title: Bowman's layer encystment in cases of persistent Acanthamoeba keratitis.
abstract: BACKGROUND
  The purpose of this study was to report Acanthamoeba encystment in Bowman's layer in Japanese cases of persistent Acanthamoeba keratitis (AK).
  
  
  METHODS
  Laser confocal microscopic images of the cornea were obtained in vivo from 18 consecutive eyes from 17 confirmed AK patients. Retrospectively, 14 cases treated over 4 months were categorized as a nonpersistent group and three cases that required prolonged therapy for more than 6 months were categorized as a persistent group. Clinical outcomes based on final best-corrected visual acuity were retrospectively analyzed, and selected confocal images were evaluated qualitatively for abnormal findings.
  
  
  RESULTS
  The final best-corrected visual acuity was significantly lower (P < 0.01) for patients in the persistent group compared with that in the nonpersistent group. At the initial visit, in vivo confocal microscopy demonstrated Acanthamoeba cysts exclusively in the epithelial layer in both the nonpersistent group (80%) and the persistent group (100%). At a subsequent follow-up visit, numerous Acanthamoeba cysts were observed in the epithelial cell layer and in Bowman's layer in all patients with persistent AK, but Acanthamoeba cysts were undetectable in all cases with nonpersistent AK tested.
  
  
  CONCLUSIONS
  Invasion of cysts into Bowman's layer was characteristically observed in patients with persistence of AK. This finding suggests that invasion of Acanthamoeba cysts into Bowman's layer may be a useful predictor for a persistent clinical course.
authors.affiliation: Department of Ophthalmology, Kanazawa University Graduate School of Medical Science, Kanazawa.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yokogawa
authors.forename: Akira
authors.initials: A
authors.lastname: Kobayashi
authors.forename: Natsuko
authors.initials: N
authors.lastname: Yamazaki
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Ishibashi
authors.forename: Yosaburo
authors.initials: Y
authors.lastname: Oikawa
authors.forename: Masaharu
authors.initials: M
authors.lastname: Tokoro
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Sugiyama