RU2817339C1 - Method of reducing intraocular pressure by peripheral laser iridotomy - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to ophthalmology. Intraocular pressure level is reduced by peripheral laser iridotomy, including laser exposure on iris to form iridotomy opening, characterized in that at the first stage, the patient undergoes optical coherent angiography (oct-a) of the iris and optical coherence tomography (oct) of the anterior segment of the eye, on the basis of which an avascular zone is determined for the formation of an iridotomic opening in the peripheral region of the iris, at the second stage in this zone applicates are applied in the form of a circle in amount of 5–15 pieces using a diode laser with wavelength of 532 nm, with power of 120–170 mW, with exposure of 0.03 ms, a spot diameter of 100 mcm, then, in the centre of the applicate application area, a series of laser pulses is performed using a YAG laser with energy of 2.4–4.2 J to form an iridotomic opening.

EFFECT: method enables to obtain a hypotensive effect and to avoid haemorrhagic complications during laser iridotomy in patients with closed-angle glaucoma and an anatomically narrowed angle of the anterior chamber.

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Description

The invention relates to the field of medicine, namely to ophthalmology, and can be used in the treatment of angle-closure or mixed glaucoma, in patients with a narrow angle of the anterior chamber of the eye, as well as in the elimination of pupillary block and pigment dispersion syndrome.

Disruption of the constant circulation of aqueous humor filling the anterior and posterior chambers of the eye leads to blockade of the anterior chamber angle and significant changes in the hydrodynamics of the eye with the development of angle-closure glaucoma. The topographic relationship of the eye structures involved in the blockade of the anterior chamber angle determines the leading pathogenetic mechanism of the blockade of the anterior chamber angle. However, the iridociliary zone, where the main processes occur during intraocular blocks, remains inaccessible to clinical research methods, which makes it difficult to differentiate the types of intraocular blocks in primary angle-closure glaucoma.

Primary angle-closure glaucoma (PACG) continues to be one of the leading causes of irreversible blindness, with an increasing trend in the number of patients (Tham YC, et al. Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis. Ophthalmology . 2014; 121(11): 2081-2090). Among the many unresolved problems of primary angle closure disease (PAC), the most important is the tactics of its management in the early stages: when primary angle closure (PAC) is suspected and directly in case of primary angle closure (PAC).

The traditional method of treating ROM is peripheral laser iridotomy (PLIT), leading to an improvement in the topography of the anterior chamber angle (Zhekov I, et al. Optical coherence tomography-measured changes over time in anterior chamber angle and diurnal intraocular pressure after laser iridotomy. Clin Exp Ophthalmol. 2019 May; 47(4): 557; Clin Exp Ophthalmol. 2018; 46(8): 895-902) and reducing intraocular pressure (IOP) fluctuations. In addition, the risk of developing ROM may be present both in the immediate (Nonaka A, et al. Cataract surgery for residual angle closure after peripheral laser iridotomy. Ophthalmology. 2005; 112(6): 974-979) and in the long term (6 -18 months) after laser intervention (Jiang Y, et al. Longitudinal changes of angle configuration in primary angle-closure suspects: the Zhongshan Angle-Closure Prevention Trial. Ophthalmology. 2014; 121(9): 1699-1705).

Residual angle closure is associated with several mechanisms of blockade of the APC, and not just pupillary block, the priority treatment for which is laser iridotomy (Kwon J., Sung K.R., Han S. Long-term Changes in Anteri - or Segment Characteristics of Eyes With Different Primary Angle - Closure Mechanisms. J. Ophthalmol. 2018; 191: 54-63).

There is a known method of treating primary angle-closure glaucoma, which consists in the fact that patients undergo laser iridotomy, after which optical correction is applied with progressive glasses for one hour. The method allows to increase the effectiveness of treatment of primary angle-closure glaucoma in the initial stage in patients with hypermetropia (patent RU 2776729 C1, published 07/26/2022)

There is a known method of treating primary angle-closure glaucoma, which consists in the fact that the patient at the first stage undergoes peripheral laser iridotomy. At least 2 months later, the density of the corneal endothelium and the depth of the anterior chamber of the eye are determined. If the density of the corneal endothelium is not less than 2436 cells/mm ² , the depth of the anterior chamber is not less than 2.62 mm, and the patient’s age is not more than 65 years, selective laser trabeculoplasty is performed (patent RU 2776729 C1, published on July 26, 2022)

There is a known method of surgical treatment of patients with primary closure of the anterior chamber angle (ACA) with intraocular pressure less than 30 mm Hg. Art. To do this, in this category of patients, the value of intraocular pressure, the length of the anterior-posterior axis of the eye, the depth of the anterior chamber of the eye are determined, and gender is taken into account. The value of Ind is calculated using the developed mathematical formula. If the Ind value is less than zero, peripheral laser iridotomy is performed. If the Ind value is greater than zero, lensectomy is performed (patent RU 2797850 C1, published 06/08/2023).

