title: Predicting sulcus size using ocular measurements.
abstract: OBJECTIVE
  To predict sulcus size using ocular measurements.
  
  
  METHODS
  Michel Pop Clinics, Montreal, Quebec, Canada.
  
  
  METHODS
  Forty-three eyes were evaluated using several techniques. Ultrasound biomicroscopy (UBM) echograms were taken to measure the anterior chamber depth (ACD), sulcus size, and central corneal thickness. The limbus size was measured with a caliper. Axial length, ACD, and pachymetry were measured by contact ultrasonography. Refraction and corneal power were also evaluated.
  
  
  RESULTS
  The coefficient of linear regression was 0.05 between the limbus and the sulcus size (P =.78), 0.76 between ultrasonography and UBM ACD measurements (P <.001), and 0.69 between ultrasonography and UBM pachymetry (P <.001). Paired t tests showed that ultrasound and UBM ACD measurements were not statistically different (P =.70) but that ultrasound and UBM pachymetry measurements were (P <.001). The sulcus versus limbus difference was 0.6 mm for myopia and 0.3 mm for hyperopia. A backward elimination multiple regression performed with all measures to predict sulcus size resulted in the following formula: Sulcus size = 18.9 - 0.023 x sphere + 0.15 x mean keratometry (R = 0.49; P =.005; statistical power = 0.89; standard error of estimate = 0.5 mm).
  
  
  CONCLUSIONS
  Traditional estimation of sulcus size through limbal measurement is inadequate because limbus size alone cannot predict sulcus size. A general formula using the sphere and the mean corneal power can help predict sulcus size. Corneal power was significantly and negatively correlated with sulcus and limbus size as well as sphere. The standard error of sulcus measurement by UBM was 0.4 mm.
authors.affiliation: Michel Pop Clinics, 9001 l'Acadie Boulevard North, Suite 900, Montreal, Quebec H4N 3H5, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Pop
authors.forename: Y
authors.initials: Y
authors.lastname: Payette
authors.forename: M
authors.initials: M
authors.lastname: Mansour
mesh_terms: D000328:Adult; D000867:Anterior Chamber / Q000000981:diagnostic imaging*; D000886:Anthropometry; D002924:Ciliary Body / Q000033:anatomy & histology*; D003315:Cornea / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007908:Lens, Crystalline / Q000000981:diagnostic imaging*; D008297:Male; D012029:Refraction, Ocular; D014463:Ultrasonography; D014822:Vitreous Body / Q000000981:diagnostic imaging*