General notions about glaucoma
Glaucoma is a chronic optic neuropathy, meaning a disease of the optic nerve, and is actually a group of disorders that typically is associated in three elements: increased intraocular pressure above the individual tolerability, damage to the optic nerve and visual field deficit .
The word “glaucoma” comes from the Greek “Glaukos = blue-gray” aspect probably referring to overcome stage of the disease as we know it today.
To what extent and why glaucomatous damage affects eyesight?
Order involves transforming light signals in retinal photoreceptor cells into electrical signals which are then transmitted through the optic nerve retinal nerve cells, which leads to the brain, where visual information is processed. Retinal nerve cells are organized hierarchically according to the complexity of the structure, the most advanced being the ganglion cells whose fibers called axons come together in a specific region of the eye, called the optic disc (papilla or optic nerve head) and form from the optic nerve. Papilla contains only axons, but not photoreceptor cells and therefore is not able to “see” anything, causing the so-called “blind spot” physiological visual field.
In glaucoma, gradually dying cells and nerve fibers, thus affected the relationship between eye and brain, thus providing the information and not its actual receipt of the retina. Visual function remains free from often the first stages of the disease, although nerve fibers are destroyed. With time the lesions are severe defects appear significant respects. Serious aspect of the disease is the fact that the patient rarely aware of their visual field changes and situations that are detected in advanced stages of the disease. Even with a perfect remote central vision (reading at least 6 feet of optotype) patient may have a severe visual field loss.
An explanation of the omission visual field defects (called scotoma) the patient is that glaucomatous damage is asymmetrical, the patient sees binocular and image processing is done at cortical brain compensate for the shortcomings of an image. Early diagnosis of glaucoma is extremely important, visual impairment can be slowed, stopped or even prevented by appropriate treatment administered on time.
Epidemiological data are worrisome: average glaucoma affects 3% of the general population (prevalence is higher in the elderly) in the world there are about 70 million glaucoma, only 50% of them are aware of the diagnosis, about 7 million sufferers suffering from bilateral glaucoma blindness (blindness) and their number is growing.
The information provided above some already outlines a terrifying picture of the disease, its diagnosis is a stigma unbearable for any patient. In modern society’s attitude regarding the diagnosis and treatment of glaucoma has led to a considerable improvement of evolution. It is true that glaucoma is a disease and that untreated can lead to blindness, but early disease detection and treatment offers a good prognosis of the disease and the patient’s life quality in the long term. So … go to the doctor. An examination of screening (early detection) can save sight.
Generally, adults begin to address ophthalmologists at 40-45 years when reading glasses are required. Then it is time for a complete ophthalmologic evaluations, inspections, for healthy individuals, making it then about 2 years. For those who come from families of glaucoma eye exam is best to do before, even 20-25 years.
Besides determining visual acuity and refractive correction of any defects (prescription glasses), intraocular pressure measurement, determination of visual field and optic nerve papilla examination are mandatory elements aimed at glaucoma screening exam. Now we are available and highly sophisticated investigations optic nerve and three-dimensional optical coherence tomography and digital stereoscopic optic nerve head photography.
Intraocular pressure (IOP) IOP is the difference between absolute and atmospheric pressure at the time. It is directly influenced by the aqueous humor, the fluid secreted actively in the eye and eliminated specific ways. Secret evacuation imbalance cause variations in IOP. Mean IOP is between 10 to 21 mmHg, but modern research introduced the notion of individual PIO tolerated, which means that there are individuals with higher values of IOP, but without the glaucomatous damage, and individuals with values ”normal” of IOP glaucoma presenting specific changes.
To note that IOP fluctuates quasi-permanent, at a time of day to another, from individual to individual. At glaucoma presión fluctuations are much more pronounced, it negatively influencing the integrity of nerve fibers. IOP measurement is via tonometry. This device has developed over time, currently being preferred aplanotonometrele (measuring the force required turtirii – aplanatiei central portion of the cornea), of which model is the gold standard Goldmann current site. Outpatient successfully used aplanotonometrele noncontact (air jet), very useful for screening, though not very accurate have the advantage that they do not come in contact with the patient’s eye, increasing the discomfort. A condition of a successful quality measurements is correct and regular calibration of the meter.
