what are the causes of glaucoma and what are the causes of glaucoma
The main cause of glaucoma is increased intraocular pressure
Normal intraocular pressure and factors affecting intraocular pressure: The pressure exerted by eyeball contents on eyeball wall is called intraocular pressure (referred to as intraocular pressure). The intraocular pressure that maintains normal visual function is called normal intraocular pressure. Under normal conditions, the aqueous humor production rate, aqueous humor discharge rate and the volume of eye contents are in dynamic balance, which are important factors to maintain normal intraocular pressure. If the dynamic balance of these three is out of balance, pathological intraocular pressure will appear. Most of the normal intraocular pressure values in Chinese people are between 1.33 ~ 2.79 kpa (10 ~ 20mmHg), those exceeding 3.19 kpa (24mmHg) are pathological phenomena, and those between 2.79-3.192 kpa (21-24mmHg) are suspicious pathological intraocular pressure. However, 4.55% of normal people have intraocular pressure exceeding 3.192 kpa (average 3 standard deviations) without glaucoma. In other words, although the intraocular pressure of these people exceeds the high limit of normal people, the optic nerve has not been damaged. Therefore, we can't simply use a numerical value as the standard for dividing pathological intraocular pressure. It is appropriate to divide intraocular pressure into normal, suspicious pathology and pathology.
Range of pathological intraocular pressure: If any part of aqueous humor channel is blocked, it will lead to elevated intraocular pressure. In normal people, the intraocular pressure fluctuates slightly within 24 hours a day, which is generally the lowest in the evening. After resting at night, the intraocular pressure gradually rises, reaches the highest before waking up in the morning, and then decreases slowly after getting up. The fluctuation range of intraocular pressure does not exceed 0.665 kpa (5mmHg), and the intraocular pressure of both eyes is basically equal or has little difference. If the 24-hour intraocular pressure difference exceeds 1.064 kpa (8mmHg), the highest intraocular pressure exceeds 2.793 kpa (21mmHg) or the binocular intraocular pressure difference exceeds 0.665 kpa (5mmHg), it should be regarded as abnormal and needs further examination.
High intraocular pressure and microcirculation disturbance of optic disc are the main causes of glaucomatous optic disc depression and visual field damage. Although high intraocular pressure is an important factor of glaucoma damage, it is not absolute. Clinically, although the intraocular pressure of some patients has exceeded the normal high limit of statistics, after long-term observation, there is no damage to optic disc and visual field, which is called ocular hypertension. There are also a few patients with intraocular pressure in the normal range or critical value, and the damage of optic disc and visual field has been very obvious, which is this type of glaucoma. It is called low-tension glaucoma or low-critical glaucoma.