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Ocular hypertension is a condition where the pressure in the eye is above normal parameters. (Learn More) It tends to occur more in African American individuals, people over the age of 40, and those who have a family history of the condition. (Learn More)
There are no discernible symptoms of ocular hypertension, and it can be caused by an inability of the eye to drain fluid properly, which itself can be triggered by different factors. (Learn More)
Treatment usually involves eyedrops and medication, but surgery is an option if there is a genuine concern that the hypertension has led to glaucoma, which is a bigger problem than the hypertension itself. (Learn More)
What Is Ocular Hypertension?
Ocular hypertension is a medical condition where the pressure in the eye (known as intraocular pressure, or IOP) is higher than it should be. The measurement for eye pressure is millimeters of mercury (mm Hg). Under normal circumstances, pressure in the eye should be between 10 to 21 mm Hg. If a person has an eye pressure above 21 mm Hg, this would meet the criteria for ocular hypertension.
High IOP is associated with glaucoma, which is a serious condition that can damage the optic nerve and cause vision loss. When ocular hypertension occurs on its own, it should not cause damage to the vision or the eyes; however, if left untreated, it does raise the possibility of glaucoma.
The American Academy of Ophthalmology explains that glaucoma is the buildup of fluid in the eye that damages the optic nerve. Like ocular hypertension, glaucoma amplifies the pressure in the eye, but unlike ocular hypertension, glaucoma can actually cause loss of sight.
Nonetheless, ocular hypertension is an important issue. The development of eye pressure is a significant risk factor for what ultimately might be glaucoma. However, there are many people who never experience increased eye pressure but do have glaucoma. This is a condition known as normal-tension glaucoma or low-tension glaucoma.
The chances of developing glaucoma increases with a number of risk factors.
- High eye pressure
- Older age
- Family history of glaucoma
- Lower systemic blood pressure
- Bleeding at the head of the optic nerve
There are many genetic and environmental risk factors that can tip the scales of ocular hypertension and glaucoma. The conditions can strike anyone, but African American people seem to develop it more than people of other races. It is the second cause of blindness among African Americans after cataracts. In addition, people over the age of 40 and those with a family history of ocular hypertension have the greatest chances of developing the condition.
The American Optometric Association also writes that ocular hypertension seems to develop more in people who have diabetes and who are very nearsighted.
Beyond that, people who have central corneal thickness measurements that are thinner than average might also be at risk.
Curiously, low blood pressure is its own risk factor for a patient developing glaucoma. Low blood pressure ultimately means lower perfusion pressure (the difference between the blood pressure and the intraocular pressure), which results in a reduced amount of blood flow to the eye and optic nerve. This, explains the American Journal of Ophthalmology, can begin the development of glaucoma.
Ocular hypertension is not by definition a disease, and it should not be thought of as such. Rather, ocular hypertension describes the condition of patients being closer to the onset of glaucoma than the general population. Because of this, patients with ocular hypertension are sometimes referred to as “glaucoma suspect” patients because there is a concern that they may have or will develop glaucoma if their hypertension is not treated.
Symptoms and Causes
What causes ocular hypertension? Due to the overlap between ocular hypertension and glaucoma, the factors that raise the chances of developing high eye pressure are quite similar.
Excessive production of the clear fluid in the eye is a potential cause. This fluid, known as aqueous humor, helps the eye maintain its shape (not unlike water filling a balloon), and it transports nutrients and immunoglobulins to fight bacteria and viruses. Aqueous is produced by the ciliary body, but if the ciliary body produces more aqueous than necessary, the pressure in the eye increases, leading to ocular hypertension.
Similarly, inadequate drainage of the aqueous, or slow drainage, will also impede the normal process of production. This will likewise cause the pressure of the eye to increase.
Medication and Trauma Causes
Some medications can induce ocular hypertension in patients. Medicines with steroids used in the treatment of asthma can increase the risk. In 2017, the Journal of Current Glaucoma Practice referred to glaucoma induced by steroids as “an avoidable irreversible blindness.” Steroid eye drops used in the postoperative care of LASIK and other forms of refractive surgery can cause eye pressure in patients who have enough risk factors for the condition.
An injury to the eye can throw off the aqueous humor production and draining processes, which can start the process of ocular hypertension. This can happen months or even years after the actual injury. A doctor carrying out an eye exam should know if their patient has had any trauma to the eye or head, either recently or in the distant past.
Treating Ocular Hypertension
How can ocular hypertension be treated? Depending on the risk of glaucoma, some doctors prescribe eye drops to lower the IOP. These medications can be expensive and cause side effects.
- Stinging and itching
- Temporarily blurred vision
- Changes in eye color or eyelid skin
- Redness or other irritation
Beta blockers (medications that reduce blood pressure by blocking the effects of the adrenaline hormone) will lower the amount of aqueous humor produced by the eye, thereby lowering the intraocular pressure. However, beta blockers come with their own side effects.
- Low blood pressure
- Slower heart rate
- Breathing difficulties
- Reduced sex drive
Another option is for doctors to regularly monitor the intraocular pressure and only intervene if there are clear signs that the patient will develop glaucoma. The increased risk for glaucoma means that patients should have their IOP regularly checked out, especially if they already have ocular hypertension.
When Should Treatment Begin?
The decision on when to begin treatment for ocular hypertension will depend on the doctor’s observations based on the results of the eye exam, assessment of risk factors, testing (like optic nerve imaging and visual field testing), and the person’s ability to work with a treatment plan.
This is important because the treatment is long term. The patient will have to endure side effects and the inevitable financial burden. In some cases, the risk of developing glaucoma will be the deciding factor regardless of other concerns.
Additionally, patients who have damage to their optic nerve or who are losing their vision due to the development of glaucoma should almost certainly receive treatment for ocular hypertension. Ophthalmology Times explains that a procedure known as selective laser trabeculoplasty is “safe and effective” for reducing intraocular pressure in patients who have glaucoma; however, this treatment does not work for all patients. Even among patients who respond well to the procedure, the effects are not necessarily permanent. That said, the process is repeatable, which might be its biggest advantage for patients who have glaucoma.
Ultimately, a person who has ocular hypertension should plan for long-term ongoing appointments with their doctor to track the potential diagnosis of glaucoma and to assess the success of the treatments for ocular hypertension. Although ocular hypertension has no cure, it can be regularly monitored and treated, so the damage it can do is diminished.
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Distribution of Ocular Perfusion Pressure and Its Relationship with Open-Angle Glaucoma: The Singapore Malay Eye Study. (July 2010). Clinical and Epidemiologic Research.
Blood Pressure, Perfusion Pressure, And Glaucoma. (May 2010). American Journal of Ophthalmology.
Glaucoma Suspect: Diagnosis and Management. (January/February 2016). Asia-Pacific Journal of Ophthalmology.
Vitreous and Aqueous Humor. (February 9, 2015). Healthline.
Steroid-induced Glaucoma: An Avoidable Irreversible Blindness. (May-Aug 2017). Journal of Current Glaucoma Practice.
Predictors And Outcomes Of Ocular Hypertension After Open-globe Injury. (January 2014). Journal of Glaucoma.
Which Medicines Treat Glaucoma? (March 9, 2017). WebMD.
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The Who, What, When, Why And How Of Selective Laser Trabeculoplasty. (December 1, 2015). Ophthalmology Times.