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.
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:
**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.**
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.
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:
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)
Anatomic measurement of your "Angle" (the area above the iris where the fluid of the anterior chamber drains
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.
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 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.
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.