Mostly genetically related but sometimes due to age, glaucoma (increased tension in the eye) can be overcome with long term medical treatment or surgery - as long as it is diagnosed early. Left untreated, it can cause deterioration of vision or even total loss of sight.
Eye diseases are an example.. But regular eye check-ups starting in childhood are important. Serious conditions like glaucoma, whatever its cause, can be detected by routine check-ups. We learned from Yeditepe University Hospitals Ophthalmologist Prof. Raciha Beril Küçümen that if left untreated, glaucoma progresses and can even lead to blindness.
Produced 24 hours a day, the aqueous humor is the watery fluid between the cornea and the crystalline lens. It maintains the pressure needed to inflate the eye and provides nutrition for the central cornea and lens as they do not have their own blood supply. It cleans the lens, iris and cornea, nourishing the eye, collecting metabolic waste and dissolving itself into the bloodstream from the area between the cornea and the iris. The pressure required to prevent the eye deforming into a kind of inflated ball requires the 24 hour production and drainage of this fluid. The intraocular pressure is simply a product of the rate of aqueous production and the rate of aqueous drainage. 95% of people’s eye pressure is 12-18 mmHg. This is measured using a device called a tonometer. These days there are also contact lenses that provide 24 hour monitoring of eye pressure.
In order to have healthy anatomic eye structure and tissue, eye pressure needs to be not too low and not too high. Eye pressure increases when for whatever reason the production of aqueous humor is greater than its drainage. This affects the inner layers of the eye, whose backmost section houses vision cells. There are about a million of these in the retinal layer that send sight stimuli to the brain. When intraocular pressure increases, the retinal nerve fiber cells are pressed against the sclera at the back of the eye and crushed. If the destroyed nerve fiber cells maintain long term increased pressure in the eye, this causes glaucoma.
It is generally caused by high intraocular pressure on the optical nerve. Glaucoma does not actually affect vision until its late stages. It causes a loss in the field of vision as the retinal nerve fibers are crushed from the edges in. That is why regular eye check-ups are important in glaucoma cases.
It does not generally show symptoms unless eye pressure reaches the level of 30-35. We should not attribute every case of headache or eye pain to eye pressure. Pain is evident when the pressure level reaches over 35- 40, generally caused by a special type of glaucoma called acute open angle closure glaucoma. The more frequently occurring type of glaucoma associated with a family history and occurring in older patients does not usually show any symptoms. Glaucoma is diagnosed by determining high eye pressure and damage to the optical nerve, followed by field of vision tests and analysis of damage to the optical nerve fiber. If eye pressure is not excessively high, primary open angle closure glaucoma does not show any symptoms. The sufferer may be unaware of the condition, but it is revealed through a routine check-up. It generally develops slowly in people over the age of 40-45.
No, not every case of high eye pressure automatically means glaucoma, and not every type of glaucoma involves high eye pressure; some cases are caused by low pressure. These are called normal and lowpressure glaucoma. People with generally low blood pressure (more common in China, Japan and Asian ethnic origin groups) and who suffer frequent migraine attacks may experience glaucoma damage to the optical nerve even when their eye pressure is normal. Other people may not develop glaucoma even though they have high eye pressure. These groups are called ocular hypertensive. There are a number of possible causes. For example, a person has high eye pressure but monitoring of their condition reveals no damage to the optical nerve fibers. Eye pressure can sometimes be measured incorrectly. Because the tonometer used to measure eye pressure does so based on the idea that normal cornea thickness is 520 – 550 microns. This means that someone with a congenitally thicker than usual cornea might have their eye pressure measured as being higher than normal. That is to say, an eye pressure recording of 22-23 mmHg in someone whose cornea is 600 microns thick and has no evident optical nerve damage might not indicate any need for glaucoma treatment.
Left untreated, the condition the patient will suffer a progressive loss in their field of vision and eventual blindness
Primary open angle closure glaucoma is a multi-factor genetic condition. 40-45% of all patients have unattributable primary open angle closure glaucoma. Examination of their eyes indicates no obvious cause for glaucoma except for increased eye pressure. This is generally an inherited condition. It does not necessarily get passed from parent to child, but there will certainly be other members of the family with high eye pressure being treated for glaucoma. Left untreated, the condition the patient will suffer a progressive loss in their field of vision and eventual blindness. Treatments aim to stop further loss of field of vision and prevent blindness. Existing damage cannot generally be reversed.
The most common form of glaucoma treatment involves regular eye drops and field of vision nerve fiber tests and monitoring. 90% of glaucoma patients are saved from blindness by regular medical treatment. Regular medical treatment is important, but not everyone can manage this, and in some cases this fails to maintain the targeted eye pressure. The ideal eye pressure range to prevent further loss of field of vision varies from patient to patient. In the event that the ideal eye pressure cannot be achieved, or if the patient is unable to maintain regular eye drop use, or suffers side effects from the medication, then surgery may be considered. There are various types of surgical intervention including laser surgery. That said, surgery is only the preferred course of action in cases where medication has failed to control the condition, to achieve a long term solution in terms of reducing eye pressure. In some cases, new channels that are surgically opened can get blocked. This may require a second intervention, or renewed medical treatment. Depending on the type of glaucoma, there is no guarantee that surgery will remove the patient’s reliance on medication. Elevated eye pressure and glaucoma can also develop as a result of eye infections, surgery and trauma. Surgery is not always effective in treating these infection- and trauma- related cases, and second or third interventions may be required, as well as renewed use of medication.
Glaucoma is anatomically classified under two types. The first is the rarely seen open angle closure glaucoma. Some people’s anatomy with respect to the angle of the region between the cornea and the iris where the intraocular fluid is absorbed, predisposes them to the condition. Stressing that this angle can be suddenly closed by other factors such as use of certain medications, reading in poor light, and swelling of the lens, Professor Küçümen states “When the angle closes the outlet gets completely blocked but since the fluid continues to be produced the pressure can exceed 35-40. This can also cause considerable pain. It needs to be treated urgently. The second type is more common. Since the angle is open there is generally no need for urgent treatment in this type of glaucoma; treatment can be carried out over the longterm. Diagnosing glaucoma is crucial. Not everyone with ocular hypertension or high eye pressure suffers from glaucoma. The importance of a correct diagnosis is that it prevents unnecessary use of medication. Because someone diagnosed with glaucoma will have to continue to use medications over the long term.”
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