Blindness (visual impairment): what it is, types, causes and treatment

Vision problems are one of the most common physical conditions among the general populationIt is estimated that the vast majority of people suffer or will suffer from some type of visual problem throughout their lives. However, a vision problem of this type does not have to imply any degree of blindness.

There are certain criteria that to consider a difficulty in vision as blindness or visual impairment. Throughout this article we will talk about what blindness is, the different types that exist and what are their associated symptoms, causes and treatment.

What is blindness or visual impairment?

Blindness, also known as visual impairment or vision loss, is a physical condition that causes a decreased ability to see. to varying degrees and that causes a series of difficulties that cannot be completely compensated with the use of glasses or contact lenses.

To be more exact, the term blindness is used to define that condition in which the loss of vision is complete or almost complete.

Vision loss can come on suddenly or suddenly, or develop gradually over time. Besides,

vision loss can be complete or partial; that is to say that it can affect both eyes or only one respectively. It may even be partial because it only affects certain parts of the visual field.

The range of causes that can cause loss of vision is extremely varied and ranges from those that directly affect the eyes to those that involve the brain processing centers visual.

Besides, vision impairment often becomes more common as you age, with the most common risk factors being the appearance of physical conditions such as glaucoma, diabetic retinopathy, age-related macular degeneration or cataracts.

According to data from the World Health Organization (WHO), it is estimated that 80% of visual impairment is preventable or curable with treatment, including those caused by cataracts, infections, glaucoma, uncorrected refractive errors, certain cases of blindness infantile etc.

In all other cases, people with significant or total blindness may benefit vision rehabilitation programs, environmental modifications, and assistive devices.

Finally, in data from 2015, there were 246 million people with low vision in the world and 39 million people diagnosed with blindness. Most of these people are in developed countries and are over 50 years of age, but this may be due to a lack of data in developing countries.

Types of visual impairment

There are different types of visual impairment depending on the degree of impairment to the ability to see. This significance can imply from partial vision to complete blindness or visual impairment. The World Health Organization (WHO) developed the following classification of the different types or degrees of visual impairment.

To measure the degree of disability, vision in the better eye is taken into account, with the best possible lens correction. Taking this into account, the classification is as follows:

• 20/30 to 20/60: mild vision loss or near-normal vision
• 20/70 to 20/160: moderate visual impairment or moderate low vision
• 20/200 to 20/400: severe visual impairment or severe low vision
• 20/500 to 20/1000: near-total visual impairment or near-total blindness
• Lack of light perception: total blindness

In addition, depending on the specific vision conditions, visual impairment can also be classified as follows:

• Poor visual acuity and full visual field
• Moderate visual acuity and reduced field of vision
• Moderate visual acuity and severe visual field loss

To better understand these terms, it should be noted that visual acuity consists of the resolution with which we see. That is, the ability to perceive and differentiate visual stimuli. While the field of vision is the observable extension at each moment.

Finally, legal blindness or extremely poor visual acuity is considered as such when the person has a visual acuity of 20/200, even after lens correction. There are a large number of people diagnosed with "legal" blindness who are able to distinguish shapes and shadows but cannot appreciate their details.

What about night blindness?

A little-known type of blindness is night blindness, also known as nyctalopia. This type of blindness is a condition that causes great difficulty or impossibility to see in relatively low light.

It can also be described as insufficient dark vision adaptation and can be a symptom of various eye diseases such as retinitis pigmentosa, retinal detachment, pathological myopia or a side effect of certain medications such as phenothiazines, among many others Causes.

Causes of visual impairment

There are many common causes of visual impairment and blindness. However, the incidence of these varies considerably between the two conditions. The main causes of visual impairment in any degree can be:

• genetic defects
• waterfalls
• Glaucoma
• eye injuries
• brain damage (cortical blindness)
• eye infections
• Poisoning or intoxication by methanol, formaldehyde, or formic acid
• Other causes such as amblyopia, corneal opacification, degenerative myopia, diabetic retinopathy, retinitis pigmentosa, etc.

existing treatments

There are some treatment options that can help correct vision defects and minimize possible further degeneration. The choice of one of these treatments will depend on the following considerations:

• Degree of visual impairment or blindness
• Causes of visual impairment
• Age of the person and level of development
• General health status
• Existence of other conditions
• Patient expectations

Potential treatments or aids for managing both visual impairment and blindness include:

• Control of the disease underlying the visual impairment
• Magnification systems such as lenses, telescopes, prisms or mirror systems
• Mobility aids such as canes, guide or guide dogs or systems based on geolocation
• Reading aids such as Braille, optical recognition applications, audio-described books or reading devices that convert printed text into sounds or Braille
• Technology systems such as screen readers or magnifiers and Braille keyboards