Types of glaucoma and diagnosis
In the United States, more than a half of the 2.5 million glaucoma patients suffer from different degrees of vision loss. More seriously, vision loss caused by glaucoma is often irreversible. Resulted from internal eye pressure (IOP) build-up and optic nerve damage, glaucoma has been the second leading cause of blindness, second only to age-related macular degeneration. At the beginning, only vision deterioration is caused but untreated glaucoma always leads to permanent damage of the optic nerve and resultant loss of visual field. Eye drops with medication can be used to control glaucoma by bringing down IOP. Careless use of these eye drops may bring higher risks of vision loss. Further treatments include glaucoma surgery, lasers and medications. This article focuses on the classification of different types of glaucoma.
Unnoticeable and noticeable glaucoma cases
From the IOP accumulation and optic nerve damage to various degrees of vision loss, there are always no obvious symptoms so that glaucoma is often called the “silent thief of sight”. One exception may happen to acute angle-closure glaucoma, which brings blurry vision, halos, intense eye pain, nausea or vomiting suddenly. Angle –closure glaucoma cases only account for approximately 10% of the total. These two major two types of will be detailed below.
IOP measurement and evaluation
A tonometer can be used to measure the intraocular pressure either by resting a small probe or sending an air puff onto the eye’s surface. An IOP above 30 mmHg indicates a problem of the amount of fluid in the eye and brings a much higher risk of developing glaucoma. Special eye drops have been developed to keep IOP at a low level and this is a popular treatment for glaucoma.
Different ways to monitor glaucoma progression
Scanning laser polarimetry, optical coherence tomography and confocal scanning laser ophthalmoscopy can be used to monitor the progression of glaucoma by setting up baselines and detecting changes. Optic nerve damage caused by glaucoma may lead to blind spots, so that visual field testing can also be used to monitor glaucoma. In addition, ophthalmoscope can be used to view the eye’s internal structures.
Chronic open-angle glaucoma causes vision damage silently
There are mainly two types of glaucoma: acute angle-closure glaucoma and chronic or primary open-angle glaucoma. Chronic glaucoma has no obvious symptoms during its process of affecting the peripheral vision. The result is that the patient is only able to see objects straight ahead. Unlike primary open-angle glaucoma, another form of open-angle glaucoma has normal IOP level, which is called normal-tension glaucoma. This type of glaucoma has no different features from primary open-angle glaucoma.
Acute narrow-angle glaucoma has noticeable symptoms from the start
Also called narrow angle glaucoma, angle-closure glaucoma brings unexpected symptoms such as eye pain, headaches, halos, red eye etc. To a certain degree, this kind of glaucoma is less harmful because it is possible to make an early detection and treatment. The phrase “silent theft of sight” does not describe angle-closure glaucoma but open-angle glaucoma. As long as no optic nerve damage is caused, glaucoma can be easily controlled and treated.
Other variations of glaucoma
Besides the above major types of glaucoma, there are still other variations. Pigmentary glaucoma is caused by iris pigment deposits, which usually clog the draining angles. This form of glaucoma also has no clear symptoms. Secondary glaucoma is always associated with eye infection, inflammation or an enlarged cataract. Infants may be born with congenital glaucoma due to natural narrow angles. Parents should take good care of their babies’ eyes, in case of congenital glaucoma signs such as cloudy, white or hazy eye.
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