Don't push my eyes


    Sensor of contact electronic tonometer

    Today I will tell you about the pressure. Only not about that which is arterial, but about intraocular. The eye is a complex and completely non-static thing. As in other systems of the body, something is constantly being calibrated, secreted and derived. One of these dynamic systems is the continuous formation and elimination of aqueous humor . In case of violation of the outflow or relatively excessive production, the intraocular pressure begins to grow, after which the person begins to go blind completely unnoticed by himself. If you think that this problem is characteristic purely for grandmothers in endless queues of polyclinics, then you are greatly mistaken. The diagnosis of glaucoma is also made to young, apparently completely healthy people.

    What to do if the leg is torn off




    Lyrical digression. You walk down the street, do not touch anyone, and you see a man who decided to save some time and run across the road in front of the tram, but didn’t run. And here he lies with a mad expression on his face, and from the remnants of his leg, interspersed with fragments of his trouser leg, pulses the scarlet fountain. Artery, you know. Your actions? If you, as a responsible citizen, immediately decided to call an ambulance, the answer is incorrect. By the time you put the phone down, the patient will spill a couple of liters of blood on the dusty asphalt, after which he will not need help.

    The optimal tactic in this situation is to drag the rest of his leg with a belt. While you are doing this, pick out the least unconscious person in the near radius and make you call an ambulance. By the way, in order to train the memory of people in a stressful situation, some kind people are constantly changing emergency phone numbers. Number 03 from a mobile phone does not work, and options are possible in the form of 030, 103, 903 and 003. Therefore, it is better to call 112 right away . You can reach him without money and even without a SIM card.

    Now you need to decide how to stop the bleeding. The main principle of action of any measures on hemostasis is to press the vessel to something solid, that is, to the bone. It will not be possible to press against a soft supple fat or a large muscle, the fabric is simply pressed under external force. Therefore, with very fat or muscular people there may be difficulties. Traditionally, the most convenient solution is the imposition of a harness on the region of large joints, where the vessels are most superficially located and the bone is close. By the way, the traditionally ridiculed tourniquet for nosebleeds also has the right to life, but only with something more serious, like head injuries (and only if you know exactly what you are doing). At the same time, a complex structure is being built with a pressing roller on the carotid artery on one side and a soft pillow on the opposite side.

    If you think about it, then all these measures are aimed at ensuring that the external pressure on the vessel exceeds the blood pressure inside it. In this case, the vessel collapses and the blood no longer flows. If the external pressure is a little less, then the blood will slowly ooze. This principle we need to parse the problems arising from glaucoma.

    Tasks about pools


    Remember these eternal school tasks about swimming pools into which something always flows in and from which everything continuously flows? Something similar happens in our eyes. The human eye produces from 3 to 9 ml of aqueous humor per day. This fluid is very similar to blood plasma, but contains less protein. It fills the space of the anterior and posterior chambers of the eye and flows through the Schlemm’s canal in the anterior chamber angle back into the bloodstream. Normally, these processes are balanced. But let's imagine that our pool is clogged up or the taps opened harder. As a result, the water level will gradually increase. But the pool is an open system, and in a closed eye cavity with elastic walls of excess fluid there is simply no place to go. As a result, the pressure in both chambers begins to increase and affect the lens and the vitreous body. The vitreous body begins to "cuddle up" to the retina and choroid. Nothing like?

    "To stop the capillary bleeding, you must press the affected area with your hand or pressure bandage until complete hemostasis . "

    That's just the vessels here are normal and the blood in them is completely unnecessary to stop. But due to the increased pressure, the blood flow deteriorates and the most sensitive to hypoxia cells — nerve, especially ganglionic, begin to die. These cells - a kind of adder nerve impulses from the retina. They aggregate the signal from several hundred photosensitive cones or rods, which allows to increase the sensitivity by reducing the resolution. Then the nerve impulse is already “compressed” discharged into the conductive fiber of the optic nerve. It is just the target number two and is also gradually degrading, turning off one fiber after another.

    The process is uneven due to the fact that the great vessels and the best blood supply go to the macula, a zone of central vision. The periphery is already feeding on what remains. That is why glaucoma is so difficult to diagnose yourself at home, and the first bell is the imperceptible prolapse of peripheral visual fields, which is detected suddenly at the doctor's appointment. Another rather unusual symptom is a sudden improvement in the quality of vision in close proximity in people over 45 years of age. The fact is that increased pressure causes a certain deformation of the cornea, as if “shifting it towards myopia,” if it can be stated in a simplified way. As a result, people with age presbyopia have an unexpected “joy,” which then turns into grave consequences.




    In the process of progression of glaucoma, the world gradually narrows to a tank gap, and then disappears completely. Moreover, the current stage is always irreversible and, at best, can be suspended indefinitely.

