The Dr. Bill Takeshita Foundation

Last Modified: Sat, 18 Aug 2007

View other Common Causes of Vision Impairment

Glaucoma is a condition where the intra-ocular pressure of the eye causes damage to the optic nerve, resulting in the loss of peripheral vision, contrast vision, color vision, and blurred sight. Glaucoma tends to be more common among adults over the age of 40 years of age and is more common among those who have family members with glaucoma. It is more prevalent among African-Americans. Glaucoma is a progressive disease and patients with uncontrolled glaucoma can become totally blind. Fortunately, treatments can slow the progression of vision loss. There is no medical or surgical treatment to reverse the damage to the optic nerve fibers. Many patients with glaucoma respond favorably to low vision aids and computer/assistive technology.

The eye contains a fluid called aqueous humor. This water-like substance is constantly produced and drained from the eye. When the aqueous humor is produced faster than it can be drained, the internal pressure of the eye increases and this damages the optic nerve. In the past, glaucoma was primarily detected by measuring the intra-ocular pressure of the eye. If the pressure was higher than 21 mmHg., it was thought that one had glaucoma and eye drops or oral medications were prescribed to lower the pressure. Today, intra-ocular pressure measurements are only one of many tests used to detect glaucoma in the early stages of the disease and there are many medical and surgical treatments to treat glaucoma and slow the progression of the disease.

Congenital glaucoma is a relatively rare condition in which the intra-ocular pressure of the eye is elevated during the development of the fetus. Infants with congenital glaucoma may have enlarged eyes as a result of the increased pressure of the eye. The cornea may also be clouded and these children may require a corneal transplant. The clarity of sight may range from 20/100 to total blindness. Many children are very sensitive to glare and bright light and require the use of filters to enable them to open their eyes and use their remaining vision.

Primary open angle glaucoma (POAG) is the most common form of glaucoma in adults. It generally describes the form of glaucoma in which the drainage system of the eye is open but the pressure is still too high for the eye. Patients with POAG generally do not have any symptoms and this is why POAG is sometimes called the “silent blinder.” As POAG goes undetected, it damages the optic nerve, which eventually causes the loss of peripheral vision. In more advanced stages of the disease, patients will have tunnel vision and their clarity of sight may be very poor.

Angle closure glaucoma is the term used to describe glaucoma in which the drainage region of the eye called the angle is narrow or closed. This anatomical shape restricts the flow of aqueous from leaving the eye. Consequently, the pressure of the eye may increase rapidly to very high levels, causing immediate pain, redness of the eye, blurred sight, and fogginess. Angle closure glaucoma is a medically urgent condition and patients with such symptoms must seek the care of an ophthalmologist immediately. Prolonged elevated eye pressure can lead to blindness within days.

Low-tension glaucoma is a form of glaucoma in which the pressure of the eye is less than 21 mmHg, but it still causes damage to the optic nerve. Low-tension glaucoma is prevalent in Asian women and can be very difficult to treat because the pressure of the can lead to an eye that does not have sufficient pressure which can cause other eye complications. Patients with low-tension glaucoma often have blind spots in their central and mid-peripheral vision. In the more advanced stages, patients may experience very blurred sight, ranging from 20/100 to 20/400.

There is no cure or treatment to reverse the damage to the optic nerve caused by glaucoma. Eye drops are generally the first mode of treatment to lower the intra-ocular pressure of the eye. Oral medications are sometimes used but these medications can cause side effects such as headaches and “ringing of the ears.” Recent advances in surgery now allows surgeons to lower the pressure of the eye by increasing the drainage of aqueous fluid or reducing the production of aqueous fluid. In cases where the cornea has become clouded as a result of glaucoma, a full thickness corneal transplant or partial endothelial transplant surgery may be performed to improve the level of vision.

Recommendations

• All adults over the age of 40 years should have a yearly eye examination that includes tonometry (measurement of the intra-ocular pressure of the eye), perimetry (peripheral vision testing), and dilated retinal examination. Patients with a family history of glaucoma should have these tests performed every year throughout their entire life. Children can also have glaucoma. Glaucoma is not a film over the eye and is not visible by friends and family members. Because it generally has no symptoms, patients with glaucoma often do not know that they have the disease.
• Infants with congenital glaucoma will benefit from vision stimulation to maximally develop the visual cortex of the brain. For specific details, please see Developing Your Child’s Vision.
• A consultation by a low vision specialist and low vision aids will be very helpful. Low vision aids such as bioptic glasses, hand held telescopes, and video magnification systems can improve distance sight to 20/20 while specialized reading glasses, hand magnifiers, and closed circuit televisions can allow patients to read small print.
• Position students with congenital glaucoma in the front portion of the classroom. Try to use black dry erase markers or bold chalk to increase readability.
• Students will benefit from having copies of material normally written on the board or presented on overhead transparencies. If PowerPoint presentations are used, a dark background with white letters written in Arial or Tahoma will improve readability for students with low vision.
• Students with glaucoma may have difficulty participating in sports such as baseball, tennis, and basketball. Their poor peripheral vision makes it difficult to catch flying balls and should be evaluated before participating in such sports.
• Computer users will benefit from changing the background of the display to a black or blue background with white letters. Enlargement of the font size will also increase readability. For information on how to modify the computer screen, see “Solutions To Help You User Your Computer.
• Specialized computer software and technology such as Zoom Text magnification software, scanning programs such as Open Book and Kurzweil may be very helpful for students with glaucoma. For more information, see Computer and Assistive Technology.
• Teenagers with glaucoma who are interested in learning whether they have sufficient vision for driving should have a low vision examination by a low vision optometrist who specializes in low vision. It will be very important to measure the peripheral vision of the patient.
• Specific low vision aids that are often helpful to patients with glaucoma include:
  • Contrast enhancing filters for reading and distance viewing. Corning CPF series, Melanin filters, and anti-reflective lenses
  • 3x to 4x bioptic spectacles for distance viewing
  • Aspheric reading spectacles with Trivex lens
  • 4x to 6x aspheric halogen illuminated pocket and stand magnifiers
  • Patients with glaucoma respond better to high quality optics with lower magnification.
  • Electronic video magnification systems such as CCTV with high contrast white background and black letters
  • Modify the computer to display a High Contrast white background with black letters. For instructions, please see Solutions to Help You Use Your Computer.
• For more information, please see Low Vision Rehabilitation