Ocular hypertension is the presence of elevated fluid

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...

inside the eye (

intraocular pressure Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma. Most tonometers are calibrated to ...

), usually with no

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. In humans, the optic nerve i ...

damage or

visual field The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments". Or simply, visual field can be defined as the entire area that can be seen when an eye is fixed straight at a point ...

loss. For most individuals, the normal range of intraocular pressure is between 10 mmHg and 21 mmHg. Elevated intraocular pressure is an important risk factor for

glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

. One study found that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma. Accordingly, most individuals with consistently elevated intraocular pressures of greater than 21mmHg, particularly if they have other risk factors, are treated in an effort to prevent vision loss from glaucoma.

Pathophysiology

The pressure within the eye is maintained by the balance between the fluid that enters the eye through the

ciliary body The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The aqueous humor is produced in the non-pigmented portion of the ciliar ...

and the fluid that exits the eye through the

trabecular meshwork The trabecular meshwork is an area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the eye via the anterior chamber (the chamber on the front of the e ...

Diagnosis

The condition is diagnosed using

ocular tonometry Tonometry is the procedure eye care professionals perform to determine the intraocular pressure (IOP), the fluid pressure inside the eye. It is an important test in the evaluation of patients at risk from glaucoma. Most tonometers are calibrated ...

and glaucoma evaluation. Increased IOP without glaucomatous changes (in optic disc or visual field) is considered as ocular hypertension.

Treatment

Ocular hypertension is treated with either medications or laser. Medications that lower intraocular pressure work by decreasing aqueous humor production and/or increasing aqueous humor outflow. Laser trabeculoplasty works by increasing outflow. The cannabinoids found in cannabis sativa and indica (marijuana) have been shown to reduce intraocular pressure, by up to 50% for approximately four to five hours. But due to the duration of effect, significant side-effect profile, and lack of research proving efficacy, the American Glaucoma Society issued a position statement in 2009 regarding the use of marijuana as a treatment for glaucoma.

Research

The LiGHT trial compared the effectiveness of eye drops and selective laser

trabeculoplasty Trabeculoplasty is a laser treatment for glaucoma. It is done on an argon laser equipped slit lamp, using a Goldmann gonioscope lens mirror. Specifically, argon laser is used to improve drainage through the eye's trabecular meshwork, from which the ...

for ocular hypertension and open angle glaucoma. Both treatments contributed to a similar quality of life but most people undergoing laser treatment were able to stop using eye drops. Laser trabeculoplasty was also shown to be more cost-effective.;

References

External links

eMedicine - Ocular Hypertension
{{Eye pathology Glaucoma