Glaucoma

Glaucoma

15 Glaucoma Myths Debunked

Myth 1
Glaucoma is a rare condition…
Glaucoma is very prevalent, and around 3 to 5 % of people (depending on risk factors, geographical location and ethnic group), will develop glaucoma in their lifetime. In fact, all people should have their ocular pressures measured at the very least from the age of 40 onwards every 5 years or so to screen for glaucoma (and earlier in their lives and more regularly if they have positive family histories for glaucoma or eye disease and other risk factors such as high degree of short-sightedness, high degree of far-sightedness, diabetes, migraine history, history of significant trauma to the eye (even if many years ago!) or uveitis (ocular inflammation). After diabetic eye disease, glaucoma is the second most common cause of blindness in the Western world if untreated!

Myth 2
Glaucoma causes painful eyes…
Most cases of glaucoma are painless, and only become painful if there is an acute rise in intra-ocular pressures for whatever reason. Thus it is false that one cannot have glaucoma if your eyes are feeling healthy and normal. The commonest form of glaucoma (primary open angle glaucoma) which affects about 95% of patients with glaucoma, is completely painless and slowly damages your optic nerve over time which results in progressive loss of one’s visual field until one develops some variation of tunnel vision with only parts of the central vision remaining, until even this also eventually disappears and one can become completely blind. So don’t wait for ocular discomfort before you have your eyes examined and the intra-ocular pressures checked! By then it usually too late to salvage useful vision!

Myth 3
Glaucoma damage can be cured…
The progressive visual field loss from glaucoma, is permanent, and cannot be turned around… Therefore it is very important to diagnose glaucoma as soon as possible in the course of the disease to prevent any further ongoing damage, since one can only hope to try and retain the vision that remains at the time of diagnosis. One eye is usually affected worse than the other, so by the time most glaucoma are diagnosed, one eye is usually significantly damaged already! And glaucoma can be controlled but never be “cured”… it is much like for example diabetes that needs to be controlled for the lifetime of the patient.

Myth 4
You can’t have glaucoma if your eye pressures are normal…
There is a significant percentage of patients with glaucomatous optic nerve damage that have relatively normal intra-ocular pressures. These patients have so-called normal tension or low tension glaucoma, and they often have compromised blood supply to the optic nerves as well, i.e. very low blood pressure, migraine patients or patients with Raynaud’s phenomenon, where they have extremely cold extremities due to peripheral vasospasm of their hands or feet (which is a sign of hyper reactive vasculature where the small blood vessels of their bodies tend to go into severe vasoconstriction which affects the blood supply to the optic nerves). Glaucoma per definition is a condition where one has ongoing and progressive loss or decrease of one’s visual fields and visual acuities over time, which corresponds to specific patterns of hollowing out of one’s optic nerves (glaucomatous optic neuropathy), and where an increased intra ocular pressure is the commonest risk factor for progression of the disease. Thus it is important to not only have one’s IOP (intra-ocular pressures) measured, but also to have a proper examination of the internal structures of the eyes such as the optic nerves and the anterior chamber angles to also be able to diagnose the normal or low tension glaucomas

Myth 5
Only old people get glaucoma…
One can be born with glaucoma! The earlier the onset of glaucoma, the more aggressive it is and the more damage will occur sooner in your life! If children have exceptionally large corneas or eyes that appear large, especially if they are very light sensitive, they should be examined by an ophthalmologist. Also, if you have a family history of glaucoma, then your chances of developing glaucoma sooner is higher and you should have your ocular pressures checked.

Myth 6
If your eyesight is normal and you have no symptoms, you can’t have glaucoma…
The commonest type of glaucoma only gives visual symptoms very late in the disease process (by this time you have advanced visual field fall out already!) Thus it is important to have your eye pressures checked regularly to screen for underlying glaucoma! Don’t wait for deteriorating vision to go for a glaucoma screening, by that time you would have permanently lost significant visual field!

Myth 7
Glaucoma is hereditary, so if you have no family history, you won’t get glaucoma…
Most types of glaucoma are not hereditary, in other words you won’t have a family history of other members of your extended family with glaucoma! So even if you have no-one in your family with glaucoma, you still have a 3 to 5 % chance of developing this dangerous disease over your lifetime!

