Glaucoma is a disease of the eye that can lead to degeneration of the optic nerve and progressive loss of vision ("blindness"). This disease is most often secondary to an increase in the pressure of "aqueous humor" inside the eye.
UNDERSTANDING DIAGNOSIS TREATMENT LIVING WITH MORE INFORMATION
Words for the evils
A liquid is produced permanently inside the eye to maintain a normal "eye tension": it is "aqueous humor".
The aqueous humor is evacuated into the anterior chamber of the eye through a filter situated at the angle between the iris and the periphery of the cornea: the trabeculae.
"Angle closure glaucoma" is an embarrassment to the flow of aqueous humor which is blocked in the angle between the iris and the cornea, resulting in an elevated ocular pressure which can be acute.
"Open-angle glaucoma" is a discomfort to the flow of aqueous humor, which is discharged less well by the filter, which is "fouled", but there is no risk of acute closure of " The iridocorneal angle ".
What is glaucoma?
Glaucoma is a disease of the eye characterized by an increase in the pressure of "aqueous humor", the fluid inside the eye (the "intraocular" pressure), the main risk of which is degeneration Of the optic nerve.
The eye works exactly like a camera. The anterior part of the eye (cornea and crystalline) allows to focus the images on a sensory receptor: "the retina" (the lens focuses). The posterior part of the eye (retina, optic nerve) thus serves to record and transmit images projected on the retina.
Aqueous humor is the liquid that fills the anterior chamber of the eye and the part between the lens and the iris. It is secreted by the epithelial cells of the ciliary processes, continuously (1% of the total aqueous humor is produced per minute).
The aqueous humor then flows between the lens and the iris and then moves to the iridocorneal angle to be eliminated through the trabecular (a sort of filter regulating the rate of evacuation). If the liquid discharge is slowed, the pressure inside the eyeball rises abnormally and causes the fibers of the optic nerve to suffer the most fragile.
The optic nerve is the nerve that transmits this information to the brain via the fibers of the visual nerve cells of the retina. It exits the back of the eye and thus transports the images perceived by the retina to the visual areas, the back of the brain.
Source of the French Society of glaucoma:
When the optic nerve is damaged, the visual field is reduced. Vision is impaired by starting from the periphery ("as if looking in a tunnel") and this can lead to blindness.
Glaucoma is most often related to increased pressure inside the eye ("intraocular hypertension"), but in a minority of cases, it develops while this pressure is normal.
Visual impairment becomes really troublesome when the disease is already very advanced, but it is then irreversible. Both eyes are not always reached in the same way, and somewhat compensate the other, which is an additional factor of diagnostic delay.
What are the different types of glaucoma?
Acute glaucoma corresponds to a sudden swelling of the eye, usually due to a closure of the angle by which the intraocular fluid passes (aqueous humor), this angle being closed by the iris.
Acute angle-closure glaucoma occurs in predisposed patients with a narrow iridocorneal angle in relation to a thicker lens and much lower anterior chamber depth than normal but It requires triggering causes. Most acute seizures are of iatrogenic origin: all locally used or generalized mydriatic drugs can trigger such a seizure.
The patient complains of a violent pain in one or both eyes, one with a red and hard eye. The person first perceives a colored halo around the sources of light, then appears a rapid decline in vision. Acute glaucoma is a medical emergency: without treatment, the sight of the affected eye can be irretrievably lost within hours.
The most important risk factors are hyperopia, age over 45, cataract onset, female sex and use of certain medications.
Medicines at risk in the case of closed-angle glaucoma include active ingredients with anticholinergic potential (peripheral effects, central effects, accessory anticholinergic properties), active ingredients with sympathomimetic alpha potential (alpha 1 stimulating effects, mixed effects alpha and Beta-stimulants, indirect effects) and active principles with indirect parasympathomimetic potential (acetylcholinesterase inhibitors).
Treatment involves opening an opening in the iris to permanently remove the risk of recurrence of glaucoma.
What causes glaucoma?
The causes of glaucoma are unknown and are likely to be multiple. Several factors seem to favor this disease of the optic nerve:
• Increased intraocular pressure above 21 mm Hg is the main factor. However, all ocular hypertension (or hypertension) does not cause glaucoma and conversely, glaucoma with intraocular pressure exists within normal limits.
