title: Corona sign: manifestation of peripheral corneal epithelial edema as a possible marker of the progression of corneal endothelial dysfunction.
abstract: OBJECTIVE
  To describe a characteristic form of the corona sign and its clinical relevance to the degree of corneal endothelial decompensation and investigate the underlying mechanism using a rabbit model.
  
  
  METHODS
  These observational cases include 31 patients undergoing penetrating keratoplasty (PKP) and 15 patients undergoing Descemet stripping automated endothelial keratoplasty (DSAEK) with special attention to the circumferentially developed corneal epithelial edema. We also conducted a laboratory observation of horizontal water flow in the rabbit cornea.
  
  
  RESULTS
  We consistently observed the corona sign at the superior periphery during the initial stage of corneal endothelial decompensation after PKP. With progressive corneal endothelial cellular loss, the epithelial edema gradually expanded circumferentially in the periphery. The endothelial cellular density associated with the corona sign significantly (P < 0.01) decreased compared with that without the sign. The endothelial cellular density decreased significantly (P < 0.05) in cases with a circumferential corona sign compared with a superior corona sign. After DSAEK, however, the corneal epithelial edema subsided from the center but persisted peripherally as a corona sign in all cases. By 3 months postoperatively, the epithelial edema was confined to the superior periphery along with uneventful corneal endothelial healing. Rabbit experiments showed that total corneal endothelial decompensation decreased the horizontal intracorneal water migration (Inoue-Ohashi phenomenon) in the corneal periphery and induced peripheral corneal edema.
  
  
  CONCLUSIONS
  The slit-lamp microscopic findings of the corona-like epithelial edema in the peripheral cornea are associated with the stage of corneal endothelial function. To support this, the developmental mechanism of the corona sign was demonstrated experimentally.
authors.affiliation: Tane Memorial Eye Hospital, 1-1-39 Sakaigawa, Nishi-ku, Osaka, 550-0024, Japan. tomonoue@gmail.com.|Department of Ophthalmology, Ehime University School of Medicine, Ehime, Japan. tomonoue@gmail.com.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Ehime, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Hara
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Ehime, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Ehime, Japan.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Ehime, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Ehime, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shiraishi
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Ehime, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ohashi
mesh_terms: D000368:Aged; D000818:Animals; D055954:Corneal Endothelial Cell Loss / Q000175:diagnosis / Q000601:surgery*; D057111:Descemet Stripping Endothelial Keratoplasty / Q000379:methods*; D018450:Disease Progression; D004728:Endothelium, Corneal / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D011817:Rabbits
keywords: Corneal endothelial dysfunction; Corona sign; Horizontal intracorneal water migration; Peripheral corneal epithelial edema; Superior corneal periphery