The effect of contact correction on the state of accommodation in patients with keratoconus

Introduction. Keratoconus (KC) is a disease belonging to the group of primary keratectasias, characterized by pronounced irregularity of corneal topography and accompanied by irregular astigmatism, myopic refraction and higher order aberrations. It is established that accommodation in cases of ametropia is strongly influenced by the wave front of eye, but the influence of aberrations on ciliary muscle work in KC remains unstudied. The aim was to study the correlation of accommodation in KC with the ectasia-induced aberrations before and after optical correction with scleral rigid contact lenses (SRCL).

Materials and methods. Thirty people (60 eyes) with newly diagnosed bilateral KC, were included in the study: 26 eyes – stage I, 29 eyes – stage II, 5 eyes – stage III. Mean age of the patients was 26,2 ± 4,3 years. The clinical recruitment period was from January to September 2022. All patients were additionally evaluated for keratometric and aberration parameters of the cornea using a Scheimpflug camera besides a standard ophthalmological examination. Objective evaluation of accommodation was performed on the Righton Speedy-I device with determination of qualitative and quantitative indices. All investigations were performed before and after one month of wearing individual SRCL.

Results. According to the data of objective accomodography a state of spasmodic accommodation asthenopia was observed in 71% of cases before started wearing pressure lenses. There was a tendency to improvement of ciliary muscle function and a “stepped” course of the accommodative curve while wearing SRCL a month later. High values of corneal aberrations decreased by 4.5 times in the course of SRCL. Correlation analysis revealed a significant trend between the state of accommodation and the corneal wavefront.

Conclusion. Objective examination of the accommodation state in KC proves the signs presence of accommodative asthenopia mediated by irregular astigmatism. The revealed correlations between the indices of induced KC aberrations and accommodation state confirm the fact of ectasia negative influence on ciliary muscle work. It was proved that optical correction with SRCL in KC reduces corneal aberrations and significantly improves the state of accommodation.

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