RU2466699C1 - Method of treating corneal keratoconus - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: femtosecond laser is used to perform two arc corneal incisions with forming intrastromal 'pocket' in the cornea of the following topographic parameters: incision depth 120-140 mcm, depending on an initial corneal thickness, diameter - 9.0, 90° and 270° symmetrical arrangement of the corneal incisions. Thereafter, a cannula syringe is used to introduce 0.1% riboflavin in the formed 'pocket', kept for 15-20 minutes to impregnate a corneal stroma in a photosensitiser, while the cornea is exposed to UV light at wave length 365-375-nm for 30 minutes.

EFFECT: method provides fast delivery of the photosensitiser into the cornea without deepithelialisation, ensured enhanced functional results ensured by the use of empirically selected, optimal parameters of the corneal incisions.

2 cl, 2 ex

Description

The invention relates to ophthalmology and can be used to treat keratoconus of the cornea.

Keratoconus or ectasia of the cornea is a degenerative disease, when the strength of the collagen fibrils of the cornea weakens about half from normal values, which leads to the formation of a conical shape of the cornea, a shift in its center and astigmatism. The etiology and pathogenesis of keratoconus is not well understood. This disease can be primary, genetically determined, or secondary, which is one of the most serious complications of refractive surgery.

Hard gas permeable contact lenses (LCDs) have long been the only treatment for the initial stages of keratoconus. LCDs have a spherical shape, which allows you to "squeeze" the formed cone and, thus, artificially recreate a spherical surface. However, the use of these lenses does not stop the progress of keratoconus, in addition, it is not tolerated by all patients (E.N. Gorskaya, E.N.Sevostyanov, Contact correction - a means of stabilizing the progression of keratoconus, 1998).

A known method of laser surgery of early keratoconus, comprising a combination of photorefractive keratectomy (PRK) and phototherapeutic keratectomy (FTK). For surgery, an EC-5000 excimer laser from NIDEK is used. The diameter of the PRK is 6.0 mm. FTK is carried out with an ablation zone of 8.00. The FTK ablation zone is shifted in the direction of the site of greatest ectasia — the vertex of the cone; the topography and localization of the vertex are previously determined using computer topography (E. A. Kasparova. Diagnosis and treatment of early keratoconus. 2001). However, this method is invasive, in connection with this, serious postoperative complications are possible.

In recent years, to stabilize the pathological process with keratoconus, a new method of treatment has been proposed, which is based on cross-linking (cross-linking) - a term used in chemistry and bioengineering to refer to the chemical-physical effect on tissues, which results in “densification” or increase in the strength of the structural elements of this fabric. The effect of low-intensity ultraviolet light on the tissue of the stroma of the cornea in the presence of a photosensitive substance - riboflavin (vitamin B2) increases the production of short-lived oxygen free radicals, which, when released, cause the formation of bonds - bridges between previously separated collagen stroma fibrils, combining them into a single, solid network, strengthening corneal strength from 3 to 6 times.

Collagen crosslinking technique using ultraviolet irradiation and riboflavin developed by T.Seller, G. Wollensak in 2003 [Wollensak G., Spoerl E., Seiler T. Stress - strain measurements of human and porcine corneas after riboflavin Ultravoilet-A- induced collagen cross-linking // J Cataract Refract Surg. - 2003 .-- Vol.29. - P.-1780-1785] is successfully used for biomechanical stabilization of the cornea with progressive corneal ectasia in patients with initial keratoconus and iatrogenic keratectasia [Caporossi A., Baiocchi S. et al Parasurgical therapy for keratoconus by riboflavin - ultraviolet type A rays induced cross - linking of corneal collagen: Preliminary refractive results in an Italian study // J. Cataract Refract. Surg. - 2006. - Vol.32. - No. 5. - P.837-845, Pinelli R., C3-Riboflavin for the treatment of keratoconus // Cataract and Refractive surgery today. - 2006. - Vol. 1. - No. 4. - R. 49-50].

For example, there is a known method for treating keratoconus, including de-epitalization of the cornea, saturating it with a 0.1% riboflavin solution for 15 minutes, followed by irradiating the cornea with a focused beam of ultraviolet light from a Zeiler lamp (wavelength 370 nm) for 30 minutes at a distance of 1 cm and density power 3 mW / cm ² (G. Wollensak, E. Spoerl, T. Seiler, Riboflavin / ultraviolet-a-induced collagen cross-linking for the treatment of keratoconus. 2003).

The disadvantages of the method are carrying out de-epithelialization of the cornea to deliver the photosensitizer to the stroma of the cornea, which leads to a very long period of swelling of the cornea, as well as the possibility of progression of keratoconus due to insufficiently strong cross-links.