Visual field of one eye is the total peripheral images that can be perceived at a time while the person looks at a fixed point. Visual field defects are called scotoma (identified as “stain” in the visual field). Determination modern visual field is done using a machine called a computer area, that tests the sensitivity to different light intensities each eye. The computer then processes the information and provides statistics on individual sensitivity and absolute standard against a witness.
Basically visual field defects occur when retinal nerve fiber is destroyed, and detecting and measuring roughly scotoamelor enable a quantitative loss of nerve fibers. Perimetry is both a diagnostic method and a follow-up of the disease, repeat visual fields at 6 months is of great use for both doctor and patient glaucoma. Accurate diagnosis of glaucoma and the rate of progression involves identifying as European Glaucoma Society Guidelines, 6 (six) consecutive measurements made over a period of 2 (two) years, with a relative distance of about 4 (four) months each.
Optic nerve papilla (assessed by ophthalmoscopy / biomicroscopy) in particular looks glaucoma. Fundus examination and consequently the papilla is best to do a dilated pupil and lens using a special contact or noncontact, allowing for stereoscopic. Develop a typical optical disc excavation (nerve fibers are lost, glial cells and blood vessels). There are many issues encountered in glaucomatous papilla, which will not be subject to this material, their interpretation is the prerogative doctor.
Another useful maneuver disease diagnosis and classification, accessible only ophthalmologist is gonioscopy, examination by a special lens configuration irido-corneal angle. This allows differentiation of the two classic forms of glaucoma – open angle or closed by. Being a specialized maneuver strict I will not detail.
There are now other more sophisticated technological methods that allow objective examination of the optic disc and quantify changes in papillary and nerve fiber layer thickness. Will include: shooting series papilla, stereophotography disk, optical coherence tomography, computerized analysis of nerve fiber layer.
Nerve fiber layer thickness determination and evaluation by optical coherence tomography computerized three-dimensional acquisition is the latest technology that allows the often determine early glaucomatous changes, long before the appearance of visual field alterations. As such patients grouped risk factors is an indication for evaluation by the advanced technology. To note that this investigation is based on laser interferometry, so it radiates, being repetitive and without risk to the patient.
It seems that “the most important criteria upon which the diagnosis of glaucoma is optic disc evaluation by a doctor” – Josef Flammer, and therefore nothing can replace experience and professionalism since an examination done by a professional.
Regarding Pathogenesis and pathophysiology of glaucomatous disease there are many theories, but researchers unanimous that there is still much to say about how to produce glaucomatous disease. In a simplistic way we can say that the main factors involved in glaucomatous damage are lower IOP and ocular perfusion. Increased IOP affects mechanical disc directly influence by compression axoplasmic flow (flow through nerve fibers) or indirectly by decreasing the blood supply to the eye.
Disruption of this circuit (the exchange of information between cells) causes death “programmed” ganglion cells (apoptosis). So nerve cells die by apoptosis glacom but also by necrosis. Cell death mechanism was explained, but still not fully understood! The other important element in the pathogenesis of glaucoma is ocular hypoperfusion, and hypotension on self vascular disorders (ability of a body to regulate its blood infusion as needed).
Ocular perfusion pressure is the difference between blood pressure (BP) and IOP and IOP or BP fluctuations have no effect on retinal or optic nerve perfusion when autoregulation mechanisms are intact. At glaucoma often is poor autoregulation and pressure fluctuations and presión occurring are more harmful than a constant level increased. The explanation is based on the theory of reperfusion, associated with the release into circulation of free radicals, which are toxic to various cellular components.
Risk factors are those conditions that contribute to the occurrence of the disease. Must differentiate risk factors increased IOP (age, family history, race, arteriosclerosis) risk factors that lead to the development of glaucoma (elevated IOP, lack of self-regulation-vascular hypotension and vasospasm -, female gender, and race myopia). I will discuss just about risk factors for glaucoma.
Probability of occurrence and progression of glaucoma is even greater as IOP is higher. I mentioned earlier that the negative role of fluctuations and growth presión chronic progressive IOP. Next phrase will create a complete confusion of the reader: “When we speak of glaucoma have always had in mind that 80% of people with high IOP will never develop glaucoma, while 30% of people with glaucoma have an IOP in the normal range statistic “- Josef Flammer. My recommendation is for the reader to form an image of a complex disease, the diagnosis is made by the doctor-patient collaboration with the direct participation of the art performance.
