Abstract
Purpose: :
To evaluate the usefulness of retinal nerve fiber layer (RNFL) thickness measurements using the Heidelberg Retina Tomograph-III (HRT-III) in normal, ocular hypertensive, and glaucomatous eyes and compare the thickness measurements using HRT-III and Stratus Optical Coherence Tomography-3 (OCT-3).
Methods: :
Sixty-nine normal eyes, 60 ocular hypertensive eyes, and 111 glaucomatous eyes were included. All participants underwent visual field testing using the Swedish Interactive Threshold Algorithm and the 24-2 program (Humphrey Field Analyzer), HRT-III, and OCT-3 examinations. Patients were classified into three groups according to intraocular pressure and visual field damage. Glaucomatous visual fields were those with a sensitivity defect in three contiguous altered locations (glaucoma definition) or abnormal glaucoma hemifield tests (GHT). The sensitivity/specificity of RNFL thickness measurements and RNFL thickness classifications using HRT-III and OCT-3 were calculated and compared to the visual field classification. The sensitivity/specificity of the height variation contour (HVC) from the HRT-III were calculated. The receiver operating characteristic curves (ROC) and areas under the ROC were plotted. Agreement between these parameters and other HRT-III parameters was calculated using Bland-Altman method and the k coefficient.
Results: :
The RNFL thickness sensitivity/specificity were 7.2%/98.6% (most specific criteria), and 32.4%/87% (least specific criteria), respectively, for the HRT-III and 58.65%/98.55% (most specific criteria), and 72.97%/81.15% (least specific criteria) for the OCT-3 in relation to the glaucoma definition. Similar sensitivities/specificities were found compared to the GHT. The RNFL thickness sensitivities/specificities were lower in early glaucoma. The RNFL thickness measured with the HRT-III was related to the visual field parameters (P<0.05). The areas under the ROC for RNFL measurements were 0.72 using HRT-III, 0.86 with OCT-3 (P=0.001), and 0.54 for the HVC. The k coefficient was 0.36. Bland-Altman analysis confirmed that the RNFL measurements were not interchangeable.
Conclusions: :
The sensitivity of RNFL damage detection using HRT-III was lower compared with OCT-3, especially in early glaucoma. RNFL thickness agreement between HRT-III and OCT-3 was only fair. HVC was not useful for glaucoma detection.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • nerve fiber layer • intraocular pressure