July 16, 2012 Glaucoma is a disease characterized by periodic or persistent elevated intraocular pressure, damage to the optic nerve and visual field deterioration, and as a result of disease it is also possible that blindness occurs. It is one of the major causes of amblyopia in people older than 40 years.
In his beginning glaucoma has no eye symptoms, which would warn the patient that “something” is going on with his vision, which is why it is often called the “silent killer of eyesight.” This is why glaucoma should be carefully sought among the population.
In the general population older than 40 years the incidence of glaucoma is 2-5% and with years it grows, so it amounts to 10-30% in the population over 65 years. In patients with cardiovascular diseases, hypertension, diabetes, and those who have relatives suffers from glaucoma prevalence is even higher.
By early detection and treatment in time the complications of serious illness
can be completely avoided.
Aqueous humor outflow
Symptoms:
Most glaucoma is asymptomatic. Those few patients who have disorders usually complain of weight in the eyes and difficulty in reading, and only exceptionally on transient blurring of vision. Some note the occurrence of rainbow colors when looking at the source of light. The phenomenon is caused by corneal epithelial edema due to high intraocular pressure: each edematous epithelial cell, like a prism breaks up light on the colors of the rainbow. These symptoms may also appear: an attack of pain in one side of the head similar to migraine, pain of the upper teeth or neuralgia, which are frequently replaced. In acute glaucoma, as already mentioned, pain and reduction of visual acuity, redness of the conjunctiva and wide non-reactive pupil are present. The pain is very strong, often accompanied by nausea and vomiting.
Types:
PRIMARY GLAUCOMA
Normal intraocular pressure is of 12-22 mm Hg.
It occurs spontaneously without any signs of other eye disease or general condition that could cause elevation of intraocular pressure.
On the basis of looks of the chamber angle glaucoma is divided:
1) Primary glaucoma of an open chamber angle
2) Primary glaucoma of a close chamber angle
Primary glaucoma of an open angle (g. simplex)
It appears in both eyes at once, asymptomatic or oligosymptomatic (vague headache) for a long time, none of the changes can be seen on the outer part of the eye.
The angle of a chamber is open, so that access of aqueous humor to the trabeculum is free and the obstacle is in its outflow into the drainage system of the eye; trabeculum, sinus venosus sclerae, or in other parts of the system for the evacuation of aqueous humor.
The characteristics of this disease are:
increased intraocular pressure> because of the reduced possibility for the flow of aqueous humor through the drainage system of the eye
excavation of the optic nerve> gouging papilla (white and atrophic) of the optic nerve, which leads to damage and atrophy of the nerve and to blindness (amaurosis).
disturbances in the visual field
Primary glaucoma is primarily diagnosed by measuring the intraocular pressure.
1) glaucoma with low-pressure around 30 mm Hg> is a glaucoma in which there is an atrophy of the optic nerve, the visual field disturbances but the intraocular pressure is within the limits that many eyes tolerate without damage, occurs in people with low systemic pressure.
2) Pseudoexfoliatiove glaucoma> is a form of glaucoma, characterized by the appearance of greyish amorphous detritus in the pupil’s edge and trabeculum on the lens.
3) pigmentary glaucoma> has a lot of pigment in the trabecular tissue, and dispersed pigment on the back wall of the cornea, often without elevated intraocular pressure.
Primary glaucoma of a close angle
Manifested in one eye, later manifested in both eyes.
Diagnostic signs are “eye as hard as stone”, painful to the touch, high intraocular pressure.
The cessation of the flow of aqueous humor in chamber corner occurs, due to mydriasis (dilation of the pupil). The iris expands and its stem is pushed into the angle of the chamber and breaks the flow of aqueous humor. This happens because of fear, excitement, and the application of mydriatics.
Etiological factors: the anatomy of the anterior eye segment (narrow angle of the chmber, the small diameter of the eyeballs, shallow anterior chambers), the changes caused by aging (increased range of lens, atrophic iris)
1) Acute glaucoma> everything mentioned above, everything happens quickly. There is a strong pain, nausea, vomiting, blurred vision, the patient sees colored circles, the pupil does not react to light. Increasing the pressure can be up to 80 mm Hg.
The appearance of the eye in acute glaucoma
A prolonged attack of acute glaucoma causes the occurance of synehias. Vision dramatically weakens and after the pharmacological treatment the vision returns. Acute seizures may cause permanent anatomical changes: necrosis of the pupillary sphincter (due to long-term ischemia) – pupil remains mydriatic and deformed; permanent blur of the anterior lens surface; front synemias.
Therapy for severe pain are morphin and sedatives.
