title: Ocular dimensions, corneal thickness, and corneal curvature in quarter horses with hereditary equine regional dermal asthenia.
abstract: OBJECTIVE
  The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia (HERDA) and unaffected horses.
  
  
  METHODS
  Five HERDA-affected quarter horses and five healthy control quarter horses were used.
  
  
  METHODS
  Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound scanning was performed on both eyes of each horse to determine the dimensions of the ocular structures and to calculate the corneal curvature.
  
  
  RESULTS
  Each corneal region examined in this study was thinner in the affected group compared with the healthy control group. However, significant differences in corneal thickness were only observed for the central and dorsal regions. HERDA-affected horses exhibited significant increases in corneal curvature and corneal diameter compared with unaffected animals. The ophthalmologic examinations revealed mild corneal opacity in one eye of one affected horse and in both eyes of three affected horses. No significant between-group differences were observed for Schirmer's tear test, intraocular pressure, or ocular dimensions.
  
  
  CONCLUSIONS
  Hereditary equine regional dermal asthenia-affected horses exhibit decreased corneal thickness in several regions of the cornea, increased corneal curvature, increased corneal diameter, and mild corneal opacity. Additional research is required to determine whether the increased corneal curvature significantly impacts the visual accuracy of horses with HERDA.
authors.affiliation: Department of Veterinary Clinical Science, UNESP - Univ Estadual Paulista, Distrito de Rubião Júnior, Botucatu, São Paulo, Brazil.
authors.forename: Peres R
authors.initials: PR
authors.lastname: Badial
authors.affiliation: Department of Animal Reproduction and Veterinary Radiology, UNESP - Univ Estadual Paulista, Distrito de Rubião Júnior, Botucatu, São Paulo, Brazil.
authors.forename: Luis Emiliano
authors.initials: LE
authors.lastname: Cisneros-Àlvarez
authors.affiliation: Department of Veterinary Surgery and Anesthesiology, UNESP - Univ Estadual Paulista, Distrito de Rubião Júnior, Botucatu, São Paulo, Brazil.
authors.forename: Cláudia Valéria S
authors.initials: CV
authors.lastname: Brandão
authors.affiliation: Department of Veterinary Surgery and Anesthesiology, UNESP - Univ Estadual Paulista, Distrito de Rubião Júnior, Botucatu, São Paulo, Brazil.
authors.forename: José Joaquim T
authors.initials: JJ
authors.lastname: Ranzani
authors.affiliation: Department of Veterinary Surgery and Anesthesiology, UNESP - Univ Estadual Paulista, Distrito de Rubião Júnior, Botucatu, São Paulo, Brazil.
authors.forename: Mayana A R V
authors.initials: MA
authors.lastname: Tomaz
authors.affiliation: Department of Animal Reproduction and Veterinary Radiology, UNESP - Univ Estadual Paulista, Distrito de Rubião Júnior, Botucatu, São Paulo, Brazil.
authors.forename: Vania M
authors.initials: VM
authors.lastname: Machado
authors.affiliation: Department of Veterinary Clinical Science, UNESP - Univ Estadual Paulista, Distrito de Rubião Júnior, Botucatu, São Paulo, Brazil.
authors.forename: Alexandre S
authors.initials: AS
authors.lastname: Borges
mesh_terms: D000818:Animals; D001247:Asthenia / Q000235:genetics / Q000473:pathology / Q000662:veterinary*; D016022:Case-Control Studies; D003315:Cornea / Q000033:anatomy & histology / Q000473:pathology*; D063171:Corneal Pachymetry / Q000662:veterinary; D005123:Eye / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology*; D005128:Eye Diseases / Q000000981:diagnostic imaging / Q000235:genetics / Q000473:pathology / Q000662:veterinary*; D005260:Female; D006734:Horse Diseases / Q000000981:diagnostic imaging / Q000235:genetics / Q000473:pathology*; D006736:Horses / Q000033:anatomy & histology; D008297:Male; D014065:Tonometry, Ocular / Q000662:veterinary; D014463:Ultrasonography
keywords: biometry; corneal pachymetry; cyclophilin B; hereditary equine regional dermal asthenia; horses; keratometry