Myth 8
High blood pressure causes glaucoma…
Glaucoma has no association with hypertension, in fact, low blood pressure is a risk factor for low or normal tension glaucoma!

Myth 9
Only people who wear glasses can get glaucoma…
Any eye can get glaucoma, even eyes that have no refractive error! Although people with very short sighted eyes (they get more optic nerve damage sooner in the disease course if they have glaucoma compared to emmetropic eyes, i.e. eyes that don’t need glasses) and people with very far sighted eyes (they have smaller eyes with crowding of the front part of the eye and have a higher risk to develop angle closure glaucoma) have increased risk for developing glaucoma

Myth 10
Glaucoma always leads to blindness…
If glaucoma goes untreated, it will invariably lead to severe visual loss or even blindness over time. But the good news is that we can treat glaucoma very efficiently nowadays, and as long as the diagnosis is made before too much visual field loss, we have very efficacious eye drops, laser options, and surgical options to manage the ocular pressure and prevent further deterioration. With modern treatment options your ophthalmologist should be able to retain good functional vision over the lifetime of the patient, if the diagnosis is early, if the correct treatment is chosen and the patient remains compliant with the drops and the regular follow-up schedule.

Myth 11
Dagga (cannabis or marijuana) can cure glaucoma…
The chemical component of dagga has a low-grade and transient beneficial effect on the eye pressure by lowering the IOP while the patient is busy smoking the dagga, but as soon as exposure to the dagga is over, the IOP lowering effect disappears. So, the patient will have to be stoned all the time for any minor lasting beneficial effect, and other than the fact that dagga is illegal in South Africa, this is not practical in real life!

Myth 12
Glaucoma examinations are painful or uncomfortable
The routine eye examination to detect glaucoma is not uncomfortable, and various techniques to measure the intra ocular pressures can be used, ranging from puff tonometry (where a small puff of air blows against the cornea) to explanation tonometry (where local anaesthetic is used and the instrument softly and gently touches the cornea without the patient even being aware of this happening! The special examinations to measure the degree of glaucoma damage such as the visual field test and the various tests used to evaluate the degree of anatomical damage to the optic nerve, are non-touch tests and also discomfort free.

Myth 13
There is only one type of glaucoma…
There are probably around 200 causes for glaucoma (some very rare), but 95% of glaucoma seen in practice will be the primary open angle glaucoma type. It is very important that the correct diagnosis of the specific cause for a patient’s glaucoma is made, since different types of glaucoma necessitate different treatment options!

Myth 14
If you don’t develop glaucoma shortly after an eye injury, you are safe…
Any injury that significantly injures the eye, can injure the parts of the eye where drainage takes place. This may only manifest many years later, and long term studies have shown that people with significant blunt or penetrating injury to the eye, will have an increased risk of developing glaucoma throughout their whole lives! Thus it is important to see your ophthalmologist regularly if you have had any significant injury to your eye.

Myth 15
If you are diagnosed with glaucoma, you must just finish the first bottle of drops and then you are cured…
It is important to realise that glaucoma is a chronic disease and needs lifelong treatment to prevent ongoing damage to the optic nerve and thus permanent loss of visual field and visual acuity! Glaucoma is currently still a PMB condition (Prescribed Minimum Benefit) on the Chronic Disease List and once patients register their glaucoma with their medical aid, this chronic and potentially blinding disease will be funded under the PMB regulations, i.e. not from the patients’ normal benefits, but from the medical aids’ general risk pool funds.




Glaucoma



What are the common types of glaucoma?
What are the risk factors for glaucoma?
What does a glaucoma evaluation involve?
What is the treatment of glaucoma?

Glaucoma is a family of more than 30 diseases that affects pressure within the eye, damaging the optic nerve. This leads to peripheral visual loss. Glaucoma is one of the leading causes of blindness worldwide. Glaucoma usually does not produce symptoms until vision is already severely damaged. But if diagnosed early, the disease can be controlled and permanent vision loss can be prevented.

What are common types of glaucoma?