2) Intermittent glaucoma> attacks are weaker but more frequent; it is a glaucoma with a temporary closure of the angle, which occurs in patients with narrow angles (shallow anterior eye chamber). Among the symptoms are: blurred vision, the appearance of colored circles, pain.
3) Chronic Glaucoma> is a result of synehias, which close the angle, so the flow of aqueous humor is continuously difficult, and intraocular pressure is permanently elevated. Symptoms include congestion, varicose veins, eyeballs look like jellyfish (caput medusae).
SECONDARY GLAUCOMA
Secondary glaucoma may result from eye diseases or systemic diseases that damage the eye or are a result of an injury and taking certain medications.
1) inflammatory secondary glaucoma> is caused by changes in chamber corner, caused by inflammation and thus interference of a flow of the aqueous humor (exudate, inflammatory cells, blood vessels, synehias, trabecular edema). It usually occurs in uveitis or iridocyclitis. Inflammation can lead to difficulty in aqueous humor outflow but also to its increased production.
Symptoms: corneal edema, dilated pupils, high intraocular pressure.
2) secondary glaucoma caused by lens> may be caused by:
changing the size of the lens (cataract blubber), changing the position of the lens (lens dislocation in the anterior ocular chamber -trauma), impaired lens capsule (trauma or ripe cataracts)
3) Traumatic secondary glaucoma> as a result of:
eye contusion (contusion, traumatic uveitis- uvea), perforated eye injuries (damage of the trabecular system), traumatic intraocular bleeding (obstruction of a trabecular system with eritroclasts)
4) Secondary vascular glaucoma> occurs after thrombosis of v.centralis retinae or due to increased pressure in the system v.ciliaris anterior. It occurs in malignant exophthalmos or orbital tumors.
5) Secondary glaucoma caused by ocular tumors> retinoblastoma, tumors of the choroid (uvea), tumors of the ciliary body, iris tumors and melanomas.
6) Secondary glaucoma caused by surgery> is a malignant glaucoma, which occurs after antiglaucomic fistulirating operations.
7) Drug-induced secondary glaucoma> occurs when taking mydriatics that spread the pupil, so with the root of the iris it closes the angle of the chamber and thus provokes an acute attack of glaucoma. Corticosteroids in some people cause glaucoma (Cortisone glaucoma).
CONGENITAL GLAUCOMA
It is the least common form of glaucoma that occurs due to a disturbance in the development of the eye.
This is the result of impaired development of the angle of the chamber at which in the fetal life mesodermal tissue is present. Residual embryonic tissue prevents normal drainage of aqueous humor, thereby increasing the intraocular pressure (aplasia of the Schlemm’s channel). The disease manifests itself in the first year of life, so we are talking about infantile glaucoma.
Congenital glaucoma
Symptoms: epiphora (excessive secretion of spontaneous tears), photophobia, blepharospasm (tonus muscle spasm that closes the eyelids), blurring the cornea, hydrophtalmus (oxeye), myopia (nearsightedness), the eye becomes extremely large due to the expansion of the sclera.
Treatment: surgery, trabeculectomy.
Treatment of glaucoma:
Glaucoma treatment ranges from simple use of eye drops in the early stage until the laser treatment, and finally by surgery in severe cases.
Primary glaucoma of an open angle (Glaucoma simplex) is an incurable disease that is being treated for life. The goal of therapy is a normalization of the elevated intraocular pressure and possibly preventing further deterioration of visual function.
In the treatment are used antihypertensive agents, which lower resistance to aqueous humor leaks (pilocarpine; miotic pupil-constriction and thus eye water slowly drains through the drainage path-sinus venosus sclerae> Schlemm’s channel) and reduce the production of aqueous humor (timolol, epinephrine)
During the treatment of primary glaucoma closed-angle the goal is to unblock the angle of the chamber and to restore normal flow of aqueous humor, and this is achieved by contraction of the eye sphincter> miosis (extractes the iris from the corner)
Treatment of acute glaucomic attacks is conducted simultaneously by instillation of miotics (pilocarpine) and giving osmotic agents (glycerol). If this therapy does not help, retrobulbar lidocaine or procaine is given.
In secondary glaucoma the causal disease should be treated. It is necessary to establish the level at which the drainage of aqueous humor is blocked. Agents that reduce the secretion are given, but they do not stretch the pupil> timolol by using osmotic preparations> glycerol
Glaucoma can be treated conservatively by surgery (laser), which destroys tissue, turning it into an amorphous mass (plasma), no thermal effect.
The types of operations:
a) filtration surgery allow leakage of aqueous humor drainage by establishing new routes. For wide-angle glaucoma and chronic glaucoma.
b) interventions that are acting on cillliary body to reduce the production of aqueous humor
c) basal iridectomy> Nd-Yag Laser