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Clinical ability of Heidelberg retinal tomograph examination to detect glaucomatous visual field changes
S Miglior1, M Casula, M Guareschi
1Department of Ophthalmology, University of Milan, Italy. smiglior@yahoo.com
Purpose:
To determine the agreement between Heidelberg Retinal Tomograph (HRT; Heidelberg Instruments, Heidelberg, Germany) and visual field examinations in differentiating normal from glaucomatous eyes and to evaluate the sensitivity and specificity of HRT optic disc examination in detecting eyes with glaucomatous damage.
Study Design:
Cross-sectional study.
Participants:
Three hundred fifty-nine patients, for a total of 359 eyes (55 normal, 209 with ocular hypertension [OHT], and 95 with primary open-angle glaucoma).
Intervention:
Optic disc imaging by HRT, using a 10 degrees angle view; a mean of three repeated images were analyzed using version 2.01 software. The optic disc was classified as "normal/glaucomatous" on the basis of multivariate discriminant analysis and cumulative frequency distribution (ranked-segment distribution curves). The visual field was examined using the DS 30 II program (Humphrey perimeter, Zeiss Humphrey System, Dublin, CA), with a glaucomatous visual field being defined on the basis of an abnormal glaucoma hemifield test and a statistically significant corrected pattern standard deviation less than 4 dB.
Main Outcome Measures:
Agreement between HRT and visual field examinations calculated by means of the kappa statistic and the sensitivity and specificity of HRT examination.
Results:
The agreement between the visual field-based and HRT definition of glaucoma was fair to poor, with a kappa statistic of between 0.48 and 0.28. The sensitivity and specificity of the HRT examination were, respectively, 80% and 65%, according to Mikelberg's analysis, and, respectively, 31% to 53% and 90% to 92%, according to the analysis based on cumulative curves of normality.
Conclusions:
In a broad clinical setting including normal, OHT, and glaucoma patients, the HRT and visual field tests have fair to poor agreement in detecting glaucoma. The HRT demonstrated a lack of specificity when using Mikelberg's multivariate discriminant analysis and a lack of sensitivity when using cumulative frequency distribution (ranked-segment distribution) curves. These values did not change when normal or OHT patients were excluded from the analysis. In the clinical setting, caution should be used when interpreting HRT results on the basis of multivariate discriminant analysis or cumulative frequency distribution curves.