Abstract
Purpose: The aim of our study was to assess the variations in fusion and stereopsis before and after refractive surgery. Methods: We conducted a retrospective study. 140 patients (78 M, 62 F) were selected, aged 20 - 59 years (mean age 36 ± 10 DS). All patients received a comprehensive ophtalmological and orthoptic examination. Surgery was performed using a MEL-80 excimer laser (Carl Zeiss Meditec, Jena, Germany). Results: Fusional convergence amplitudes after refractive eye surgery range from at near 18 - 20 PD in 42 (30%) patients; 25 - 30 PD in 56 (40%) patients; 35 - 40 PD in 42 (30%) patients, at far 20 - 25 PD in 84 (60%) patients; 30 - 40 PD in 56 (40%) patients, fusional divergence at near after refractive eye surgery range from at near 6 - 8 PD in 108 (75.7%) patients; 10 - 12 PD in 52 (37.1%), at far 6 - 8 PD in 126 (90%) patients; 10 - 12 PD in 14 (10%) patients. None of the patients developed any ocular deviations. NCP, on average, decreases from 9.4 ± 1.5 cm to 9.1 ± 0.9 cm after. None of these patients with a normal NCP before surgery developed an abnormal NCP after refractive surgery. Eighteen patients (12.8%) had a stereopsis higher than 60 s of arch before surgical intervention. Of these, in 2 cases (2.8%) stereopsis increased from 200 to 40 s of arch after surgery. In the rest of patients stereopsis remained unchanged. Conclusion: The increase in fusion at near appears to be considerably interesting, whereas there is no worsening of stereopsis. A careful pre-surgery orthoptic evaluation is extremely revelant for a safe refractive surgery, this reducing the risk of complications associated with fusion and stereopsis.
Highlights
The aim of our study was to assess the variations in fusion and stereopsis before and after refractive surgery
Fusional convergence amplitudes after refractive eye surgery range from at near 18 - 20 PD in 42 (30%) patients; 25 - 30 PD in 56 (40%) patients; 35 - 40 PD in 42 (30%) patients, at far 20 - 25 PD in 84 (60%) patients; 30 - 40 PD in 56 (40%) patients, fusional divergence at near after refractive eye surgery range from at near 6 - 8 PD in 108 (75.7%) patients; 10 - 12 PD in 52 (37.1%), at far 6 - 8 PD in 126 (90%) patients; 10 - 12 PD in 14 (10%) patients
A careful pre-surgery orthoptic evaluation is extremely revelant for a safe refractive surgery, this reducing the risk of complications associated with fusion and stereopsis
Summary
Refractive surgery offers some advantages: neutralization of the prismatic effects, improvement in visual acuity, improvement in binocular vergence and fusion, strengthening or recovery of binocular vision. In 2005 Sabetti et al demonstrated how the refractive surgery allows the correction of accommodative esotropia and without the modification of the forms of esotropia is not caused by an abnormal AC/A ratio [1]. Hashemi (2013) highlights hot the near poing of convergence and the near point of accommodation may increase significantly after photorefractive keratectomy (PRK) [2]. In 2014 Han reported an increase in the fusional vergence at near following refractive surgery [3]. Chung (2014) underlines the risk of a change in the ocular alignment, particulary in cases with a large-angle heterophoria/ heterotropia [4]
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