title: In Vivo Measurement of Human Corneal Impedance Value.
abstract: OBJECTIVE
  To examine the validity of in vivo electrical corneal resistance (CR) measurements taken by a corneal resistance device (CRD).
  
  
  METHODS
  Eighty-two eyes (mean age ± SD, 50.1 ± 23.3; range, 22-87 years: 50 eyes of 33 males and 32 eyes of 17 females) of patients who had undergone cataract surgery and volunteers at the Kanazawa Medical University Hospital were enrolled. The CR was compared among gender; age; side, that is, left versus right eye; healthy (fluorescein-negative) versus epithelium-injured eyes (fluorescein-positive), corneal radius of curvature; corneal endothelial cell count; and corneal thickness.
  
  
  RESULTS
  The mean ± SD of the CR in the 82 eyes was 273.2 ± 78.2 Ω. By age group, the mean ± SD CR was 283.3 ± 87.4 Ω (30 eyes) in the 20s, 275.0 ± 50.0 Ω (4 eyes) in the 30s, 266.7 ± 70.7 Ω (9 eyes) in the 40s, 257.1 ± 53.5 Ω (7 eyes) in the 50s, 242.9 ± 78.7 Ω (7 eyes) in the 60s, 266.7 ± 84.0 Ω (18 eyes) in the 70s, and 300.0 ± 81.6 Ω (7 eyes) in the 80s, with no significant difference among the groups. By gender, the mean ± SD CR was 270.0 ± 83.0 Ω (50 eyes) in males and 278.0 ± 71.0 Ω (32 eyes) in females. By side, the CR values were 282.9 ± 83.4 Ω (44 eyes) in the right eye, 265.9 ± 71.3 Ω (41 eyes) in the left eye, with no significant difference among the groups. By status, the values were 280.0 ± 70.0 Ω (44 eyes) in healthy eyes and 200.0 ± 144.2 Ω (13 eyes) in injured eyes, with a significant between-group difference (P = 0.009). The mean ± SD corneal thickness (0.56 ± 0.03 mm) in 46 healthy eyes was slightly correlated with the CR.
  
  
  CONCLUSIONS
  The CRD quantitatively measured the CR in healthy eyes. The CR did not differ significantly by age, gender, or left versus right eye. The significant difference in CR between the healthy and injured eyes showed that the measurements have validity.
authors.affiliation: Department of Ophthalmology, Kanazawa Medical University, Ishikawa, Japan.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Fukuda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sasaki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002452:Cell Count; D003315:Cornea / Q000033:anatomy & histology / Q000502:physiology*; D063171:Corneal Pachymetry; D003941:Diagnostic Techniques, Ophthalmological; D017097:Electric Impedance; D004728:Endothelium, Corneal / Q000033:anatomy & histology; D019573:Epithelium, Corneal / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D041623:Tomography, Optical Coherence; D055815:Young Adult