Glaucoma Testing

Glaucoma Testing

Glaucoma Testing

Glaucoma Testing

Glaucoma Testing

What is Glaucoma?

Glaucoma is a completely painless disease that has no symptoms or warning signs so it is often called the "silent thief of sight." Because there are no outward symptoms, it is important to get a COMPREHENSIVE eye HEALTH exam annually to check for any signs of glaucoma.  Glaucoma falls into four main types:

1) Open Angle Glaucoma: Open Angle Glaucoma happens when the eye does not drain fluid as well as it should, the eye pressure rises and starts to damage the optic nerve and nerve fiber layers of the retina. 

2) Normal Tension Glaucoma:  This type of glaucoma occurs when a patient with "normal" eye pressure has sensitive optic nerves and still develops glaucoma damage over time.  

3) Narrow Angle/Chronic Angle Closure Glaucoma: This type of glaucoma occurs when a person's "angle" (the area where the fluid drains) is narrow so the fluid does not have much room to drain, the eye pressure rises and starts to damage the optic nerve and nerve fiber layers of the retina.  Again because there are few or no outward symptoms, it is important to get a COMPREHENSIVE eye HEALTH exam annually to check for any signs of glaucoma. 

4) Secondary Glaucomas:  Secondary glaucoma is the name used to describe glaucomas that occur as a side effect or “secondary” to another underlying medical condition or trauma.

  • Pigmentary Glaucoma: This secondary glaucoma results from Pigmentary Dispersion Syndrome and occurs when the pigment rubs off of the iris and subsequently raises eye pressure causing damage to the optic nerve and nerve fiber layers of the retina. 
  • Pseudoexfoliation Glaucoma: Pseudoexfoliation occurs when the edge of the lens starts to flake away like dandruff, they clog up the trabecular meshwork and stop the aqueous fluid from draining efficiently raising eye pressure and damage the optic nerve and nerve fiber layers of the retina. This condition tends to be more common in older people and in people of Scandinavian and Southern Mediterranean origin.
  • Uveitic Glaucoma: Uveitis occurs when a part of the eye called the uvea becomes swollen and inflamed. If uveitis leads to increased pressure, we get uveitic glaucoma.
  • Neovascular Glaucoma: Neovascular (“new blood vessels”) glaucoma occurs when poor blood supply within the eye causes new blood vessels to grow on the surface of the eye and into the drainage channel. The new blood vessels can cause eye pressure to rise by blocking the outflow of aqueous fluid. This type of glaucoma is usually associated with other eye conditions like diabetic retinopathy.
  • Steroid-Induced Glaucoma: Medicine-related secondary glaucoma is the result of inflammation caused by medication, typically steroids. Steroids are used for a variety of medical conditions and can be inhaled (inhalers), taken orally as tablets, injected or applied directly to the skin or eye. They are an important type of medicine, but a possible side effect is increased eye pressure. This effect is called ‘steroid response’.
  • Trauma Induced Glaucoma: Trauma can mean either a blow to the eye, a penetrating injury (when something pierces the eye) or a chemical injury (such as an alkali burn). It can happen immediately after the injury or develop over time. Blunt trauma (such as a blow to the eye) can affect the shape of the eye, meaning the pressure builds up over several years. People affected will need to be monitored to limit the chance of developing glaucoma in the future.
  • Iatrogenic Glaucoma: Iatrogenic literally means ‘caused by a doctor’ and unfortunately this is one of the most common reasons people experience secondary rises in eye pressure. The main iatrogenic cause is following retinal surgery. During retinal surgery, the surgeon may need to put gas or silicone oil in the eye. These substances can have the side effect of raising the eye pressure. 

Most of the time, glaucoma develops very slowly which means that many people don’t realize that they are affected until some damage to their vision has already occurred. However, occasionally a person can have an Angle Closure Glaucoma "attack," their already narrow angles close, the fluid can no longer drain and the pressure in the eyes can rise drastically causing sudden and severe or complete vision loss.  An Angle Closure Glaucoma attack can develop quickly, and symptoms do occur, especially when going from a dark environment into light. These can include:  

  • Red eyes
  • Intense headaches
  • Tenderness around the eyes
  • Eye pain
  • Seeing rings/halos around lights
  • Blurred vision
  • Nausea and vomiting

**If you notice any of these symptoms, it’s important to CALL DR. KUBOTA'S OFFICE RIGHT AWAY so that you can be examined as soon as possible. If the office is closed, please go IMMEDIATELY to the nearest emergency room and ask to see the ophthalmologist on call.**

Glaucoma Testing

You might be surprised at how many tests are needed to diagnose glaucoma. A proper diagnosis requires careful evaluation of many aspects of your eye’s health from eye pressure to cornea thickness to the health of your optic nerve and nerve fiber layer of the retina. This section describes how Dr. Kubota will assesses your risk and all the tests needed to properly diagnose glaucoma.

