What is glaucoma?
The term “glaucoma” is used for a group of diseases whose common characteristic is damage of the optic nerve and visual loss. It is a leading cause of blindness for people over 60 years old. Glaucoma is associated with increased pressure in the eye. Glaucoma is a potentially blinding condition where the increased pressure inside the eye damages the optic nerve.
The optic nerve is the “cable” that carries visual stimulants from the eye to the brain. The optic nerve is composed of a large number of nerve fibers.
Each fiber of the optic nerve is responsible for conveying visual stimuli from a specific point of our visual field, and the damage to a bundle of these fibers leads to a reduction or loss of vision in the corresponding segment.
The nerve fibers that were unfortunately destroyed can not be regenerated and the part of our visual field in which vision was reduced or lost does not return.
Progressive Loss of Visual Field in Glaucoma
The main problem with the most common form of glaucoma called “chronic simple glaucoma” is the absence of symptoms. The eye does not hurt nor is it easy to “perceive” the reduction of the visual field without the use of specific medical tests.
Modern high-tech diagnostic tools are used today for the diagnosis of the early stages glaucoma patients. Early diagnosis of this very common disease can stop the progression and in conjunction with the latest medications, prevent the blindness.
However, reality is different. The is a lack of awareness amongst patients so as to promptly visit an ophthalmologist for an examination, resulting in too many glaucoma cases remaining undiagnosed and millions of people around the world to losing their sight without reason.
There are two major types of glaucoma.
Primary open-angle glaucoma
This is the most common type of glaucoma.
Open-angle glaucoma develops slowly over time, there is no pain and causes no vision changes, at first. Peripheral vision is affected first, but eventually the entire vision will be lost resulting in blindness, if not treated.
But blindness from glaucoma can often be prevented with early treatment.
Regular eye exams is the only way to find early signs of damage to their optic nerve.
Angle-closure glaucoma (also called “closed-angle glaucoma” or “narrow-angle glaucoma”) In close/narrow-angle, the drainage angle is completely closed because of forward displacement of the iris against the cornea, resulting in the inability of the aqueous fluid to flow from the posterior to the anterior chamber and then out of the trabecular network. This accumulation of aqueous humor causes an acute increase in pressure and pain.
Angle-closure glaucoma is a true eye emergency, can cause blindness if not treated right away.
The most common symptoms of an acute angle-closure glaucoma attack: Severe eye pain, headache, nausea, vomiting, blurred vision, rainbow-colored rings or halos around lights.
Screening for glaucoma is usually performed as part of a standard eye examination.
Testing for glaucoma should include: measurements of the intraocular pressure via tonometry, anterior chamber angle examination or gonioscopy, and examination of the optic nerve to look for any visible damage.
OCT – Glucoma
A formal visual field test should be performed. The optic nerve and the retinal nerve fiber layer can be assessed with imaging techniques such as optical coherence tomography (OCT).Visual field loss is the most specific sign of the condition; however, it occurs later in the condition.
Optic Nerve with Glaucoma and its Visual Field Defect
The modern goals of glaucoma management are to avoid nerve damage, and preserve visual field and total quality of life for patients, with minimal side-effects. This requires appropriate diagnostic techniques and follow-up examinations, and judicious selection of treatments for the individual patient.
Although intraocular pressure (IOP) is only one of the major risk factors for glaucoma, lowering it via various pharmaceuticals and/or surgical techniques is currently the mainstay of glaucoma treatment. A review of people with primary open-angle glaucoma and ocular hypertension concluded that l IOP-lowering treatment slowed down the progression of visual field loss.
The goal of currently available glaucoma therapy is to preserve visual function by lowering intraocular pressure (IOP) below a level that is likely to produce further damage to the nerve.
Intraocular pressure can be lowered with medication, usually eye drops, laser treatment, or surgery. If treated early, it is possible to slow or stop the progression of disease.
Poor compliance with medications and follow-up visits is a major reason for vision loss in glaucoma patients. Patient education and communication
must be ongoing to sustain successful treatment plans for this lifelong disease with no early symptoms.
Laser treatments may be effective in both open-angle and closed-angle glaucoma. A number of types of glaucoma surgeries may be used in people who do not respond sufficiently to other measures ( eye drops or laser ).
Treatment of closed-angle glaucoma is a medical emergency.
Glaucoma surgery, facilitates the escape of excess aqueous humor from the eye, decreases intraocular pressure and prevents vision loss.
Conventional surgery to treat glaucoma makes an opening in the trabecular meshwork, which helps fluid to leave the eye and lowers intraocular pressure.