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Visual acuity normalization in cases of keratoconus after intrastromal corneal ring implant and further fitting of permeable contact lenses

Poster Details

First Author: E.Tom SPAIN

Co Author(s):    F. Pastor   R. Mont           

Abstract Details


After implanting the intrastromal corneal ring segments, the structure of the cornea is reinforced offering a more regular topography of the surface as well as an improvement in the visual acuity (VA). Nevertheless after the intrastromal ring implant the VA can be improved, due to the persistence of a sphero-cylindrical refractive error or to the presence of an irregular astigmatism furthermore the halos appearing due to the implants presence in the entrance pupil area. With the aim to achieve the maximum VA, gas permeable contact lenses (RGP) are fitted after corneal ring surgery.




Given a specific case*. Grade IV keratoconus. Through the Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany), the previous and posterior intracorneal ring segment implant measures are taken: Topography, aberrations and keratometry measure. OCT (Visante, Carl Zeiss S.A., Espańa) of the anterior segment of the eye. And measure of the VA. Corneal surgery is performed, intracorneal ring (keratoconus) Intralaser, 322 µm tunnel depth, 30ŗ degrees incision, tunnel size 6-6.9mm, ring 150ŗ/250 µm . Further fitting of a RGP contact lens, with specific geometry KAKC-N, Boston EO (Conoptica, SL., Barcelona, Espańa). The lens fitting is performed through trial and error method determining the first test lens by the Pentacam topography elevation map. The topography, aberrometry, OCT and VA are valued again with the contact lens.


The values achieved in aberrometry (Coma) are shown as well as the results of VA (LogMar) previous to surgery and after surgery and the further contact lens fitting as evaluators of the visual efficiency of the treatment in the keratoconus case. Previous to surgery: Coma: 4.758 µm, pupil 3. 82 mm. VA: 0.9 LogMAR Posterior to surgery: Coma: 2.513 µm, pupil 3.82 mm. VA: 0.6 LogMAR Posterior to RGP: Coma: 0.766 µm, pupil 3.82 mm. VA: 0.00 LogMAR OCT of the anterior segment of the eye contributes both to the ring surgery and to further fitting and the study about the placement of the RGP contact lens on the corneal surface.


In the keratoconus treatment, the changes produced by the intrastromal ring segment insertion and a further RGP contact lenses fitting, with specific geometry, provide a significant normalization of the VA. The combination of intrastromal rings and RGP contact lenses make it possible to achieve a very satisfactory level of VA, so that the decision about a corneal transplant can be delayed if the VA results after the rings implant are not satisfactory. FINANCIAL DISCLOSURE?: No

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