RU2822813C1 - Method of treating progressive keratoconus of stages iii-iv - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to ophthalmology. Femtosecond keratotomy is performed with opening of produced notches, UV-crosslinking. High-frequency low-energy femtosecond laser interface applanation is performed, wavelength is 1,040-1,060 nm, pulse repetition frequency is 1 MHz, pulse duration ≤250 fs, maximum peak power of pulse – 800 W, maximum output power of laser beam – 300 mW, size of focusing spot less than 2 mcm. Further, the first stage involves formation of radial notches from 6 to 10, with punching of all layers to depth of 80% of the minimum value of keratopachymetry in the operation site using a femtosecond installation. Second step involves sequential opening of notches formed by femtosecond laser and introduction of 0.1% riboflavin solution into them. Further, de-epithelisation is performed on the periphery in the area between the notches without affecting the optical area.

EFFECT: method enables reducing postoperative complications such as epithelial ingrowth and formation of epithelial plugs, achieving higher visual acuity, stabilizing the keratectatic process by flattening the cornea and changing its shape.

1 cl, 2 ex

Description

The invention relates to medicine, namely to ophthalmology, and can be used for the purpose of conducting pathogenetically based treatment of keratoconus stages III-IV.

The relevance of keratoconus is determined by modern trends in increasing incidence, bilateral damage to the organ of vision, a wide age range - from 10 to 89 years, social significance due to the progressive nature of the course, leading patients to visual disability at a young working age (Sevostyanov E.N., Gorskova E.N., 2006).

As is known, keratoconus belongs to the collagenosis group of diseases; in this disease, the compaction of collagen in the corneal stroma is disrupted, which leads to weakening of its frame, thinning with subsequent sagging, cone-shaped protrusion and, as a result, even greater thinning. We have developed a new method for treating stage III-IV keratoconus using femtosecond laser incisions and UV cross-linking. The proposed invention interrupts this pathogenetic chain and makes it possible to delay or avoid keratoplasty in the absence of opacities in the central optical zone.

In keratoconus, corneal thickness varies significantly depending on the measurement point. In patients with advanced keratectasia, the cornea is extremely uneven. The proposed modern method for treating stage III-IV keratoconus allows you to adjust the depth of incision depending on pachymetry data, using optical coherence tomography (OCT) intraoperatively, the length and number of radial incisions. This method consists of successive stages of surgical intervention. A femtosecond keratotomy (FS-keratotomy) is performed simultaneously with the opening of the resulting incisions, followed by UV cross-linking.

In the preoperative period, all patients undergo a complex of diagnostic examinations: visometry with determination of BCVA and BCVA, biomicroscopy, computer keratotopographic examination of the cornea to study its topography, as well as pachymetry (μm) using the OCT method.

The closest analogue is a method for treating stage I-III keratoconus (variants) (patent No. 2676076). It consists of making 4-12 radial incisions in the annular zone of the cornea with a distance of 60 microns from the anterior surface of the cornea using the FemtoVisum femtolaser. Then UV crosslinking is performed.

Disadvantages of this method is an unsatisfactory refractive effect, lack of de-epithelialization of the cornea.

The objective of the claimed invention is to develop an effective, pathogenetically oriented method for treating keratoconus stages III-IV, allowing to stop its progression, avoid or significantly delay keratoplasty, increase visual functions, and improve the patient’s quality of life.

The technical result of our proposed method is the reduction of postoperative complications, such as epithelial ingrowth and the formation of epithelial plugs, achieving increased visual acuity, stabilizing the keratectasis process due to flattening of the cornea and changing its shape.

The technical result is achieved by the fact that in case of an advanced form of ectasia, 6-10 radial incisions are applied to cut through the epithelial layer, and in order to avoid complications, the incisions are simultaneously washed with a solution of riboflavin and filled with riboflavin for 30 minutes, followed by UV crosslinking.

The treatment method is as follows.

The surgical field is treated and drip anesthesia is administered. Applanation of the interface of a high-frequency low-energy femtosecond laser “Ziemer Femto LDV Z8” (Switzerland) is performed with the following parameters: wavelength 1040-1060 nm, pulse repetition frequency 1 MHz, pulse duration ≤250 fs, maximum peak pulse power - 800 W, maximum output laser beam power – 300 mW, focusing spot size less than 2 microns. The first step is to adjust the cutting parameters, namely the cutting depth, the length of the cuts, their number (from 6 to 10), and make cuts, depending on the type, stage of keratoconus and the amount of corneal astigmatism, with cutting through all layers to a depth of 80% of minimum keratopachymetry value at the surgical site using a femtosecond unit. The second step is to sequentially open the incisions formed by a femtosecond laser and introduce a 0.1% riboflavin solution into them. Next, de-epithelialization is performed on the periphery in the area between the incisions, without affecting the optical zone. The next step is UV crosslinking. The final stage was the instillation of an antiseptic and the application of a bandage contact lens.