• Age: Glaucoma usually occurs from age 45 and its frequency increases with age.
• Very high myopia.
• Heredity: Approximately 30% of glaucoma is hereditary and screening should be strengthened in families with a history of glaucoma.
What are the complications of glaucoma?
Glaucoma is the leading cause of blindness in France, faced with age-related macular degeneration (AMD)
Glaucoma: DIAGNOSIS
When should glaucoma be evoked?
In addition to angle closure glaucoma, where eye pain is associated with hardness during palpation and a rapidly evolving visual acuity, open-angle glaucoma usually progresses silently. Visual discomfort or pain in the eye only appears late.
This is why his diagnosis is often made during an ophthalmological examination for another reason (myopia, presbyopia ...).
To date, treatments have stopped its evolution, but they do not restore vision when the disease is already evolved. Early detection of glaucoma is, therefore, essential.
Glaucoma should be detected in follow-up studies in a person with glaucoma predisposing factors: age 45 years, family history of glaucoma, very high myopia, high blood pressure, diabetes, sleep apnea or prolonged intake of corticosteroids.
How to diagnose glaucoma?
In the case of suspicion of glaucoma, the ophthalmologist performs a clinical examination and complementary explorations.
The first examinations are those of the head of the optic nerve (called "optical disc") by fundus ("ophthalmoscopy") or "optical coherence tomography" (or OCT), the measurement of intraocular pressure by " Tonometry ", the examination of the angle of flow of the aqueous humor by" gonioscopy "and the evaluation of the visual field. These examinations can reveal an already significant repercussion on the optic nerve and its progression. Glaucoma is characterized by a gradual and irreversible impairment of the visual field, first peripheral and long undetected. Central vision is normal, but it is disturbed all around, "as if looking in a tunnel".
Radiological examinations may be useful, such as MRI.
All intraocular hypertension does not cause glaucoma. Some open-angle primitive glaucoma develops with the intraocular pressure within normal limits (known as normal-pressure glaucoma).
When should a doctor be consulted?
An emergency doctor, at best an ophthalmologist, should be consulted in case of eye pain associated with the hardness of the eyeballs on palpation and a rapidly decreasing visual acuity.
glaucoma: TREATMENT
What can be done in acute glaucoma cases?
It is necessary to install the person who suffers in the supine position, which favors the recoil of the "ride-lenticular diaphragm" and thus helps the mechanical opening of the iridocorneal angle. Then call your doctor or the emergency department.
What is the treatment for acute glaucoma?
In the case of acute glaucoma crisis, medicinal treatment is introduced urgently to decrease the intraocular pressure. It is followed by laser treatment or more rarely by surgery.
• The first class of drugs that can be used to initially manage an acute angle closure glaucoma is ocular hypnotizing agents to lift the pupil block and lower intraocular pressure.
These are essentially carbonic anhydrase inhibitors which decrease the aqueous humor secretion and are used in the form of an ampoule of acetazolamide 500 mg by slow intravenous injection associated with 1 tablet 250 mg per os, respecting Contraindications (renal or hepatic insufficiency, sulphonamide allergy) and compensating for potassium leakage. It is preferable to avoid topical carbonic anhydrase inhibitors in the initial phase for which a lower rate of efficacy than that of the intravenous route has been demonstrated at this stage.
The hyperosmolar osmotic agents act by the osmotic pressure gradient they create between the blood and the internal media of the eye, which leads to relative dehydration of the vitreous: mannitol 20% intravenous (1 to 2 gram per kilogram body weight, 250 ml in 20 minutes, contraindicated in patients with cardiac or renal insufficiency and in the elderly), or glycerol 50% per oz (1 gram per kilogram, contraindicated in diabetics). Their use is no longer systematic.
• Locally, in the initial phase, the therapist has a choice between beta-blockers (LP, timolol LP) and alpha 2 agonists in the case of contraindication to beta-blockers. It is preferable to avoid in the initial phase the inhibitors of carbonic anhydrase by the topical route, for which at this stage a speed of efficiency less than that of the IV route was probably demonstrated, probably in connection with a lesser diffusion related to l Corneal edema.
