title: Clinical Evidence of Decreased Iris Resistance in Patients With Keratoconus.
abstract: OBJECTIVE
  To compare the total energy required for producing patent neodymium:yttrium-aluminum-garnet laser peripheral iridotomy in patients with or without keratoconus (KC).
  
  
  METHODS
  In this case-control study, 36 eyes from 36 patients with KC and 24 eyes from 24 patients with myopia with or without astigmatism (as control group) who were scheduled for phakic intraocular lens implantation underwent neodymium:yttrium-aluminum-garnet laser peripheral iridotomy 1 week before surgery. The total laser energy was recorded and compared between the 2 groups.
  
  
  RESULTS
  Mean total laser energy was significantly lower in patients with KC compared with the control group (114.7 ± 41.0 mJ and 263.9 ± 79.6 mJ, respectively, P < 0.01). Total laser energy was not correlated with patients' age, sex, race, refraction, maximum keratometry, or corneal thickness.
  
  
  CONCLUSIONS
  Lower tissue resistance may be present in other ocular structures, such as iris, in patients with KC. Our findings supported a generalized abnormality in patients with KC rather than a localized corneal disease, at least in some cases.
authors.affiliation: *Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; and †Laser Application in Medical Sciences Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Mehdi
authors.initials: MM
authors.lastname: Sadoughi
authors.forename: Danial
authors.initials: D
authors.lastname: Roshandel
authors.forename: Javad
authors.initials: J
authors.lastname: Rezaei
authors.forename: Neda
authors.initials: N
authors.lastname: Einollahi
authors.forename: Bahram
authors.initials: B
authors.lastname: Einollahi
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000150:complications / Q000601:surgery; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D032801:Iridectomy; D007498:Iris / Q000601:surgery*; D007640:Keratoconus / Q000150:complications*; D017075:Laser Coagulation; D053844:Lasers, Solid-State; D019654:Lens Implantation, Intraocular; D008297:Male; D009216:Myopia / Q000150:complications / Q000601:surgery*; D054120:Phakic Intraocular Lenses; D055815:Young Adult