  • Acute Angle Closure Glaucoma: acute closure of the peripheral drainage angle, characterised by a sudden increase in intraocular pressure.
  • Chronic Angle Closure Glaucoma: the iris obstructs the eye’s drainage angle in a slow, progressive fashion.
  • Primary Open Angle Glaucoma: the drainage angle is open but does not allow fluid to drain adequate for unknown reasons.
  • Pseudo exfoliation Glaucoma: deposits of a fibrillary material obstruct drainage of fluid from the eye.
  • Pigmantary Glaucoma: pigment dislodged from the iris obstructs the eye’s drainage structures.
  • Angle Recession Glaucoma: scar tissue from blunt trauma obstructs the outflow of fluid.
  • Neovascular Glaucoma: various disorders cause blood vessels to proliferate on the iris and in the eye’s drainage structures..
  • Congenital Glaucoma: the eye’s drainage channels form abnormally in utero.

What are the risk factors for glaucoma?

Although glaucoma is most common in adults over the age of 40, susceptibility is not determined by age alone. Studies have shown individuals at greater risk for glaucoma may fit one or more of the following criteria:

  • are over the age of 60
  • family history of glaucoma
  • African race
  • diabetes
  • myopia

Since early detection is critical to avoiding permanent loss of vision, individuals who possess any of the non-age-related risk factors should have regular examinations by an ophthalmologist every one or two years.

Individuals in the general population should have a glaucoma evaluation every two or three years after the age of 40, and every one or two years after the age of 60.

 Normal eye



What is involved in a glaucoma evaluation?

  • Measurement of intraocular eye pressure (IOP). Elevated IOP is considered a major risk factor for the development of glaucoma. Studies have shown that optic nerve damage becomes more likely as the IOP increases.
  • Assessment of the optic nerve. A non-invasive slit lamp examination is used to determine whether or not there are changes in the optic nerve in the diagnosis for glaucoma. Digital scanning of the optic nerve is also performed in some cases.
  • Evaluation of a patient’s visual field. Glaucomatous damage produces characteristic defects in the visual field.
  • Corneal pachimetry to establish true intra ocular pressure.

What is the treatment for glaucoma?

Glaucoma treatment aims to decrease intraocular pressure and prevent damage to the optic nerve. Different types of glaucoma require different therapies to prevent progressive damage to the optic nerve. Eye drops is usually the first line therapy in the treatment of glaucoma (congenital glaucoma is always a surgical condition) Treatment modalities include:
  • Eye drops (or combination of eye drops and pills) to reduce intraocular pressure. Several different classes of glaucoma medications are available to provide pressure reduction including beta blockers, prostaglandin analogues, alpha adrenergic agaonists, miotic, epinephrine compounds, and oral and topical carbonic anhydrase inhibitors. These medications work by either reducing the rate at which fluid in the eye is produced or increase the outflow of fluid from the eye.
  • Laser treatment to open the drainage angle and reduce intraocular pressure.
  • Surgery to create a new passage for fluid drainage. Surgery is usually reserved for cases that cannot be controlled by medication.


Frequently Asked Questions About Glaucoma

Is blindness due to glaucoma preventable?

Regular diagnostic examinations by an ophthalmologist are the key to preventing loss of vision due to glaucoma. Ophthalmologists are medical doctors, specialists in eye care and trained to examine and treat eye diseases. Although there is no way to reverse damage, if glaucoma is diagnosed and treated early, blindness almost always is preventable.

What are the symptoms of glaucoma?

In most cases, glaucoma is asymptomatic (has no symptoms). By the time an individual experiences decreased vision, the disease is frequently in its advanced stages. Since early warning signs of glaucoma are rare, it is important especially for those at risk to have medical eye examinations at appropriate intervals, as described in this section.

Symptoms depend on the type of glaucoma the individual has.
  • Those who have chronic glaucoma may not be aware of any symptoms because the disease develops slowly and patients rarely notice loss of peripheral vision.
  • Those who have an acute form of glaucoma may develop severe symptoms because ocular pressure rises quickly and they may experience:
    • Blurred vision, especially at night
    • Halos or rainbows around lights
    • Severe headaches or eye pain
    • Nausea

How does glaucoma affect the eye?

The eye has an internal pressure created by production of a clear fluid called aqueous humor. This fluid circulates through the eye and exits through the anterior chamber angle and ultimately drains into the blood stream. In glaucoma, the aqueous humor outflow is obstructed, resulting in increased eye pressure and, eventually, optic nerve damage.

Glaucoma Affected eye