title: Specificity of the Heidelberg Retina Tomograph's diagnostic algorithms in a normal elderly population: the Bridlington Eye Assessment Project.
abstract: OBJECTIVE
  To determine the specificity of the Moorfields regression analysis (MRA) and R. Burk (RB) and F. S. Mikelberg (FSM) linear discriminant functions (LDFs) in classifying the optic discs of normal elderly patients imaged with the Heidelberg Retina Tomograph.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Optic nerve head analysis of 459 eyes of 459 normal elderly patients was performed by 2 operators. All patients were consecutive in a cohort screened for eye disease. Normals were defined as having a normal visual field (VF) on automated suprathreshold screening, normal intraocular pressure, and normal visual acuity.
  
  
  METHODS
  Specificity of the optic nerve head classification by MRA and the RB and FSM LDFs.
  
  
  RESULTS
  Subjects' mean age (262 female, 197 male) was 72.6 years. Males were found to have significantly larger cups than females. Eighty-three percent, 11.3%, and 5.7% of discs were classed as within normal limits, borderline, and outside normal limits by MRA. Percentages of optic discs classified as outside normal limits in the smallest and largest quartiles for disc size were 0.9% and 14.9%. The association of disc size with the classification of outside normal limits was significant in males only. Agreement in MRA classification between 2 investigators separately placing the optic disc contour was moderate (Cohen's kappa = 0.54, P<0.001). The RB and FSM LDFs classified 6.8% and 11.8% of discs as diseased. The RB LDF was significantly more likely to return a diagnosis of disease in larger discs, though only in males. The FSM LDF tended to the same drop in specificity, although not significantly.
  
  
  CONCLUSIONS
  Using the MRA and RB/FSM LDFs, specificity fell dramatically with increasing disc size, particularly in males. This may reflect the finding of significantly larger cups in males than in females in the normal elderly population. This divergence was not predicted by these diagnostic functions, which were developed on samples of younger subjects.
authors.affiliation: Department of Ophthalmology, Queen's Medical Centre, Nottingham, United Kingdom.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Hawker
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Vernon
authors.forename: Gerard
authors.initials: G
authors.lastname: Ainsworth
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003430:Cross-Sectional Studies; D003941:Diagnostic Techniques, Ophthalmological; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D007834:Lasers; D008297:Male; D009887:Ophthalmoscopy; D009898:Optic Disk / Q000033:anatomy & histology*; D011237:Predictive Value of Tests; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D014054:Tomography / Q000379:methods; D014792:Visual Acuity