rgp design tk4

the keratoconus "fitting system"

TK4 is the innovative optical keratoconus compensation modality introduced by TSLAC to simplify the corneal RGP lens fitting. The system allows to adapt to each stage of ectasia a specific geometry, favoring the respect of the corneal morphology and improving the subjective response of comfort.
The TK4 range offers multiple corrective options, described in the following table:



TK4 has a tangential aspherical trend with optical areas and eccentricity values differentiated according to each model; this development follows the typical variations in profile of the ectasic morphologies, favoring the distribution of the lens on a more extended area and the bio-mechanical respect of the cornea.


Thanks to the shape factor, specific to each model, the ideal fluoroscopic pattern is well distributed and in the adaptation of the TK4 it is possible to use large diameters, with a more centered positioning and a less wide dynamic to the blink, fitting elements that promote overall comfort and lens stability.

apex location

The position of the corneal apex is a significant factor for successful application; If keratoconus occurs in the central area, Nipple-Kone, it is possible to use symmetric geometries, with variable diameter depending on the eyelid opening and evolutionary degree.

non rotationally symmetric

When the apex is located in the paracentral area, Oval-Kone, the cornea in the lower sector shows an evident variation in shape. In such circumstances it is necessary to adopt a profile with ASIM development (p. 28) in order to minimize the lifting to 270°, reducing the possibilities of decentralization and the annoying interactions with the eyelid edge.