IntraOcular Pressure

. The method used to quantify it is called tonometry, which expresses the measurement in millimeters of mercury (mmHg). For the correct function of the eye and its structures, it is very important to keep the intraocular pressure within values ​​between 10 and 21 mmHg. Maintaining the pressure within this physiological range is necessary to maintain the optimal anatomical conditions for refraction, therefore for allow a correct vision. From a physiological point of view, in fact, intraocular pressure helps to stabilize the shape of the eyeball and protects it from deformations that could be caused by the weight of the eyelids and the tone of the extraocular muscles. of swelling, through the drainage and return to blood circulation of liquids containing waste metabolites.

Several factors can transiently affect blood pressure, such as diurnal deviation, heart rate, alcohol and caffeine consumption, exercise, and fluid intake or certain systemic and topical medications. A pathological change in ocular pressure, on the other hand, can have unpleasant consequences for visual function and can occur without the patient being aware of it.

The high pressure inside the eye is an important indicator in the evaluation of glaucoma, of which it is a risk factor. This ocular disease, generally, does not cause pain or particular symptoms, but produces characteristic changes in the optic nerve and neural cells in the retina. If glaucoma continues to progress and is not adequately treated, it can affect peripheral vision and cause irreversible damage to the optic nerve, which can lead to blindness. In most cases, pressure is detrimental when greater than 21 mmHg, but some patients may be adversely affected at lower intraocular pressures (normotensive glaucoma). Conversely, some people can tolerate higher than normal blood pressure levels without damage to the optic nerve or loss of visual field (ocular hypertension).