Influence of age on IOP glaucoma explained by increasing age (“aging” network trabecular aqueous humor drainage), by increasing the number of risk factors throughout life and the loss of nerve fibers in the process of senescence. Heredity plays an important but not decisive role both in the development of elevated IOP and in setting up a certain sensitivity to the optic nerve. The genetic code can cause presión tolerance of each individual.
Lack of self-regulation can also be inherited vascular. So people with a family history of glaucoma require attention from your doctor. Although there is no difference between women and men in terms of raising IOP was found that women have a higher risk of developing glaucomatous damage at normal IOP values due to higher frequency of vasospasm. Myopia are at high risk of glaucoma (open angle primitive) via increased sensitivity of the optic nerve and ocular perfusion disorders.
Classification of different types of glaucoma is mainly depending on the root cause of the increase IOP, which is usually represented by increased resistance to aqueous humor drainage through the trabecular meshwork (located irido-corneal angle level).
Depending on the age when glaucoamele can be congenital, infantile, juvenile and adult. Depending on the root cause exist or secondary glaucoma (when known cause), and depending on the angle between the iris and cornea configuration there open-angle glaucoma and closed-angle glaucoma.
My exposure to refer particularly to the most common type of glaucoma and the most dangerous, in fact, the insidious onset and evolution, namely the open-angle glaucoma (POAG).
A mention must be made about closed-angle glaucoma – the acute form, called the attack of glaucoma. In this situation IOP rises sharply at high levels, inducing headaches and eye pain. May occur associated abdominal cramps, nausea, vomiting. The eye is bloodshot, to the patient is reduced. During the attack, the sources of light are perceived unclear and appear surrounded by colorful circles. Treatment is urgent, is in hospital and I will not elaborate on these lines.
About POAG can say that the eye is the angle camerular has a normal conformation and increased IOP appears inadequate drainage of aqueous humor through the trabecular network, the blocked more or less for various reasons. The condition is chronic, develops over many years and are not the consequence of concomitant eye diseases.
There is an arbitrary classification of POAG in: high pressure POAG (glaucomatous damage and increased IOP), normal pressure POAG (glaucomatous damage and IOP in the normal range, but over individually tolerated IOP) and ocular hypertension (elevated IOP without glaucomatous damage) .
Fortunately there is a wide range of therapeutic options with high efficiency. Given the crucial elements of glaucoma therapy should target both lower IOP and optic nerve protection and better circulation. At present the entire arsenal successfully addressing therapeutic levels decrease IOP to prevent glaucomatous damage progression. These values are determined solely by the treating physician, obviously with the direct support of the patient.
Treatment options are: drug therapy with drops which administered at a rate characteristic can decrease and maintain reduced IOP, laser treatment, aiming repermeabilizarea trabecular network and surgical treatment (filtering), which “increases” aqueous humor drainage pathway . A discussion about the choice of therapy and determine its effectiveness would be too long and maybe too technicist.
Here are some tips but often useful for glaucoma patients:
- To ingest a sufficient amount of liquid, but distributed in small doses (rapid ingestion increases IOP)
- To sleep on a pillow higher (in some patients IOP increases by changing body position)
- Sufficient sleep
- Play sports (to improve circulation)
- To follow a diet rich in vitamins and low in fat
- To eat fruits and vegetables every day
- To eat fish at least once a week
- Do not smoke
- To control weight
There are risk factors that can not be influenced (age, gender and race), but others can be treated. Signs of vascular autoregulation disorders are both vasospasm (cold hands) and hypotension. They can be relieved by certain lifestyle changes: exercise, a healthy diet, adequate fluid intake and salt.
The most important is to present to the doctor in time: after 40 years it’s good to make an eye examination more than once every five years, if there is suspicion of glaucoma checks must increase, in individuals with a family history of glaucoma control specialty should be done earlier.
In conclusion, if the disease was diagnosed and treated properly, glaucoma patient may have a normal life. He has but to observe the treatment and present regular eye checks thoroughly.
My last row can be only an urge: go to a specialist for an evaluation even “routine”. The fact that you can go without framing in pathology should enjoy.