What is glaucoma?
Glaucoma is a name for a group of eye diseases that all share damage to the optic nerve, the structure responsible for transmitting visual information from the eye to the visual centers in the brain. Progressive damage to the optic nerve leads to narrowing of the visual field, so that in the final stage the patient sees as if looking through a tube.
How does glaucoma develop?
A fluid called aqueous humor is constantly produced inside the eye and leaves the eye through the drainage angle. If the production of aqueous humor is increased, or its outflow from the eye is obstructed, intraocular pressure rises and this leads to damage to the optic nerve. The optic nerve can also be damaged at normal intraocular pressure values. Risk factors for glaucoma include:
- elevated intraocular pressure (above 21 mmHg)
- genetic predisposition
- older age (over 50 years)
- systemic diseases (diabetes, high blood pressure, migraines, poor circulation, etc.)
- high myopia and high hyperopia
Diagnosis of glaucoma
Thanks to advances in technology, glaucoma can now be detected at an early stage , without having to wait for visible changes in the visual field. It is recommended that patients, after they receive their first reading glasses, that is after the age of 40, have a comprehensive eye examination with dilated pupils once a year, during which it can be determined whether there is any suspicion of glaucoma. If glaucoma is suspected, a set of functional tests for glaucoma is performed:
- computerized visual field (CVF) (provides insight into the functional status of the visual field, which is related to structural damage of the nerve fibers that form the optic nerve)
- gonioscopy (examination of the anterior chamber angle, through which aqueous humor drains from the eye)
- pachymetry (measurement of corneal thickness, essential for correct interpretation of the true value of intraocular pressure)
- optical coherence tomography (OCT) (imaging of the optic nerve head and the retinal nerve fiber layer, which allows early damage to be detected even up to five years before the first defects appear in the visual field)
Types of glaucoma
- The most common form of the disease is open angle glaucoma, which usually occurs in people older than 60-65 years. It can progress for a long time without symptoms or with very subtle symptoms (occasional blurred vision, eye fatigue, etc.).
- Angle closure glaucoma is an emergency condition in ophthalmology and requires urgent and aggressive treatment in order to preserve vision. Symptoms include: sudden rise in intraocular pressure, eye redness and a dramatic drop in vision, severe pain and headache accompanied by nausea and vomiting.
- Secondary glaucoma develops as a consequence of various eye diseases, tumors, injuries, previous operations, as well as long term use of corticosteroids.
- Congenital glaucoma is a form of glaucoma present from birth, which is treated exclusively surgically, as early as possible in the child’s life.
- Optic nerve damage can occur even at normal intraocular pressure values. It is believed that normal tension glaucoma is caused by poor blood supply to the optic nerve.
Treatment of glaucoma
Glaucoma is an incurable disease, but with adequate and timely treatment it is possible to stop further progression of the disease. Glaucoma therapy depends on the type of glaucoma. The goal of treatment is to lower intraocular pressure and achieve and maintain the target pressure.
- The primary treatment is conservative therapy with eye drops. Treatment usually starts with so called monotherapy (one type of eye drops that the patient will use for life). If the target pressure is not reached with one medication, the therapy is changed or a second drug is added.
Conservative treatment of glaucoma - If intraocular pressure cannot be adequately controlled with medication, one of the laser treatments is used (depending on the type of glaucoma):
- Argon laser trabeculoplasty (ALT)
- Nd:YAG laser iridotomy
- Selective laser trabeculoplasty (SLT)
Laser treatments are performed under topical anesthesia and are painless. They are done on an outpatient basis and take only a few minutes.
YAG laser iridotomy - Surgical treatment is the final option and is used in cases where other therapies do not achieve the desired effect:
- Conventional glaucoma surgery (trabeculectomy) is performed under local topical anesthesia. It involves creating an opening in the drainage angle that facilitates outflow of aqueous humor from the anterior chamber under the conjunctiva.
- Minimally invasive glaucoma surgery, which includes implantation of microstents or shunts, is used less frequently. These methods reduce the rate of intraoperative and postoperative complications and allow easier combination with cataract surgery.
Glaucoma surgery