ABSTRACT
INTRODUCTION: A practical nomogram has been designed in order to present the results obtained from the Ocular Hypertension Study (Gordon et al. Arch Ophthalmol 2002; 120: 714-720), where the relation between intraocular pressure (IOP) and corneal thickness becomes apparent, involving the risk of evolution from ocular hypertension into glaucoma within a 6 year period. MATERIAL AND METHODS: We used a multiple logarithmic regression for the nine parameters shown in figure 1 of the above mentioned paper. RESULTS: A correlation coefficient of 0.91 (p<0.001) permits to establish the following equation: Probability of evolution (%) = 13539.5 x (1.1385IOP) x (0.9818(CORNEAL THICKNESS)). This implies that a variation of 10 microns on corneal thickness leads to an IOP's modification of 1.5 mmHg in the same sense. From these data, we designed the nomogram included in this paper. CONCLUSIONS: IOP and pachymetry together allow an estimation of the risk of evolution from ocular hypertension into glaucoma in a graphical practical way. From this indirect estimation, the influence of corneal thickness on IOP's measure seems to be much higher than previously estimated.
Subject(s)
Nomograms , Ocular Hypertension/diagnosis , Disease Progression , Humans , Intraocular Pressure/physiology , Logistic Models , Risk , Tonometry, OcularSubject(s)
Glaucoma, Angle-Closure/surgery , Phacoemulsification , Cataract Extraction , Humans , Intraocular Pressure , Iris , Laser TherapyABSTRACT
BACKGROUND: To compare the ability of Glaucoma Progression Analysis (GPA) and Threshold Noiseless Trend (TNT) programs to detect visual-field deterioration. METHODS: Patients with open-angle glaucoma followed for a minimum of 2 years and a minimum of seven reliable visual fields were included. Progression was assessed subjectively by four masked glaucoma experts, and compared with GPA and TNT results. Each case was judged to be stable, deteriorated or suspicious of deterioration RESULTS: A total of 56 eyes of 42 patients were followed with a mean of 7.8 (SD 1.0) tests over an average of 5.5 (1.04) years. Interobserver agreement to detect progression was good (mean kappa = 0.57). Progression was detected in 10-19 eyes by the experts, in six by GPA and in 24 by TNT. Using the consensus expert opinion as the gold standard (four clinicians detected progression), the GPA sensitivity and specificity were 75% and 83%, respectively, while the TNT sensitivity and specificity was 100% and 77%, respectively. CONCLUSION: TNT showed greater concordance with the experts than GPA in the detection of visual-field deterioration. GPA showed a high specificity but lower sensitivity, mainly detecting cases of high focality and pronounced mean defect slopes.