Table 1: Glaucoma classification according to severity of the disease.
(a) Open-angle glaucoma reproduced from [1], with permission from Elsevier

SuspectOne or two of the following:
() IOP > 21 mm Hg
() Suspicious disc or C/D asymmetry of >0.2
() Suspicious 24-2 (or similar) VF defect

Early() Early glaucomatous disc features (e.g., C/D < 0.65)
() Mild VF defect not within 10° of fixation (e.g., MD better than −6 dB on HVF 24-2)

Moderate() Moderate glaucomatous disc features (e.g., vertical C/D 0.7–0.85)
() Moderate VF defect not within 10° of fixation (e.g., MD from −6 to −12 dB on HVF 24-2)

Severe() Advanced glaucomatous disc features (e.g., C/D > 0.9)
() VF defect within 10° of fixation (e.g., MD worse than −12 dB on HVF 24-2)

C/D, cup-to-disc; HVF, Humphrey visual field; IOP, intraocular pressure; MD, mean deviation; VF, visual field.
refers to vertical C/D ratio in an average size nerve. If the nerve is small, then a smaller C/D ratio may still be significant; conversely, a large nerve may have a large vertical C/D ratio and still be within normal limits. † also considers baseline 10-2 VF (or similar).
Recent evidence indicates that ganglion cell loss should also be taken into consideration when staging/classifying glaucoma [2].
(b) Angle closure

Disease staging≥180° appositionally closed (where posterior TM not visible [grade 1]) Ocular hypertension and/or peripheral anterior synechiaeGanglion cell, optic nerve, and visual field damage

PACS+
PAC++
PACG+++

PAC, primary angle closure; PACS, primary angle closure suspect; PACG, primary angle closure glaucoma.
The above definitions could be used to guide decisions regarding the target IOP range (i.e., for patients with more advanced disease and/or evidence of rapidly progressing disease, targeted IOP should be in the lower targeted range). To achieve this, patients may require a more aggressive therapy from initiation of therapy; see Figure 3, suggested range for initial target IOP, and Figure 5, proposed treatment algorithm.