Night Blindness, also referred to as Nyctalopia, is a vision-linked condition wherein individuals cannot view objects clearly at night or in a dark surrounding with low lighting. This creates difficulties in performing certain activities such as driving vehicles during the night or searching for belongings and valuables in poorly lit places. Even in commonplace situations like reading the dinner menu in a restaurant or watching a movie in a theatre, it poses obstacles in seeing things distinctly.
Night blindness is essentially the incapability of the eyes to switch over quickly and smoothly from a brightly lit environment to a dark area with barely any lighting, but it does not result in complete blindness. Moreover, night blindness is not a standalone health anomaly; it does not occur by itself but is rather an accompanying sign of an underlying eye disorder, for example, defects in the retina or myopia i.e. nearsightedness.
The eyes are the pair of sensory organs responsible for sight and being a crucial part of the human body for performing almost all activities, are always functioning and vigilant. During the course of the day, the eyes have to continuously adapt to varying intensities of light, such that the pupils constrict or become smaller when exposed to bright rays and dilation of pupils i.e. them becoming larger in size occurs in dim settings.
In the darkness, the dilated pupils permit more light waves to enter the eyes, which are absorbed by the retina. The retina is the light-sensitive layer at the rear end of the eyes, encompassing specialised rod cells - which aid in perceiving things in the dark and cone cells - that assist in identifying different colours. Hence an ailment developing in the rod cells or structural flaws, tissue injuries in that segment of the retina lead to night blindness.
Causes Of Night Blindness:
Night blindness is induced by pre-existing eye conditions, most of which can be effectively treated or managed with proper medical care. The most common and frequently reported causes are:
Vitamin A Deficiency: Vitamin A, also called retinol, is a vital nutrient that preserves optimal functioning of the eyes, by facilitating light absorption in the retina and promoting healthy vision. Thus, a lack of vitamin A triggers vision problems and night blindness.
Cataracts: An eye disorder that arises from ageing, wherein the eye lens is impaired from damaged protein assemblies and have a cloudy appearance, thereby obstructing eyesight in dark surroundings.
Glaucoma: Glaucoma occurs due to defective optic nerve structures, which prompt excessive pressure in the eyes and hamper vision, including at night.
Nearsightedness: Myopia or nearsightedness is the inability to see objects that are farther away precisely, due to improper lengthy/curved shape of the eyeball or cornea, with the eyes not being able to focus light accurately on the retina.
Retinitis Pigmentosa: Also termed rod-cone dystrophy, retinitis pigmentosa results in the hampered structure of the retina due to genetic flaws and leads to tunnel vision and night blindness.
Usher Syndrome: This is a very rare genetic condition that is characterised by damaged hearing abilities along with retinitis pigmentosa.
Risk Factors For Night Blindness:
Certain factors significantly increase the chances of acquiring night blindness and include:
Diabetes: which involves high blood sugar/high blood glucose levels and causes vision problems such as diabetic retinopathy, diabetic macular oedema and night blindness
Pancreatic Ailments: like cystic fibrosis, in which fat absorption by cells is hindered, increasing the risk of vitamin A deficiency, as vitamin A is fat-soluble and subsequently inducing night blindness
Poor Nutrition: with insufficient intake of foods high in vitamin A, which leads to the deficiency disorder of night blindness
Symptoms Of Night Blindness:
The defining symptom of night blindness is challenges in seeing things properly in dark environs or at night time. Other accompanying indications of night blindness depend on the exact cause and comprise:
- Pain in the eyes
- Persistent headaches
- Nausea and vomiting
- Blurred and hazy vision
- Increased sensitivity to light, particularly bright rays
- Problems in viewing distant objects
Diagnosis And Treatment Of Night Blindness:
The eye doctor or ophthalmologist records the entire medical history of the patient to determine if any serious eye injuries have been encountered in the past. An eye exam is also conducted, which thoroughly studies the various aspects of vision, such as reading small text or print, peripheral or side vision, optic nerve structures, eye pressure and pupil dilation. Furthermore, the physician takes a blood sample of the patient, to evaluate the levels of vitamin A and glucose in the blood, to identify if a nutrient deficiency or diabetes is instigating night blindness.
Treatment for night blindness is based on the cause of the condition.
- If myopia is triggering night blindness, then corrective glasses/contact lenses will help fix the eye defect.
- Cataracts can be rectified with surgery to resolve the clouding of the eye lens and enable clear vision.
- Glaucoma is treated with prescription eye drops, laser procedures, surgery and/or medications, which although do not completely mend eye problems, do help to reduce eye pressure and improve vision.
- Vitamin A deficiency leading to night blindness is treated with vitamin A supplements that should be taken at the prescribed dose.
- However, if genetic aberrations like retinitis pigmentosa and Usher syndrome are the cause of night blindness, they cannot be cured or completely treated. Such individuals are advised by the healthcare professional to avoid driving, especially at night and not engage in complex activities in the dark that strain the eyes.
How Can Night Blindness Be Prevented?
While genetic disorders that lead to night blindness cannot be prevented, adopting some healthy lifestyle practices helps avert acquired eye defects, thereby avoiding night blindness. These consist of:
- Eating foods rich in vitamin A, such as carrots, spinach, milk, eggs, sweet potatoes, mangoes and pumpkins
- Go for routine eye checkups, to detect any vision problems early on and treat them efficiently
- Wear protective sunglasses in bright outdoor places, which shield the eyes from harmful UV rays
Night blindness is not an eye ailment by itself but is a symptom of an underlying vision problem like myopia, cataracts, glaucoma and other defects of the retina that arise from vitamin A deficiency or genetic faults. It does not lead to permanent blindness and can be remedied effectively by identifying the cause and undergoing pertinent medical treatment by a doctor.