title: Anomalies of binocular function in patients with longstanding asymmetric keratoconus.
abstract: OBJECTIVE
  To study binocular function in patients with longstanding asymmetric keratoconus.
  
  
  METHODS
  In 20 adult patients with longstanding asymmetric keratoconus managed with a scleral contact lens a full clinical and orthoptic assessment was performed with and without the scleral contact lens in the poorer eye.
  
  
  RESULTS
  All 20 patients had a corrected acuity of at least 6/9 in their better eye. With the scleral lens in situ the acuity of the poorer eye ranged from 6/6 to 6/60 and without the lens from 6/18 to hand movements. Patients were aged from 18 to 68 years and had worn a scleral contact lens for between 3 and 106 months. Without the contact lens in their poorer eye all patients had a small exotropia and all showed suppression, with the exception of one patient who had a right hypertropia with diplopia. With the scleral lens in situ 12 patients had an exophoria or esophoria, six a microexotropia, and two a manifest exotropia with suppression.
  
  
  CONCLUSIONS
  Binocular function breaks down in some adult patients with longstanding asymmetric keratoconus. This is probably caused by longstanding unilateral visual deprivation. There are similarities to the breakdown of binocular function seen in some patients with a longstanding dense unilateral adult onset cataract who can develop intractable diplopia following cataract surgery.
authors.affiliation: Strabismus and Paediatric Service, Moorfields Eye Hospital, City Road, London EC1V 2PD, UK.
authors.forename: H
authors.initials: H
authors.lastname: Sherafat
authors.forename: J E
authors.initials: JE
authors.lastname: White
authors.forename: K W
authors.initials: KW
authors.lastname: Pullum
authors.forename: G G
authors.initials: GG
authors.lastname: Adams
authors.forename: J J
authors.initials: JJ
authors.lastname: Sloper
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003261:Contact Lenses; D005099:Exotropia / Q000209:etiology*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000150:complications* / Q000503:physiopathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009988:Orthoptics; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity