Computer Densitometry of Retinal Nerve Fiber layer Photographs

ABSTRACT

Computer densitometry using MATLAB 4.2b [The MathWorks, Inc.] was developed for the quantitiative measurement of diffuse retinal nerve fiber layer [RNFL] atrophy. Intra- and inter-operator reliability and clinical validity of densitometry were evaluated. Twenty-one RNFL photographs of 21 patients that show varying degrees of atrophy underwent computer densitometry by two operators on two separate occasions. And the association between RNFL measurements and retinal sensitivity was investigated. Coefficient of variation in the densitometric measurements was 1.2~5.4%. Intra-and inter-oprator reliabilities were excellent [Pearsons correlation coefficient > 0.96, p=0.00]. The agreement between total density variations in the upper and lower ninety degrees along the circle of 1.5 and 2.5 times optic disc radius and retinal sensitivity of Humphrey C30-2 visual field was moderate [Spearmans correlation coefficient=0.52 -0.54, p=0.00]. Computer densitometry of RNFL photographs provides objective and quantitative measurement of diffuse RNFL atrophy.