The disadvantage of the known methods is that the personal anatomical features of the iris are not taken into account, which reduces the effectiveness of laser iridotomy.

It is known that the incidence of hemorrhagic complications when performing peripheral laser iridotomy using Nd:YAG lasers reaches 40%. (Jiang Y, et al. Immediate changes in intraocular pressure after laser peripheral iridotomy in primary angle-closure suspects. Ophthalmology. 2012 Feb;l 19(2):283-8). The presence of heme residues in the juxtacanalicular trabecular meshwork prevents the outflow of aqueous humor from the anterior chamber angle and causes an increase in IOP.

The prototype closest to the claimed method is a method for reducing the level of intraocular pressure by standard peripheral YAG laser iridotomy, which consists of the following. 30 minutes before surgery, local anesthesia is instilled with a 0.4% solution of oxybuprocaine or corresponding analogues. Then an Abraham lens is installed on the patient’s eye, the beam is focused on the front surface of the iris and a series of several (5 to 10) pulses are produced with a power of 2.0 to 6.0 mJ. When the iris is perforated, the flow of fluid with pigment into the anterior chamber is visualized. (Glaucoma. National Guidelines 2022, ed. GOETAR-Media).

The disadvantage of the traditional method of laser iridotomy is the lack of an objective assessment of the angioarchitecture of the patient’s iris, which leads to a high risk of developing hemorrhagic complications, accompanied by decreased visual function, increased IOP, and staining of the corneal endothelium with blood. All of the above complications significantly reduce the effectiveness of this operation.

The objective of the invention is to develop a personalized, more effective method for reducing intraocular pressure using peripheral laser iridotomy.

The technical result of the proposed method is to increase efficiency and reduce the risk of hemorrhagic complications.

The proposed method is as follows.

At the first stage, before performing an iridotomy, the patient undergoes optical coherence tomography (OCT) of the anterior segment of the eye and optical coherence angiography (OCT) of the iris. According to October data, skeletonization of the image is performed in order to determine the avascular zones of the iris. This image is combined with the data from the anterior segment octography and the topographically optimal, avascular zone is determined for the formation of an iridotomy hole in the peripheral region of the iris. At the next stage, coagulation of the iris is performed in this area by applying single applications. Applications are applied in the form of a circle in quantities from 5 to 15 pieces using a dioid laser with a wavelength of 532 nm, with the following laser parameters: power 120-170 mW, exposure 0.03 ms, spot diameter 100 μm. Next, in the center of the application area, a series of several laser pulses is performed using a YAG laser (YAG laser iridotomy) with an energy of 2.4-4.2 J to form an iridotomy hole, while the number of laser pulses depends on the thickness and degree of pigmentation of the iris . At the moment of perforation of the iris, the flow of fluid with pigment from the posterior chamber of the eye to the anterior chamber is visualized.

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

1) For the patient, in accordance with his anatomical features of the iris, based on optical coherence tomography with the angiography function of the anterior segment, the most favorable avascular zone with the minimum thickness of the peripheral region of the iris for the formation of the iridotomy hole is determined.

2) In the avascular zone, coagulation of the iris is performed by applying single applicates in the form of a circle in the amount of 5-15 pieces using a dioid laser with a wavelength of 532 nm, with an energy of 120-170 mW, with an exposure of 0.03 ms, with a spot diameter of 100 microns, which reduces the risk of developing intraoperative hemorrhagic complications.

2) In the center of the application area, YAG laser iridotomy is performed with an energy of 2.4-4.2 J, which makes it possible to achieve the formation of a complete iridotomy opening using a smaller number of pulses, thereby reducing the laser effect on the corneal endothelium.

The invention is illustrated by the following examples of specific implementations of the method.

Example 1.

Patient M., 75 years old, diagnosis: Pupillary block. Anterior chamber intraocular lens (IOL). On examination, mild swelling of the corneal stroma, a shallow anterior chamber, and swelling of the iris were observed. During gonioscopy, the trabecula is not visualized. When performing ultrasound biomicroscopy, the anterior chamber is 1.5 mm, the anterior chamber lens is filled, the anterior chamber angle is closed in all meridians, the posterior IOL arms are evenly tucked behind the iris. Intraocular pressure was measured by the Maklakov applanation method and was 28/14 mm Hg.

