This article aims to help you to understand ocular hypertension and glaucoma.
Ocular hypertension (OHT) is defined as the finding of ocular (eye) pressure greater than 21mmHg. For around 2.5% of the population it is not uncommon for the eye pressure to occasionally normally be measured in the range of 21-25mmHg. Therefore, the term OHT is usually reserved for patients who regularly have recorded pressures greater than 21mmHg.
Sometimes patients have relatively normal eye pressures, but the optic nerve has thinning and appears damaged in a way that looks typical of glaucoma (see figure 1). These patients are usually referred to as a ‘glaucoma suspect’. Glaucoma can occur in some susceptible individuals even if the pressure is normal, and therefore a normal pressure does not always mean that glaucoma suspects are safe, they still need monitoring.
Monitoring and progression to glaucoma
High eye pressure is the major risk factor for the development of glaucoma. Patients with OHT therefore usually benefit from annual monitoring with visual field tests and optic nerve optical coherence tomography (OCT) scans. High eye pressure can lead to optic nerve damage and in its early stages this is best detected with an OCT scan. Later on, once more damage occurs, typical visual field defects occur, and a diagnosis of glaucoma is made. Ideally, patients with OHT are monitored and treated if needed to prevent them from developing glaucoma. This is achieved by lowering the eye pressure down using topical eye drops or laser treatments.
As the pressure goes up the risks of developing glaucoma become greater, for example if the eye pressure is greater than 25mmHg, treatment is normally considered. For some people however, there may be sensible reasons why treatment is not needed unless the pressure is above 30mmHg. Generally speaking, if the patient has other risk factors such as a strong family history of glaucoma, or an optic nerve that has some suspicious signs of glaucoma damage, then treatment will be considered even if the pressure is in the range of 21-25mmHg. Your eye consultant will be able to advise whether or not treatment is needed depending on parameters specific to you.
The aim of treatment is typically to try and get the eye pressure down below 21mmHg and ideally below 18mmHg. At below 18mmHg most major studies of standard glaucoma patients show the risk of progression to significant visual field loss is lower.
Figure 1: A typical optic nerve appearance of glaucoma, however the patient had normal visual fields and normal eye pressures. This patient would be referred to as a glaucoma suspect and should ideally be monitored regularly with optic nerve OCT scans and visual field tests.
How can OcuPlan help?
If you have OHT or are a glaucoma suspect, then depending on your risk factors, eye pressure and eye appearance, it is likely that you will benefit from monitoring and possibly treatment. Using the OcuPlan scheme allows you to have regular visual field tests and optic nerve OCT scans to look for any sign of progression. By detecting signs of glaucoma early, treatment can be started to help reduce your risk of developing visual field loss.