By Dr Raghuram Y.S. MD (Ay) & Dr Manasa, B.A.M.S
Night Blindness is a type of vision impairment. It is also called by the name ‘nyctalopia’. In this condition people experience poor vision at night or in dim light. Night blindness is a symptom of some other underlying conditions and comprises many causes.
Night blindness actually means that one cannot see at night. But in actual terms the person finds it difficult seeing or driving in darkness. It is often associated with an inability to quickly adapt from a well-illuminated environment to a dim light environment. People having myopia will have difficulties with night vision and are not due to retinal disease.
The eye as a rule should adapt to dim light. Night blindness does not cause complete blindness though it adversely affects ability to see in dim light. It may create problems in seeing road signs while driving at night and hence night driving should be avoided in this condition. Apart from this it will take longer for eyes to adapt when going from light to dark or bright light to dim light settings.
Some types of night blindness can be treated and some cannot be treated. First the underlying cause of the visual impairment should be detected. Once the cause has been identified steps to correct the vision can be taken.
Read – Ayurveda Treatment of Day Blindness and Night Blindness
Table of Contents
Difficulty seeing in the dark
Poor vision when driving due to intermittent brightness brought about by headlights and streetlights on the road.
Other symptoms –
Pain in the eyes
Sensitivity to light
Cloudy / blurring vision
Difficulty to see in the distance
(Read more here)
Causes of night blindness
This problem comes from a disorder of the cells in retina which allows to see in dim light.
Below mentioned eye conditions can cause night blindness –
Nearsightedness – This condition occurs when the eye grows too long and no longer focuses light correctly. These people cannot see objects in the distance accurately.
Cataracts – This condition occurs when the lens of the eyes become cloudy. This happens when due to ageing breakdown of proteins takes place in the lens. Clouding of lens can impair vision which may also occur in dim lighting.
Retinitis Pigmentosa – This is a group of eye diseases that damage the retina. It is a genetic disorder which results in ‘difficulty in seeing in low light’.
Usher syndrome – a genetic condition that affects both vision and hearing
Night blindness most often occurs in older adults since they have a greater risk of developing cataracts. Blindness due to cataracts is not as common in children or young adults as in older adults.
Vitamin A Deficiency – Vitamin A is an essential nutrient needed for the health of eyes and for vision. This vitamin makes up a protein that absorbs light in the retina and supports functioning of the eye. Deficiencies of vitamin A can have a serious impact on vision.
Read – Vitamins In Ayurveda – Sources, Functions, Deficiency Disorders
People with pancreatic insufficiency have greater risk of developing this disorder. These people have problems absorbing fat. Since Vitamin A is fat soluble these people have greater risk of having vitamin A deficiency which in turn puts them into a greater risk of developing night blindness.
High blood glucose levels – also puts people into the risk of developing eye diseases such as cataracts which in turn may cause night blindness.
Glaucoma – In this condition optic nerve damage causes pressure in the eye. This may cause permanent impairment of vision. Medications prescribed for glaucoma which closes your pupil and keratoconus can also cause night blindness.
Read – Glaucoma – Causes, Symptoms, Types, Prognosis, Treatment
Night blindness will be diagnosed following a detailed medical case history and thorough eye examination. Blood samples may be taken to measure blood sugar levels and vitamin A levels. The cause of night blindness should be found out and treated promptly.
Read – Trachoma – Causes, Symptoms, Prognosis, Treatment, Remedies
Treatment of night blindness depends on its cause.
Night blindness caused by vitamin A deficiency, cataracts or nearsightedness is treatable. Corrective lenses can help in improving nearsighted vision during both day and night. If one has trouble seeing in dim light even after using lenses shall contact the doctor immediately. Use of specific types of glasses or contact lenses can help to support correction of vision.
Read – Dhumadarshi (Smoky Vision) Meaning, Causes, Symptoms, Treatment
Sunglasses – protects the eye from ultraviolet light. You need to wear sunglasses regularly. UV rays increase risk of glaucoma, macular degeneration and cataracts. Your sunglasses should be able to block out at least 99% UVA and UVB rays, protect eyes from every angle and should be able to filter 75-90% of visible blue light.