The treatment was carried out using the claimed method. At the first stage, the patient underwent optical coherence tomography (OCT) of the anterior segment of the eye and optical coherence angiography (OCT) of the iris according to the Angio Retina 6 - mm protocol through the center of the pupil on an Optovue RTVue tomograph. After performing OCT and OCT of the iris and skeletonizing this image, the thinnest avascular zone of the iris was determined, which was located at 6 o’clock in the right eye and at 10 o’clock in the left eye. Then, in the selected area, the iris was coagulated using a laser with a wavelength of 532 nm, with an energy of 170 J, with an exposure of 0.03 ms, a spot diameter of 100 μm, the number of applications was 15 pieces, which were applied in the form of a circle. Next, in the center of the application area, a YAG laser iridotomy was performed with an energy of 2.4 J, the number of pulses was 7. At the moment of perforation, the flow of fluid with pigment from the posterior chamber of the eye to the anterior chamber was visualized.

After the operation, deepening of the anterior chamber, opening of the anterior chamber angle, and a decrease in intraocular pressure to 21 mm Hg were observed.

Example 2.

Patient K., 82 years old, diagnosis: suspected glaucoma. Anatomically narrowed angle of the anterior chamber. Complicated cataract. Nonproliferative diabetic retinopathy, moderate. Moderate hypermetropia. At the time of examination, the depth of the anterior chamber was 2.3 mm, the length of the anterior-posterior axis of the eyeball was 22.5 mm, and the thickness of the lens was 4.55 mm. Intraocular pressure was measured by the Maklakov applanation method and was 24/20 mm Hg. Gonioscopy revealed a narrow angle of the anterior chamber in all meridians.

The treatment was carried out using the claimed method. After performing OCT and OCT of the iris and skeletonizing this image, the thinnest avascular zone of the iris was determined, which was located at 5:30 o’clock in the right eye and 11:15 o’clock in the left eye. Then, in the selected area, the iris was coagulated using a laser with a wavelength of 532 nm, energy 150 J, exposure 0.03 ms, spot diameter 100 μm, the number of applications was 10 pieces, which were applied in the form of a circle with the center filled. In the center of the application area, a YAG laser iridotomy was performed with an energy of 2.6 J, the number of pulses was 6. At the moment of perforation, the flow of fluid with pigment from the posterior chamber of the eye to the anterior chamber was visualized.

After the operation, deepening of the anterior chamber and a decrease in intraocular pressure to 16/14 mm Hg were observed.

Example 3.

Patient K., 55 years old, diagnosis: suspected glaucoma. Anatomically narrowed angle. Mild hypermetropia. At the time of examination, the depth of the anterior chamber was 2.4 mm, the length of the anterior-posterior axis of the eyeball was 21.6 mm, and the thickness of the lens was 4.91 mm. Intraocular pressure was measured by the Maklakov applanation method and was 15/15 mm Hg. Gonioscopy revealed a narrow angle of the anterior chamber in all meridians.

The treatment was carried out using the claimed method. After performing OCT and OCT of the iris and skeletonizing this image, the thinnest avascular zone of the iris was determined, which was located at 6 o'clock in the right eye and 6:30 o'clock in the left eye. Then, in the selected area, the iris was coagulated using a laser with a wavelength of 532 nm, with an energy of 120 J, with an exposure of 0.03 ms, a spot diameter of 100 μm, the number of applications was 5 pieces, which were applied in the form of a circle. Next, in the center of the application area, a YAG laser iridotomy was performed with an energy of 4.2 J, the number of pulses was 5. At the moment of perforation, the flow of fluid with pigment from the posterior chamber of the eye to the anterior chamber was visualized.

After the operation, deepening of the anterior chamber and a decrease in intraocular pressure to 12/12 mmHg were observed.

The use of the proposed method will allow obtaining the maximum hypotensive effect and avoiding hemorrhagic complications when performing laser iridotomy in patients with angle-closure glaucoma and an anatomically narrowed anterior chamber angle.

Claims (1)

A method for reducing the level of intraocular pressure by means of peripheral laser iridotomy, including laser exposure to the iris to form an iridotomy opening, characterized in that at the first stage the patient undergoes optical coherence angiography (OCTA) of the iris and optical coherence tomography (OCTA) of the anterior segment of the eye , on the basis of which the avascular zone is determined for the formation of an iridotomy hole in the peripheral region of the iris, at the second stage, circle-shaped applicates are applied in this zone in an amount of 5-15 pieces using a diode laser with a wavelength of 532 nm, with a power of 120-170 mW , with an exposure of 0.03 ms, a spot diameter of 100 μm, then a series of laser pulses are performed in the center of the application area using a YAG laser with an energy of 2.4-4.2 J to form an iridotomy hole.