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Patterns of optic disk damage in patients with early focal visual field loss
A Emdadi1, L Zangwill, P A Sample
1Glaucoma Center and Research Laboratories, University of California, San Diego, La Jolla 92093-0946, USA.
Purpose:
To study the patterns of structural damage of the optic disk in patients with early focal visual field loss using a confocal scanning laser ophthalmoscope.
Methods:
Thirty-nine subjects with repeatable early focal visual field loss were included. The Heidelberg Retina Tomograph (Heidelberg Engineering, Heidelberg, Germany) was used to obtain topographic optic disk measurements. For analysis of structural damage, the topographic measurements were divided into 36 10-degree sectors. Sector analysis was performed using sector rim area to sector disk area ratio. Patients were assigned to one of three groups based on the measurement of the optic disk damage: (1) diffuse disk damage; (2) focal disk damage; or (3) no detectable disk damage.
Results:
Approximately half of the patients with early focal glaucomatous visual field loss showed diffuse optic disk damage, one quarter to one third had focal damage, and one sixth had no detectable damage. Optic disk area was smallest in the no-detectable-damage group (1.71 + 0.19 mm2), followed by the focal-damage group (2.06 + 0.54 mm2), and was largest in the diffuse damage group (2.29 + 0.48 mm2; P = .22).
Conclusion:
In patients with early focal glaucomatous visual field loss, observable optic disk damage can be diffuse, focal, or undetectable. The Heidelberg Retina Tomograph may be capable of detecting different patterns of diffuse or focal structural damage.