There is a cause-and-effect relationship between the set of actions and the achieved technical result, aimed at stabilizing the keratecstatic process and increasing visual functions in the future.

The results of this method of treating stage III-IV keratoconus are confirmed by clinical examples.

Example No. 1. Patient A., 42 years old.

Diagnosis of OU: Keratoconus stage III (according to the Amsler-Krumeich classification, Izmailova S.B.).

Before surgery: Vis OD 0.04 sph -6.75 cyl -2.0 ax 65. BCVA: 0.1 n/k.

Before surgery, the patient underwent optical coherence tomography (OCT) to determine the thickness of the cornea, which was 298 μm in the center. The average corneal refractive power was 65.01 diopters. The operation was carried out with the following femtolaser parameters: wavelength 1040 nm, pulse repetition frequency 1 MHz, pulse duration ≤250 fs, maximum peak pulse power – 800 W, maximum output power of the laser beam – 300 mW, focusing spot size less than 2 μm. The first stage involves the formation of 6 radial incisions, with cutting through all layers to a depth of 80% of the minimum keratopachymetry value at the surgical site using a femtosecond unit. The second step is to sequentially open the incisions formed by a femtosecond laser and introduce a 0.1% riboflavin solution into them. Next, de-epithelialization is performed on the periphery in the area between the incisions, without affecting the optical zone. The next step is UV crosslinking.

The patient underwent a series of diagnostic studies at 1 week, 2 months, 4 months, 1 year and 2 years after surgery.

A week after surgery, the minimum thickness of the cornea according to OCT data was 294 μm, which is associated with compaction of the corneal stroma due to exposure to UV crosslinking. The average refractive power of the cornea (AveK) is 55.62 diopters. After two months, a decrease in the refractive power of the cornea was also observed, while its thickness remained unchanged. 1 year after surgery, AveK decreased to 49.2 diopters. The data is stable. The postoperative period was uneventful. 2 years after the operation, a study of the keratotopographic map of the cornea revealed a decrease in the area of ectasia and flattening of the cornea. At the same time, the average thickness of the cornea remains stable. Vis OD=0.5 n/k.

Example No. 2. Patient B., 39 years old. Entered the Federal State Institution “National Medical Research Center “MNTK Eye Microsurgery” named after. Academician S.N. Fedorov" of the Ministry of Health of the Russian Federation with complaints of low vision in both eyes.

Diagnosis of OU: Keratoconus stage III (according to the Amsler-Krumeich classification, Izmailova S.B.). Before surgery: Vis OS 0.05 sph -6.0 cyl -3.5 ax 140. BCVA: 0.2 n/k.

The minimum corneal thickness before surgery was 398 mm. The refractive power of the cornea was 58 diopters.

The operation was carried out with the following femtolaser parameters: wavelength 1060 nm, pulse repetition frequency 1 MHz, pulse duration ≤250 fs, maximum peak pulse power – 800 W, maximum output power of the laser beam – 300 mW, focusing spot size less than 2 μm. 8 radial incisions are formed, with all layers being cut to a depth of 80% of the minimum keratopachymetry value at the surgical site using a femtosecond unit. Next, the notches formed by the femtosecond laser are opened and a 0.1% riboflavin solution is introduced into them. The next stage is de-epithelialization on the periphery in the area between the notches, without affecting the optical zone. UV crosslinking was performed after FS keratotomy.

One month after surgery, the minimum corneal thickness was 370 µm. The average refractive power of the cornea (AveK) is 56 diopters. 1 year after surgery, AveK decreased to 51.09 diopters. The data is stable. The postoperative period was uneventful. 2 years after surgery, the patient underwent repeated diagnostic examinations. Visual acuity without correction was 0.5. No postoperative complications were observed.

The data obtained indicate an increase in visual functions with stabilization of the keratectic process. The proposed method makes it possible to avoid or significantly delay keratoplasty in stages III-IV of keratoconus.

Claims (1)

A method for treating progressive keratoconus of stages III-IV, characterized by femtosecond keratotomy with opening of the resulting incisions, UV cross-linking, characterized in that they perform applanation of the interface of a high-frequency low-energy femtosecond laser, wavelength 1040-1060 nm, pulse repetition rate 1 MHz, pulse duration ≤ 250 fs, maximum peak pulse power – 800 W, maximum output power of the laser beam – 300 mW, focusing spot size less than 2 µm, then the first stage is the formation of radial notches from 6 to 10, with cutting through all layers to a depth of 80% of the minimum value keratopachymetry at the surgical site using a femtosecond installation, the second stage is the sequential opening of the incisions formed by the femtosecond laser and the introduction of a 0.1% riboflavin solution into them, then de-epithelialization is performed on the periphery in the area between the incisions, without affecting the optical zone.