title: The prismatic effect on stereoacuity in intermittent exotropia.
abstract: OBJECTIVE
  To evaluate the effect of acrylic refractive prism and Fresnel membrane prism on stereoacuity in intermittent exotropia.
  
  
  METHODS
  Stereoacuities of fifty-two patients (mean age, 12.4 years; range 6 to 45 years) with intermittent exotropia were measured using the Titmus and TNO stereotests, while they wore prisms of varying power on nonfixating eye or evenly on each eye.
  
  
  RESULTS
  Stereoacuities were significantly reduced with increasing prism power for both prisms, ranging from 8 to 25 prism dipotres. The effects on stereoacuity in single acrylic prism and single Fresnel prism were similar, whereas spilt Fresnel prisms reduced stereoacuity more than spilt acrylic prisms. Spilt prisms were found to have much less effect on stereoacuity than single prisms for both acrylic and Fresnel prisms.
  
  
  CONCLUSIONS
  The use of acrylic refractive prism shared evenly on each eye would be optimal method to minimize the reduction of stereoacuity during the prismatic therapy for intermittent exotropia.
authors.affiliation: Department of Ophthalmology, National Health Insurance Corporation Ilsan Hospital, Goyang, Korea.
authors.forename: Kyoung Sub
authors.initials: KS
authors.lastname: Choi
authors.forename: Seung Ah
authors.initials: SA
authors.lastname: Chung
authors.forename: Kyu Sung
authors.initials: KS
authors.lastname: Lee
authors.forename: Jong Bok
authors.initials: JB
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003867:Depth Perception / Q000502:physiology*; D005099:Exotropia / Q000503:physiopathology / Q000628:therapy*; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult