Ocular Hypertension
Definition
Intraocular pressure consistently above the statistically normal range (> 21 mmHg) in the absence of optic nerve damage or visual field loss, representing a significant risk factor for the development of primary open-angle glaucoma.
Clinical Snapshot
Ocular hypertension (OHT) is defined as IOP consistently > 21 mmHg in the absence of optic nerve damage or visual field loss. It is a significant risk factor for POAG — approximately 10% of untreated OHT patients develop POAG over 5 years. However, the majority of OHT patients never develop glaucoma, making risk stratification essential to avoid overtreating low-risk individuals while ensuring high-risk patients receive appropriate intervention.
Epidemiology
OHT affects approximately 3–6% of adults over 40. The OHTS demonstrated that topical IOP-lowering therapy reduces the 5-year risk of POAG development from 9.5% to 4.4% in OHT patients.
Pathophysiology
Elevated IOP in OHT results from increased resistance to aqueous outflow through the trabecular meshwork, without the structural optic nerve changes that define glaucoma. The optic nerve in OHT is structurally normal — the distinction from POAG is the absence of glaucomatous damage.
Risk Factors
- IOP level (higher IOP = higher risk of conversion to POAG)
- Thin central corneal thickness (< 555 μm)
- Large cup-to-disc ratio
- Advanced age
- African ancestry
- Pattern standard deviation on visual field testing
Clinical Presentation
OHT is asymptomatic. It is detected on routine IOP measurement. The optic nerve and visual fields are normal by definition. Careful optic nerve assessment and baseline visual field testing are essential to confirm the absence of glaucomatous damage.
Diagnostic Pearls
- The OHTS risk calculator (available online) provides a 5-year risk estimate for POAG development — use it to guide treatment decisions.
- Central corneal thickness (CCT) is essential — thin corneas underestimate true IOP and independently increase POAG risk.
- Baseline optic nerve photographs and visual fields are required to confirm the absence of glaucomatous damage.
- Gonioscopy should be performed to confirm an open angle and exclude secondary causes of elevated IOP.
Differential Diagnosis
- Primary open-angle glaucoma (optic nerve damage present)
- Secondary open-angle glaucoma (pigmentary, pseudoexfoliative)
- Steroid-induced IOP elevation
- Measurement artifact (thick cornea overestimates IOP)
Evidence-Based Management
Treatment decisions are guided by risk stratification. High-risk OHT (OHTS risk > 15% over 5 years) warrants IOP-lowering therapy — prostaglandin analogues are first-line. Low-risk OHT may be managed with observation and monitoring. The OHTS demonstrated that treatment reduces conversion risk but does not eliminate it — monitoring remains essential regardless of treatment decision.
Monitoring & Follow-Up
IOP measurement, optic nerve assessment, and visual field testing at 6–12 month intervals depending on risk level. OCT RNFL provides sensitive structural monitoring for early glaucomatous change.
Clinical Pearls
- Use the OHTS risk calculator — it provides an evidence-based framework for treatment decisions.
- CCT measurement is mandatory in OHT evaluation — it affects both IOP interpretation and independent risk assessment.
- Not all OHT requires treatment — risk stratification prevents overtreatment of low-risk patients.
- Monitoring is essential regardless of treatment decision — OHT can convert to POAG at any time.
Related Therapeutics — Clinician's Companion
- Glaucoma Therapeutics — Prostaglandins (Clinician's Companion)
Key References
- 1.Kass MA, et al. The Ocular Hypertension Treatment Study. Arch Ophthalmol. 2002.
- 2.Gordon MO, et al. The OHTS risk calculator. Arch Ophthalmol. 2002.
This entry is an educational reference designed to support clinical reasoning and awareness. It does not constitute medical advice, establish a standard of care, or replace individualized patient assessment. Clinicians should consult current guidelines and applicable clinical resources when making patient care decisions.