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Ocular Hypertension: Symptoms, Causes, Treatment and Glaucoma Risk
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Ocular hypertension (noun, abbreviated OHT or OHTN): ocular hypertension means the pressure inside the eye (intraocular pressure, or IOP) is higher than normal, but the optic nerve looks healthy and there is no loss of vision. It happens when fluid does not drain from the eye as well as it should. It is not glaucoma, but it raises the risk of glaucoma, so it is monitored by an eye specialist such as Prof. Dr. Ahmet Satıcı, who leads glaucoma care at Laser Istanbul Clinic.
Ocular hypertension: key facts
- What it is
- Eye pressure that is consistently above normal, with a healthy optic nerve and normal visual fields
- Normal eye pressure
- Usually considered to be between 10 and 20 mmHg (American Academy of Ophthalmology)
- Usual definition
- Pressure consistently above 21 mmHg without optic nerve damage or visual field loss (EyeWiki); UK guidance (NICE) uses 24 mmHg or more to decide on treatment and referral
- Symptoms
- Usually none; it is found at a routine eye test
- Main risk
- Slowly developing primary open-angle glaucoma. In the Ocular Hypertension Treatment Study (OHTS), 9.5% of untreated people had developed it at 5 years, and 45.6% of all participants after 20 years
- Main treatments
- Observation, prescription eye drops (usually a prostaglandin analogue) or selective laser trabeculoplasty (SLT)
- ICD-10
- H40.0 (glaucoma suspect, which includes ocular hypertension); ICD-10-CM H40.05-
- Specialist
- Ophthalmologist with glaucoma experience; at Laser Istanbul Clinic, Prof. Dr. Ahmet Satıcı
What is ocular hypertension, and is it the same as glaucoma?
Ocular hypertension is a risk state, not a disease of the optic nerve. Your eye constantly makes a clear fluid called aqueous humour, and an equal amount drains away, which keeps eye pressure steady. In ocular hypertension the drainage is less efficient, so pressure builds up. Glaucoma is the condition in which pressure damages the optic nerve and vision is lost. According to the American Academy of Ophthalmology (AAO), people with ocular hypertension have a normal-looking optic nerve and no sign of vision loss, but they are at increased risk of glaucoma and are considered "glaucoma suspects".
| Ocular hypertension | Glaucoma | |
|---|---|---|
| Eye pressure | Higher than normal | Often raised, but can be in the normal range |
| Optic nerve | Healthy | Damaged |
| Visual field | Normal | Loss of vision in the visual field |
| Symptoms | None | Usually none in the early stages |
| Aim of care | Monitor, and lower pressure if the risk is high | Lower pressure to slow or stop further damage |
The NHS notes that pressure can sometimes be in the normal range and still damage the optic nerve, which is why the optic nerve, not the pressure reading alone, decides whether you have glaucoma.
Ocular hypertension causes: why does eye pressure rise?
The direct cause is reduced outflow of aqueous humour. EyeWiki, the AAO's clinical wiki, explains that fluid leaves the eye through two routes, the trabecular meshwork and the uveoscleral pathway, and that ocular hypertension occurs when resistance in these routes rises. The eye keeps producing fluid at a normal rate, so pressure goes up. Age-related changes in the trabecular meshwork contribute, which is one reason it becomes more common with age.
What diseases and conditions cause ocular hypertension?
Most ocular hypertension is "primary", meaning no other disease is behind it. But doctors must first rule out secondary causes, because these need different treatment. EyeWiki lists:
A pressure rise can also be falsely recorded: an incorrectly calibrated tonometer, poor technique, or short-term effects such as straining, stress or breath-holding.
- Steroid response: corticosteroid use can raise eye pressure in susceptible people.
- Pigment dispersion syndrome: pigment released inside the eye can affect drainage.
- Pseudoexfoliation syndrome: a flaky deposit that can affect drainage.
- Inflammation inside the eye (uveitis): inflammation can raise pressure.
- Eye injury (trauma): injury can damage the drainage angle or the trabecular meshwork.
Risk factors
The AAO lists these risk factors for ocular hypertension: a family history of ocular hypertension or glaucoma, diabetes or high blood pressure, age over 40, African-American or Hispanic ethnicity, high short-sightedness (myopia), long-term steroid use, previous eye injury or surgery, and pigment dispersion or pseudoexfoliation syndrome.