Cataracts causing night blindness can be removed through surgery. This will help in improving the night blindness significantly after surgery provided cataract is causing your night blindness.
Vitamin A supplements shall be recommended if vitamin levels are low. It shall be added to the diet if vitamin A deficiency is the cause of night blindness.
Retinitis pigmentosa and other genetic conditions which cause night blindness cannot be treated. These people should be extra cautious because the condition does not respond to corrective lenses or surgery and they should avoid night driving.
Orange and yellow vegetables – These contain vitamin A which is good for eyes and vision.
Eye Surgery – In more severe cases of night blindness eye surgery may be necessary. LASIK is a type of surgery that changes the shape of cornea to improve vision. Other surgeries may be needed to remove cataract from the eye or to release pressure in the eye as a part of treatment of glaucoma.
Regular eye examination
Exercises – Regular exercise may reduce risk of eye conditions. It also might lower eye pressure and blood glucose levels.
Note – Some cases of night blindness may not be treatable. Retinitis Pigmentosa has not effective and proven treatments till date. Certain eye devices and therapy services might improve symptoms and quality of life.
Read – Importance Of Diet (Pathya) For Specific Diseases
If night blindness is due to birth defects or genetic conditions there is no prevention. You can anyhow monitor blood sugar levels and take a balanced diet to make this condition less likely.
Foods rich in vitamins, minerals and antioxidants will prevent cataracts. Foods having high levels of Vitamin A also preferred.
Vitamin A rich foods include
Dark, leafy green vegetables
Cod liver oil
Orange and yellow vegetables and fruits
Vitamin A can also be found in spinach, milk and eggs.
Our ancestors had very powerful night vision – New genetic evidence confirms that our earliest mammalian ancestors had powerful night-time vision. The findings published in ‘Journal Scientific Reports’ suggests that adapting to dark life and darkness helped early mammals find food and avoid reptilian predators that hunted by day.
Vitamin A fortified orange maize improves night vision – Rural children in Zambia, part of the study got meals made from vitamin A biofortified orange maize. In this group of children improved night vision, dark adaptation and better engagement in day to day activities were observed.
Gene therapy would preserve vision in dogs with night blindness – In a study involving dogs with naturally occurring late-stage retinitis pigmentosa which is one of the main causes for night blindness and progressive degeneration of retina, gene therapy has been found to preserve vision. These are interesting findings. This could lead to clinical trials for people with blinding eye disorder for which there is no cure currently.
Calcium protein mutation – Researchers at Johns Hopkins University School of Medicine have found the molecular mechanism behind the ‘calcium channel protein’ mutation that causes congenital stationary night blindness.
An eye wear like Google Glass has been patented by IBM which will have red-eyed night vision capabilities according to a media report. It doesn’t promise a true night vision but the device is described in the patent to improve sight under low light. This is achieved by tricking the brain to focus on high contrast imagery. (Read more)
An ethnographic study of night blindness ‘ratauni’ among women in the Terai of Nepal – The findings of this study have relevance for reproductive health and nutrition of women throughout the Indian sub-continent. History of night blindness might prove to be a practical tool to identify women with nutritional and health risks. In vitamin A deficient areas of the world maternal night blindness should be investigated routinely. This should be done to define the magnitude of the problem and to develop programs / interventions that specifically target this population.
Prevalence of night blindness in Bashagard district in Hormozgan, Iran, in 2011 – In the study which was conducted about 60% participants were uneducated or with low education. 2/3 cases (out of 814 people) had problems with night vision. Therefore the prevalence of night blindness in Bashagard was 3.93%. Prevalence of night blindness in Bashagard is thrice higher than its prevalence in all Iran. Therefore preventive interventions such as dietary regimes with vitamin A enrichments or supplementations are recommended.
Read – Corneal Opacities – Causes, Symptoms, Preventive, Treatment
A disease condition of vision which has been explained by Master Sushruta in the name of ‘Shleshma Vidagdha Drishti’ can be closely correlated to ‘night blindness’. In this condition the vision is hampered and afflicted by vitiated kapha wherein the person will be able to see things properly in day time and the vision will get deteriorated in dark or night time.