Nyctalopia is the scientific name for 'night blindness'. It is also known as nyctanopia, or keratomalacia. It is one of the commonly observed problems of the eyes. People having night blindness find it difficult to see at night or in any kind of poor light. The retina of the eye is made up of rod cells and cone cells. The outer part of the retina consists of more rod cells than cone cells. We can see in poor illumination with the help of the rod cells present in the outer part of the retina; because the rod cells can function well in poor light. The rods are about 100 times more sensitive to a single photon of light than cones. Disorder of the rod cells leads to night blindness.
Night blindness mostly occurs, when rod cells in the retina are unable to respond to the light. In progressive nyctalopia, the rod cells lose their capacity of responding to the light gradually. If dysfunction of the rod cells is a congenital problem, then it is usually genetic. In such cases, the rod cells may function a little or may not function at all. This condition which prevails throughout the life span without getting worse, is known as 'X linked congenital stationary night blindness'.
Night blindness is known as 'retinitis pigmentosa' (RP) when it is caused by genetic eye conditions and when it leads to progressive loss of vision. The optic nerve becomes pale white (optic atrophy). The daytime vision may also be affected in such cases and it may lead to incurable blindness. The person experiences 'defective dark adaptation' in earlier stages. He may experience reduction of the peripheral visual field (reduced tunnel vision) and may lose central vision in the advanced stage of the disease. Knowing the causes of night blindness may help prevent the advancement of the disease.
- Deficiency of retinol (vitamin A) is one of the major causes of retinal disorder. Supply of vitamin A ensures the supply of the pigment needed by the rod cells. Scarcity of vitamin A can make the eyes very dry, and can lead to night blindness. People of less developed countries are more susceptible to vitamin A deficiency and hence, more prone to vision problems like nyctanopia. Vitamin A deficiency symptoms like poor vision, corneal inflammation, etc., need prompt medical attention.
- In spite of a balanced diet, one may suffer from vitamin A deficiency if the body is not able to absorb vitamin A from the food. This situation can arise after a surgery of the pancreas or liver. Chronic liver and intestinal disorders can eventually lead to night blindness.
- Zinc enhances the function of vitamin A. So lack of zinc in diet can cause eye problems. Balanced diet helps prevent electrolyte imbalance.
- Chronic diseases like diabetes can affect the vision seriously. So controlling diabetes with medications, diet and exercise is very important.
- Cataracts which are visible as the cloudy areas on the lens of the eye, can cause night blindness. Older people are more likely to develop cataracts.
- Functional problem in the rods of the retina leads to the loss of side vision and night blindness. An injury, malnutrition or any other eye problem can make a person night blind.
- Even excessive stress, anxiety disorders, or fear of the darkness can cause severe vision problem like nyctalopia.
- Untreated myopia (nearsightedness), leads to night blindness. So, eye problems should never be neglected.
- Glaucoma medications constrict the pupil, which eventually can lead to keratomalacia.
- Excessive exposure to sunlight can temporarily affect your night vision.
- Eyes take more time to adjust when you come from a brightly lit area to a dimly lit area. Glaring car headlights can momentarily affect the vision of the person.
- The person may not be able to watch television or read a book for a longer time. The eyes may get tired after working with a computer for a few hours.
- One may not be able to see the pedestrians walking alongside when the street is poorly lit. It is one of the notable symptoms of night blindness.
- Difficulty to see at night, difficulty to see in less intense light or in darkness during day-time, are the main symptoms of night blindness.
- Reduced contrast sensitivity sometimes occurs as a result of laser vision surgery procedures and in turn, it may lead to serious vision problems.
- People with nyctalopia may suffer from dry eyes.
- They may complain about blurred vision and may have problem seeing even when the place is well illuminated.
- The person may not be able to see stars in a clear sky at night.
- A person with affected vision may have difficulty driving at night.
- A person with night blindness may require extra light to read.
- He would not be able to recognize images in dim light
- The person may have problem walking through a dark theater.
- Often stumbling on the stairs or pavements can be a symptom of night blindness.
Treatment of night blindness depends upon the cause and the severity of night blindness symptoms. Once the cause is detected, the doctor can determine the mode of the treatment, which generally involves:
- Removal of cataracts
- Stopping the consumption of glaucoma medications. Changing the medications.
- Getting the eyes tested for nearsightedness from a recognized ophthalmologist and changing the glasses.
- Adding vitamin A rich foods (like fish oil, liver and dairy products) to the regular diet and if required, taking vitamin A supplements.
This HealthHearty article is for informative purposes only, and should not be used as a replacement for expert medical advice. An eye doctor can examine the eyes thoroughly and take the necessary steps required for the improvement of the vision. In extreme cases, like cataracts, surgery is required. Proper eye care and vitamin A rich diet usually help improve the vision to a certain extent. The age and the overall health of the patient determine the effectiveness of the treatment.