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T Umeda, M Nagayama, N Tamura, H Ohtsuki, T Sugimoto, K Yamaguchi; Reproducibility of the Heidelberg Retina Tomograph 2 . Invest. Ophthalmol. Vis. Sci. 2002;43(13):994.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The Heidelberg Retina Tomograph (HRT 2)(version 2.01) is an easily handled machine for routine optic disc examination in glaucoma clinics. We investigated the possibility of using the HRT 2 as an adjuvant machine to check the progress of glaucoma during the follow-up period. Although the HRT 2 is an easily handled model, the data may differ according to measuring situation. Therefore, we evaluated the reproducibility of the HRT 2. Method: We performed two trials focusing on the reference height (The reference height is located 50µm posterior to the mean height of -4°∼-10°contour line of the disc. It is assumed that this height does not change until the late stage of glaucoma.). The optic disc images of 22 eyes of 11 normal volunteers were taken using the HRT 2 by the same examiner. In the first trial, the optic disc images were taken twice without checking fluctuation of the reference height. In the second trial, careful attention was paid for the reference height. If the reference plane shifted more than 50µm, the optic disc images were taken again. We defined two indexes to evaluate the reproducibility of the topographic parameters (cup area, rim area, cup volume, rim volume, C/D ratio). (A) Difference of measurements =( primary topographic parameter (x1) - secondary topographic parameter (x2) )/( (x1+x2) / 2 )×100 (%) (B) Repeatability = ±1.96×standard deviation (x1-x2) Results: In the first trial, the mean of (A) (difference of measurements) was 10.5% (range: 3.37∼22.4%), and the range of (B) (repeatability) was ±0.038∼±0.280. In the second trial, the mean of (A) (difference of measurements) significantly improved to 3.11% (range: 1.11∼9.63%) (p = 0.0012), and the range of (B) (repeatability) was significantly narrowed to ±0.031∼±0.074. (p = 0.0015). The reproducibility significantly improved by careful attention to the reference plane. Conclusion: The HRT 2 has high reproducibility when the reference plane is constant in position. It may be useful in the follow-up of the glaucoma patients.
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