Ocular hypertension symptoms: how do you know you have it?
Usually you do not. The AAO states that ocular hypertension usually has no signs or symptoms, and NICE states that ocular hypertension and early glaucoma are symptomless. You will not feel the pressure, your vision stays normal and the eye does not look different. This is why it is found at a routine eye test, and why regular tests matter. The NHS advises everyone to have an eye test at least every 2 years, and more often if you are at higher risk, for example if a parent, brother or sister has glaucoma.
Does ocular hypertension cause headaches?
No. A headache is not a symptom of ocular hypertension, and most headaches have nothing to do with eye pressure. The exception is a sudden attack of glaucoma, a different and rarer situation in which the NHS lists intense eye pain, a red eye, tenderness around the eyes, rainbow-coloured circles around bright lights, blurred vision, nausea and a headache. That is a medical emergency: go to an emergency department immediately (see "When to see a doctor" below).
Is ocular hypertension dangerous?
Ocular hypertension itself does no direct harm, but it is a major treatable risk factor for glaucoma, and glaucoma can cause permanent sight loss. The risk is real but modest for most people. The landmark Ocular Hypertension Treatment Study (OHTS) followed 1,636 people aged 40 to 80 with eye pressure of 24 to 32 mmHg in one eye and no glaucoma damage.
| OHTS result | Figure |
|---|---|
| Developed glaucoma within 5 years, no treatment | 9.5% |
| Developed glaucoma within 5 years, with pressure-lowering drops | 4.4% (hazard ratio 0.40) |
| Developed glaucoma over 20 years, all participants | 45.6% |
| Developed glaucoma over 20 years, lowest-risk third | 31.7% |
| Developed glaucoma over 20 years, highest-risk third | 59.8% |
| Developed visual field loss over 20 years | 25.2% |
Two things follow. First, most people with ocular hypertension do not lose vision: only about one in four of the OHTS participants developed visual field loss in 20 years. Second, risk varies widely from person to person. The OHTS found that older age, higher eye pressure, a thinner central cornea, a larger vertical cup-to-disc ratio (a measure of the optic nerve) and a higher visual-field "pattern standard deviation" predicted who developed glaucoma. A central corneal thickness below 555 micrometres is one of the strongest warning signs, according to EyeWiki. In the 20-year follow-up, 55.2% of Black and African American participants developed glaucoma, against 42.7% of other participants.
How is ocular hypertension diagnosed?
Diagnosis means confirming the pressure is truly high and proving the optic nerve is healthy. NICE and EyeWiki list the tests:
Tonometry
the pressure measurement. The standard is Goldmann applanation tonometry at the slit lamp, after numbing drops. NICE says a decision to refer should not rest on non-contact ("air puff") tonometry alone. Readings are repeated, often at different times of day, because pressure varies.
Central corneal thickness (pachymetry)
measured because corneal thickness affects how accurate the pressure reading is, and because thin corneas carry extra risk.
Gonioscopy
a lens placed on the numbed eye to look at the drainage angle and rule out angle-closure glaucoma.
Dilated optic nerve examination
to check the cup-to-disc ratio and look for early damage.
OCT scan of the optic nerve and nerve fibre layer, and disc photographs
a baseline for future comparison.
Visual field test
ideally two reliable tests, to confirm a normal baseline.
Your specialist then estimates your risk of developing glaucoma. NICE tells doctors to weigh the level of eye pressure, corneal thickness, family history and life expectancy. The free OHTS online risk calculator combines age, pressure, corneal thickness, cup-to-disc ratio and pattern standard deviation.
Ocular hypertension treatment: do you need it?
Not always. The AAO says that if pressure is only slightly raised, the ophthalmologist may monitor rather than treat. NICE advises not to treat people with ocular hypertension who are not at risk of visual impairment within their lifetime. Treatment is aimed at those with higher pressure or higher-risk features. In the OHTS the goal of treatment was to lower pressure by at least 20%, and the 2025 AAO guideline calls a 20% reduction a reasonable initial target.
