title: Idiopathic horseshoe-like macular tear: a case report.
abstract: BACKGROUND
  Although a few cases with idiopathic horseshoe-like macular tear have been reported, the mechanism remains unknown and a standard treatment has yet to be determined.
  
  
  OBJECTIVE
  To report the outcome for a patient with idiopathic horseshoe-like macular tear who underwent vitreous surgery.
  
  
  METHODS
  A 65-year-old man with no previous injury or ophthalmic disease presented with abnormal vision in his left eye. Best-corrected visual acuity was 0.8 in the right and 0.3 in the left, and the relative afferent pupillary defect was negative. Ophthalmoscopy revealed a horseshoe-like tear on the temporal side of the macula in the left eye. The tear size was 0.75 disc diameters (DD). Optical coherence tomography showed that the focal retinal detachment reached the fovea. A few days after the first visit, there was no longer adhesion of the flap of the tear to the retina and the tear size had increased to 1.5 DD. The patient underwent vitreous surgery similar to large macular hole surgery, with the tear closure repaired using the inverted internal limiting membrane flap technique with 20% SF6 gas tamponade. Although the tear decreased to 0.5 DD after the surgery, complete closure of the tear was not achieved.
  
  
  CONCLUSIONS
  While cases with horseshoe-like macular tear following trauma and branch retinal vein occlusion have been reported, to the best of our knowledge, this is the first reported idiopathic case. In the present case, there was expansion of the tear until the patient actually underwent surgery. If vertical vitreous traction indeed plays a role in horseshoe-like macular tears, this will need to be taken into consideration at the time of the vitreous surgery in these types of cases.
authors.affiliation: Department of Ophthalmology, The Jikei University School of Medicine Kashiwa Hospital, Chiba.
authors.forename: Masaomi
authors.initials: M
authors.lastname: Kubota
authors.affiliation: Department of Ophthalmology, The Jikei University School of Medicine Kashiwa Hospital, Chiba.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Shibata
authors.affiliation: Department of Ophthalmology, The Jikei University School of Medicine Kashiwa Hospital, Chiba.
authors.forename: Hisato
authors.initials: H
authors.lastname: Gunji
authors.affiliation: Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsuneoka
keywords: horseshoe-like macular tear; retinal detachment; vitreous surgery; vitreous traction