Systems for Staging the Amount of Optic Nerve Damage in Glaucoma: A Critical Review and New Material

Pearls for Correct Assessment of Optic Disc at Glaucoma Diagnosis

“…In contrast to GON, in which the optic cup deepens and enlarges as associated with the glaucoma type and the level of intraocular pressure (IOP), the optic cup does not show significant enlargement in eyes with non-GON. [1][2][3][4][5][6]12,21,[25][26][27][28][29][30][31] Greenfield criteria consist of age less than 50 years, visual acuity less than 20/40, optic nerve pallor in excess of cupping, and vertically aligned VF defects can be used for the suspicious for non-glaucomatous cupping in patients with normal pressure. It has been recommended that patients who have one or more of the Greenfield criteria need to have neuroimaging performed to identify the causes of non-glaucomatous cupping.…”

“…The size of the optic cup always seems smaller in monoscopic examination than in stereoscopic examination. 21,[25][26][27][28][29][30][31] The direction or point of deviation of small blood vessels on the surface of the ONH is used to determine the size of the optic cup (contour method) but not the area of pallor in the center of the optic disc (colorcontrast method). 21,[25][26][27][28][29][30][31] Physiologically large cups can occur more commonly in patients with normally large chorioscleral canals and large discs.…”

“…In normal eyes, the shape of the optic cup is horizontally oval as the vertical optic disc diameter is about 8% higher than the horizontal ones. [1][2][3][4][5][6]12,15,21,[25][26][27][28][29][30][31] The average CDR is 0.4. However, CDR ratio in normal patients can range from 0.0 to 0.9 because of inter-individual variation in disc size and cup size.…”

“…Large scleral openings cause large CDR while small openings give the appearance of a small CDR. [1][2][3][4][5][6]12,21,[25][26][27][28][29][30][31] A CDR less than 0.4 without an abnormally small optic disc size usually indicates a non-glaucomatous optic disc. A CDR between 0.4 and 0.8 which was calculated to the optic disc size may belong to a subject with a normal optic disc (physiologic cupping) or a glaucoma suspect or early/moderate glaucoma.…”

“…Pearls for Correct Assessment of Optic Disc at Glaucoma Diagnosis Saucerization is a shallow diffuse excavation in the cup and it is very hard to detect in some cases because of the need for careful detection of the contour. [1][2][3][4][5][6]12,21,[25][26][27][28][29][30][31] Estimation of CDR has only limited value in the identification of GON because of the wide variation in the size of the optic disc and cup in the normal population. In addition, there is the significant individual measurement variability among glaucoma specialists in the evaluation of CDR.…”