Ocular hypertension eye drops
Eye drops are the most common treatment. NICE recommends a generic prostaglandin analogue for people with newly diagnosed ocular hypertension and pressure of 24 mmHg or more who are at risk of visual impairment, if they choose not to have laser or laser is unsuitable. EyeWiki gives the reasons it is the usual first choice: once-daily use, low cost, an average pressure reduction of about 30% and a favourable side-effect profile. Common side effects are eye redness, darkening of the skin around the eye and longer eyelashes.
| Drop class | Examples (EyeWiki) | Notes |
|---|---|---|
| Prostaglandin analogues | latanoprost, bimatoprost, travoprost, tafluprost | Usual first choice; once daily |
| Beta-blockers | timolol, betaxolol, carteolol, levobunolol | Alternative or add-on; suitability depends on your general health |
| Carbonic anhydrase inhibitors | dorzolamide, brinzolamide | Alternative or add-on |
| Alpha agonists | brimonidine, apraclonidine | Alternative or add-on |
| Rho kinase inhibitor | netarsudil | NICE also recommends latanoprost–netarsudil as an option in adults with ocular hypertension |
What is the best eye drop for ocular hypertension?
There is no single best drop for everyone. A prostaglandin analogue is usually tried first because it lowers pressure most and is used once a day, and your doctor changes or adds drops if the pressure target is not reached. NICE's glaucoma guideline says preservative-free drops can be considered if you are allergic to the preservative or have significant, symptomatic ocular surface disease. Drops only work if used every day and correctly, so ask your doctor or nurse to watch your technique. EyeWiki recommends a pressure check 4 to 6 weeks after starting drops.
Ocular hypertension laser treatment: SLT
Selective laser trabeculoplasty (SLT) is a laser treatment that improves drainage through the trabecular meshwork. NICE recommends offering 360-degree SLT to people with newly diagnosed ocular hypertension, pressure of 24 mmHg or more and risk of lifetime visual impairment (apart from pigment dispersion syndrome). Patients should be told that SLT can delay the need for drops and may reduce, but not remove, the chance of needing them, and that it may need repeating later. In the LiGHT trial of SLT versus drops as first treatment for glaucoma and ocular hypertension, 69.8% of eyes in the SLT group stayed at target pressure at 6 years without further medical or surgical treatment, no serious laser-related adverse events occurred, and fewer eyes needed trabeculectomy than in the drops group (13 versus 32).
Treatment with us: glaucoma and eye-pressure care, including laser treatment to lower pressure, is led by Prof. Dr. Ahmet Satıcı. Doç. Dr. Muhammet Derda Özer (Doç. means Associate Professor) sees pressure problems linked to uveitis or corneal disease. No operation is recommended for ocular hypertension alone; EyeWiki notes that if you also have a visually significant cataract, cataract surgery can be considered, as it lowers pressure.
Can ocular hypertension go away?
Sometimes the pressure comes down, but you cannot count on it. Eye pressure varies naturally through the day, and NICE advises repeating a high reading before acting on it. In the OHTS observation group, who had no treatment, pressure fell by an average of 4.0% over the study. But when high pressure is confirmed, it usually needs regular checks over the long term. Treatment lowers pressure only while it continues, and EyeWiki notes that treatment delays glaucoma but does not remove lifetime risk. NICE says people at low risk with an acceptable pressure may discuss stopping treatment, with a pressure check 1 to 4 months afterwards.
Ocular hypertension ICD-10 code
In the WHO's ICD-10, ocular hypertension is classified under H40.0 "Glaucoma suspect", which includes ocular hypertension. In the US ICD-10-CM system the codes are H40.051 (right eye), H40.052 (left eye), H40.053 (both eyes) and H40.059 (unspecified eye). The code is a records label; it does not mean you have glaucoma.
Follow-up: how often should ocular hypertension be checked?
It depends on your risk. EyeWiki gives typical intervals: for low-risk people, a pressure check every 6 to 12 months and a full dilated exam yearly; for higher-risk people, every 4 to 6 months. NICE sets intervals for treated ocular hypertension (baseline pressure 24 mmHg or more) with a normal optic nerve and visual field:
| Situation | Next assessment |
|---|---|
| Pressure not controlled | 1 to 4 months |
| Pressure controlled, conversion to glaucoma uncertain | 6 to 12 months |
| Pressure controlled, no sign of glaucoma | 18 to 24 months |
If the optic nerve or visual field changes, the diagnosis is reconsidered and you move to glaucoma care. According to EyeWiki's summary of long-term OHTS results, when conversion happened it was typically late and mild.