The mystics, by tightening the root of the iris can help lift the pre-trabecular block and increase the ease of flow of the aqueous humor. The initial high ocular hypertonia causing paralysis of the sphincter of the iris, these agents must be used when the intraocular pressure is already reduced by the medical treatment and the iris is again mobilizable: ie 1 h after the beginning of intravenous treatment, Ie 1 to 2 hours after the installation of beta blockers if used alone without associated treatment, such as an inhibitor of intravenous carbonic anhydrase (IAC and / or osmotic agents).
Local steroidal anti-inflammatory drugs are intended to reduce inflammation (1 drop x 4 / day). The prostaglandin analogs contraindicated in the initial inflammatory phase, have shown their interest at the end of the acme of the crisis in the partial residual closures of the iridocorneal angle.
• The creation of an opening in the iris definitively eliminates the risk of recurrence of glaucoma and thus makes this particular form of glaucoma reversible. This opening is called "iridotomy" when it is performed by laser and "iridectomy" when performed surgically.
What is the treatment of open-angle glaucoma?
The aim of the treatment of open angle glaucoma is to protect the optic nerve by reducing the intraocular pressure in order to limit the evolution of the degradation of the optic nerve. Optic nerve damage can be avoided by a long-term treatment that is well followed and, especially, started early. When intraocular pressure is moderate, drug therapy can normalize and protect nerve cells in the vast majority of cases.
• The disease can be monitored by drug monotherapy in about half of patients with chronic glaucoma. In others, it is necessary to combine several medications and to use laser and/or surgery to stop the progression of the disease.
Several classes of drugs can be used and possibly associated with each other: prostaglandins or beta-blockers. These drugs are most often administered as eye drops. These drops decrease the intraocular pressure by reducing the secretion of the aqueous humor, or by facilitating its elimination. They must be applied at the regular time, for life and without interruption.
These products often suffice to control the disease. However, like all medicines, they can cause side effects.
• If the treatment fails, trabeculumPoor tolerance or very high intraocular pressure, laser treatment or surgery are interesting alternatives.
The laser stimultrabecularells under the impulse of light energy and increases the flow of the aqueous humor. The results are generally not final. It is then necessary to reinforce or resume treatment by eye drops a few months or a few years later.
The surgery consists in opening the trabeculum under local anesthesia. The operation involves creating a new way of evacuating the aqueous humor to maintain normal pressure in the eye. The intervention stops the progression of glaucoma, but does not recover lost visual capacities.
It should be noted that all treatments of glaucoma increase the risk of developing a cataract, and especially surgery.
Glaucoma: LIVING WITH
How to be followed when you have glaucoma?
Regular medical follow-up and well-observed treatment are essential to avoid aggravation of glaucoma. Glaucoma itself does not impose any particular constraints, except to avoid shocks in the eyes.
Regular medical follow-up is based on clinical examinations and complementary explorations, the aim of which is to verify good compliance and tolerance of the treatment while detecting an aggravation or complication of glaucoma.
Treatment is effective, but because chronic glaucoma is a progressive and insidious disease and an interruption of treatment does not result in immediate consequences, too many patients take their treatment irregularly, Definitive blindness.
How can I live with glaucoma?
When taken early, glaucoma is most often compatible with normal life. In the event of visual impairment caused by glaucoma, it can affect daily activities.
Regular follow-up is essential and should never be stopped without talking to your doctor. In case of consultation with another doctor, it is necessary to report glaucoma because some treatments are contraindicated.
Most of the time, work can be practiced normally and professional reclassification is not essential. However, glaucoma can be embarrassing if professional activity asks the eyes very much like a work of precision or on screen.
The practice of sport is compatible with glaucoma and is even advised, as eye pressure drops slightly during physical activity. However, some violent sports are contraindicated and it is essential to avoid direct shocks on the eyes (wear protective glasses). After surgery for glaucoma, sport is generally banned for a month.
In most cases of glaucoma screened and treated in time, driving is possible. In case of more advanced disease, it becomes difficult and dangerous.
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