RU2552096C1 - Measuring instrument for determining surgical approach parameters in cataract phacoemulsification in patients suffered radial keratotomy - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: instrument for measuring distances between keratotomic scars and corneal tunnel edges in cataract phacoemulsification in the patients suffered a radial keratotomy is made of stainless steel and contains a graduated scale. It also contains a plate in the form of a sphere sector 1.8-2.4 mm wide and 8.0 mm long, 0.3 mm thick, with a curvature radius of 8.0 mm having a matt surface provided with a holder attached at 100° to the plate plane. The graduated scale is provided on the inner edge of the plate facing the corneal centre and graduated at a pitch of 0.25 mm. In the centre of the graduated scale, there is a sector 1.8-2.4 mm wide limited by two graduations.

EFFECT: invention is supposed to provide accuracy when measuring the distance between the keratotomic scars and corneal tunnel edges taking into account the keratotomic scars approaching the corneal centre.

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Description

The proposed device relates to medicine, namely to ophthalmology, and is intended to measure the distance between keratotomy scars and the edges of the corneal tunnel during surgical treatment of cataracts by phacoemulsification in the eyes with previously performed radial keratotomy.

One of the main stages of cataract phacoemulsification is the formation of a corneal tunnel incision through which the tip of the phacoemulsifier enters to remove a cloudy lens. In patients after radial keratotomy, scars form in the area of radial incisions. During phacoemulsification of cataracts, manipulations in the tunnel zone are often complicated by the maladaptation of the edges of keratotomy scars located in the immediate vicinity of the tunnel. This is especially true for the removal of dense brown cataracts, which are more common with myopia. A discrepancy in the keratotomy scar can occur when it is crossed with a surgical knife during the formation of a corneal tunnel incision. The low strength of keratotomy scars is associated with the peculiarities of their histological structure - a weakly expressed cell-fibrous matrix and the absence of proteoglycans.

In order to prevent scar discrepancy during cataract phacoemulsification, it is necessary to leave a zone of intact cornea with a width of at least 0.5 mm between the edges of the tunnel and keratotomy scars and use a microsurgical knife of a minimum width (1.8 mm).

In practice, an approximate determination of the distance between the edges of the tunnel and keratotomy scars occurs by simply applying a knife to the area of the proposed tunnel.

It is known to use the Castroviejo compass to measure the distance between scars. This device, taken as a prototype, contains articulated working legs, the working part is straight or curved, equipped with a graduated scale in millimeters, allows measuring from 0 to 20 mm, the total length of the device is 87 mm [Castroviejo compiler [Electronic resource] .- 2013. Access mode: http://www.medtech.ru/catalog/ophthalmology/section.php?SECTION_ID=501. Date of appeal 05.16.2014]. A drawback of the Castroviejo compass is the inability to take measurements with sufficient accuracy to 0.25 mm.

The objective of the invention is the selection of the optimal location zone of the tunnel incision in order to prevent maladaptation of keratotomy scars during cataract phacoemulsification.

The technical result is a simplification and increased accuracy of measuring the distance between keratotomy scars and the edges of the corneal tunnel, taking into account the convergence of keratotomy scars to the center of the cornea using the proposed device.

The specified technical result is achieved by the fact that the instrument for measuring the distances between keratotomy scars and the edges of the corneal tunnel during phacoemulsification of cataracts in patients after radial keratotomy, made of medical stainless steel, containing a graduated measuring scale, according to the invention contains a plate in the form of a sector of a sphere with a width of 1.8 -2.4 mm, length 8.0 mm, thickness 0.3 mm, radius of curvature 8.0 mm with a frosted surface, which is equipped with a handle holder attached at an angle of 10 0 ° to the plane of the plate, and a graduated measuring scale is made on the inner edge of the plate facing the center of the cornea, has divisions of 0.25 mm increments, while in the center of the measuring scale, a sector of 1.8-2.4 mm wide, limited by two divisions, is made.

The invention is illustrated by figures made on a scale of 10: 1. In FIG. 1 shows a measuring tool, a top view; in FIG. 2 - measuring tool, side view; in FIG. 3 - measuring tool, front view.

A tool for measuring the distances between keratotomy scars and the edges of the corneal tunnel contains a plate 1 in the form of a sector of a sphere 1.8-2.4 mm wide, 8.0 mm long, 0.3 mm thick, and a radius of curvature of 8.0 mm made of medical stainless steel with a matte surface that matches the width of the corneal tunnel for phacoemulsification. On the inner edge of the plate facing the center of the cornea, a graduated measuring scale 2 is made, including divisions of 0.25 mm pitch. In the center of the measuring scale, sector 3 was made 1.8–2.4 mm wide, corresponding to the width of the knife for forming a corneal tunnel for micro-invasive cataract surgery by phacoemulsification, limited to two divisions. This allows with the specified accuracy to measure the distance between the central 1 sector and keratotomy scars by counting the number of divisions on the edge of the plate. The plate 1 is equipped with a handle-holder 4, attached at an angle of 100 ° to the plane of the plate (Fig. 1). Matting the surface of the plate prevents glare from the illuminator of the operating microscope.

