RU239441U1 - Aphakic optical cylinder keratoprosthesis with an elongated intraocular part - Google Patents

Abstract

The utility model relates to medicine, namely to ophthalmology, and can be used to perform the second stage of keratoprosthetics or when replacing the optic cylinder in patients with recurrent retroprosthetic membrane (RPM). The technical result is achieved in that the aphakic keratoprosthesis optic cylinder has an elongated intraocular portion, including an extraocular portion with an outer surface diameter of 2.8 mm and a height of 0.5 mm and an internal intraocular portion, which in turn consists of a threaded portion 1.65 mm long and 0.4 mm high, and a threadless portion, wherein the length of the internal intraocular threadless portion is 1.5 mm, the total length of the optic cylinder is 3.65 mm. The use of this cylinder in performing the second stage of keratoprosthetics or when replacing the optic cylinder in patients with recurrent retroprosthetic membrane contributes to the stabilization of the anterior chamber.

Description

The utility model relates to medicine, namely to ophthalmology, and can be used to perform the 2nd stage of keratoprosthetics or to replace the optical cylinder in patients with recurrent retroprosthetic membrane (RPM).

Keratoprosthesis is the only effective method for restoring vision in patients with burn-related or terminal degenerative leukomas. The formation of keratoprosthetic membranes is one of the most common complications, significantly reducing the optical effect of keratoprosthesis.

RPM most often develops as a result of aseptic inflammation and is the eye's response to surgical trauma involving the introduction of a foreign body. Other common causes of RPM include chronic inflammation of the ocular membranes, primarily caused by bacterial flora, and a history of optical reconstructive procedures, such as penetrating keratoplasty, corneal prosthetic transplantation, or cataract extraction. These procedures can be accompanied by severe bleeding during surgery in patients with vascular corneal leukomas.

The RPM is a connective tissue composed primarily of fibroblasts, whose proliferation leads to a steady increase in membrane thickness. As it develops, the RPM gradually expands across the posterior surface of the cornea and the optic cylinder of the keratoprosthesis, leading to a significant decrease in visual acuity and an increase in intraocular pressure, which, in turn, can lead to protrusion of the keratoprosthesis support plate and the risk of its loss.

Discision of the retinal retinal membrane is performed in three ways, depending on its thickness and etiology. For thin retinal retinal membranes (RPM) less than 100 µm thick, YAG laser discision is possible. If this method is not feasible, or if the retinal retinal membrane recurrs after laser treatment, or if the retinal retinal membrane thickness is greater than 100 µm, discision of the retinal retinal membrane can be performed through the keratoprosthesis's optical cylinder opening. If a recurrence occurs after attempting to remove the retinal retinal membrane through the optical cylinder opening, the retinal retinal membrane is removed with a vitreous cutter using a three-port vitrectomy. However, despite the absence of retinal retinal membrane recurrence in patients whose retinal retinal membranes were removed with a vitreous cutter, this technique is rarely used, as it requires specialized vitreoretinal equipment and surgical skill, given the limited visualization area.

One of the most effective methods of RPM discission is its removal through the opening of the optical cylinder, however, the frequency of unscrewing the optical cylinder is limited due to the risk of tearing and twisting of the sleeve, which is driven into the sleeve of the inner ring of the support plate, which, in turn, entails the risk of repeating keratoprosthetics.

Currently, keratoprosthetics is performed in the Russian Federation using the Fedorov-Zuev keratoprosthesis, which is the closest analogue of the device (RU Patent No. 1802703). The keratoprosthesis consists of two parts: a support plate and an optical cylinder. The latter, in turn, is made of polymethyl methacrylate and has extra- and intraocular parts. The extraocular part of the optical cylinder is 0.5 mm high. The outer extraocular surface of the optical cylinder has a diameter of 2.8 mm and contains two blind-closed holes congruent with the pins of the key. The total length of the intraocular part of the aphakic optical cylinder is 2.65 mm. The intraocular part of the optical cylinder is divided into threaded and non-threaded parts. The threaded intraocular portion of the optical cylinder, 1.65 mm long, has a 0.4 mm high thread around its circumference, congruent with the thread of the sleeve on the inner surface of the keratoprosthesis support plate ring. The threadless intraocular portion of the optical cylinder is 1.0 mm long for an aphakic optical cylinder. The diameter of the inner intraocular portion of the optical cylinder is 2 mm. The total length of the aphakic optical cylinder is 3.15 mm.

However, this model of the optical cylinder keratoprosthesis has a number of disadvantages, in particular, in the case of a sluggish inflammatory process, in which the likelihood of recurrence of RPM is high, removal of RPM through the opening of the optical cylinder is an effective method, but only for a short period, given that the intraocular part of the cylinder is located flush with the posterior surface of the corneal leukoma, which significantly increases the risk of tissue creeping onto the lumen of the cylinder, significantly reduces visual acuity and leads to an increase in intraocular pressure.

In view of all the above reasons, the development of an optical cylinder with an elongated intraocular part is a pressing issue.

The objective of the utility model is to perform the second stage of keratoprosthetics and replace the optical cylinder for patients with RPM with the possibility of removing RPM through the opening of the optical cylinder with minimal risks of recurrence and without resorting to vitreoretinal equipment, as well as reducing the level of intraocular pressure.

