The WHO has confirmed more than 2 billion people around the world affected by visual impairment or near-blindness! This means that more than one-third of the world’s population is missing one of the most important senses, which prevents them from becoming functioning society members and impairs their daily life routine. WHO has also estimated that more than 1 billion cases could be prevented or treated and their vision could be restored!  

what is visual impairment?

According to the International Classification of Diseases 11 (2018), visual impairment is classified into two main groups (distance and near impairment). In the first group, the distance vision impairment is further categorized into mild, moderate, severe impairments and blindness. This classification depends on the degree of visual acuity ranging from 6/12 to worse than 3/60. The categories are as follows:

• Mild visual impairment: if acuity is worse than 6/12.
• Moderate visual impairment: if it is worse than 6/18.
• Severe visual impairment: if the eye’s visual acuity is worse than 6/60.
• Blindness: total vision loss if visual acuity is worse than 3/60.

Near visual impairment is having near visual acuity that is worse than N6 or M.08 with existing visual correction. While the American Optometric categorizes visual impairment into other two main categories:

• Partially blind: when the patient has visual acuity that ranges between 6/18 to 6/60 with correction.
• Legally blind: when the patient has visual acuity worse than 6/60 with correction and/or an impaired or restricted vision field that is less than 20 degrees wide.

 

What are the common causes of visual impairment?

In the 1 billion people with reversible visual impairment (if managed early enough) there are very common causes that include:

• refractive errors
• cataract
• glaucoma
• corneal opacities
• diabetic retinopathy
• macular degeneration
• retinal detachment.
• strabismus
• trachoma
• unaddressed presbyopia is the most common cause (more than 800 million patients).

While in children, more problems could be added to visual impairment causes:

• Cortical visual impairment (CVI): if any problem affects the visual area of the brain at any point in the child’s life (for example brain injury, cerebral palsy, encephalitis, meningitis) then this child will suffer from temporary/permanent visual impairment
• Retinopathy of prematurity (ROP): preterm babies are at great risk of visual impairment due to the abnormalities of blood vessels of the retina. If the baby is fortunate enough then it will self-resolve if not, blindness is the end-stage of ROP.
• Albinism: though uncommon, but this genetic condition causes many eye problems in albino that eventually lead to vision loss.
• Congenital visual impairment: if the pregnant mother has any STD that affected her fetus or she is a smoker/drug addict, then her baby is at risk of congenital cataract, congenital glaucoma, and other eye diseases.
• Trachoma is a very serious infectious disease that affects children and may lead to blindness.

According to WHO, the prevalence of each disease is related to the region affected, meaning that developed countries have far fewer cases of visual impairment than third world countries.  

How is visual impairment diagnosed?

An eye examination is the only method to detect and diagnose any eye problem, visual impairment and low vision included. An experienced ophthalmologist can diagnose the problem and its cause, all you have to do is visit the nearest eye care center whether in a routine checkup or if you suffer any visual difficulties or eyestrain. Your doctor will perform the eye examination after taking a full medical history this includes questions about: your general health, your eye’s health, and your family’s history. If you have any chronic disease, then its history is important too including the medications you take to treat it. And the most important question, how is your daily life affected by your visual impairment!

• After checking for visible signs of any eye disease, your doctor will then use certain instruments and tools to diagnose the extent of the problem and its probable cause.
• To measure your visual acuity, your eye care specialist will use special charts to test your vision (to detect nearsightedness, farsightedness, and/or astigmatism), your depth perception and your visual field.
• Another device is used known as slit-lamp to diagnose any corneal problem (including corneal abrasions, keratoconus), lens problems (including cataract)
• A fundus examination is important if your doctor suspects any retinal damage due to macular degeneration or retinal detachment or glaucoma. This examination requires adding a few pupil-dilating eyedrops in order to see the back of the eye properly.

 

How can visual impairment be treated?

If visual impairment is mild or moderate then according to the cause of the visual impairment your doctor will advise the treatment plan. For example:

• Refractive errors: prescription eyeglasses and contact lenses are their first line of treatment.
• Cataract: cataract surgery is the best treatment option.
• Glaucoma: certain eyedrops could be helpful in treating glaucoma or at least slow its progression.
• Corneal opacities: corneal transplant is the go-to treatment modality.
• Diabetic retinopathy: since it is highly dependent on your blood sugar levels, then keeping your sugar levels in check is the best prophylactic method against its complications.
• Strabismus: diagnosing crossed eyes as early as possible and correcting its main problem is the only prophylactic method against vision loss in one or both eyes.
• Trachoma: access to clean water and antibiotics are the best line of defense against it.
• Retinal detachment: treating it as an emergency situation helps prevent vision loss
• Age-related diseases: since we can’t fight age and its marks on our body, our only available treatment is early detection of the disease, preventing its complications and slowing down the aging process by eating healthy and exercising

 

How to treat severe visual impairment?

If your vision has already been affected massively, where any surgery, medication or laser can’t help restoring it then visual aids come in handy. Visual aids include:

• Magnifying or telescopic glasses.
• Hand magnifiers.
• Reading prisms.
• White canes

Technology is now advancing enough to help many visually impaired patients by providing alternative solutions that include high-tech visual aids, video reading systems, certain color restoring lenses, autofocus spectacles and of course talking applications.  

Magrabi’s advice

More than 50% of visually impaired cases could have been treated if detected early. This is a global problem that is addressed by multinational NGOs and Magrabi’s hospitals have had their share in helping visually impaired patients restore their vision and quality of life. It is never too late to restore your vision, if you complain of any eye problem you must visit your ophthalmologist as soon as possible to prevent all its complications especially vision loss.