Physiological blind spot enlargement

Introduction Expansion of the physiological blind spot: Since the optic nerve of the human eye is in front of the retina, they are collected at a point and connected to the brain through the retina. If the image of an object just falls on this point, it will not be seen, called a blind spot. The disease causing the expansion of the physiological blind spot has pseudo-brain tumors and acute angle-closure glaucoma.

Cause

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.

an examination

Related inspection

Eye and sacral area CT examination external examination

Symptoms and signs of pseudo-brain tumors 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.

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.

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. At a certain point, you will find 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

1. Secondary glaucoma: in addition to acute angle-closure glaucoma, blood-stained glaucoma, lens expansion, lens solubility, glaucoma caused by subluxation of the lens, neovascular glaucoma, secondary glaucoma caused by uveitis Can cause acute increase in intraocular pressure, and even left the signs of ocular damage caused by high intraocular pressure, in order to identify the above situation, the most important of which is to check the contralateral eye, for primary angle-closure glaucoma Both eyes often have the same anatomical features. If the contralateral eye is found to have the same characteristics, further examination should be performed to make a differential diagnosis.

2. Acute iridocyclitis and acute conjunctivitis: The differential diagnosis has been introduced in general textbooks, which is relatively easy, but it must be emphasized that there are contradictions in the treatment of these three diseases. Therefore, a wrong diagnosis will lead to a worsening of the condition and even the possibility of blindness.

3. Malignant glaucoma: Because of the clinical manifestations of the primary malignant glaucoma and the anatomical signs of the eye and the disease have many similar aspects, it is easy to cause misdiagnosis. In addition, because the treatment principles of the two diseases are different, the misdiagnosis can cause serious losses, so the differential diagnosis of the two is very important. Malignant glaucoma also has a narrow feature of the anterior segment of the eye, but it is often narrower than the anterior segment of the eye, the thickness of the lens is thicker, the axis of the eye is shorter, and the relative position of the lens is higher. The anterior chamber is shallower and the disease is different. The iris appears to be anteriorly consistent with the front of the lens. The most important thing is that the condition deteriorates after treatment with the miotic agent.

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