A known method of treating keratoconus by saturating the cornea with 2-5% riboflavin solution using 7-10 electrophoresis procedures, daily or with an interval of 1 to 2 days, followed by ultraviolet irradiation of the cornea with a power of 3 mW / cm ² and a total exposure of 30 minutes (patent RU 2345696 published on 02/10/2005).

The disadvantage of this method is its complexity and duration, since ultraviolet irradiation is carried out after each electrophoresis procedure against a background of medical myosis of the cornea.

The closest to the claimed method - the prototype - is a method of treating keratoconus, which consists in the following (patent RU 2388436, publ. 05/10/2010). After de-epithelialization of the cornea, a photosensitizer is instilled into the conjunctival cavity and the cornea is irradiated with ultraviolet light with a wavelength of 365-375 nm, while a 0.2% Photosens solution is used as a photosensitizer.

A disadvantage of the known method is to carry out corneal epithelialization for delivery of a photosensitizer to the stroma of the cornea, which leads to a very long period of corneal edema, a difficult recovery period, a long period of patient rehabilitation, and also the risk of infection.

An object of the invention is to reduce the risk of side complications, reducing the rehabilitation of patients and achieving high functional results of the operation.

The technical task is achieved by the proposed method, which consists in the following.

The femtosecond laser is programmed, which controls all the programmed parameters of the corneal incisions using a computer program and a sterile disposable aspherical interface. After preparation of the surgical field and local anesthesia, using a femtosecond laser, two arcuate corneal incisions are performed with the formation of an intrastromal “pocket” in the cornea with the following topographic parameters: incision depth 120-140 μm, the diameter of the application of corneal incisions is 9.0 mm, the location of the incisions is symmetrical 90 ° and 270 °. Then, the quality of the formed “pocket” is revised, for which a spatula is inserted through the upper corneal incision into the intrastromal space of the “pocket”, and the possibly remaining tissue bridges are additionally separated along the diameter of the entire “pocket”. After this, a 0.1% riboflavin solution is introduced into the intrastromal "pocket" with a syringe and cannula, wait 15-20 minutes to soak the corneal stroma with a photosensitizer, and the cornea is irradiated with ultraviolet light with a wavelength of 365-375 nm for 30 minutes. During irradiation, a 0.1% riboflavin solution is periodically instilled onto the cornea and the latter is injected with a syringe with a cannula into the intrastromal pocket. After the procedure is completed, an antibiotic is instilled into the conjunctival cavity and a soft contact lens is applied.

The determining differences of the proposed method, compared with the prototype, are:

- using a femtosecond laser, in accordance with the programmed parameters of the incisions, two arcuate corneal incisions are made with the formation of an intrastromal “pocket” intended for introducing a 0.1% riboflavin solution, which allows you to quickly deliver the photosensitizer to the cornea without de-epithelization and provide a short rehabilitation period;

- for the formation of the corneal “pocket”, experimentally selected, optimal topographic parameters of the corneal sections are used: the location of the corneal sections is 90 ° and 270 ° symmetrical, the section depth is 120-140 μm, the diameter is 9.0 mm, which ensures the most accurate location of the corneal “pocket” »And contributes to the achievement of the highest functional results with the least negative impact on the biomechanics of the cornea.

Thus, the formation using a femtosecond laser of the intrastromal corneal “pocket” of a predetermined optimal depth, shape and width for intrastromal administration of riboflavin, without de-epithelialization of the cornea, can significantly reduce the risk of surgical complications, increase the clinical safety and effectiveness of the proposed method.

In the postoperative period, it is possible to immediately prescribe corticosteroids (due to intact epithelium) for three weeks, as well as antibiotics during the first week.

The proposed method is illustrated by the following examples.

Example 1

Patient K., 24 years old (no. History of illness 00283002), sought advice from the Novosibirsk branch of the IRTC “Eye Microsurgery” with complaints of decreased vision. From the anamnesis it was found that visual impairment occurred about 3 years. Spectacle correction was not performed.

A complete ophthalmological examination was performed. Diagnosis: Keratoconus I degree of the right eye, II degree of the left eye.

Diagnostic data before surgery:

Visual acuity: right eye 0.6 s corr. Sph - 0.0 cyl - 0.75 ax 90 = 0.7

left eye 0.5 n / a

Refractometry: right eye Sph - 1.00 cyl - 0.75 ax 92

left eye Sph - 1.25 cyl - 1.50 ax 126

Keratometry: right eye Ver. Mer. 45.00 ax 163 Mountains Mer. 44.00 ax 73

left eye Ver. Mer. 46.25 ax 38 Mountains Mer. 44.25 ax 128

Pachymetry: right eye, center 469 microns

left eye, center 429 microns

The patient was treated with keratoconus of the claimed method.

