Binocular contrast sensitivity in patients with intermittent exotropia in relation to angle of strabismus and level of compensation
Babak Masoomian1 *, Mohammad Reza Akbari2 , Fatemeh Moradi3
- Farabi Eye Hospital, Tehran University of medical sciences
- Farabi eye hospital. Tehran university of medical sciences
- Iran university of medical sciences
Abstract: Intermittent exotropia (IXT) causes photophobia and photophobia has been studied by measurement of contrast sensitivity (CS). CS was reduced in children with IXT. We compared binocular CS (BCS) in patients with IXT and normal subjects in relation to the angle of strabismus and control of IXT.
Methods: This case-control study perfomed on 40 patients with IXT and 40 normal subjects who were examined with the CSV1000 CS device in mesopic (3 cd/m2) and photopic (85 cd/m2) conditions with and without a glare stimulus, at 3, 6, 12, and 18 cycle/degree (cpd) spatial frequencies. Angle of strabismus and near stereoacuity were also measured. The patient’s compensation of IXT was graded based on the office control scale.
Results: The mean age for IXT and normal participants were 12.30 ± 0.60 (range, 6-18) and 11.00 ± 0.78 (range, 6-18) years, respectively (p=0.34). IXT patients had lower binocular CS than controls at all spatial frequencies (P<0.001). The largest decrease in CS occurred at 6 cpd spatial frequency under mesopic condition (1.61 ± 0.07 vs 1.38 ± 0.15, p<0.001) and photopic condition with glare (2.03 ± 0.06 vs 1.77 ± 0.13, P<0.001). Patients who had better control scores having higher levels of BCS also, the score of BCS showed a significant decreased in patients who had a deviation of 25 prism diopter or more, compared to those who have less deviation. BCS correlated at 3 and 6 cpd with near stereoacuity (r = -0.652, P<0.001 and r = -0.613, P<0.001).
Conclusion: : Binocular CS in patients with IXT correlates with angle of strabismus and level of compensation.
