Keratoconus is a degenerative disease of the cornea, in which the cornea gets thinner with the formation of a conical protrusion (corneal protrusion). This disease belongs to the group of keratectasias, it has a multifactorial nature, and occurs in approximately 25% of cases of all corneal pathologies. The disease can be both primary, which is based on dystrophic changes in the cornea, and secondary, which develops against the background of intrauterine keratitis. Over the past 20 years, iatrogenic keratoconus, which develops as a result of refractive eye microsurgery, has become widespread. Most often, primary keratoconus manifests itself during puberty, progresses up to 30-40 years, after which its spread slows down. An early clinical manifestation of this cornea pathology is a progressive decrease in vision and the appearance of a feeling of double vision with the development of a severe headache against this background. Subsequently, there is the development of monocular polyopia, multi-contour images and symbols. In advanced stages, there is a pronounced dry eye, itching, and photophobia. In some cases, the diagnosis of keratoconus can be quite complicated, since the use of conventional research methods can only show refractive error in the form of myopia or astigmatism. To establish the correct diagnosis, it is necessary to take into account the impossibility of correcting visual impairment using conventional methods, such as glasses or contact lenses. As a rule, establishing the diagnosis of keratoconus requires the use of an extended range of instrumental research methods.