POAG and Ocular Hypertension: Diagnosis, Risk and Treatment

Last updated: November 2026

Primary open-angle glaucoma (POAG) is the commonest glaucoma worldwide: a chronic, progressive optic neuropathy with characteristic disc and field changes, an open angle, and no secondary cause. Ocular hypertension (OHT) is raised pressure without damage. Deciding who to treat, and how hard, is the core of glaucoma practice.

Definitions

Term	Definition
POAG	Glaucomatous optic neuropathy (disc or RNFL damage with a matching field defect), open angle on gonioscopy, no secondary cause; IOP usually above 21 mmHg but not always
Normal-tension glaucoma	The same damage with IOP always within the normal range: see the NTG page
Ocular hypertension	IOP above 21 mmHg on repeated measurement, normal disc, RNFL and fields, open angle
Glaucoma suspect	Suspicious disc, field or IOP not yet meeting the definition of glaucoma

Risk factors

Raised IOP (the main modifiable risk factor), older age, family history (first-degree relatives), African or Afro-Caribbean ancestry, myopia.
For OHT conversion (OHTS): older age, higher IOP, thinner central cornea, larger vertical cup-to-disc ratio, higher pattern standard deviation.
Others: diabetes (debated), low ocular perfusion pressure, disc haemorrhage, pseudoexfoliation.

Diagnosis checklist

IOP with time of day (applanation), and central corneal thickness.
Gonioscopy in every patient to confirm an open angle and exclude secondary causes.
Dilated disc examination and OCT RNFL and ganglion cell analysis.
Standard automated perimetry (24-2, plus 10-2 if central damage); repeat to confirm a defect.
Baseline photographs to judge progression later.

When to treat OHT

OHTS showed that lowering IOP by about 20% halved the 5-year conversion rate (9.5% to 4.4%), so many patients with OHT never develop glaucoma. Treat when risk is high: IOP of 25 mmHg or more with thin corneas, a suspicious disc, family history, or a single-eyed patient. Many low-risk patients can be monitored.

Treatment ladder for POAG

Step	Options
First line	Prostaglandin analogue drop at night, or selective laser trabeculoplasty (LiGHT trial)
Add or switch	Beta-blocker, carbonic anhydrase inhibitor, alpha-agonist, rho-kinase inhibitor, or fixed combinations to reduce the drop burden
Surgery	Trabeculectomy with antimetabolite, tube surgery, or MIGS in milder disease, when target IOP is not reached or progression continues

Set a target IOP (often 20–30% below baseline, lower for advanced damage), check adherence and technique before adding drugs, and adjust the target if the disease progresses.

Follow-up

Situation	Typical review
Low-risk OHT, stable	Every 12–24 months
High-risk OHT or early POAG, stable at target	Every 6–12 months
Advanced disease, not at target, or progressing	Every 1–4 months

Where residents slip

Diagnosing POAG without gonioscopy.
Treating every OHT patient for life regardless of risk.
Forgetting central corneal thickness.
Adding a third drop before checking adherence and technique.

Test yourself: flip cards

Key sources

European Glaucoma Society. Terminology and Guidelines for Glaucoma, 5th edition. 2020
American Academy of Ophthalmology. Primary Open-Angle Glaucoma Preferred Practice Pattern. 2020
Kass MA, et al. The Ocular Hypertension Treatment Study. Arch Ophthalmol. 2002;120:701-713

📘 Want more exam-ready material? See Most Commons in Ophthalmology on Kindle, or browse all my books.

Written by Dr. Dhaval Patel, MD (Ophthalmology, AIIMS New Delhi)

Consultant, Cataract & Refractive Surgery — among a small number of AIIMS-trained ophthalmologists practicing in Gujarat. Read full credentials & experience or view his 28 publications on ResearchGate.

📚 Also the author of OKAT Decoded and other high-yield ophthalmology exam-prep books used by residents and PG aspirants.

Looking for an eye specialist in Ahmedabad? Learn about our Eye Department or book a consultation with Dr. Dhaval Patel.