When to see a doctor
Seek emergency care immediately if you have:
- sudden severe eye pain with a red eye, blurred vision, rainbow-coloured circles around lights, nausea or vomiting and a headache (the NHS describes this as a medical emergency)
- a sudden change in vision
Book a routine appointment if:
- you have not had an eye test in the last 2 years
- a parent, brother or sister has glaucoma
- you use steroids long term, or have had an eye injury or eye surgery
- you have been told your eye pressure was "a bit high" and no follow-up was arranged
- you have been diagnosed with ocular hypertension and want a second opinion on whether to treat
If you already have your pressure readings, optic nerve scans and visual field results, you can send them for review before you travel.
Frequently asked questions
Ocular hypertension is eye pressure that is higher than normal, with a healthy optic nerve and normal vision. It is not glaucoma, but it raises the risk of developing it, so your eyes are monitored.
In ocular hypertension the pressure is high but the optic nerve is healthy. In glaucoma the optic nerve is damaged and the visual field is affected. Glaucoma can also occur when pressure is in the normal range.
Usually there are none. The AAO and NICE both say it is symptomless, so it is found at an eye test. Headache is not a symptom, and sudden severe eye pain with a red eye and blurred vision needs emergency care.
Reduced drainage of the eye's fluid, usually without a clear cause. Steroids, pigment dispersion, pseudoexfoliation, uveitis and eye injury can also raise pressure and are checked for first.
Not by itself, but it can lead to glaucoma. In the OHTS, 9.5% of untreated people developed glaucoma within 5 years, and about one in four lost some visual field over 20 years.
No. Lower-risk people are monitored. NICE recommends treatment mainly when pressure is 24 mmHg or more and you are at risk of visual impairment within your lifetime.
Drops (usually a prostaglandin analogue) or SLT laser, chosen with your doctor according to your risk. In the LiGHT trial, SLT gave better long-term disease control than drops as a first treatment.
Pressure varies and can settle on repeat checks, but confirmed ocular hypertension usually needs long-term monitoring.
H40.0 (glaucoma suspect, including ocular hypertension) in WHO ICD-10, and H40.05- in ICD-10-CM.
Sources for the facts on this page
- American Academy of Ophthalmology. What Is Ocular Hypertension? https://www.aao.org/eye-health/diseases/what-is-ocular-hypertension
- American Academy of Ophthalmology. What Is Normal Eye Pressure? https://www.aao.org/eye-health/tips-prevention/eye-pressure
- EyeWiki (AAO). Ocular Hypertension. https://eyewiki.org/Ocular_Hypertension
- NICE. Glaucoma: diagnosis and management (NG81), published 1 Nov 2017, last updated 26 Jan 2022. https://www.nice.org.uk/guidance/ng81/chapter/Recommendations
- Kass MA, et al. The Ocular Hypertension Treatment Study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma. Arch Ophthalmol 2002;120(6):701–713. https://pubmed.ncbi.nlm.nih.gov/12049574/
- Gordon MO, et al. The Ocular Hypertension Treatment Study: baseline factors that predict the onset of primary open-angle glaucoma. Arch Ophthalmol 2002;120(6):714–720. https://pubmed.ncbi.nlm.nih.gov/12049575/
- Kass MA, et al. Assessment of cumulative incidence and severity of primary open-angle glaucoma among participants in the Ocular Hypertension Treatment Study after 20 years of follow-up. JAMA Ophthalmol 2021;139(5). https://pubmed.ncbi.nlm.nih.gov/33856434/
- Gazzard G, et al. Laser in Glaucoma and Ocular Hypertension (LiGHT) Trial: six-year results of primary selective laser trabeculoplasty versus eye drops. Ophthalmology 2023;130(2):139–151. https://pubmed.ncbi.nlm.nih.gov/36122660/
- American Academy of Ophthalmology. Primary Open-Angle Glaucoma Suspect Preferred Practice Pattern (2025). https://www.aao.org/education/preferred-practice-pattern/primary-open-angle-glaucoma-suspect-ppp
- NHS. Glaucoma. https://www.nhs.uk/conditions/glaucoma/
- WHO. ICD-10 (2019 version), H40.0 Glaucoma suspect. https://icd.who.int/browse10/2019/en#/H40.0
- US National Library of Medicine, Clinical Tables: ICD-10-CM H40.05 Ocular hypertension. https://clinicaltables.nlm.nih.gov/api/icd10cm/v3/search?terms=H40.05&sf=code&df=code,name
High eye pressure on your last eye test?
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