Atrophy of optic nerve fibres in compression of the chiasm. Observer variation in assessment of atrophy.

Different observers' assessment of atrophy according to a semi-quantitative method was analysed. Five observers scored the degree of atrophy on magnified black-and-white fundus photographs from normal controls and from patients with chiasmal lesions of different severity. Four of the five examiners achieved a reasonably uniform assessment of atrophy. The results of the test prompted some modification in the grading system.