The advantage of the proposed device is the simplicity of manufacture, the permissibility of re-sterilization, the possibility of manufacturing measuring instruments with different widths of the plate and the central sector (2.0 mm; 2.2 mm; 2.4 mm) depending on the presence of corneal knives of different widths at the surgeon's disposal. The distance between keratotomy scars decreases in the direction from the limb to the center of the cornea. A measuring scale applied to the inner edge of the plate, the width of which should correspond to the width of the central sector, allows this to be taken into account.

The proposed tool is used as follows. After local anesthesia, the patient is given an eyelid expander. The plate 1 held by the holder-holder 4 is mounted on the surface of the cornea 5 near the limb 6, while the outer edge of the plate is congruent to the circumference of the limb, the inner edge of the plate is facing the center of the cornea (Fig. 2-3). The central sector of the measuring scale is oriented in the middle between adjacent keratotomy scars. Under a large magnification of the operating microscope, readings are made on the measuring divisions on the plate to the right and left of the central sector. By summing the number of divisions on the inner edge of the plate, the distance between the edges of the tunnel for phacoemulsification and keratotomy scars is determined.

Example 1. Patient G., 62 years old, was admitted with a diagnosis of OD - high myopia, complete complicated cataract, condition after radial keratotomy. Visual acuity with a maximum correction of 0.03. Keratotomy was performed in 1991 with 10 keratotomy scars on the cornea. The patient is planned phacoemulsification of complicated cataract with implantation of a developing intraocular lens. The determination of the distance between the scars and the selection of the optimal zone for performing the corneal tunnel were carried out using the proposed tool. After local drip and subtenon anesthesia, the measuring instrument is mounted on the surface of the cornea near the limb by the holder handle. The outer edge of the plate is located strictly around the circumference of the limb. The central sector of the measuring scale is oriented in the middle between keratotomy scars at 11 o’clock. Under a large magnification of the operating microscope, measurements were made on the measuring divisions on the plate to the right and left from the central sector to keratotomy scars. Defined by 2.5 divisions of the scale, which amounted to a safe intact zone of the cornea with a width of 0.6 mm, sufficient to prevent maladaptation of keratotomy scars. A corneal tunnel 1.8 mm wide was formed, through which cataract phacoemulsification and implantation of a developing intraocular lens were performed.

On the first day after surgery, uncorrected visual acuity of the right eye is 1.0.

Example 2. Patient 3., 50 years old, was admitted with a diagnosis of OS - moderate myopia, complete complicated cataract, condition after radial keratotomy. Visual acuity - light perception with the correct light projection. A keratotomy was performed in 1990 with 8 keratotomy scars on the cornea. The patient is scheduled for phacoemulsification of complicated cataract with implantation of a developing intraocular lens. The determination of the distance between the scars and the selection of the optimal zone for performing the corneal tunnel were carried out using the proposed tool. After local drip and subtenon anesthesia, the measuring instrument is mounted on the surface of the cornea near the limb by the holder handle. The outer edge of the plate is located strictly around the circumference of the limb. The central sector of the measuring scale is oriented in the middle between keratotomy scars at 11 o’clock. Under a large magnification of the operating microscope, measurements were made on the measuring divisions on the plate to the right and left from the central sector to keratotomy scars. 5 divisions of the scale were determined, which amounted to a safe intact area of the cornea with a width of 1.2 mm, sufficient to prevent maladaptation of keratotomy scars. A corneal tunnel 1.8 mm wide was formed, through which cataract phacoemulsification and implantation of a developing intraocular lens were performed.

On the first day after surgery, uncorrected visual acuity of the left eye is 1.0.

The proposed measuring instrument was used in a clinic in 7 patients with phacoemulsification of cataracts in the eyes after undergoing radial keratotomy. Disadaptation of keratotomy scars during cataract phacoemulsification did not occur. Any complications in the intra- and postoperative period associated with its use have not been established.

Advantages of using this measuring tool:

- ease of use;

- the accuracy of measuring the distance between the edges of the tunnel and keratotomy scars;

- selection of the optimal zone for the location of the corneal tunnel.

Thus, the use of the tool allows us to simplify and improve the accuracy of measuring the distance between keratotomy scars and the edges of the corneal tunnel, taking into account the convergence of keratotomy scars to the center of the cornea, and also to choose the optimal location area of the tunnel incision in order to prevent maladaptation of keratotomy scars during cataract phacoemulsification.

Claims (1)

Instrument for measuring the distances between keratotomy scars and the edges of the corneal tunnel during phacoemulsification of cataracts in patients after radial keratotomy, made of medical stainless steel, containing a graduated measuring scale, characterized in that it contains a plate in the form of a sector of a sphere 1.8-2.4 mm wide , length 8.0 mm, thickness 0.3 mm, radius of curvature 8.0 mm with a frosted surface, which is equipped with a handle holder attached at an angle of 100 ° to the plane of the plate, and graduated measuring I scale is formed on the inner edge of the plate facing the center of the cornea, has a dividing step of 0.25 mm, wherein the center of the measuring scale is formed bounded by two sector divisions width 1.8-2.4 mm.

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