Blind spot

Introduction Since the optic nerve of the human eye is in front of the retina, they gather at a point and pass through the retina and connect to the brain. If the image of an object just falls on this point, it will not be seen, called a blind spot. It is necessary to find the disease that causes blind spots as soon as possible, and actively treat the primary disease, while paying attention to eye health and diet and health care, can effectively control the disease.

Cause

The formation of a blind spot is a creature in a certain part of the evolution process. The front end of the optic nerve is produced. Its offspring can only be tinkered on this basis and will not make major changes to it, so that it is now like this. It is said that there is no blind spot in the eyes of the squid, because their ancestors evolved in the direction of the optic nerve behind the retina.

an examination

Related inspection

Ophthalmoscopy, fundus examination, tonometry

Do your own experiment, draw a solid black dot and a hollow white dot on a piece of white paper, then close one eye, stare at the white spot with the other eye, slowly increase and decrease the eye and The distance of the paper, at some point, will reveal that the black spots are gone. (In this process, keep the open eyes and always stare at the white point.) By changing the size of the black point, you can measure the abnormality of the blind spot of the visual field.

Differential diagnosis

The diseases that cause the expansion of physiological blind spots are:

1 pseudo-brain tumors: Symptoms and signs include varying degrees of headache (often mild) and optic nerve head edema, and the patient appears to be healthy in all other aspects. Partial or complete monocular blindness (the only serious neurological sign) can be seen in about 5% of cases, and the physiological blind spots are often enlarged. CT scans and magnetic resonance imaging are generally normal, or show that the ventricular system is slightly smaller. The EEG is normal. Cerebrospinal fluid pressure is increased, but the composition of cerebrospinal fluid is normal.

2 acute angle-closure glaucoma: most people with acute, chronic, subacute or intermittent angle-closure glaucoma have no signs and symptoms. But some people can have some signs, such as red eyes, pain, blurred vision or headache, and the expansion of the physiological blind spot. Sometimes this eye discomfort can be improved by sleep, which may relieve the onset of intermittent or subacute glaucoma due to sleep induced dilation of the pupil.

Symptoms of acute angle-closure glaucoma are usually obvious: severe eye pain and redness, loss of vision, color halos, headache, nausea and vomiting, and expansion of the physiological blind spot. Patients with acute glaucoma attacks are sometimes misdiagnosed as neurological or gastrointestinal problems when they go to the emergency room for medical treatment. Patients with an acute glaucoma episode were examined for typical tearing, edema of the eyelids, conjunctival hyperemia, corneal haze, loose and fixed pupils, and often anterior chamber inflammation. Because the cornea is turbid and the corneal epithelium is easily broken, the anterior chamber gonioscopic examination is difficult. However, the contralateral eye is examined as a narrow angle or may be a closed corner; if the contralateral eye is a completely open angle, It can be considered not to be primary angle-closure glaucoma.

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