Risk Factor Assessment

Dr. Kubota will begin by assessing your risk level for developing glaucoma. This will help determine the frequency and extent of testing needed. Through personal and family medical history questions, Dr. Kubota will weigh your risk factors for glaucoma which include:

  • Age

  • Ethnic background such as African or black Caribbean, Hispanic, Asian or Scandinavian descent

  • Family history of glaucoma in any genetically related realtive such as a sibling, parent or grandparent.

  • History of eye conditions, injuries or surgeries

  • Prolonged corticosteroid use (eye drops, pills, inhalers or creams)

  • Chronic conditions that affect blood flow, such as migraines, diabetes, low blood pressure or hypertension

  • Current or former smoker

Once you have completed your comprehensive eye exam, Dr. Kubota will also consider these risk factors:

  • Eye pressure higher than normal (above 20 mm Hg)

  • Corneal Thickness

  • Anatomic measurement of your "Angle" (the area above the iris where the fluid of the anterior chamber drains

  • Your prescription. (People with farsightedness and cataract formation are at a higher risk for narrow-angle glaucoma, a more serious type that can advance quickly. While nearsightedness is associated with open-angle glaucoma, which progresses slowly without any symptoms.  However, some patients have mixed-mechanism glaucoma.)

Standard Glaucoma Tests:

During a comprehensive eye exam, Dr. Kubota will always check for glaucoma, regardless of the risk level. This provides a baseline for comparison as you age.  Here are some of the tests performed:


Tonometry measures the fluid pressure in your eye.  The Non-Contact Tonometer measures this without touching you by blowing a puff of air.  If Goldmann Tonometry is needed, then Dr. Kubota will instill anesthetic eye drops with fluorescein dye to numb your eyes. Then she will use a device with a probe to gently touch your cornea to read your eye pressure.

Eye pressure is unique to each person, so ALONE, it is not always a reliable indicator for glaucoma. It is simply another piece of information to help Dr. Kubota assess your risk.  Most glaucoma cases are diagnosed with pressure over 20mm Hg, however, some people have "Low Tension Glaucoma" where they are losing eyesight with "normal" eye pressure.

Optos Retinal Scan or Dilated Fundus Evaluation (Extended Ophthalmoscopy):

These procedures examine your central and peripheral retina. 

The Optos Retinal Scan requires no dilation and it takes digital images of both the central and peripheral retina.  It obtains a full, detailed view of the optic nerve, macula, blood vessels and peripheral retina.  It can also provide a more in depth examination of the retina by allowing analysis of the different layers of the retina and allowing the comparison of previous images to check for subtle changes over time.

During a Dilated Fundus Evaluation (Extended Ophthalmoscopy), Dr. Kubota will use eye drops to dilate your pupils. Then, using a head-mounted device with a light (binocular indirect ophthalmoscope), your central and peripheral retina can be viewed.  You will be light sensitive and possibly blurry for up to 8 hours after the examination so you need a driver to take you home and you should stay indoors and avoid sunlight.

Optical Coherence Tomography (OCT): 

Optical Coherence Tomography takes a scan of specific structures in the back of the eye, like the macula and/or optic nerve.  The OCT measures the thickenesses of your retinal nerve fiber layer in microns, then statistically analyzes the results by age to determine if your eyes are normal for your age.  It also allows Dr. Kubota to compare past OCTs to determine if a patient's eyes have changed over time.  This instrument can pick up subtle, early nerve fiber layer loss, allowing glaucoma to be diagnosed even earlier than just by visually observing the optic nerve alone.

Perimetry (Visual Field Testing)

Static automated perimetry uses a machine to quantify how well a patient is able to detect flashing lights of varying size and brightness in different areas of their visual field.  There are screening, comprehensive and specialty visual field tests.  The patient fixates on a central point and responds by pushing a button when they see the light. Visual field testing is non-invasive, painless and doesn’t require patients to have their eyes dilated.  Automated perimetry produces the test results in a series of charts that are then viewed by Dr. Kubota for analysis and interpretation. If you’ve been diagnosed with glaucoma, a comprehensive visual field test is usually recommended once or twice per year to assess changes to your vision.


Supplemental Glaucoma Tests:


Dr. Kubota may want to use pachymetry as another way to confirm a diagnosis. Pachymetry measures the thickness of your cornea, the clear window at the front of the eye. The OCT with a special lens attachment is used to take Pachymetry and can help clarify your diagnosis because corneal thickness has the potential to influence eye pressure readings.


This diagnostic test helps examine the "angle" between your iris and cornea (the area where the aqueous fluid drains). First, you’ll receive eye drops to numb the eye.  Then a special hand-held magnifying lens with mirrors is gently placed on the eye. The mirrors show Dr. Kubota more details of the angle (wide, open, narrow, closed, how much pigment is present, blood vessel growth, etc.)

Glaucoma diagnosis is not as simple as you might expect. Be sure to have annual COMPREHENSIVE eye HEALTH exams , especially if you have any of the risk factors for glaucoma.

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