The operation of forming corneal incisions with the formation of an intrastromal “pocket” was performed using a Technolas 520F femtosecond laser using radiation from a single-mode neodymium-glass optical quantum diode pump with a wavelength of 1053 nm and a pulse repetition rate of 700-800 fs. A femtosecond laser monitors all programmed incision parameters using a computer program and a sterile disposable aspherical interface.

After the installation of the vacuum ring, the laser console was docked using an aspherical interface with the patient’s cornea. For more convenient visualization and centering of the cornea during joining, the cornea was moistened with 2-3 ml of physiological saline. After the docking was completed and the necessary compression was achieved, the vacuum ring was closed, preventing the interface from moving along the patient’s cornea. Next, the process of applying corneal incisions with the formation of an intrastromal corneal “pocket” at a depth of 120 μm, a diameter of 9.0 mm, the location of the corneal incisions is symmetrical at 90 ° and 270 °.

Then the patient was transferred under the eyepieces of an excimer laser microscope and, using a flat spatula, introducing him through a 90 ° incision, made the final separation of tissue bridges over the entire radius of the corneal intrastromal “pocket”. Then, using a syringe with a minimum thickness of the cannula, 5 ml of a 0.1% solution of riboflavin was introduced into the intrastromal space of the cornea, 20 minutes were waiting to soak the stroma of the cornea with the preparation, and then the cornea was irradiated with ultraviolet light with a wavelength of 365 nm for 30 minutes. During irradiation, a 0.1% riboflavin solution was injected periodically (2 times per 1 minute) onto the cornea and the latter was injected using a syringe with a cannula into the intrastromal corneal “pocket”. After completion of the procedure, an antibiotic was instilled into the conjunctival cavity and a soft contact lens was applied.

The visual acuity of the left eye the day after removing the soft contact lens without correction is 0.50 n / a.

Visual acuity after 2 months: OS 0.5 corr. Sph - 0.75 cyl - 1.00 ax 132 = 0.6, after 3 months: 0.6 corr. Sph - 0.0 cyl - 1.00 ax 145 = 0.8

Example 2

Patient G., 24 years old (no. History of illness 00288540), sought advice from the Novosibirsk branch of the IRTC “Eye Microsurgery” with complaints of decreased vision of the left eye. From the anamnesis it was found that vision impairment occurred about 2 years. Spectacle correction was not performed.

A complete ophthalmological examination was performed. Diagnosis: Keratoconus I degree of the right eye, III degree of the left eye.

Diagnostic data before surgery:

Visual acuity: right eye 1.0

left eye 0.04 Sph 0.75 cyl - 6.0 ax 124

Refractometry: right eye Sph - 0.50 cyl - 0.0 ax 0

left eye Sph - 1.25 cyl - 7.25 ax 124

Keratometry: right eye Ver. Mer. 44.25 ax 101 Mountains Mer. 43.50 ax 11

left eye Ver. Mer. 49.5 ax 29 Mountains Mer. 42.5 ax 119

Pachymetry: right eye, center 498 microns

left eye, center 481 μm

The patient was treated with keratoconus of the claimed method analogously to example 1, except that the depth of the corneal incisions using a femtosecond laser was 140 μm (given the large thickness of the cornea).

Visual acuity after 1 month: OS 0.2 corr. Sph - 0.00 cyl - 4.00 ax 120 = 0.4.

According to keratotopography, after 2 months, a noticeable decrease in irregularity and a flattening of the curvature of the cornea were noted.

Using the proposed method will eliminate the stage of corneal de-epithelization and, accordingly, the associated side complications in the form of a corneal syndrome (pain, lacrimation, photophobia), lasting from one to two days, to quickly deliver the photosensitizer to the cornea without de-epithelization, and also to obtain high functional results through the use of experimentally selected, optimal parameters for performing corneal incisions.

Claims (2)

1. A method of treating keratoconus of the cornea, including the formation of an intrastromal pocket using a femtosecond laser, followed by introducing into the formed pocket a 0.1% solution of riboflavin, impregnating the cornea with the latter and irradiating the cornea with ultraviolet light with a wavelength of 365-375 nm for 30 minutes characterized in that first, using a femtosecond laser, in accordance with the programmed parameters of the cuts, two arched corneal cuts are performed with the following topographic parameters: the lubin of the incisions is 120-140 μm, the diameter of the application of corneal incisions is 9.0 mm, the arrangement of the incisions is symmetrical at 90 ° and 270 °, and then an intrastromal pocket is formed. 2. The method according to claim 1, characterized in that they use a femtosecond laser company "Technolas 520F" with a wavelength of 1053 nm, a pulse repetition rate of 700-800 fs.