Loss of vision can occur suddenly or develop gradually over time. Vision loss may be complete (involving both eyes) or partial, involving only one eye or even certain parts of the visual field.
Vision loss is different from blindness that was present at birth, and this article is concerned with causes of vision loss in an individual who previously had normal vision. Vision loss can also be considered as loss of sight that cannot be corrected to a normal level with eyeglasses.
Causes
The causes of loss of vision are extremely varied and range from conditions affecting the eyes to conditions affecting the visual processing centers in the brain. Impaired vision becomes more common with age. Common causes of vision loss in the elderly include:
- Diabetic retinopathy – a diabetes complication that affects the eyes. It’s caused by damage to the blood vessels of the light-sensitive tissue at the back of the eye (retina).
- Glaucoma – a group of eye conditions that damage the optic nerve, which is vital to good vision. This damage is often caused by an abnormally high pressure in your eye.
- Age-related macular degeneration (AMD) – a condition that affects the macula, a small area in the retina, the light-sensitive tissue lining the back of the eye. The macula is the part of the retina that is responsible for your central vision, allowing you to see fine details clearly.
- Cataract – clouding of the normally clear lens of your eye.
Diagnosis
An ophthalmologist will perform a complete and thorough eye examination.
Treatment and Management
For management for patients some considerations are important:
- The degree of impairment, disability, or handicap
- Cause of visual impairment and possible outcome
- Age of the patient and level of development
- General health of the patient
- Patient’s other impairment and adjustment to the vision loss and patient’s expectations from therapy
Treatment will depend on the cause of the vision loss. Treatment and management of visual impairment include:
Control of diabetes – This prevents progression of diabetic retinopathy and resulting visual impairment to some extent. However in advanced cases this may be of little help.
Cataract surgery – In cases of visual impairment due to cataracts, surgery may be opted. Usually an artificial lens is placed within the eye as a replacement of the damaged and clouded lens. This, more often than not restores vision
Magnification systems – This is achieved using appropriate lens, reading telescopes or surgical systems etc. Hand magnifiers may also be offered. For improvement of visual fields prisms and mirror systems may be prescribed.
Glaucoma – medications in eye drops are prescribed to control glaucoma. These may contain drugs like Latanoprost, tafluprost, travoprost which are prostaglandin analogues.
The drugs may include Beta-blockers like betaxolol hydrochloride or carbonic anhydrase inhibitors dorzolamide and Sympathomimetics like brimonidine tartrate.
Glaucoma may also be managed surgically using open microscopic surgery, laser corrections, etc.
AMD – At present there are no cures for age-related macular degeneration, especially of the dry variety.
For wet AMD there are therapies that help to stop the progression. These include Photodynamic therapy. This uses a light-sensitive medicine called verteporfin injected into a vein of the arm. The drug identifies the abnormal blood vessels in the eyes and attaches itself to the proteins in these blood vessels. This is followed by a low-powered laser therapy.
Some new types of medications called Anti-VEGF medication may also be used. One example is Ranibizumab.
