The Silent "Vision Thief"

By Dr. Tim Moser, Denver House Calls in Denver
Posted

Pierce was having problems with his vision.  No one noticed at first, since the changes had been so gradual.  Pierce’s daughter was the first to ask if he was seeing things okay.  He had some near misses while driving, due to not seeing objects off to the side.  Pierce had absolutely no eye pain, so he ignored the tunnel vision he was developing until it started to interfere with his reading the newspaper.  Reluctantly, he agreed to a complete eye examination.  A device was used to measure the pressure in his eye by applying a gentle puff of air to the eyeball.  Later, the eye doctor examined Pierce’s eye carefully.  The diagnosis of glaucoma was made, and appropriate eye drops were prescribed.

Glaucoma is a silent thief of a person’s vision.  Since there is no pain associated with the most common form of glaucoma, and the central vision is not affected, the disease can become very advanced before detected.

 

Eye, Eye captain!

The devastating effects of glaucoma can be traced to damage inflicted to the optic nerve.  The eye is a globe which keeps its shape thanks to 3 chambers.  The vitreous chamber is largest, and is filled with a clear, gelatin-like substance called the vitreous humor that helps give the eyeball a round shape.  In front of the Vitreous chamber is the posterior chamber, which is the smallest of the three chambers.  This area is filled with a thinner clear liquid known as the aqueous humor. This watery fluid provides oxygen and nutrients to the eye lens.  (In the context of anatomy, there is nothing funny about the word humor.  It refers to a normal body fluid).

The Anterior Chamber is located between the outer layer of the eye (the cornea), and the colored portion of the eye (the iris). The anterior chamber is also filled with thin aqueous humor.

 

Glaucoma begins

 A healthy eye is a marvelous thing.  As aqueous humor is produced in the eye, the fluid is circulated from the anterior chamber to the posterior chamber, and is then returned to the bloodstream.  This fluid is constantly being produced, and then returned to the body to be recycled.  Pressure of the fluid in the eye is tightly regulated by the body, lest damage occur to the delicate structures involved.  If the eye pressures rise above a critical level, the optic nerve can be damaged, sometimes permanently.

 

Types of glaucoma

In all cases, glaucoma is caused by an increase of pressure in the anterior chamber of the eye.  The most common type is open angle glaucoma, which occurs gradually over time, and is completely painless.  Peripheral vision is lost as the optic nerve is damaged by the high eye pressures.  Loss of peripheral vision occurs, leaving permanent ‘tunnel vision’ in the affected eye.  This is treated with eye drops or oral medications.

Closed angle glaucoma is a difficult condition to miss, since extreme eye pain is usually present.  In closed angle glaucoma, the aqueous humor is unable to circulate normally in the eye.  This is a medical emergency, since blindness can occur within days if not treated promptly with oral medication and eye drops.  Usually only one eye is affected at a time.  Laser surgery may be appropriate to open a new pathway inside the eye for the fluid to circulate.

Congenital glaucoma is relatively rare, and affects babies.  Symptoms include eye cloudiness, enlargement of one eye, or persistent eye redness.  Treatment usually involves surgery, and the prognosis is good if detected and treated in time.

 

Prevention

Since the most common type of glaucoma has no symptoms, regular eye exams are critical for early detection and treatment.  Both the measure of eye pressures as well and visual acuity are essential.  A complete eye exam should be performed every 1-2 years on all adults.

If glaucoma is diagnosed, using the eye drops or oral medication is essential to prevent further loss of vision.

 

Want more information on glaucoma?

http://www.mayoclinic.com/health/glaucoma/DS00283

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002587

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