RESUMEN
BACKGROUND: Aim of the study was to evaluate the validity of quantitative planimetry of the optic disc with a new digital method and to assess the correlation of the measurements with morphological changes in eyes with low tension glaucoma. MATERIAL AND METHODS: The study included 40 eyes from 40 patients (age 61+/-12 years) with low tension glaucoma with a mean follow-up of 4.9+/-2.1 (range 3-9) years. All patients underwent annually complete ophthalmological examination including 15 degrees color optic disc photographs and automated white-white visual fields. RESULTS: Out of 40 eyes morphological examination showed signs of progression in 18 eyes and in 22 eyes no morphological changes of the optic disc were detected The digital planimetrically measured optic disc area did not vary between the first and the last photos. The mean differences between measured values for optic disc area between two examinations were 0.027+/-0.071 mm(2) and the reliability coefficient (Cronbachs alpha) was 0.99. Neuroretinal rim area decreased statistically highly significantly in eyes with morphological progression, and in eyes without morphological changes decreased only slightly. CONCLUSIONS: The variation of measurements of the optic disc area can be minimized by consideration and adjustment of the individual image magnification of the photos using digital planimetry. This method allows the quantitative assessment even of slight changes of the neuroretinal rim area and is a useful examination for follow-up of glaucoma patients.