title: How might corneal elasticity help us understand diabetes and intraocular pressure?
abstract: OBJECTIVE
  To determine how changes in corneal elasticity/stiffness might influence intraocular pressure (IOP) readings in diabetic patients.
  
  
  METHODS
  A systematic review of the literature was performed to understand the conflicting relationship between diabetes, elevated IOP, and glaucoma progression.
  
  
  RESULTS
  Diabetic patients have been found to have statistically significant higher IOP readings in some population-based studies compared to non-diabetics. Insulin resistance states, hyperglycemia and glycosylated hemoglobin have been correlated with higher IOP (1 mmHg) measurements in diabetic patients. In the Ocular Hypertension Treatment Study (OHTS), a self reported history of diabetes was found to be protective against the progression of primary open-angle glaucoma. Small differences in IOP measurements in diabetic patients may be due to corneal stiffening, as demonstrated by the protective effect of glucose-mediated collagen cross-linking against the manifestation and keratometric progression of keratoconus. Different collagen cross-linking agents may induce different degrees of corneal stiffening, which can result in differences in measured IOP.
  
  
  CONCLUSIONS
  Glucose-mediated corneal stiffening due to collagen cross-linking might be responsible for IOP overestimation in diabetic patients. Corneal stiffening might explain why diabetic eyes tend to have higher IOP readings in large population-based studies and why those with ocular hypertension have a reduced risk for glaucoma progression.
authors.affiliation: Cole Eye Institute, Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195, USA. krueger@ccf.org
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Krueger
authors.forename: Jerome C
authors.initials: JC
authors.lastname: Ramos-Esteban
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D003094:Collagen / Q000502:physiology; D003315:Cornea / Q000503:physiopathology*; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology*; D018450:Disease Progression; D004548:Elasticity; D005901:Glaucoma / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D012307:Risk Factors
chemical_list: D001786:Blood Glucose; D003094:Collagen