Condition of stereoscopic vision in children with various types of refraction

    T.A. Kornyushina, T.P. Kashchenko, A.V. Ibragimov

    Condition of stereoscopic vision in children with various types of refraction

    The Pediatric Ophthalmic Center of the S. Fyodorov Eye Microsurgery Complex – Federal State Budget Institution, Moscow

    Purpose. To study a condition of stereoscopic vision (SV) with use of lattices with different spatial frequency in children with a various refraction.

    Material and methods. There were examined 61 schoolchildren aged 10-15 years: out of them 21 persons with emmetropia (mean refraction: +0.17±0.07D, visual acuity (VA): 0.99±0.01), 19 with hyperopia (mean refraction: +1.3±0.21D, uncorrected VA (UCVA): 0.94±0.03) 21 persons with myopia (mean refraction: -1.35±0.36D, UCVA: 0.5±0.07). All patients had a binocular vision. Stereovision research was performed with optical correction of ametropia at distances: 5; 2,5; 1; 0,5; 0,33 m from the object according to the Stereopsis program.

    Results. In patients with various types of refraction the stereovision (SV) acuity for distance of 2.5 m was measured in the range of spatial frequencies of 0.4-16 cpd. In patients with emmetropia and hyperopia the disparity angle ranged from 1.6 to 3.2". There was observed a tendency to an increase of disparity angle with an increasing spatial frequency grating. In patients with myopia the maximum disparity angles were observed upon presentation of a lattice with a spatial frequency of 0.4 and 0.5 cpd. (disparity angle equaled respectively 13.3 and 12.5") and 1.4 and 5.7 cpd. (19 and 10.2" respectively).

    In all kinds of refraction the maximum SV acuity was noted in patients’ location at the distance of 5m from the object, closer to the object the SV acuity decreased. Between the SV acuity and the accommodation expenditure in different types of refraction there is a dependence: in emmetropia the expenditures of accommodation were less than the calculated values on the average by 0.4D, the SV acuity averaged 6.3±0.1"; in hyperopia the accommodation expenditure exceeded the calculated data on the average by 0.1D, the SV acuity averaged 15.4±0.3"; in myopia the accommodation expenditure decreased on the average by 1.0D the SV acuity averaged 25.4±0.3".

    Conclusions. The use of lattices with different spatial frequency during determination of stereovision acuity is a sensitive test that allows to judge a work stability of binocular system in fixation of the object located at various distances. For a 2.5 m distance in the range of spatial frequencies 0.4-16.0" in patients with myopia the disparity angle is higher than in patients with emmetropia and hyperopia, i.e. the stereovision acuity in myopia is lower than in emmetropia and hyperopia. For all types of refraction the highest stereovision acuity was found in study at a 5m distance, and the lowest SV acuity was revealed in study at a 0.33 m distance. The highest SV acuity is noted in emmetropic patients, a lower SV acuity – in hyperopic patients, the lowest SVA – in myopic patients. There is a close relationship between accommodation and binocular systems. Accommodation expenditure in emmetropia is lower than the theoretical values and has the smallest disparity angle, in hyperopia accommodation expenditure exceeds the theoretical values, disparity angle – higher than in emmetropia, thereby characterizing the overstrain of both accommodative and binocular systems. Accommodation expenditure in myopia is lower than in emmetropia, disparity angle – the highest pointing out a weakness of both accommodative and binocular systems.

    Keywords: stereoscopic vision, accommodation expenditures, refraction.