Purpose: To compare the rates of optic nerve damage in early human glaucoma as measured by four methods to evaluate change in the optic nerve and nerve fiber layer.
Methods: Four techniques were used to detect progressive glaucomatous damage in a prospective, longitudinal study: (1) qualitative evaluation of stereoscopic color optic disk photographs, (2) qualitative evaluation of monochromatic nerve fiber layer photographs, (3) manual stereoplanimetric measurements of disk rim area, and (4) computerized measurement of peripapillary nerve fiber layer height. One eye of each patient with glaucoma or ocular hypertension was evaluated at the beginning and end of a follow-up period of not less than one year. The rates of structural change measured by these techniques and the rate of visual field change measured with threshold automated perimetry were determined.
Results: We followed up 193 patients for a mean (+/- S.D.) of 3.3 +/- 1.0 years (range, one to six years). Twenty-nine (15%) of 193 eyes progressed by qualitative optic disk evaluation, 14 (7.2%) of 193 eyes progressed by qualitative nerve fiber layer evaluation, seven (3.6%) of 193 eyes progressed by stereoplanimetry, and 24 (13.2%) of 182 eyes progressed by measurement of nerve fiber layer height. Visual field deterioration was detected in 12 (5.2%) of 193 patients and correlated best with qualitative optic disk and nerve fiber layer evaluations. Evaluation by stereoplanimetry and nerve fiber layer height measurement detected change in eyes with primarily diffuse structural damage, a pattern not well detected by qualitative methods.
Conclusion: Both qualitative and quantitative methods of optic disk and nerve fiber layer evaluation contribute to the identification of progressive damage, depending on the stage of disease and the characteristics of optic nerve cupping.