SU1680162A1 - Method for treating keratoconus - Google Patents

Abstract

The invention relates to ophthalmology and allows to prevent the development of high myopia in the postoperative period after end-to-end cornea transplantation for keratoconus due to the transplantation of a cornea transplant of a donor eye with a diameter smaller than the bed breakout bed of the recipient by a pre-calculated amount that is determined by the formula RH dg 2Rgsln af-p -arcsln Re 2RH do - dp 2 Rg sin a) where dg is the diameter of the donor graft; Rg is the radius of curvature of the cornea of the donor eye; RH 7.8 mm - the specified radius of curvature of the cornea of a normal eye, providing emmetropia in the postoperative period; do is the diameter of the base of the conical part of the recipient's cornea; dp is the diameter of the trapanation bed of the recipient's cornea; a - the angle between the generatrix of the conical surface of the peripheral part of the cornea and the axis of the eye of the recipient.

Description

The invention relates to medicine, namely to ophthalmology.

The aim of the invention is to prevent postoperative refractive myopia.

The method is carried out as follows.

Before the operation, the angle between the conical surface of the peripheral part of the cornea and the axis of the eye of the recipient, the diameter of the base of the conical part of the cornea of the recipient, the radius of curvature of the cornea of the donor eye are determined, and the diameter of the trepanation bed of the cornea of the recipient, i.e.

select the appropriate diameter of the trephination bed of the operated eye, based on surgical considerations, depending on the stage of keratoconus. Then by the formula

D0 2R9sin "(- -arcsin d °

Re

2 RH

O 00 o

about

go

- ° p

2 Rg sin a

where Dg is the diameter of the donor graft;

Rg is the radius of curvature of the cornea of the donor eye;

RH 7.8 mm - the specified radius of curvature of the cornea of the normal eye, which provides emmetropia in the postoperative period;

d0 is the diameter of the base of the conical part of the cornea of the recipient;

dp is the diameter of the trephination bed of the recipient's cornea;

a - angle between the conical surface of the peripheral part of the cornea and the axis of the eye of the recipient: the diameter of the donor graft for this operation is determined.

During the operation, the cornea through disk is cut out and removed from the eye of the recipient in order to prepare the trepanation bed of the recipient of a given diameter, in which place a cornea through donor graft with a diameter (smaller than the bed of the recipient), determined by the formula, and sewn it to the edge of the trepanation bed of the recipient. The stitches are removed after 6-10 months after the operation.

Example. Patient V. 30 years. The diagnosis of keratoconus in both eyes was determined at the age of 17 years. The pore examinations revealed that the corneas of both eyes are extremely protruding anteriorly, conical, thinned, and there are opacities in the central zone, at the apex of the cone. The front camera is very deep, 4.5 mm, uneven. The intraocular pressure of both eyes is normal, 20 mm Hg. The visual acuity of the right eye is 0.01, it is not corrected with spectacles, it does not tolerate contact lenses (the radius of curvature of the front surface of the cornea at the top is 4.4 mm). Visual field within normal range. Colors distinguish correctly. The phenomenon of autoophthalmoscopy (Purknm) is positive. The acuity of the vision of the left eye is 0.02, the glasses are not corrected, with a contact lens of 0.5. The tolerance of the contact lens with the left eye is satisfactory. Taking into account the condition of the worst right eye, indications for the operation of a through cornea transplant were curled: the presence of keratoconus is far from the advanced stage, visual acuity is low, not corrected by eyeglasses, contact lens intolerance.

The patient underwent a complete ophthalmologic examination, in addition, before performing a through cornea transplant, the proposed method was used to measure the angle between the conical surface of the peripheral part of the cornea and the axis of the eye, 35 °, the diameter of the conical base

parts of the cornea, do 9.5 mm. The radius of curvature of the cornea of the donor eye was Rg 8.0 mm. Taking into account the far advanced stage of keratoconus, the extreme degree of corneal prolapse with thinning at the periphery, the corneal trap was selected for cutting out the bed of the recipient with a large diameter, dp 8.5 mm. Then by the formula

R Dg 2Rgsin "(--- arcsln

Ro

15

rfj

2 Rg sin a

).

where Dg is the diameter of the donor graft;

Rg is the radius of curvature of the cornea of the donor eye:

RH 7.8 mm - a given radius of curvature of the cornea of a normal eye, providing emmetropia in the postoperative period;

do is the diameter of the base of the conical PD of the cornea of the recipient;

dp - diagram of the trephination bed of the recipient's cornea;

a - the angle between the conical generator

the surface of the peripheral part of the cornea m axis of the eye of the recipient, determined the required diameter of the donor graft for this operation. dg 8.1 mm. As can be seen, the diameter of the donor

the graft in this case should be 0.4 mm smaller than the diameter of the prepared trepanation bed of the cornea of the recipient. (Calculations show that if in this case the transplant is transplanted

the cornea of the donor of the same diameter as the diameter of the bed of the recipient, then myopia (9.5 diopters) will be formed in the postoperative period). During the operation, the patient was cut out of the cornea and cut-through

A disk with a diameter of 8.5 mm (in a formed bed was placed a through disk of a donor cornea with a diameter of 8.1 mm and sewn with a continuous suture (synthetic monofilament standard, 10: 0) to the edges of the trepanation bed. The operation and the postoperative period proceeded without complication. Engraftment of the cornea the transplant is transparent. The acuity of the vision of the right eye is 0.7, with a correction of 0.75 diopter 1.0. The observation period is 5 years.

Thus, the proposed method has a significant advantage over the known one: it prevents the formation in the postoperative period

high myopic refraction, do - dp h

which provides a functional result of 2 Rg sin d-

healing ability.

Claims (1)

where Dg is the diameter of the donor transplant - Formula of the invention 5 ta; The method of treating keratoconus by Rg is the radius of curvature of the cornea of a donor-through cornea transplant, a distinguishing eye; Sch and with the fact that, in order to prevent d0 - the diameter of the base of the conical chaposleo-operative refractive myosia of the cornea of the recipient; PI, the donor graft diameter — 10 dp — the diameter of the trap bed is determined according to the recipient formula; a is the angle between the conical part along the D 2R sfn (Tj arcsirv d ° - the upper parts of the peripheral part of the cornea 99 Rg 2-7,8i the axis of the eye of the recipient.