Blindness has many types and causes, ranging from injuries and infections to neurological or congenital conditions. Blindness can be classified according to its cause or whether a person has total or partial blindness. Blindness is a general term that includes people who are visually impaired and those who cannot see. A wide range of conditions can cause it in newborns, children, and adults. This article presents the different types of blindness and some examples of their causes.
What are the types of blindness?
Health professionals classify types of blindness into the following categories:
Total blindness: This is when a person cannot see anything, including light. Only 15% of people with eye problems have total blindness.
Low vision: Low vision describes visual impairments that medical professionals cannot treat using conventional methods, such as glasses, medications or surgery.
Visual impairment: Visual impairment is a general term that describes people with vision loss that interferes with daily activities, such as reading or watching television.
The types of blindness can also be classified according to their cause. Here are some of the conditions that can lead to vision loss.
Age-related blindness
Visual impairment is more common in older people. The potential causes are as follows
Age-Related Macular Degeneration (AMD): AMD is an eye condition that occurs when aging damages the macula, which controls sharp, direct vision.
Cataract: A cataract is a cloudy area that develops on the lens of the eye. It can cause clouding or blurring of vision, color fading and reduced night vision.
Diabetic retinopathy: This complication of diabetes is more likely to develop in older adults. It occurs when high blood sugar damages the tiny blood vessels that supply the retina.
Glaucoma: Glaucoma is an eye disease that damages the optic nerve at the back of the eye. It is more common in people aged 60 and over and can cause vision loss.
Eye injuries
Eye damage can lead to vision loss or blindness in some cases. They can occur as a result of
the practice of a sport
physical abuse
motor vehicle accidents
chemical burns
exposure to toxins
falls or collisions
objects such as darts, bullets, explosives or fireworks
Infectious diseases
Many infectious diseases can cause vision loss. Here are some examples
Trachoma: This is a bacterial infection that can cause itching, irritation, discharge and swelling of the eyelids. Trachoma is the cause of more vision loss and blindness than any other infection in the world.
Shingles: The virus that causes chickenpox is also the cause of shingles. When shingles affects the eyes, it can lead to scarring, ulceration and perforation of the cornea, which results in severe loss of vision.
Cytomegalovirus (CMV): CMV is a herpes virus that can cause CMV retinitis, a serious viral infection that destroys the retina and damages the optic nerve. This disease is more common in people with weakened immune systems.
Histoplasmosis: Histoplasmosis is a fungal lung infection. The infection can travel from the lungs to the eyes, causing ocular histoplasmosis syndrome and loss of vision.
Keratitis: This is an inflammation of the cornea that usually occurs as a result of a bacterial, viral or fungal infection. If left untreated, it can lead to serious complications that permanently damage vision.
Syphilis: Syphilis is a sexually transmitted infection (STI) that can affect the eyes, leading to loss of vision and permanent blindness in some cases.
Toxoplasmosis: This disease is caused by a parasitic infection. Some people are at risk of ocular toxoplasmosis, which causes inflammation of the retina. If left untreated, it can lead to progressive loss of vision.
Uveitis: Uveitis is inflammation of the middle layer of the eye, called uvea, which can cause loss of peripheral vision and complications that can lead to blindness.
Non-infectious conditions
Several non-infectious conditions can also cause blindness. These include in particular
Amblyopia: Amblyopia or “lazy eye” is an impairment that occurs in one or both eyes due to a failure in the way the eye and brain work together. Without treatment, amblyopia can cause vision loss.
Stroke: If a stroke damages a part of the brain responsible for sight or eye movement, sufferers may experience vision changes or loss.
Retinopathy of prematurity (ROP): ROP is an eye disease that occurs in premature infants when atypical blood vessels develop in the retina. At an advanced stage, ROP can lead to retinal detachment and blindness.
Cancer: Certain types of cancer, such as orbital tumors, can cause complications, including retinal detachment and blindness.
Nutrition blindness
Nutritional blindness is caused by vitamin A deficiency. This deficiency can lead to
xerophthalmia, which causes dry eyes and inflammation
keratomalacia, i.e. drying and clouding of the cornea
corneal necrosis, which is the death of cells and tissues in the cornea.
According to the World Health Organization (WHO), 250,000 to 500,000 children with vitamin A deficiency go blind each year.
Snow blindness
Snow blindness occurs when UV rays from the sun reflect off ice or snow, damaging the cornea and conjunctiva. Snow blindness can also refer to freezing of the cornea or severe drying of the surface of the cornea due to air dryness. It usually occurs in people who ski, mountaineer or snowmobile. Although snow blindness is temporary, repeated exposure to UV rays without sunglasses can lead to other eye disorders causing permanent vision loss.
Night blindness
Night blindness, or nyctalopia, is characterized by poor vision in dimly lit environments or at night. Despite the name, people with night blindness are not blind, but may have difficulty seeing in places such as movie theaters, restaurants, or driving at night. Night blindness can be caused by eye conditions, such as myopia, cataracts and retinitis pigmentosa. Vitamin A deficiency can also be the cause.
Genetic and congenital blindness
Several genetic diseases can cause blindness.
Blindness can be present from birth, this is called congenital blindness. In some cases, however, blindness develops later. Here are some examples:
Leber’s hereditary optic neuropathy (LHON): LHON is an inherited condition that is passed from biological parent to child. It causes clouding and blurring of vision, which progress to blindness.
Oculocutaneous albinism: Albinism is characterized by the absence of melanin in the hair, skin and eyes. This can sometimes affect vision.
Retinoblastoma: this type of eye cancer can be hereditary and occur as a result of changes in certain genes.
Inherited retinal diseases (IRDs): Inherited retinal diseases are rare conditions that can lead to vision loss and blindness. Genetic mutations in more than 260 genes can cause these diseases. Inherited retinal diseases can include conditions such as:
retinitis pigmentosa
choroideremia
Stargardt’s disease
taper rod dystrophy
X-linked retinoschisis
Blindness can also be due to birth defects, such as
anophthalmia, which is the failure of a fetus to develop one or both eyes
microphthalmia, when one or both eyes are very small
coloboma, which is characterized by part of the eye not growing in the usual way
childhood glaucoma
Other causes of congenital blindness include:
congenital disorder cornea
congenital cataract
optic nerve damage
cerebral visual impairment, which occurs as a result of brain injury
ophthalmia neonatorum, which is an eye infection that newborns can get if their birth parent has an STI.
Is color blindness a type of blindness?
Color blindness does not cause blindness or loss of vision. However, sufferers see colors differently than others. Color blindness tends to run in families. Color blindness can make it difficult to distinguish between certain colors, such as red and green or blue and yellow. Some people are completely color blind and cannot see any color. However, this situation is infrequent.
What is the most common type of blindness?
Age-related eye diseases, such as AMD and cataracts, are the main causes of low vision and blindness.
Summary
There are several ways to classify blindness. Certain categories describe the degree of vision loss a person has, ranging from some impairment to complete blindness. Blindness can also be classified by its causes, which vary widely, from congenital conditions to those that occur later in life. The most common causes of blindness are age-related, including conditions such as AMD and glaucoma. Blindness can also result from injuries, infections, vitamin A deficiencies, UV damage, birth defects, and many other conditions.
