Optic disc morphology on presentation of chronic glaucoma (original) (raw)

Key Papers on Optic Disc Evaluation in Glaucoma

Optic nerve diseases, such as the glaucomas, lead to changes in the intrapapillary and parapapillary region of the optic nerve head. These changes can be described by the following variables: size and shape of the optic disk; size, shape, and pallor of the neuroretinal rim; size of the optic cup in relation to the area of the disk; configuration and depth of the optic cup; ratios of cup-to-disk diameter and cup-to-disk area; position of the exit of the central retinal vessel trunk on the lamina cribrosa surface; presence and location of splinter-shaped hemorrhages; occurrence, size, configuration, and location of parapapillary chorioretinal atrophy; diffuse and/or focal decrease of the diameter of the retinal arterioles; and visibility of the retinal nerve fiber layer (RNFL). These variables can be assessed semiquantitively by ophthalmoscopy without applying sophisticated techniques. For the early detection of glaucomatous optic nerve damage in ocular hypertensive eyes before the development of visual field loss, the most important variables are neuroretinal rim shape, optic cup size in relation to optic disk size, diffusely or segmentally decreased visibility of the RNFL, occurrence of localized RNFL defects, and presence of disk hemorrhages. ( Surv Ophthalmol 43 :293-320, 1999. © 1999 by Elsevier Science Inc. All rights reserved.) Key words. cup/disk ratio • neuroretinal rim • optic cup • optic disk • optic disk hemorrhages • optic disk pallor • parapapillary atrophy • peripapillary scleral ring • retinal nerve fiber layer • retinal vessel diameter ABSTRACT Purpose: The major objective of this study was to test the reproducibility of a new method of estimating the amount of optic disc damage in patients with glaucoma.

Clinical measurement and categorization of optic disc in glaucoma patients

Indian Journal of Ophthalmology, 2009

Background: Assessment of optic disc size is an important component of optic nerve head examination. Agreement between different methods of disc size measurements is not very good. Purpose: To assess the agreement between the disc size assessed by Heidelberg retina tomograph (HRT) and stereobiomicroscopy with a 90 diopter (D) lens. To report the clinical (measured by biomicroscopy) disc diameters of small, average and large optic discs categorized by HRT disc areas. Setting and Design: Observational study of subjects examined in the glaucoma clinic of a tertiary eye institute. Materials and Methods: Seventy-five eyes of 75 glaucoma subjects were studied. Disc diameter was measured using stereobiomicroscopy and HRT. The agreement between the two sets of measurements was assessed by intraclass correlation coefficient (ICC). Discs were classified into small (<1.6 mm 2), average (1.6-2.6 mm 2) and large (>2.6 mm 2) depending on cutoffs provided by the manufacturers of HRT. The means (95% CI) of the corresponding vertical disc diameter in these groups were assessed. Statistical Analysis: ICC, Bland and Altman plots. Results: ICC for measurements of clinical and HRT horizontal disc diameter was 0.518 and for vertical disc diameter measurement was 0.487. The mean difference between the clinical and HRT measurements as analyzed by the Bland and Altman plot was 0.17 (95% CI, 0.13-0.47) for horizontal and 0.22 (95% CI, 0.11-0.54) for vertical disc diameter. Of the 75 eyes, 3 eyes had small discs, 54 average and 18 large discs. The mean clinical vertical disc diameter for small discs was 1.55 mm (95% CI, 1.2-1.7), for average discs was 1.91 mm (95% CI, 1.87-1.96) and for large discs was 2.15 mm (95% CI, 2.03-2.27). Conclusion: The agreement between clinical and HRT disc diameter measurements is moderate. Disc diameter measurement on stereobiomicroscopy can be used to categorize discs into small, average and large discs.

Expert Agreement in Evaluating the Optic Disc for Glaucoma

Ophthalmology, 1992

T he authors studied intraobserver and interobserver agreement, under monoscopic and stereoscopic conditions, in estimating vertical cup-to-disc ratios and in assessing whether a disc had glaucomatous damage. Six glaucoma experts evaluated 75 optic disc photographs under both viewing conditions. The experts also re-evaluated 25 photographs. Intraobserver agreement in estimating vertical cup-to disc ratios was high (median weighted kappa, 0.79). Interobserver agreement in estimating vertical cup-todisc ratios was moderate (stereoscopic median weighted kappa, 0.67); individual experts differed by as much as 0.2 disc diameters (~O) monoscopically and 0.16 DO stereoscopically. The observers estimated larger vertical cup-to-disc ratios when evaluating the same discs under stereoscopic conditions than under monoscopic conditions. Intraobserver agreement in assessing glaucomatous disc damage was substantial (median kappa, 0.76). Interobserver agreement in assessing glaucomatous damage was moderate (stereoscopic median kappa, 0.50). This study confirms the ability of experts to reliably evaluate the optic disc within themselves and emphasizes the need for developing standardized methods for interobserver evaluation of the optic disc in glaucoma.

Comparison of clinical optic disc assessment with tests of early visual field loss

Clinical and Experimental Ophthalmology, 2002

Clinical optic disc assessment may identify glaucomatous optic neuropathy prior to a patient developing visual field abnormalities on achromatic automated peri-metry (AAP). Tests targeting axons that are selectively damaged or whose redundancy is low, such as short wavelength automated perimetry (SWAP) and frequency doubling perimetry (FDP), may detect visual field loss before it is seen on AAP. This study investigated whether patients in whom characteristic glaucomatous optic disc damage was present without AAP abnormalities had visual field abnormalities with SWAP and FDP. A sample of patients (n = 50) with ocular hypertension (normal AAP) were selected, who had SWAP, FDP and stereofundus photography performed. The photographs were then analysed by two glaucoma subspecialists who were masked to the assessments of the other and to the patients&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; SWAP and FDP results. A categorization of the optic discs was made as either normal or abnormal and this was compared with their SWAP and FDP findings. On comparing SWAP and FDP with clinical optic disc assessment as the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;gold standard&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 33%, 92%, 57% and 81%, respectively, for SWAP and 25%, 89%, 49% and 79%, respectively, for FDP. In glaucoma suspects, the study suggests that SWAP and FDP identify subjects with early glaucomatous optic neuropathy missed by AAP.

Optic disc interpretation in glaucoma: is confidence misplaced?

Ophthalmic and Physiological Optics, 1993

A photographic questionnaire has been used to investigate whether or not clinicians have realistic expectations of their ability to distinguish optic discs associated with glaucomatous visual field loss from discs of healthy eyes. The questionnaire consisting of 30 non-stereoscopic fundus photographs from 15 patients was administered to 40 ophthalmologists of varying experience and 10 optometrists. Each group displayed large discrepancies between their expected and achieved scores suggesting that clinicians may overestimate their ability to recognize the glaucomatous optic disc. This could lead to diagnostic errors especially in cases where tonometric and visual field parameters are considered equivocal. An over-reliance on the cup/disc ratio appeared to be the most likely cause of error. ,