title: Long-term change in central corneal thickness from a glaucoma perspective.
abstract: OBJECTIVE
  To investigate the longitudinal change in central corneal thickness (CCT) over 3 years in patients with glaucoma.
  
  
  METHODS
  The Chennai Glaucoma Follow-up Study, an offshoot of the Chennai Glaucoma Study, was designed to evaluate the progression of glaucoma. A cohort of participants in the Chennai Glaucoma Study that were suffering from glaucoma or were at a higher risk for glaucoma underwent comprehensive ophthalmic evaluation at the base hospital at 6-month intervals during the years 2004 to 2007. The CCT (average of 10 readings) was measured between 11 am and 1 pm on any given day using an ultrasonic pachymeter. Patients with a history of ocular surgery, corneal disease and usage of topical carbonic anhydrase inhibitor were excluded. No patient was a contact lens wearer.
  
  
  RESULTS
  One hundred and ninety-six patients (84 male, 112 female) met the inclusion criteria. We analyzed data from the right eye. The mean age of the patients was 59.97 ± 9.06 years. Fifty-nine (30.1%) of the patients were diabetic. The mean change in CCT (CCT at first patient visit--CCT at last patient visit) was 3.46 ± 7.63 μm. The mean change in CCT was 0.75 μm per year (R² = 0.00). Age, gender, intraocular pressure at the first patient visit and diabetic status had no significant influence on the magnitude of change in CCT.
  
  
  CONCLUSIONS
  A carefully obtained CCT reading by a trained examiner need not be repeated for at least 3 years as long as the ocular and systemic factors known to affect the measurement of CCT are constant.
authors.affiliation: Department of Glaucoma project, Chennai Glaucoma Study, Vision Research Foundation, Sankara Nethralaya, 18, College Road, Chennai 600006, India.
authors.forename: Nikhil S
authors.initials: NS
authors.lastname: Choudhari
authors.forename: Ronnie
authors.initials: R
authors.lastname: George
authors.forename: Ramesh Ve
authors.initials: RV
authors.lastname: Sathyamangalam
authors.forename: Prema
authors.initials: P
authors.lastname: Raju
authors.forename: Rashima
authors.initials: R
authors.lastname: Asokan
authors.forename: Lokapavani
authors.initials: L
authors.lastname: Velumuri
authors.forename: Lingam
authors.initials: L
authors.lastname: Vijaya
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003315:Cornea / Q000473:pathology*; D063171:Corneal Pachymetry / Q000379:methods*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005901:Glaucoma / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014065:Tonometry, Ocular