Comparison of disc damage likelihood scale, cup to disc ratio, and Heidelberg retina tomograph in the diagnosis of glaucoma

Abstract

Aim: To evaluate the relative diagnostic strength of cup to disc (C/D) ratio, clinical disc damage likelihood scale (DDLS), a new clinical method of documenting glaucomatous optic disc changes, and Heidelberg retina tomograph (HRT-II) in patients with glaucoma, glaucoma suspects, and normal controls.

Method: Consecutive observational case series. 110 eyes from 110 patients categorised as glaucoma, glaucoma suspect, or normal were examined clinically to grade the DDLS score. HRT-II examination was performed by an examiner masked to the clinical examination findings. Optic disc parameters and Moorfields regression analysis findings were recorded. Stereophotographs of the optic disc were examined independently by two glaucoma specialists in masked fashion to determine the C/D ratio. Zeiss SITA Standard 24-2 visual fields were obtained within 3 months of HRT-II and clinical examination. For each patient, the eye with the worse mean deviation of the visual field test was enrolled in the study, and each field was additionally graded by the four level Hodapp-Parrish-II-Anderson staging. Specificity and sensitivity were calculated by receiver operating characteristic (ROC) curves.

Results: Mean patient age was 58 years (SD 13.3) with 45 glaucoma patients, 23 glaucoma suspects, and 42 normals. The mean deviation on Humphrey visual field assessment using SITA-Standard was −4.95 D (SD 5 D) Clinical examination using DDLS had the best predictive power with an area under the ROC curve value of 0.95 when glaucoma patients and suspects were separated from borderline or normals. This was followed by clinical examination of C/D ratio (0.84), and HRT-II Moorfields analysis (0.68). The order of diagnostic strength did not change when definite glaucoma was compared to borderline and normals.

Conclusions: The DDLS grading performs well compared to C/D ratio and HRT-II evaluation. Attention to disc diameter and to rim width may increase the value of clinical optic disc examination.