title: Diagnostic Efficacy of Normalization of Corneal Deformation Variables by the Intraocular Pressure in Glaucomatous Eyes.
abstract: OBJECTIVE
  To analyze the diagnostic efficacy of normalization of corneal deformation variables by the IOP in healthy, primary-angle closure (PACG), and primary open angle glaucoma (POAG) patients.
  
  
  METHODS
  Fifty-nine healthy, 83 POAG, and 57 PACG eyes, matched for age and pachymetry, were included in a prospective, observational, cross-sectional study. Goldmann applanation tonometry (GAT-IOP), Corvis-ST IOP, IOPg (Goldmann correlated), and IOPcc (cornea compensated) from the ocular response analyzer were acquired. Corneal hysteresis (CH) and corneal resistance factor (CRF) from the ORA, and deformation amplitude (DA) from Corvis-ST were analyzed. Further, ratios of CH, CRF, and DA to IOP were assessed among the groups and defined as new variables (e.g., ratio [CH, IOPcc] was the ratio of CH to IOPcc).
  
  
  RESULTS
  Goldmann applanation tonometry-IOP, IOPcc, and IOPg of PACG and POAG eyes were significantly higher than normal (P < 0.05). Corvis-ST IOP of healthy eyes was similar to POAG (P > 0.05) but lower than PACG (P = 0.02). Corneal hysteresis and CRF of PACG and POAG were significantly lower than normal (P < 0.0001). The ratio (CH, IOPcc), ratio (CRF, IOPcc), and ratio (DA, IOPcc) of healthy eyes were significantly higher than those of PACG and POAG eyes (P < 0.0001). The sensitivity and specificity of ratio (CRF, IOPcc) and ratio (DA, IOPcc) was significantly better than CRF and DA alone in PACG eyes (P < 0.001). However in POAG, only the sensitivity and specificity of ratio (DA, IOPcc) was significantly better than DA alone (P < 0.001).
  
  
  CONCLUSIONS
  Presence of glaucoma may be indicated better by ratio variables than by CH, CRF, or DA alone.
authors.affiliation: Glaucoma and Ocular Hypertension Division Narayana Nethralaya, India.
authors.forename: Sushma
authors.initials: S
authors.lastname: Tejwani
authors.affiliation: Glaucoma and Ocular Hypertension Division Narayana Nethralaya, India.
authors.forename: Sathi
authors.initials: S
authors.lastname: Devi
authors.affiliation: Glaucoma and Ocular Hypertension Division Narayana Nethralaya, India.
authors.forename: Shoruba
authors.initials: S
authors.lastname: Dinakaran
authors.affiliation: Vice-Chairman, Narayana Nethralaya, India.
authors.forename: Rohit
authors.initials: R
authors.lastname: Shetty
authors.affiliation: Glaucoma and Ocular Hypertension Division Narayana Nethralaya, India.
authors.forename: Priti
authors.initials: P
authors.lastname: Meshram
authors.affiliation: Imaging, Biomechanics and Mathematical Modeling Solutions, Narayana Nethralaya Foundation, Bangalore, India.
authors.forename: Mathew
authors.initials: M
authors.lastname: Francis
authors.affiliation: Imaging, Biomechanics and Mathematical Modeling Solutions, Narayana Nethralaya Foundation, Bangalore, India.
authors.forename: Abhijit
authors.initials: A
authors.lastname: Sinha Roy
mesh_terms: D000368:Aged; D003315:Cornea / Q000473:pathology* / Q000503:physiopathology; D063171:Corneal Pachymetry / Q000379:methods; D003430:Cross-Sectional Studies; D004548:Elasticity; D005260:Female; D005500:Follow-Up Studies; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis / Q000473:pathology* / Q000503:physiopathology; D005902:Glaucoma, Open-Angle / Q000175:diagnosis / Q000473:pathology* / Q000503:physiopathology; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D014065:Tonometry, Ocular; D014794:Visual Fields