    Bob, paint and eyes


    Any physiologist will tell you that the most correct method for measuring blood pressure is to insert a mercury manometer somewhere in the aorta. So do the animals. Did, more precisely. In humans, intraocular pressure is more comfortable to measure with a pneumotonometer. He blows with a dosed effort in the eye, and the device measures the degree of deformation of the cornea. The harder it sells, the lower the pressure. This is a screening method. It allows you to reach a large crowd of people and catch among them those who clearly go beyond the boundaries of the norm. That's what they are taking to a more interesting next stage - contact measurement of intraocular pressure. This is the so-called applanation tonometry.

    With this method, the pressure is determined based on the effort required to form a flat surface of a given area of ​​the cornea, which is a consequence of Amber-Fick's law. Roughly speaking, the smaller the footprint, the higher the pressure. Very similar to the stain of contact with the ground in automobile and bicycle tires. In Russia, one of the most common methods is Maklakov tonometry. Cheap and angry. The weight of the standard mass is smeared with paint and placed directly on the patient's eye. Eye, of course, under anesthesia. Part of the paint is washed off at the point of contact. The more paint was washed away, the lower was the pressure. The process itself can be viewed on the video below:


    In principle, everything is not as scary as it seems, and for the patient quite comfortable. There is a story about a patient who, out of love for art, decided to undergo this examination and then begged himself for the resulting ink prints for some strange purposes. Then it turned out that he had scanned them, transformed them into a format that could be understood by the CNC laser mill, and made a seal for the company with the original ring-shaped logo in the middle.



    Another contact method for measuring pressure, more common in the world, is the Goldman tonometer. It also requires anesthesia and is based on the optical effects that occur on the special prism that contacts the cornea. In this case, the doctor must adjust the pressure of the measuring device until the green semicircles in the viewfinder match.

    There are quite a few methods for measuring pressure, and among them there are even such exotic ones as rebound tonometry. Rebound tonometers determine intraocular pressure by hitting a small cornea-coated metal probe with a plastic tip. The device uses an induction coil to magnetize the probe and strike the cornea. When the probe jumps to the cornea and back into the device, it creates an induction current, from which the intraocular pressure is calculated. There are even modifications for independent use. I did not see it live.

    Treatment


    The treatment of this insidious disease is very diverse, but it can be reduced to conservative and operational methods. Conservative methods include life-long therapy with various drops, which help to improve the outflow, reduce the production of moisture and reduce the pressure to normal values. There is also marijuana, which in some countries is sold for medical purposes, but it is very fairly criticized. The antihypertensive effect is not particularly pronounced, rather short, and the patients are a bit inadequate in the end, which is bad for continuous therapy. In Russia, it also does not approve of the Criminal Code. Operational methods are also very diverse, but basically these are various options for improving the outflow with the help of laser therapy, the creation of new outflow paths and the installation of micro drainage systems.

    Red eye problem


    There is a misconception that glaucoma and dry eye syndrome are expressed in the form of eye redness and pain. This is true, but in practice it is very easy to distinguish one from the other. Dry eye syndrome is what you are most likely to have, pain becomes stronger at the end of the workday (especially when sitting at a computer or under an air conditioner). Glaucoma often goes unnoticed for a long time and only sometimes manifests itself in the form of an acute attack (unforgettable pain) with red eyes, which is remarkable, more often in the early morning hours.

    "Household" symptom is this: people accidentally begin to notice that they are fighting about objects. They do not notice how someone came to the side and so on. The field of view of one eye narrows at this stage quite significantly. But this is not the imposition of a black or matte mask, but simply the imperceptible disappearance of a part of the visual field. Consciously notice hard. A blind spot is most similar to the problem of glaucoma. Nobody notices him, but it is very large. The brain is able to compensate for such areas, especially since we have part of the nerve fibers from the left eye comes to the center of perception for the right eye and vice versa.

    Dry eye syndrome is dryness, irritation, redness, feeling of sand and "fatigue." Details here, in a post about a tear. A little later, the deterioration of vision due to the fact that the cornea was dry. At this point, our medical development will no longer help you and tear substitutes will come into business. What is unpleasant, drugs for the treatment of glaucoma contribute to the appearance of dry eyes and can enhance computer syndrome, but you can not cancel them - go blind.

    If you do not have the feeling that the door crept from somewhere on the side and suddenly, just do not forget to check your eyes during medical examinations. Nothing bad will happen. With pain in your eyes, never wait for anything - go to an optometrist (not to an optometrist at an optician, not to a pharmacy, but to an optometrist, especially since there are on-duty hospitals in large cities where you will be treated with acute pain at any time of day).

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