Lecture of the cause of blurred vision

2021-02-02 12:00 AM

An eye examination can reveal a small cornea, a shallow anterior chamber, fundoscopy must adjust the convergence glasses to clearly see the fundus image, the small papillary image can be seen

Blurred vision is an important symptom in ophthalmology. Before a blurred case, a systematic examination is needed to find the cause.

Things to do for diagnosis

Asked the disease

Need to ask the patient when blurred vision occurs, gradually blurred or sudden? Ask the patient and family history (eye diseases and related systemic diseases).

Medical examination

Measure vision away and near vision.

If the vision is less than 7/10, try to have the patient see through the peephole, if the vision increases, then let the patient measure the refraction, test the glasses.

Examination of the anterior and posterior part of the eyeball (microscopy and fundoscopy).

Measure the market, the spot, the blind spot if needed.

Do subclinical examinations: ultrasound, retinal electrophoresis, fluorescence angiography, x-rays of the sinuses, skull and brain, tomography, magnetic resonance imaging ...

The causes of blurred vision slowly

Blurred vision due to refractive error


Cause: Refraction of the cornea, due to the vitreous body, because the anterior and posterior axis of the eyeball is longer than usual, so the image of the object is in front of the retina.

Symptoms: Reduced vision in one eye, squinting, eye pain.

An eye examination can show convex eyes in case of severe nearsightedness, when fundoscopy must adjust divergent glasses to clearly see fundus image, in severe myopia, signs of dark retinal degeneration due to nearsightedness market ...

Eye ultrasound helps to evaluate the eyeball axis, degenerative retinal lens fluid ...

Treatment: Nearsighted people must wear divergent eyeglasses, choose the lowest number of glasses for the highest vision. There can be surgical treatment or laser correction.

Severe nearsightedness can have complications: cataract, detachment of the retina, degenerative retina ...

Picture: Myopia


Cause: Refraction of the cornea, vitreous, because the anterior and posterior axes of the eyeball are shorter than usual, so the image appears behind the retina (Figure 2).

Symptoms: If low farsightedness can be normal, if long-sightedness is severe, both long-sightedness and near vision will be reduced, the farsighted or moderated is prolonged, causing eye pain or fatigue, possibly causing confusion.

Photo: Farsighted eye

An eye examination can show small corneas, shallow precaution, fundoscopy, to adjust the convergence glasses to clearly see the fundus image, can see small or normal papillary images, no dark degeneration images. cornea.

Treatment: Need to wear focusing glasses, choose the maximum number of glasses for the highest vision. Laser excimer can be used to treat farsightedness


Cause: Due to the unequal corneal curvature radius across the meridians, refraction by meridians is also different.

Symptoms: Reduced vision in one eye, often distorted and distorted picture.

Treatment: Adjust with cylindrical glass. Can surgery corneal incision, excimer laser.

Blurred vision due to a regulation disorder (presbyopia)

Cause: Due to the change of refraction in people over 40 years old due to a decrease in the regulation ability of the vitreous body. Presbyopia increases with age, near-sighted people appear more slowly, whereas presbyopia people appear earlier.

Symptoms: The elderly cannot see clearly, when reading books, they often have to move far away to see clearly.

Treatment with converging eyeglasses for a close view (old glasses).

Blurred vision due to eye diseases

Diseases of the anterior part of the eyeball:

Cornea: Scarring of the cornea due to ulcers, trauma, trachoma complications, malnutrition ...

Treatment with corneal transplant surgery.

Open-angle glaucoma: Narrowing of the field, concave atrophy of the papillae, and decreased late vision. The eyes are usually not red, not painful.

Treatment with ophthalmic medication, laser, hole surgery.

Chronic eyelid iritis: Marginal erection, corneal precipitation, anterior Tyndall sign, pupil shrinkage, iris sticking and secretion.

Treatment with anti-inflammatory drugs, corticosteroids, atropine dilates the pupils, anti-stick, paralysis to regulate the reduction of eyelid secretion.

Glass chisels:

Cataract of the elderly: Slowly blurred eyes, no redness, no pain.

Congenital cataract: Often has two eyes, should be operated early to avoid amblyopia.

Pathological cataracts: Diabetes, Tetani disease, uveitis ...

Cataracts are secondary to cataract in children or young people.

Treatment with artificial glass replacement.

