Ocular Hypertension

Ocular hypertension is intraocular pressure persistently above the statistical normal range (above 21 mmHg on repeated measures) without optic nerve damage or visual field loss, and with open angles.

• Affects 4 to 10 percent of people over 40; most never develop glaucoma. The 5-year risk of progression to glaucoma in untreated individuals is about 10 percent overall.
• Strong risk predictors for conversion to glaucoma: older age, higher intraocular pressure, thin central corneal thickness (under 555 micrometres), larger vertical cup to disc ratio, higher pattern standard deviation on perimetry, disc haemorrhage, African ancestry, and family history.
• Secondary causes of raised pressure must be excluded: steroid use, uveitis, pigment dispersion, pseudoexfoliation, angle recession, raised episcleral venous pressure.

• Asymptomatic; found at routine screening.
• Normal optic discs and retinal nerve fibre layer, normal visual fields, normal OCT, open angles.
• Intraocular pressure usually between 22 and 30 mmHg.
• Corneal thickness may influence measurement: thick corneas overestimate pressure, thin corneas underestimate it.

• Repeated Goldmann tonometry on at least 2 visits and at different times; adjust for central corneal thickness.
• Gonioscopy to exclude angle closure and secondary mechanisms.
• Dilated optic disc examination and photographs for baseline, OCT of the nerve fibre layer and optic nerve head, and standard automated perimetry (24-2) done twice for baseline.
• Calculate individual risk using age, intraocular pressure, central corneal thickness, vertical cup to disc ratio and pattern standard deviation.
• Exclude contributory systemic and ocular factors: medications, thyroid eye disease, uveitis.

• Stratify risk: low risk (pressure under 25 mmHg, normal thickness, no other factors) can be observed; medium and high risk (pressure over 25 to 28 mmHg consistently, thin cornea, large cup, positive family history, African ancestry, high pattern standard deviation, disc haemorrhage) justify treatment, which reduces 5-year conversion from about 9.5 to 4.5 percent.
• Treatment aims for at least 20 percent reduction in pressure: latanoprost 0.005 percent at night, or travoprost 0.004 percent or bimatoprost 0.01 percent at night, or timolol 0.5 percent twice daily if a prostaglandin is not tolerated, or brimonidine 0.2 percent twice daily. Selective laser trabeculoplasty (about 100 spots over 360 degrees at 0.6 to 1.2 mJ) is an alternative.
• Observation: intraocular pressure and discs every 6 to 12 months, perimetry and OCT every 12 months (more often in the first 2 years), re-evaluate risk.
• Pressure above 30 to 35 mmHg: treat regardless of other risk factors.
• Advise on adherence and avoidance of steroid exposure where possible; check family members.
• Treat reversible causes (stop topical or systemic steroids, treat uveitis).