Decreasing the Influence of Clinical Data on Glaucomatous Optic Nerve Evaluation Using the Disc Damage Likelihood Scale

Abstract

Abstract: : Purpose: Previous studies have demonstrated that optic cup/disc ratio measurement is influenced by clinical data such as patient age, intraocular pressure (IOP) and visual fields. This study was designed to determine whether utilization of the Disc Damage Likelihood Scale (DDLS) decreases the influence of clinical data on glaucomatous optic nerve evaluation. Methods: Twelve observers (1 glaucoma specialist, 4 ophthalmology residents and 7 medical students) utilized the DDLS to independently evaluate fifty-two stereo disc photos from patients with mild, moderate and advanced glaucoma. The identical slides were shuffled and evaluated twice more at separate readings. These additional two readings were accompanied by two differing sets of clinical information. The observers evaluated the stereo disc photographs in the context of the clinical information consisting of age, visual field, and IOP results that accompanied each pair of photographs. This clinical information was modified so that some cases received the same clinical information while other cases had the clinical variables changed between the two readings. The number of agreements (i.e. within one DDLS stage of the initial reading) between the three readings was tabulated. Results: There was an overall 83.6% exact agreement between the three readings (range 71.2% - 98.1%). This level of agreement is higher than the 74% seen in previous studies utilizing cup/disc ratio measurements as the basis for optic nerve evaluation in the face of changing clinical information. Conclusion: While clinical information such as age, intraocular pressure and visual field affects the subjective clinical evaluation and staging of the glaucomatous optic nerve, utilization of the DDLS minimized this influence. The DDLS standardized measures are useful clinical tools in evaluation of optic nerves in patients with glaucoma to overcome bias in the subjective evaluation.

Keywords: optic disc