METHOD FOR PERSONALIZED DETERMINATION OF OPTICAL STRENGTH OF AN INTRAOCULAR LENS WITH INTRACAPSULAR FIXATION IN PATIENTS WITH KERATECTASIA Russian patent published in 2018 - IPC A61B3/00 A61F2/16 

FIELD: medicine.

SUBSTANCE: invention relates to medicine, namely to ophthalmic surgery, and can be used for personalized determination of the optical strength of the intraocular lens (IOL) with intra-capsular fixation in patients with keratectasia. Length of the eye, the radius of curvature of the anterior and posterior surfaces of the cornea, the thickness of the cornea at the center, the refraction of the cornea, the constant A of the intraocular lens, as well as astigmatism of the cornea and the angle of the kappa between the visual and optical axes of the eye. Optical strength of the spherical component of the IOL is determined by the formula:

;

determine the optical strength of the cylindrical component of the IOL according to the formula:

,

where IOL_SPH – spherical component of the optical power of the IOL, dpt; where IOL_CYL – cylindrical component of the optical power of the IOL, dpt; L – length of the eye, mm; R=333/(K₁*1.114+K_1p) – standardized radius of curvature of the anterior surface of the cornea in a strong meridian, mm; p – distance between the anterior surface of the IOL and the top of the cornea, mm, defined by the formula:

,

R_s=40/K_1p – standardized radius of curvature of the posterior surface of the cornea, mm; d – diameter of the cornea, mm; A – constant A of IOL, installed by the IOL manufacturer; H – thickness of the cornea in the center, mm; κ – angle between the optical and visual axes, degrees; K₁ – standardized refraction of the anterior surface of the cornea in a strong meridian, dpt; K_1p – refraction of the posterior surface of the cornea in a strong meridian, dpt; K₂ – standardized refraction of the anterior surface of the cornea in a weak meridian, dpt; K_2p – refraction of the posterior surface of the cornea in a weak meridian, dpt; AST_cornea – corneal astigmatism equal 1.114(K₁-K₂)+(K_1p-K_2p), dpt.

EFFECT: method provides an increase in the accuracy of IOL calculation, an improvement in the predictability of postoperative refraction, a reduction in the risk of occurrence of refractive errors by measuring a number of the above-described parameters of the eye, the constant A of IOL and also due to the calculation of the optical force in the spherical and cylindrical components of the IOL.

1 cl, 2 ex