CS255208B1 - Contact guides - Google Patents

Abstract

A small contact lens of which the sagittal depth is equal to or greater than the square root of its diameter reduced by 0,2 and less than the square root of its diameter increased by 0,4 mm. Its maximum thickness is at least 26 to 90 times less than its sagittal depth. Contact lens for correction of wide range of eye keratometric values and is well tolerated.

Description

The invention relates to a contact lens of small thickness which is suitable for correcting refractive errors or for other medical or cosmetic purposes.

Previously known contact lens designs are thin only in the central part. The edges have thicker contact lenses both for easier machinability and for good centering on the eye even at low sagittal depth. The average thickness of these contact lenses exceeds desirable well, when oxygen permeation through the mass of the contact lens is sufficient. It is also not possible to uniformly transfer oxygen through the entire surface of the contact lens. Another disadvantage of these contact lenses is the lack of eye movement. This results in generally inferior corneal metabolism and greater possibility of clogging the contact lens with the products of corneal metabolism. The inferior movement of these contact lenses is attributed to the thinness of the contact lens.

These disadvantages are overcome by the contact lens according to the invention, characterized in that the sagittal depth of the lens is equal to or greater than the square root of its diameter reduced by 0.2 mm and less than the square root of its diameter increased by 0.4 mm. Its maximum thickness is at least 26 to 90 times less than its sagittal depth.

With the contact lens according to the invention, a suitable combination of the basic dimensional parameters, i.e. diameter, sagittal depth and thickness, has succeeded in eliminating the drawbacks of the contact lenses so far produced. The contact lenses of the present invention can be manufactured with a very low average thickness which ensures better oxygen transmission to the cornea evenly over the entire surface of the contact lens, with the lenses centering properly on the eye while maintaining sufficient mobility. The movement of the contact lenses according to the invention during blinking allows the pumping of tears, which then roll off the products of corneal metabolism.

The contact lenses according to the invention are produced by centrifugal casting from a variety of soft materials, whether anhydrous, surface-hydrophilizable on the basis of silicone rubbers or to various degrees of water-swellable vinyl-type polymer gels.

The contact lenses of the invention are suitable for application to eyes with a large range of ceramic values. They are well tolerated since the first deployment.

The following table 1 shows the contact lenses according to the invention which have been prepared and have been successfully verified in practice.

Table 1:

Lens weight (mg) Diameter (mm) Vrcholová refraction (D) Středová thicker (mm) TI. 3 mm from center lens (mm) Tl. 5 mm from center lens (mm) Sagit. depth (mm) 18.1 14.0 -2.0 0.08 0.10 0.10 3.75 22.2 14.0 -4.0 0.09 0.12 0.13 3.75 26.2 14.1 -6.0 0.08 0.12 0.14 3.80 20.0 13.6 -4.0 0.08 0.11 0.12 3.65 21.2 14.6 -2.0 0.09 0.10 0.11 3.90 21.0 14.1 -4.5 0.07 0.11 0.12 3.65 21.6 14.1 -6.0 0.06 0.11 0.13 3.65 25.2 14.1 -8.0 0.04 0.10 0.14 3.65 21.7 14.6 -4.0 0.08 0.11 0.13 3.80 23.5 14.6 -5.5 0.06 0.10 0.13 3.80 27.5 14.6 -7.0 0.06 0.11 0.14 3.80

SUBJECT OF THE INVENTION

Claims (1)

SUBJECT OF THE INVENTION A contact lens characterized in that its sagittal depth is equal to or greater than the square root of its diameter reduced by 0.2 and less than the square root of its diameter increased by 0.4 mm, its maximum thickness being at least 26 to 90 times less than its sagittal depth.