As mentioned previously, glaucoma is a group of eye disorders. However, for the purpose of organization, glaucoma may be categorized into 2 basic types: Closed Angle Glaucoma or Open Angle Glaucoma. The glaucoma doctors at Coastal Vision Medical can screen for all types, and recommend treatment options and glaucoma management.
Angle Closure Glaucoma
Angle closure glaucoma refers to a condition where the aqueous fluid is unable to reach the trabecular meshwork (the eye's drain), which sits inside the angle of the eye. This results in elevated Intra-ocular Pressure (IOP). Angle closure has many causes, and may be acute or chronic.The main risk factors of angle closure glaucoma are:
- Asian race
Acute Angle Closure Glaucoma / Narrow Angles
This most commonly occurs as a result of a Narrow Angle. In normal cases, there is enough space within the angle for the aqueous fluid to reach the trabecular meshwork. Some patients have Narrow Angles, which means that the angle is crowed by the structures within the eye (i.e. the cornea and the iris are too close to each other). This can lead to a very sudden increase in eye pressure. Some patients may be born this way, and in others it is due to cataracts getting bigger in size. In any event, Acute Angle Closure is a very dangerous and sight-threatening condition, which may lead to vision loss in a matter of 24 to 48 hours if left untreated.As previously mentioned, Acute Angle Closure Glaucoma may quickly lead to vision loss and even blindness.
The signs and symptoms of this condition include:
- Sudden Increase in Eye Pressure
- Severe Eye Pain
- Severe Headache and Browache
- Nausea and Vomiting
- Red Eye
- Mid-dilated Pupil
- Blurry Vision
- Halos Around Lights
If you experience these symptoms, it is imperative that you seek medical attention immediately. The treatment for this condition may include eye drops, pills and Laser Peripheral Iridotomy on an emergent basis. Of course, this is a very preventable condition. If your doctor notices that you have Narrow Angles, they will most likely recommend that you undergo a Laser Peripheral Iridotomy. This treatment will, in most cases, protect you from having an Acute Angle Closure episode.
Open Angle Glaucoma
This form of glaucoma is a very slowly progressive disorder that, unfortunately, has no symptoms until very late in the course. In contrast to angle closure glaucoma, open angle glaucoma has an angle that is wide open (as its name suggests) and available to drain aqueous. The problem in open angle glaucoma is that the trabecular meshwork (the eye's drain) does not work properly, thereby leading to an increased IOP in most cases. It is important to note that almost one-third of open angle glaucoma cases do not have an elevated IOP, thus leading many to look beyond the trabecular meshwork in the pathophysiology of glaucoma.Open angle glaucoma is a dangerous form of glaucoma because of the lack of signs and symptoms, and so, it is sometimes referred to as the"Silent Thief of Sight".
The main risk factors for open angle glaucoma are:
- Age greater than 70
- Elevated IOP
- African American or Hispanic Race
- Myopia (Nearsightedness)
- Sleep Apnea
- Family History
- Thin Corneas
Ocular Hypertension (OHTN)
Ocular hypertension just means that the pressure inside the eye is above the normal range of 10-21 mmHg. It is important to remember that an above normal IOP does not necessarily mean that a person has glaucoma. In fact, most patients with OHTN do not develop glaucoma.
Normal or Low Tension Glaucoma (NTG OR LTG)
This form of open angle glaucoma may be diagnosed when glaucomatous damage to the optic nerve occurs despite the patient having a normal IOP. NTG or LTG may be a more aggressive form of glaucoma, and is in many cases more difficult to treat because the IOP is already in the normal range. Some risk factors for NTG are listed below:
- Raynaud's Phenomenon
- Low Blood Pressure
- Family History
Some have postulated that the cause for NTG is poor blood flow to the optic nerve, while others consider it to be a primary degenerative process.
Pigmentary Glaucoma / Digment Dispersion Syndrome
In order to understand this condition, you need to understand a bit more about the eye's anatomy:
- The IRIS is a pigmented structure also known as the colored part of the eye
- The CILIARY BODY is the structure inside the eye, behind the iris, that makes the aqueous humor (the fluid inside the eye).
- The LENS is a structure inside the eye that is clear when a person is born. The lens grows in size, and changes in color to become a cataract, which may obstruct vision.
- The ZONULES are the little fibers that attach the lens of the eye to the ciliary body.
Pigmentary Dispersion Syndrome (PDS) occurs because the posterior part of the iris rubs on the zonules. This rubbing causes the iris pigment to disperse inside the eye and clog the trabecular meshwork (the eyes drain). Once the trabecular meshwork is sufficiently clogged, the IOP will rise and cause damage to the optic nerve. Up to 50% of patients with PDS may go on to develop Pigmentary Glaucoma.
Pseudoexfoliation Glaucoma (PXF)
This is a condition most commonly seen in those of Scandanavian descent, although it may occur in anyone. In PXF glaucoma, the lens capsule as well as the zonular material exfoliates. This exfoliative material may clog the drain of the eye, and thereby lead to increased IOP, which may damage the optic nerve. It is very common for people with PXF to develop an aggressive glaucoma.
One of the main issues with PXF is that it leads to weakening of the zonules, which attach the lens to the wall of the eye. This may increase the risk of complications during cataract surgery.
Blunt trauma to the eye may lead to glaucoma many years down the road. Traumatic glaucoma occurs in many cases because the angle of the eye has been damaged, and sometimes the angle structures have been displaced from their normal anatomic position.
This form of glaucoma is most commonly due to diabetes. In diabetes, the blood flow to the eye becomes compromised as a result of damage to the small blood vessels that nourish the eye. The eye forms new blood vessels to improve blood flow, but these new vessels are very problematic. They very frequently bleed, and can lead to an aggressive glaucoma by covering and scarring the trabecular meshwork inside the angle.
Steroid Induced Glaucoma
Patients who are on chronic steroids, such as prednisone, are at risk for developing an elevated IOP. It is very important for these patients to have frequent eye examinations so that your doctgor may measure their eye's pressure. One thing to remember is that not only oral steroids can lead to an elevated IOP. The steroid containing creams or inhalers and cortisone injections may lead to a steroid response inside the eye.
Uveitis is a condition in which a person's immune system recognizes the eye as foreign and begins to attack certain structures within the eye. Unfortunately, a large number of uveitis patients may develop glaucoma secondary to scarring or inflammation of the trabecular meshwork, or due to the steroid treatments.