Photo: Old age glass chisels

 Disease in the back of the eyeball

Glass fluid cloudiness caused by retinitis, haemorrhage, vitreous degeneration in the elderly .... Patient has a feeling of fog or flies flying in front of his eyes, fundus can see he can play in the chamber glass translation.

Blurred vision caused by diseases of the retina and optic nerve:

Dark retinitis: diffuse or walled, with discharge, swelling or changes in pigmentation.

Systemic diseases such as high blood pressure, diabetes, nephritis ... can cause important changes in the bottom of the eye (see more eye articles and systemic diseases).

Pigmentation of the retina causes night blindness, narrowing of the market, black pigmentation patches in the periphery of the retina and around the blood vessels, discolored papillae, and artery system of the retina. shrink.

The damage of the macula (oedema, macular degeneration in the young and the elderly, trauma) causes the central focus point. Fundoscopy shows that the macular area has convergence, central blurred vision, haemorrhage, discharge.

Neuropathy with manifestations of edematous papillae, erection, blurred margins, dilated retinal veins, erection, may have a parietal haemorrhage. Neuropathy can lead to atrophy of the papillae, the white papilla.

Blurred vision due to the cerebral cortex occurs due to a tumour, trauma to the occipital region, the patient is blind or semi-fragile, and then the pupil reflex to light is still good.

Blurred vision caused by lack of vitamin A causes night blindness, narrowing of the market.


Strabismus: because the visual axis is skewed, the image of the object does not fall properly on the two macular points of the eyes, gradually squinting will be eliminated from the vision, decreasing vision leading to amblyopia.

The examination that the eyes are not aligned, the eyes may stick inward, outward or stagger.

Treatment: with optical glasses, practice to avoid amblyopia, restore binocular vision, or strabismus surgery. Treatment should be taken as early as 6 years to avoid amblyopia (blurred vision due to not using the eye)

The causes of the blurred vision fast

Blurred vision due to damage seen in the fundus

Clogged central retinal artery:

It is an emergency disease, caused by infectious diseases, cardiovascular disease ...

Symptoms: Sudden decreased vision, no red eyes, no pain.

Fundoscopy: the retinal area of ​​the occlusion artery is white oedema, the macular is crimson (signs of cherry macular)

Need emergency treatment with vasodilators (divascol, oral nitroglycerin ...) then find the cause for treatment. Treatment is required early from the first hour, however, the prognosis is very severe.

Obstruction of the central vein of the retina:

The cause is usually high blood pressure, infection, heart disease ...

Symptoms: Eyesight decreased for several days.

Fundoscopy: The central vein dilates, bulges each segment, the disc area has clusters of haemorrhages and secretions (image of a crater).

Complications: Complications of neovascular proliferation, vitreous haemorrhage, neovascular glaucoma ...

Treatment of causes, blood digestion, macular hyperemia, retinal laser photocoagulation treatment, cryotherapy, complications ...

Acute neuritis:

Causes: Usually due to infection, sinusitis.

Symptoms: Eyesight decreased rapidly, often with a central point.

Fundoscopy: Edema of the disc and retina around the disc.

Treatment of the cause, anti-inflammatory, reducing oedema.

Figure: Acute neuritis

Retinal detachment:

Cause: Severe myopia, trauma ...

Symptoms: At first, you can see flashes of light in front of your eyes, see things deformed, eyesight decreased, vision changes

Fundoscopy: the pupil is light grey in colour corresponding to the detachment area, the retina protrudes anteriorly, sometimes the wall of the zone, the blood vessels curl along the zones.

Surgical treatment, the purpose of repairing the tear, draining the fluid under the retina, the sclera or cutting the retinal seal fluid from the inside with gas or silicone oil.

Eales disease:

Inflammation of hemorrhagic wall in young people, the disease often causes hemorrhage of vitreous and prosperous retinopathy.

Rapid blurred vision due to unseen lesions in the back of the eye

Acute post-ocular neuropathy:

Due to inflammation, poisoning (methyl alcohol, ethambutol ...), the cause of the damage is far behind the eyeball, so there is no abnormal manifestation in the disc.

Eyesight decreased rapidly, or the central focus point.

Diagnosed by X-ray, magnetic resonance imaging, chromatography.

Histeria radical blindness:

Common in young women.

Usually blurred on both sides, pupil reflexes remain.

Diagnose after excluding other causes

Cortical blindness:

 Occurring after a trauma to the occipital region, the patient became blind, but no damage was seen in the eyeballs. Vision may be partially reversible or the disease can cause permanent consequences.