for the correction of residual myopia after keratotomy, including repeated radial keratotomy using a keratotomy knife (Fedorov S.N. Sarkizova MB, Effect of using a dosed knife on the effectiveness of repeated neratotomy, Collection of scientific papers "Surgery of eye refraction anomalies" p. 43 - 47, - M., 1081).

 However, when using the known method, macro-and microperforations are possible. In addition, the method is not effective in cases where residual myopia is large, and with a primary keratotomy, the maximum number of incisions of the maximum possible length and depth was performed.

 The technical task is to create a method for repeated correction of residual myopia after keratotomy in order to increase visual functions without correction by evaporation of the upper layers of the cornea, which can be done in almost all cases.

 Thus, the indications expand, opportunities for the correction of residual myopia.

 The technical result achieved by using the invention is to improve visual functions without correction due to the evaporation of the surface layers of the cornea of the desired shape.

 The technical result is achieved by the fact that the surface layers of the central zone of the cornea are evaporated by the radiation of a UV laser transmitted through the myopic forming system (ed. St. 1637795, class A 61 F 9/00 - Method for the surgical treatment of moderate and high myopia), capturing no more than 1/2 the length of the keratotomy scar from the center, while the remaining thickness of the cornea should be at least 300 microns.

The exposure is carried out by a UV laser with an energy density of 170 - 270 mJ / cm ² , a frequency of 10 Hz, a pulse duration of 15 ns, in the central zone of the cornea with a diameter of 5 - 7 mm.

 UV laser radiation is passed through the myopic forming system, by means of which the surface layers of the cornea of the desired shape are evaporated in accordance with the refractive parameters of the patient, that is, they change the radius of curvature of the cornea after surgery.

 The method is as follows.

 Patients undergo anesthesia with a 1% solution of dicain, instilling it in the conjunctival sac twice with an interval of 5 minutes. They put the patient on a special operating mobile table having 3 degrees of freedom. Combine the center of the cornea with the center of the laser beam, moving the patient with a table. The eyelids are held by a special eyelid holder. The patient fixes his gaze on the helium-neon beam. Under visual control, using an operating microscope, keratoablation is performed with energy and the number of pulses calculated in advance using a special computer program.

 The eye is washed with a 0.25% solution of chloramphenicol and an aseptic dressing is applied.

 Influenced by UV laser radiation transmitted through the myopic formation system (ed. St. USSR 1637795, 1989) on the cornea, capturing no more than 1/2 the length of the keratotomy scar from the center, since an increase in the area of laser exposure can weaken the previously achieved refractive effect after keratotomy, an increase in the invasiveness of the operation or failure to achieve the required refractive effect.

 Example 1. B-naya K., 27 years old, diagnosis: High degree residual myopia after radial keratotomy of the left eye.

Visual acuity OS 0.05 sph-6, OD 0.6. The diameter of the cornea is 12 mm. The central area without notches is 3.0 mm. An excimer laser keratectomy was performed with an energy of 170 mJ / cm ² , a frequency of 10 Hz, a pulse duration of 15 ns, and a diameter of refraction of 5 mm. Keratotomy scars are ablated less than 1/2 of the length from the center, the residual thickness of the cornea in the center is 350 microns. At the end of the operation, a 0.25% solution of chloramphenicol was instilled into the conjunctival cavity, an aseptic dressing was applied. Visual acuity after 2 weeks 0.6 without correction.

 Example 2. Patient B., 38 years old, diagnosis: Residual moderate myopia after radial keratotomy of the right eye.

Visual acuity OD 0.08 sph-4.5 D 0.9, diameter of the cornea 11.8 mm, the central zone without incisions 3.2 mm. An excimer laser keratectomy was performed with an energy of 270 mJ / cm ² , a frequency of 10 Hz, a pulse duration of 15 ns, and a diameter of refractive exposure of 7 mm. Keratotomy scars are ablated no more than 1/2 of the length from the center, the residual thickness is 410 microns. An instillation of a 0.25% solution of chloramphenicol in the conjunctival cavity was made, an aseptic dressing was applied. Visual acuity after 2 weeks 0.9 without correction.

Claims (1)

A method of surgical correction of residual myopia after keratotomy, which consists in the implementation of a surgical intervention, characterized in that the surface layers of the central zone of the cornea are evaporated by the UV laser transmitted through the myopic forming system, capturing no more than 1/2 the length of the keratotomy scar from the center, the remaining thickness of the cornea should be at least 300 microns, with exposure to a UV laser with a beam energy density of 170 - 270 mJ / cm ² , a frequency of 10 Hz, and a pulse duration and 15 ns in the central zone of the cornea with a diameter of 5 to 7 mm.