The technical result is stabilization of the anterior camera.

The technical result is achieved by the keratoprosthesis's optical cylinder with an elongated intraocular portion, made of polymethyl methacrylate and consisting of an intra- and extraocular portion, as well as a thread located in the intraocular portion of the optical cylinder over a 1.65 mm length and congruent with the thread of the inner ring sleeve of the Fedorov-Zuev keratoprosthesis's support plate. The thread extends around the entire circumference of the threaded intraocular portion of the optical cylinder and has a height of 0.4 mm. On the anterior extraocular surface of the keratoprosthesis's optical cylinder, 2.8 mm in diameter, are two blind-closed holes congruent with the key pins. The key is a metal cylinder with a diameter of 3 mm and a length of 5 cm. Its end sections are equipped with two 0.2 cm metal pins congruent with the blind holes in the keratoprosthesis plug and the optical cylinder. The threadless intraocular portion of the aphakic optical cylinder is 1.5 mm long, which limits tissue overgrowth onto the optical cylinder from the inside and reduces the risk of recurrence. The elongated intraocular portion, due to its protrusion into the anterior chamber, stabilizes it, opens the anterior chamber angle, and reduces intraocular pressure. The threaded intraocular portion of the optical cylinder is 1.65 mm. The extraocular portion is 0.5 mm long. The diameter of the inner intraocular portion of the optical cylinder is 2 mm. The total length of the aphakic optical cylinder is 3.65 mm.

The utility model is illustrated by Fig. 1 and 2. Fig. 1 is a top view, Fig. 2 is a side view. Position 1 denotes the anterior extraocular surface of the optical cylinder of the keratoprosthesis with a diameter of 2.8 mm, position 2 – 2 blind-closed openings congruent to the pins of the key, position 3 – the extraocular part of the optical cylinder of the keratoprosthesis, position 4 – the length of the optical cylinder of the keratoprosthesis - 0.5 mm, position 5 – the intraocular part of the optical cylinder of the keratoprosthesis, position 6 – the intraocular threaded part of the optical cylinder, position 7 – the length of position 6, which is 1.65 mm, position 8 – thread, 0.4 mm high, 1.65 mm long, position 9 – intraocular threadless part of the optical cylinder, position 10 – the length of position 9, which is 1.5 mm, position 11 – the diameter of the intraocular part of the optical cylinder is 2 mm, pos.12 – total length of the optical cylinder - 3.65 mm.

The operation of the device is explained by the following example.

Patient A, 31 years old. Diagnosis: OS. Vascular corneal opacity. Result of a chemical burn. Condition after the second stage of keratoprosthetics. Retroprosthetic membrane OD. Anophthalmos.

The patient's medical history indicates that three years ago he suffered an industrial lime burn to both eyes. His right eye was enucleated immediately after the burn at his place of residence. Two years ago, the second stage of keratoprosthesis surgery was performed on his left eye at the Scientific and Technical Complex of the Moscow City Hospital. His visual acuity at discharge was 0.3 with a corrected sph of -3.0 = 0.6.

Biomicroscopy of the left eye reveals a vascularized corneal leukoma, a centrally located optic cylinder, and the presence of vascularized retinopathy. The underlying media are not ophthalmoscoped.

Visual acuity: OS – 1/∞ projectia lucis certa. IOP is normal by palpation.

In OCT of the anterior segment of the left eye, the keratoprosthesis occupies the correct central position, and the RPM is visualized behind the posterior part of the vascular leukoma.

Electrophysiological studies revealed minor changes in the left eye.

According to B-scan data: the membranes of the left eye are adjacent, destruction of the vitreous body.

Taking into account the potential of visual functions, the correct central position of the keratoprosthesis and the presence of RPM according to OCT data, it is advisable to perform a discission of the RPM with the replacement of the optical cylinder with an aphakic one with an elongated intraocular part.

The early postoperative period was uneventful. Moderate swelling and hyperemia were noted in the first few days. Visual acuity in the left eye was 0.05 without correction. Palpable intraocular pressure was normal.

Upon discharge from the hospital on the 7th day: the eye is calm, the sutures are strong. Visual acuity: 0.1 with correction sph -2.0 D cyl -1.75 D ax 80 = 0.3. IOP is normal by palpation.

Upon examination three months later, the patient's eye was calm. Visual acuity was 0.3 with correction of sph -2.0 D=0.6. Palpable intraocular pressure was normal.

A 6-month examination revealed a calm eye. OCT data showed the keratoprosthesis to be correctly positioned centrally. Visual acuity: 0.3 with correction of sph -2.0 D=0.6. Palpable intraocular pressure was normal.

Claims (1)

An aphakic optical cylinder keratoprosthesis with an elongated intraocular part, including an extraocular part with an outer surface diameter of 2.8 mm and a height of 0.5 mm and an internal intraocular part, which, in turn, consists of a threaded part 1.65 mm long and 0.4 mm high, and a threadless part, while the length of the internal intraocular threadless part is 1.5 mm, the total length of the optical cylinder is 3.65 mm.