Long-Term Variability in Intraocular Pressure

Introduction:

Increased eye pressure over a long time can cause ocular hypertension, which leads to damage to the optic nerve fibers and causes glaucoma. Ocular pressure can rise due to many reasons, including age changes, hereditary factors, race, or other underlying diseases. The natural method of the eyes that maintains the ocular pressure fails and results in the rise of intraocular pressure (IOP). The early detection and proper treatment of ocular hypertension can prevent further eye damage and vision loss.

What Is Intraocular Pressure?

Intraocular pressure is referred to as the pressure of fluid present in the eye. It is also called eye pressure. Naturally occurring ocular pressure plays an important role in vision and maintaining eye health. The thick, gel-like material present in the chamber at the back of the eye is called the vitreous humor. The fluid present in the front of the eye is called aqueous humor, which is thinner and waterier in content.

The intraocular pressure is regulated naturally. When the eye creates new aqueous humor, the same amount of old aqueous humor is removed from the eye. The older aqueous humor leaves the eye through a drainage angle, a small spot where the iris of the eye meets the sclera of the eye. Iris is the colored part, and the sclera is the white part of the eye.

How Is Intraocular Pressure Measured?

Intraocular pressure is the force inside the eyes, more specifically the fluid pressure of aqueous humor. An average human intraocular pressure is between 10 mmHg and 20 mmHg. An eye specialist measures eye pressure through an eye pressure test called tonometry. It is done by flattening the cornea. When more force is required to flatten the cornea, the intraocular pressure increases. Tonometry is a type of non-contact or air puff tonometry. The machine shoots a puff of air into the eye and measures how much of the cornea is moved.

Another way to measure eye pressure is by numbing the eyes with special eye drops and pressing a tool against the cornea.

Causes of Increase in Intraocular Pressure:

• Eyes produce a higher amount of aqueous humor.

• Trauma associated with the eye.

• The drainage angle is blocked which prevents the drain of aqueous humor from the eye.

• Medications like corticosteroids.

What Is Long-Term Variability in Intraocular Pressure?

• Long-term variability is defined as the variation in intraocular pressure that is obtained for a particular period of several days for one year.

• The long-term variation of intraocular pressure can cause glaucoma.

• Long-term increase in IOP can increase the risk of developing glaucoma, due to damage to the optic nerve. The risk can be reduced if the ocular hypertension is treated with medications or laser surgery.

• Ocular hypertension can make the veins of the retina blocked, resulting in retinal vein occlusion, which can lead to vision loss.

What Is the Importance of Assessment of Intraocular Pressure?

An important parameter in the eye health assessment. It gives an important picture of eye health and signs of optic nerve damage. Ocular hypertension is not conserved as a disease itself, but the increased IOP shows a high risk of glaucoma development. Assessment of intraocular pressure helps in identifying and closely monitoring people at high risk of developing glaucoma.

What Are the Clinical Features Associated With Increased Intraocular Pressure?

An increase in intraocular pressure results in ocular hypertension, and the IOP is greater than 21 mmHg. An increase in intraocular pressure will not show any clear symptoms. The pressure variations are detected during a routine eye examination. In ocular hypertension, the optic nerve appears normal, and no signs of other eye diseases are seen.

What Are the Factors Influencing the Long-Term Variability of Intraocular Pressure?

• Heredity - In primary open-angle glaucoma, there is a hereditary change associated with having higher IOP.

• Age - In individuals over 40 years of age, there is a slight increase in the mean intraocular pressure, due to age-related changes in the reduction of aqueous outflow.

• Sex - In order of age group, there is a mean increase of intraocular pressure in females than in males. Also higher for developing ocular hypertension, especially after menopause.

• Race - Population-based studies have shown differences in mean IOP race also influence the variation of intraocular pressure.

• Refractive Error - In myopic eyes (near-sightedness) tend to have slightly increased intraocular pressure compared to the normal eye.

How Are Intraocular Hypertension and Glaucoma Related?

Glaucoma is the second large cause of blindness worldwide. It occurs due to the damage of retinal ganglion cells and optic nerve fibers. Increased intraocular pressure is considered an important risk factor for developing glaucoma. When the natural mechanism for maintaining intraocular pressure is lost, the pressure and strain increase, resulting in compression, and deformation that eventually result in damage to retinal ganglion cells. Ocular hypertension increases the risk for primary open-angle glaucoma.

How Is Ocular Hypertension Treated?

• Medication - Ocular hypertension is treated with medications that help the aqueous humor to drain out of the eye or help to lower the production of aqueous humor, as prescribed by ophthalmologists some of the medications are prostaglandins, nitric oxides, beta-blockers, and carbonic anhydrase inhibitors.
• Surgery - Through a surgical procedure an outlet is created to allow the drainage of excess fluid.

What Are the Methods to Reduce the Risk of Developing Increased Intraocular Pressure?

• Routine eye examinations help in the early detection and treatment of eye problems.

• Smoking is bad for the eyes, as it increases the chance of developing a cataract, glaucoma dry eye, and diabetic retinopathy.

• Maintaining eye health and a healthy balanced diet, including green leafy vegetables, like kale and spinach. Include fish that provide omega-3 fatty acids like tuna, salmon, and halibut.

• Exercise regularly.

• Proper control of blood pressure level, blood sugar levels, and cholesterol levels.

Conclusion:

A proper eye examination is important for detecting intraocular pressure. It is important to start medications as early as possible to reduce the risk of further eye damage. With proper steps of treatment, the intraocular pressure can be regulated, thus preventing further damage to the optic nerve and preserving eye vision.