Recent technological advances make it possible to evaluate visual quality in both an objective and subjective way. It is for this reason that, as visual and ocular health professionals, optometrists must consider the importance of prescribing optical correction based on visual image quantity and quality during their clinical practice, as it determines a quantitative factor, such as visual acuity from the patient’s subjective point of view, and a qualitative factor, such as quality and clarity with which images are seen. Physical optics applied to the human eye creates the possibility of analyzing light wavefronts refracted through the ocular media, making it possible to see the optical behavior of the dioptric system of the eye. Optical aberrations generated by the cornea or the lens are defined as visual system imperfections, therefore producing defective retinal images in the patient and limiting their vision

Visual and ocular health professionals are currently faced with the typical cases of primary and secondary corneal ectasia, and even though the most frequent ones are keratoconus, it is not always so. Hence the importance of a good clinical correlation, as well as of the request of special tests in order to help achieve a better diagnosis. It is essential to remember that, in most cases, they are asymmetric binocular processes, so that if one eye presents more advanced symptoms, the opposite eye should also be monitored, because the condition will most likely develop further. The case of a sixteen year old Computer Technology student diagnosed with keratoconus is presented.

<em><strong>Objective:</strong></em> To identify whether there are significant variations in the degree of higher-order corneal aberrations after implantation of intrastromal rings in patients diagnosed with corneal ectasia. <em><strong>Materials and methods:</strong></em> An analytical and longitudinal study of intervention in patients over 18 years was carried out. The refractive state was evaluated, as well as the visual acuity measured by logmar; the topographic keratometry, the corneal optical aberrations coma, the trifoid, the spherical and the Root Mean Square High Order (rms Ho), by the Keratron Scout topograph, and the visual quality through Mars letters test for contrast sensitivity. All of this was done in three times before surgery, first and third post-op months. Results: In 39 eyes of 26 patients evaluated before, after one and three months after the implantation, clinical differences were significant, though not statistical: a) visual acuity was increased with no correction, b) there was a decrease in spherical and cylindrical values, c) flattening in K1 and K2, d) differences in the degree of high order optical aberrations of cornea after the procedure, e) a better visual quality for these patients and f) use of ophthalmic lenses with a greater tolerance. <em><strong>Conclusion:</strong></em> The optical aberrations of the anterior surface of the cornea do not have a statistically significant difference before or after the implantation of intrastromal segments, although there are changes at a clinical level and in magnitude.