‘Light-out’ in the eyes: A closer look at night blindness

It is another night in Kumasi. The lights, once bright, have gone dim again followed by that unrehearsed but well-timed chorus Ghanaians yell out when the lights go off. As it has been the case for the past weeks, many parts of the country have been equally enveloped by darkness without warning.

The tropical heat makes the room hot, driving Elsie (pseudonym) and her family outside. Her elder brothers and other tenants lament the unfortunate situation, condemning the government and the power company for the recurring dumsor (off and on), an Akan expression that has become associated with erratic power outages in the country.

But for the blazing indoor heat and the nocturnal onslaught of mosquitoes outside, Elsie would not be bothered so much about the habitual lack of electricity in the evening. Why? Her eyes have been used to their own ‘dumsor’ for many years. She struggles to see in the evening. It is not an errant power company that dims her world at night, but an often overlooked eye condition known as night blindness.

Night blindness

The condition also known as nyctalopia is an insufficient adaptation to darkness.

An optometrist and Chief Executive Officer of Firmer Eye Care, Dr Emmanuel Ekow Ampiah, explains it is normal for people not to see well in the dark but it is the considerable difficulties seeing at night or in poorly lit areas that is termed night blindness.

In other words, the condition is associated with one’s inability to quickly adapt from a well-illuminated to a poorly illuminated area.

“When one enters a dark room, one should be able to locate switches or some basic things but if there is considerable inability to do so, then there is a problem”, he said.

Causes

Dr. Ampiah underscores myopia, or nearsightedness, as one of the causes of night blindness. He explains, “Myopia means that you are unable to see things that are far away. People who are short-sighted often experience challenges seeing well at night”, he said.

Another significant contributor to night blindness is glaucoma, a condition characterised by increased pressure within the eye. It is the number one cause of irreversible blindness globally. According to Dr Ampiah, individuals with glaucoma may experience a loss of peripheral vision, impacting their ability to see objects from the side, especially at night.

Cataracts, often associated with ageing, also play a pivotal role in night blindness. People with cataracts develop cloudy vision, making it challenging to see well, especially in low-light settings.

Furthermore, diabetes emerges as a notable contributor to night blindness. Dr. Ampiah elaborates, “High sugar levels in diabetes can distort vision, making it challenging to see well, particularly at night.”

Dr. Ampiah delves into the genetic condition of retinitis pigmentosa, characterized by pigment buildup on the retina. He explains that “This condition creates tunnel vision, limiting peripheral sight and posing challenges for nighttime navigation.”

Vitamin A
Deficiency in Vitamin A plays a key role in night blindness. According to the World Health Organisation (WHO), night blindness is one of the first signs of vitamin A deficiency.

In its more severe forms, vitamin A deficiency contributes to blindness by making the cornea very dry, thus damaging the retina and cornea. An estimated 250, 000–500, 000 children who are vitamin A-deficient become blind every year, and half of them die within 12 months of losing their sight.

Deficiency of vitamin A is associated with significant morbidity and mortality from common childhood infections, and is the world’s leading preventable cause of childhood blindness.

The WHO states that Vitamin A deficiency also contributes to maternal mortality and other poor outcomes of pregnancy and lactation. It also diminishes the ability to fight infections. Even mild, subclinical deficiency can be a problem, because it may increase children’s risk for respiratory and diarrhoeal infections, decrease growth rates, slow bone development and decrease the likelihood of survival from serious illness.

This is because Vitamin A plays a crucial role in transforming nerve impulses into images on the retina. A deficiency in this vitamin can lead to night blindness.

Dr Ampiah explained that vitamin A plays a pivotal role in the synthesis and production of a pigment called rhodopsin, which is predominantly found in the back of the eye.

Rhodopsin is particularly crucial for night vision, as it enables the retina to capture and process light in low-lit conditions. When the body lacks an adequate supply of vitamin A, the synthesis of rhodopsin is hindered, leading to a deficiency that can result in impaired vision at night.

Statistics
Due to the interconnectedness of night blindness to other eye conditions, there is no stand-alone data on its prevalence. This means that the condition could be as prevalent as the other forms of eye conditions.

According to data from the WHO states that at least 2.2 billion people globally have a near or distance vision impairment with the leading causes being refractive errors and cataracts.

In Ghana, a 2022 report by Daily Graphic states that there are 331,700 people suffering from severe visual impairment, representing 1.07 per cent of the country’s population.

The Head of the National Eyecare Unit, Institutional Care Division of the Ghana Health Service, Dr Hornametor Afake, is reported to have said another 229,400 people, about 0.74 per cent of the population, were totally blind.

People who were blind from cataract constituted 54.8 per cent or 126,170 of the blind population; glaucoma accounted for 44,503 people, about 19.4 per cent; posterior segment, 12.9 per cent — 29,822 people, while cornea opacity was 11.2 per cent – 25,234 people.

Of the 1.07 per cent who had severe visual impairment, refractive error accounted for 44.4 per cent of the cases, translating into 145,948 people, while cataract constituted 42.2 per cent of the cases, numbering 139,314.

Elsie’s case
Elsie has suffered night blindness since she was a toddler – nearly 30 years. Her parents spotted her inability to see at night when she kept crawling and crashing into stationary objects in the evening. Several efforts, including medical and spiritual have been made but the underlying cause of her visual impairment still prevails.

Now living on her own and working, she has learned to finish her chores before dark so she does not crash into items. Many people who have this condition, have devised similar means of survival.

Risk factors
While specific risk factors for night blindness itself remain elusive, the optometrist highlighted that underlying conditions such as myopia, glaucoma, cataracts, and vitamin A deficiency can increase the likelihood of developing this condition. Night blindness is often diagnosed through a comprehensive examination, which includes taking the patient’s medical history and conducting specific tests tailored to the individual case.

Treatment
Dr Ampiah shared insights into the treatment of night blindness, emphasizing the importance of addressing the underlying cause.

“The treatment for night blindness depends on the cause. If it’s myopia, we do refraction to provide the person with glasses. If it is cataracts, we can recommend surgery for the cataracts. If it’s glaucoma, we try to reduce the eye pressure.”

Lifestyle changes, including dietary adjustments, were also mentioned as potential contributors to managing or improving night vision.

Night blindness can manifest as either a temporary condition or a persistent and progressive issue, depending on the underlying factors. Genetic factors, such as retinitis pigmentosa, may lead to a persistent and progressive form of night blindness, while conditions like myopia, cataracts, and diabetes can be managed and treated to eliminate or alleviate night blindness symptoms.

However, certain conditions, such as glaucoma, may have limitations in restoring vision due to irreversible optic nerve damage, Dr Ampiah explained.

Furthermore, he emphasised the importance of a comprehensive approach to eye health, as multiple conditions can coexist and contribute to night blindness. Encouraging a balanced diet rich in vitamin A, including foods such as green leafy vegetables, milk, eggs, and potatoes, can significantly support overall eye health and potentially aid in managing night vision concerns.