Glaucoma Exam & Diagnostics

Glaucoma Evaluation

Because it has no noticeable symptoms, glaucoma is a difficult disease to detect without regular, complete eye exams.
During a glaucoma evaluation, Dr. Haas may perform the following tests:

 

  • Tonometry. This measures the pressure in your eyes (intraocular pressure, or IOP) using a technique called tonometry. Tonometry measures your IOP by determining how your cornea responds when an instrument (it used to be a painful puff of air) presses on the surface of your eye. Eyedrops are used to numb the surface of your eye for this test.

Slit-lamp tonometer:



Handheld tonometer:

  • Pachymetry. Pachymetry measures the thickness of your cornea, or the front, clear part of the eye.  Corneal thicknesses vary greatly from person to person, and this test allows us to determine the thickness of your individual corneas.  This measurement will allow Dr. Haas to better know the accuracy of your intraocular pressure measurements, which are highly dependent on the individual corneal thickness.                                

Handheld pachymeter:               

  • Gonioscopy. This test inspects your eye’s drainage angle—the area where fluid drains out of your eye. During gonioscopy, you sit in a chair facing the microscope used to look inside your eye. You will place your chin on a chin rest and your forehead against a support bar while looking straight ahead. Anesthetic drops are placed for numbing, and the gonio-lens is put lightly on the front of your eye and a narrow beam of light is directed into your eye while Dr. Haas looks through the slit lamp at the drainage angle.                                               

Gonio-lens:                                   

  • Ophthalmoscopy. With this test, Dr. Haas can evaluate whether or not there is any optic nerve damage by looking at the back of the eye (called the fundus). There are two types of ophthalmoscopy: direct and indirect. With direct ophthalmoscopy, Dr. Haas uses a small flashlight-like instrument with several lenses that magnifies the eye up to about 15 times. This type of ophthalmoscopy is most commonly done during a routine physical examination. With indirect ophthalmoscopy, Dr. Haas wears a headband with a light attached and uses a small handheld lens to look inside your eye. Indirect ophthalmoscopy allows a better view of the fundus, even if your natural lens is clouded by cataracts.
  • Visual field test. The peripheral (side) vision of each eye is tested with visual field testing, or perimetry. For this test, you sit at a bowl-shaped instrument called a perimeter. While you stare at the center of the bowl, lights flash. Each time you see a flash, you press a button. A computer records your response to each flash. This test shows if you have any areas of vision loss. Loss of peripheral vision is often an early sign of glaucoma.         
  • Photography. Sometimes photographs or other computerized images are taken of the optic nerve to inspect the nerve more closely for damage from elevated pressure in the eye.
  • Special imaging. Different scanners may be used to better determine the configuration of the optic nerve head or retinal nerve fiber layer.

Each of these evaluation tools is an important way to monitor your vision to help ensure that glaucoma does not rob you of your sight. Some of these tests will not be necessary for everyone. Dr. Haas will discuss which tests are best for you. Some tests may need to be repeated on a regular basis to monitor any changes in your vision caused by glaucoma.

 

OCT (Optical Coherent Tomography) for Nerve-Fiber-Layer Analysis

Early in the disease process of glaucoma, individual nerve fibers in the eye’s optic nerve are lost, causing an associated pattern of nerve-fiber-layer thinning. This problem can later translate into loss of tissue at the optic nerve head, resulting in visual field defects and, ultimately, loss of vision.

New techniques have been devised to help measure the thickness of the nerve fiber layer, helping Dr. Haas diagnose glaucoma earlier and monitor progression of the disease.  One technique used to measure the nerve fiber layer is called optical coherence tomography (OCT). A low-level laser is used to provide cross-sectional views of the retina and optic nerve, and measures variations in thickness to the 1/1000 of a millimeter!  This imaging technique can help provide an objective measurement of the nerve fiber layer, enhancing the ability of Dr. Haas to effectively diagnose and monitor glaucoma and various retinal problems.

 

Optic Disc Photographs

Photographic images of the optic disc are also essential for monitoring glaucoma.

Glaucoma damage is seen clinically as loss of the nerve fiber layer and an associated thinning of tissue at the optic nerve head. With this damage, Dr. Haas looks for “cupping” of the optic nerve. Stereoscopic disc photos of the optic nerve are helpful in providing baseline information about the optic nerve’s condition for future comparison. These photographs are taken in our office using a special camera that can create a stereo image.

Optic disc photography is invaluable because the baseline photos can be used for future comparison. This will help identify signs of glaucoma progression.  Also, should you ever move out of the area, these pictures can be sent to any other physician’s office at any time in the future allowing continuity of your personalized eye care. 
Despite many new imaging techniques for glaucoma, disc photos and a careful clinical examination are still the standard of care for glaucoma.

Fundus and Optic Nerve (stereo) Camera:


Visual Field Testing

Because it has no noticeable symptoms, glaucoma is a difficult disease to detect without regular, complete eye exams.

One particular test, called a visual field test (or perimetry test), measures all areas of your eyesight, including your side, or peripheral, vision. A visual field test can help find certain patterns of vision loss and is a key way to check for glaucoma. It is very useful in finding early changes in vision caused by nerve damage from glaucoma.

To take this painless test, you sit at a bowl-shaped instrument called a perimeter. While you stare at the center of the bowl, lights flash. Each time you see a flash you press a button. A computer records the location of each flash and whether you pressed the button when the light flashed in that location. At the end of the test, a printout shows if there are areas of your field of vision where you did not see the flashes of light. This test shows if you have any areas of vision loss. Loss of peripheral vision is often an early sign of glaucoma. Regular perimetry tests are an important technique for learning how, if at all, your vision is changing over time. It can also be used to see if treatment for glaucoma is preventing further vision loss.

Visual Field Machine:               



Visual Field loss (glaucoma) in the right eye:   

Dr. Haas will use your clinical exam findings along with these various diagnostic studies to assure you are receiving the best care for your glaucoma and glaucoma screenings.  Haas Vision Center has all of the instruments listed above, and you can feel comfortable in knowing that your care is top-notch with the utilization of the latest technologies to guide your treatment.