What are the examinations for glaucoma?

(1) IOP: An tonometer is used to measure IOP. Anesthetize the eyes first, and the tonometer determines the intraocular pressure by the pressure required for the collapse of the outer wall of the eyeball.

The range of normal intraocular pressure is 12 ~ 22 mmHg, and "mmHg" means "mmHg", which is the unit for measuring intraocular pressure.

Generally speaking, the intraocular pressure of pressure gauges greater than 22 mm Hg increases. There are also a few cases of glaucoma with normal intraocular pressure. Sometimes it takes many times to check the intraocular pressure or long-term observation to diagnose glaucoma.

(2) Ophthalmoscope (an instrument for examining the fundus) inspection: Ophthalmoscope is used to inspect the inside of eyes. If necessary, first dilate the pupil with eye drops, and then check it in the darkroom with an instrument with a small light source at the end.

Turn on the light source of the ophthalmoscope, and the ophthalmoscope can enlarge the observation. The doctor checks the shape and color of the optic nerve through the pupil. If the optic nerve is "cup-shaped" or has no normal pink color, you should pay attention.

Sometimes doctors use special lenses to observe the anterior chamber and external drainage channels, that is, gonioscopy.

(3) Visual field examination: Glaucoma can cause peripheral visual field loss or visual field scotoma.

In order to find out whether there is a dark spot, the doctor will let the subject look at a spot in front of him and check whether the subject can see the light spots appearing in other parts of the visual field (visual field examination). You can use the visual field screen and visual target to check the visual field, or use a computer visual field meter that automatically flashes light spots to check the visual field.

The treatment of glaucoma patients depends on accurate diagnosis.

The diagnosis of glaucoma, like other diseases, needs to be combined with medical history, clinical manifestations and auxiliary examination. For suspicious patients, intraocular pressure should be measured first. If the intraocular pressure is greater than 3.20kPa(24mmHg), it is pathological ocular hypertension. But glaucoma can't be diagnosed by a high intraocular pressure. Similarly, a normal intraocular pressure cannot rule out glaucoma.

Intraocular pressure fluctuates periodically within a day. Daily IOP fluctuation is greater than 1.07kPa(8mmHg).

Normal eyes have similar intraocular pressure. If the difference between the two intraocular pressures is greater than 0.67kPa(5mmHg), it is also pathological intraocular pressure.

Next, check the fundus and observe the changes of optic disc. The optic disc changes in glaucoma have certain particularity and important clinical value. Often manifested as pathological depression. At present, the ratio of depression to optic disc diameter (C/D) is widely used to indicate the size of depression.

C/D greater than 0.6 or binocular C/D difference greater than 0.2 is abnormal; The thinning of the optic disc edge is often accompanied by uneven width and notch along the optic disc edge, suggesting that the number of optic nerve fibers along the optic disc edge decreases; The changes of optic disc blood vessels are as follows: marginal hemorrhage of optic disc, cranial blood vessels, nasal displacement of optic disc blood vessels and central retinal artery pulsation.

In addition, retinal nerve fiber layer defect can be observed by fundus examination, which is considered as one of the early diagnosis indications because it can appear before visual field defect.

Visual field examination is also of great value in the diagnosis of glaucoma. Because the visual field defect reflects the damage of optic nerve.

The common types of visual field defects in clinic are: general visual threshold reduction, arcuate defect, nasal staircase, vertical staircase, temporal sector defect, central and temporal island visual field.

Through the above examination, the existence of glaucoma can be diagnosed, but the type of glaucoma has not yet been determined.

In order to classify glaucoma, we should also check the anterior chamber angle. Those with open angle are open angle glaucoma, and vice versa.

If it is still difficult to diagnose glaucoma by angle examination, you can check the water flow coefficient (C value).

The C value is less than 0. 1, and the applanation ratio (Po/C) is greater than 150, which is mainly seen in open angle glaucoma.

However, it should be noted that after repeated attacks of angle-closure glaucoma, C value and pressure ratio may also be abnormal.

In addition, for some suspected glaucoma, some excitation tests can be selected to assist the diagnosis.

The diagnosis of secondary glaucoma should include ocular or systemic diseases, ocular hypertension and optic nerve injury.

Through gonioscopy, we can know whether the cause of high intraocular pressure is angle closure or trabecular filtration dysfunction, so as to diagnose secondary open-angle glaucoma or angle-closure glaucoma.

Through the above examination, glaucoma and its classification can be roughly determined, so as to adopt correct treatment methods.