Table 1.

Classification of field series using Humphrey printouts

	Clinician B
Clinician A	Definitely stable	Probably stable	Probably progressing	Definitely progressing
Definitely stable	5	4	1	0
Probably stable	4	1	2	1
Probably progressing	0	3	1	3
Definitely progressing	0	1	0	1

*Weighted kappa = 0.28 (SE 0.08).

Classification of the 27 visual field series by clinician A and clinician B when using Humphrey printouts. These two clinicians agreed exactly on the assessment of eight series (along the diagonal of the table). Note that one field series was assessed as being “probably stable” by clinician A but “definitely progressing” by clinician B. This level of disparity in assessment occurred with three series in total. These “serious disagreements,” which are accounted for in the calculation of the weighted kappa value, were a feature of the results from other pairs of clinicians when Humphrey printouts were the method of assessment.