A camera may mimic visual disturbances or Blurred vision out of focus. When lenses can not correct it, eye disease will then be suspected.
What are visual disturbances?
Most people experience occasional minor and temporary defects of vision from a variety of obvious causes such as watering and eye discharge.
By far the commonest forms of visual disturbance are simply the result of minor defects in the optical system of the eyes. These are correctable with glasses or contact lenses.
Real visual disturbances are frequently more severe and are often persistent. From middle age onwards most people perceive vitreous floaters in their field of vision.
These are nearly always harmless and can usually be safely ignored.
How are visual disturbances diagnosed?
Visual disturbances due to eye disease can readily be distinguished from optical errors and are often brought to light when an optician finds that the vision cannot be corrected by spectacles.
In such a case it is the duty of the optician to refer you to a doctor for further investigation. In many cases, the optician’s examination will reveal the cause of the problem, and they will outline the findings in the referral letter.
The doctor may then decide to treat you or may feel that further referral to an eye specialist (ophthalmologist) is required.
The doctor will confirm your visual disturbance, check the optics of your eyes and then proceed to an examination using various viewing instruments.
The original ophthalmic examination equipment is called a slit lamp. This is a binocular microscope linked to an intense source of focused light.
This enables a significantly magnified view of every detail of the inside of the front segment of the eye to be made every day. Sometimes the slit lamp is used in conjunction with special contact lenses to allow viewing of distant parts of the interior of the eye.
In addition to the slit lamp, the ophthalmologist invariably uses an instrument called an ophthalmoscope.
This allows a detailed inspection of the retina at the back of the eye.
Other instruments used include devices for visual field testing, for measuring the pressure in the eyes and for testing the accuracy with which the eyes work together.
The examination may also include color vision testing, photography of the retina, an analysis of the eye movements, a check for strabismus (eye misalignment) and a neurological examination (systematic consideration of the nerves) concentrating on the eyelids and face.
How are visual disturbances treated?
Treatment depends on the cause and the nature of the eye disease.
This common disorder is usually treated by surgical removal of the clouded lens and its replacement by a small, optically perfect lens implant. The results are almost uniformly excellent.
These can be treated by corneal grafting in which a small central disc is cut out of the opaque cornea and replaced by a transparent drive of identical size which is cut from a donor’s eye.
Treatment is by pressure-reducing eye drops and sometimes by drainage surgery. This will not restore lost function but can prevent further deterioration in vision.
Although sometimes treated by surgical removal of the opaque vitreous gel, the condition often resolves spontaneously. However, in many cases, recurrences are likely, especially if hemorrhages are caused by diabetes.
This can be treated by indenting the white of the eye with a small silicone rubber sponge which is sewn into place. The sponge absorbs fluid under the retina which can then resume its correct position.
Very low temperatures applied to the outside of the eye can then cause intentional inflammation and adhesion (growing together) of the tissues. Performed in time, this operation can give excellent results.
Symptoms of visual disturnances
- Double vision.
- Fogging or blurring of vision.
- Perception of dense floating specks or spots.
- Loss of part of the field of vision of one or both eyes.
- Changes in color perception.
- The partial blackout of the field of vision in one eye.
- The breakup of the image.
- Distortion of the image
- An apparent change in the size of the object viewed.
- Complete loss of vision in one or both eyes.
When should I see my doctor?
Most obvious difficulties are a matter for an optician. You should report without delay any disturbance of vision that you cannot explain, that seems unusual, that reduces your ability to see generally, that causes double vision, or that deprives you of any part of your field of vision towards the sides.
Brief, unexplained episodes of visual loss or disturbance may be due to TIAs (transient ischaemic attacks), and it is important to report these as they may indicate that you are at risk of stroke.
What causes visual disturbances?
Opacities in the outer lens (the cornea) from ulceration and scarring.
Inflammation is affecting the iris and leading to the deposition of cells on the inside of the cornea (anterior uveitis).
An abnormal and damaging rise in the pressure within the eye (glaucoma).
Opacities in the lens behind the iris (cataract).
Bleeding into the gel of the eye behind the lens (vitreous hemorrhage).
Bleeding into the retina (retinal hemorrhage).
Retinitis pigmentosa. This is usually of genetic origin.
Optic nerve inflammation (retrobulbar neuritis).
Malfunction of the nerves that control eye movement so that squint (strabismus) and double vision results.
Interference with the nerve tracts (the visual pathways) carrying impulses from the eyes to the back of the brain, from stroke, brain tumor, brain abscess or other serious brain conditions.
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