title: Clinical findings before the onset of myopia in youth. I. Ocular optical components.
abstract: OBJECTIVE
  A study was conducted to identify variables that were different in children who were emmetropic and became myopic and in children who remained emmetropic.
  
  
  METHODS
  A cohort of initially emmetropic children had eye and vision examinations at 6-month intervals for a period of 3 years. Ocular optical components were measured by keratometry and ultrasonography. Crystalline lens power was calculated using Bennett's formulas.
  
  
  RESULTS
  There was a tendency for keratometer power of both principal meridians to be greater in the became-myopic group than in the remained-emmetropic group. Axial length to corneal radius (AL/CR) ratio was significantly greater in the became-myopic group than in the remained-emmetropic group. The variable with the highest sensitivity and specificity was the AL/CR ratio using the horizontal meridian corneal radius.
  
  
  CONCLUSIONS
  Greater corneal powers and greater AL/CR ratios are risk factors for youth onset myopia.
authors: School of Optometry, Indiana University, Bloomington, USA.
authors: D A
authors: DA
authors: Goss
authors: T W
authors: TW
authors: Jackson
mesh_terms: D000293:Adolescent; D000867:Anterior Chamber / Q000502:physiology; D002648:Child; D003315:Cornea / Q000502:physiology*; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D009216:Myopia / Q000209:etiology / Q000503:physiopathology*; D009799:Ocular Physiological Phenomena; D011446:Prospective Studies