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Br J Ophthalmol 1998;82:769-772 doi:10.1136/bjo.82.7.769
  • Original Article
    • Clinical science

RA/DA cumulative curve analysis of local and diffuse neuroretinal rim area damage in glaucoma patients

  1. Maurizio Rolando,
  2. Angelo Macrì,
  3. Michele Iester,
  4. Michele Altieri,
  5. Giovanni Calabria
  1. University Eye Clinic, Genoa, Italy
  1. Angelo Macrì, MD, Clinica Oculistica dell’Università di Genova, Largo R Bensi-Ospedale S Martino Pad 9, 16132 Genoa, Italy.
  • Accepted 29 January 1998

Abstract

AIM To evaluate the validity of cumulative rim/disc area (RA/DA) curve analysis as a clinical tool for the identification of glaucoma induced optic disc pathology.

METHODS 71 normal and 83 glaucomatous eyes were evaluated from a series of 154 subjects recruited for this study. For each eye, the cumulative distribution of RA/DA was calculated from 36 equally spaced rim sectors of each optic disc obtained by the automatic evaluation of simultaneous videographics (Image-net X Rev.3/51b). To increase the sensitivity of this analysis in early glaucoma and in normal eyes, these cumulative curves were subsequently divided into two equal segments and the slopes of their respective regression lines compared.

RESULTS The median RA/DA value obtained from the 36 sectors was significantly different in glaucomatous eyes compared with normals (p <0.001). Nevertheless, the curves (5th–95th percentile of the cumulative curves distribution) of early glaucomatous eyes fell within the normal range. When the cumulative curve of these marginal cases was then divided into two equal segments, the comparison of the slopes of the regression lines showed a significant difference (p <0.05) in 100% of early glaucomatous eyes. Furthermore, normal eyes were shown to be true negatives in 93% of the cases in which no significant difference between the two slopes was observed.

CONCLUSION Analysis of the RA/DA cumulative curve from 36 sectors of the optic disc was a valid method for the identification of glaucomatous disc pathology; however, a further calculation of the slopes of the two RA/DA regression lines was needed to identify early glaucomatous damage.

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