The eye also has its own pressure, independent and independent from that of the blood. Unlike blood pressure, eye pressure cannot be measured at home, but must be checked by the ophthalmologist with special equipment. We must imagine the eye as a sort of balloon filled with liquid, the aqueous humor, which helps to keep the cornea swollen and curved: when the pressure of this fluid increases, we speak of ocular hypertonus, a condition that can gradually compromise functionality. of the optic nerve, exposing you to the risk of glaucoma. “For everything to work correctly, it is essential that the intraocular pressure is kept within values between 10 and 21 millimeters of mercury”, explains Dr. Franco Spedaleophthalmologist at Eyecare Clinic, Brescia, and director of the Ophthalmology department of the Asst of Franciacorta di Chiari, Brescia.
What is eye pressure
The so-called aqueous humor – a saline and transparent liquid that occupies the space between the cornea and the crystalline – is subject to a continuous exchange, because it is constantly produced and reabsorbed inside the eye, in order to maintain a stable and physiological pressure. It is precisely the balance between secretion and elimination that gives the eye a hard-elastic consistency: “Its tone is given by the amount of liquid that fills it, as for car tires is determined by the amount of air introduced”, he simplifies Doctor Spedale. “Unfortunately, however, something can go wrong: if the aqueous humor is produced in excess or if there is an obstacle to its outflow, there is an increase in pressure and this poses a risk to vision and can lead to glaucoma“.
What are the symptoms of glaucoma
Generally, the pressure inside the eye begins to increase between the ages of 45 and 55, without causing any disturbance. «It is no coincidence that glaucoma is defined as the ‘silent thief of sight’, because it progresses in a subtle and silent way, without showing evident signs for many years», warns the expert.
“Over time, however, i damage to the optic nerve begins to affect the peripheral portions of the visual fieldso it may happen that the patient begins to bump against walls or edges, to stumble often while walking or to crawl the side of the car while maneuvering to enter the usual box.
To be diagnosed with glaucoma, there must be three characteristics: the increase in ocular pressure, an alteration of the visual field and an anatomical modification of the optic nerve head, that point of connection between the eye and the brain that allows images to be perceived. Just one of these symptoms is not enough ». Sometimes, then, the increase in ocular pressure can be accompanied by non-specific signs, such as burning, tearing and redness, which are not always indicative of ocular hypertonus. Indeed, in most cases, they are due to something else.
What are the causes of glaucoma
Exist various forms of glaucoma. That chronic is the most frequent and is due to a difficulty of the aqueous humor to flow from the inside to the outside of the eye through the normal anatomical ways that are predisposed for this purpose: in this case, the increase in ocular pressure has a very slow and silent evolution, so the patient becomes aware of the disease only in the terminal phase, when the damage is very advanced and now irreparable.
“Glaucoma acuteon the other hand, it manifests itself suddenly and is caused by a total obstruction of the outflow routes, like a sink that is completely clogged, preventing water from passing through », explains Dr. Spedale. “This form of glaucoma affects the eyes that are predisposed due to a particular conformation: these are rather small eyes, where the iris and the cornea meet, generating a very narrow angle, which due to various stimuli can close, preventing the leakage of aqueous humor. Unlike chronic glaucoma, in this case the patient feels pain, often violent and sometimes associated with nausea and vomiting ». Forms of glaucoma secondary to other diseases, such as various eye inflammations, which normally lead the patient to go to the ophthalmologist, are also quite painful.
How it is measured
Ocular hypertonus is diagnosed during a routine eye examination thanks to the tonometer, an instrument equipped with a very light probe thanks to which screening is quick and painless. “In most cases, the increase in ocular pressure begins after the age of 40 for reasons that are still unknown, so there are no really effective daily habits or behaviors,” admits Dr. Spedale.
«On the other hand, a great advantage can be obtained from secondary preventionwhat does it mean early diagnosis: from 40-45 years onwards, it is essential to undergo a check-up every year. But it is important that the ophthalmologist and not an optician measure the eye pressure. While the first uses an applanation tonometer, the second uses the breath one: the difference is not only in the type of examination, however quick and painless in both cases, but in the fact that the second often overestimates the ocular tone, so the measurement may not be reliable ».
How it corrects itself
Once the problem is diagnosed, you try to slow down the evolution of the disease with the instillation of one or more eye drops, in a regular way and without suspensions, which allow to lower the ocular pressure. «If pharmacological interventions are not sufficient, the surgical therapy. Today there are different methods that allow you to create an alternative route for the outflow of aqueous humor “, describes the expert,” but it must always be the specialist who establishes the treatment to be followed on a case by case basis, after discussing it with the patient. For example, there are cases in which the increase in pressure alone, not accompanied by an alteration of the visual field and the anatomical modification of the optic nerve head, may require simple periodic monitoring. He also counts the patient’s age, taking into account that untreated glaucoma leads to blindness within thirty years ».