title: Central Corneal Thickness and its Relationship to Intra-Ocular and Epidmiological Determinants.
abstract: OBJECTIVE
  To measure central corneal thickness in Pakistani population and determine its relationship to intra-ocular pressure, age, gender and ethnicity.
  
  
  METHODS
  Cross-sectional observation study.
  
  
  METHODS
  Pakistan Institute of Medical Sciences, Islamabad, Pakistan, between December 2013 and February 2015.
  
  
  METHODS
  The right eyes of 1000 cases (496 males and 504 females) were recruited for this study. Inclusion criteria were Pashtun or Punjabi ethnicity, intra-ocular pressure < 22 mmHg, gonioscopically open angles, cup-disk-ratio < 0.5, and age matched normal visual fields. Cases with prior ocular surgery, contact lens use, corneal pathologies, myopia or hypermetropia > ±3.0 diopters, astigmatism of > ±1.0 diopters were excluded. Central corneal thickness was measured using a TopCon non-contact specular microscope. Intra-ocular pressure was measured using Goldmann applanation tonometer. Frequency distribution, test of significance, and regression analysis was carried out using Statistical Package for Social Sciences version 20.0.
  
  
  RESULTS
  Mean age was 47.31 ±11.78 years. Ethnic composition was 51.6% (n=516) Pashtun and 48.4% (n=484) Punjabi. The mean central corneal thickness was 503.96 (±12.47) µm, while the mean intra-ocular pressure was 15.61 (±2.68) mmHg. Regression analysis showed a significant association between central corneal thickness and intra-ocular pressure (p=0.00) and age (p=0.00). A±100 µchange in central corneal thickness was associated with change in IOPof ±3.30 mmHg, whereas central corneal thickness decreased by 0.12 µm per year. No significant association could be established between central corneal thickness and ethnicity (p=0.19).
  
  
  CONCLUSIONS
  Central corneal thickness of the studied races was comparable to non-Caucasians which affects intra-ocular pressure measurements, and decreases with increasing age. No relationship was observed between central corneal thickness and ethnicity or gender.
authors.affiliation: Department of Ophthalmology, Shifa College of Medicine, Islamabad.
authors.forename: Ali
authors.initials: A
authors.lastname: Tayyab
authors.affiliation: Department of Ophthalmology, Shifa College of Medicine, Islamabad.
authors.forename: Amena
authors.initials: A
authors.lastname: Masrur
authors.affiliation: Department of Ophthalmology, Pakistan Institute of Medical Sciences, Islamabad.
authors.forename: Farooq
authors.initials: F
authors.lastname: Afzal
authors.affiliation: Department of Ophthalmology, Pakistan Institute of Medical Sciences, Islamabad.
authors.forename: Fyza
authors.initials: F
authors.lastname: Iqbal
authors.affiliation: Resident Medical Officer, Urgent Care Centre, Alexandra Hospital, Cheadle, UK.
authors.forename: Kamran
authors.initials: K
authors.lastname: Naseem
mesh_terms: D000328:Adult; D044466:Asian People; D016022:Case-Control Studies; D003315:Cornea / Q000033:anatomy & histology*; D003430:Cross-Sectional Studies; D005123:Eye / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010154:Pakistan; D014065:Tonometry, Ocular / Q000379:methods*; D055815:Young Adult