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What is Hemeralopia & How is it Treated? | Causes, Symptoms, Prevention of Hemeralopia

What is Hemeralopia?

Hemeralopia, also known as day-blindness, is the hindrance caused in vision or the inability to see clearly in bright light. Hemeralopia is the absolute opposite to nyctalopia, which is the inability to see in low light conditions. The name of these diseases had been derived from the Greek goddesses Hemera and Nyx. They were known to be the goddesses of day and night respectively. The definition of the two words has been used in the opposite sense on several instances. More accurately, Hemeralopia can also be defined as the insufficient adjustment of the eyes to bright or glaring light. This phenomenon of mal-adjustment to bright light is also known as Heliophobia. When someone is suffering from Hemeralopia, their vision during day time gets deterred. This is followed by photoaversion or the aversion to bright light rather than photophobia, which is the fear of bright light. A person’s vision mostly remains unchanged as an individual’s eyes depends on rods during the night rather cones which are used during the day. These cones are affected by Hemeralopia, which hinders the daytime optical response. This is exactly why several patients claim that they see better after dusk rather than during the day time.

What is Hemeralopia?

What are the Causes of Hemeralopia?

Hereditary: Hemeralopia is a rare type of eye dieses that is mostly hereditary in nature. It hinders the patient from being able to see clearly in bright light or in daytime.

Other Eye Conditions: It is known to be caused due to several ocular conditions such as cone dystrophy and achromatopsia.

Cone Dystrophy is known to be an ocular disorder which is also inherited. It takes place due to the loss of adequate cone cells, as well as the photoreceptors on which one is dependant for their central and color vision. Achromatopsia on the other hand is a non-progressive disorder which causes lack of color vision, high light sensitivity, nystagmus and decreased vision. It also involves the absence of functional cones in the retina.

Medications: An anti-epileptic drug Trimethadione can also be a cause for Hemeralopia in some cases.

Adie Syndrome: The Adie Syndrome is also a known cause of Hemeralopia. It is a neurological disorder which is seen mostly in females with absent knees or even impaired sweating.

Aniridia & Albinism: Two other plausible causes can arise from the condition of aniridia and albinism. Aniridia is actually the absence of the iris and this condition can either be congenital or can be due to an injury involving penetration. Albinism on the other hand is primarily a congenital disorder which involves the lack of pigmentation in the skin, hair as well as the eyes.

Cataract: In more elderly individual’s central cataract which involves fogging of the eye lenses, which is responsible for dispersing the light before it reaches the retina. This leads to Hemeralopia and photoaversion in its earlier stages.

Cancer Associated Retinopathy: A serious cause of Hemeralopia is C.A.R or Cancer Associated Retinopathy. This particular syndrome is seen especially when certain cancer cells become responsible for the production of antibodies that act against retinal components.

Cohen Syndrome: The Cohen Syndrome, also known as the Pepper Syndrome, is a genetic condition. This is seen in people suffering from obesity and mental retardation. It is also seen in cases of craniofacial dysmorphism, which occurs due to the mutation of 8q22-23. This on several rare occasions can lead to Hemeralopia.

What are the Symptoms of Hemeralopia?

The primary symptom of Hemeralopia is the inability to see in bright lights or in day time; and being able to see in dim lights or at dusk time.

Treatment & Management of Hemeralopia

As of now there is no well-defined cure for Hemeralopia. The causes of this ocular condition are so numerous and diverse that it is hard to ascertain a cure without knowing the exact cause or condition. If the cause of Hemeralopia is cataract, then removal of the cataract is possible in early stages via prescribed surgery by a medical practitioner.

On the other hand if Hemeralopia is more genetic in nature, then treatment of the same may be far more complicated. Therefore, it is always highly recommended to properly assess your visual condition before undergoing any sort of medical treatment. It is mostly recommended to all those suffering from day blindness to keep their eyes well protected from bright light. In this case, the use of sun glasses or specialized glasses allows one to do just that. In more extreme situations specialized eye drops and light filtering lenses are proposed, but only after being properly reviewed by an eye specialist. Such glasses have lenses in which the passing of light has been properly adjusted according to the requirements of the patient suffering from Hemeralopia.

How to Prevent Hemeralopia?

There are certain steps and healthy habits that can be taken up in order to have a well protected eye sight. As there are a number of deficiencies that may lead to day blindness or night blindness, it is imperative to keep them in mind.

Good Diet to Prevent Hemeralopia

The first thing to keep in mind while continuing efforts to gain healthier vision is to follow a healthy diet. There are several types of proteins you can customize your diet with. Your food does affect your health. Bright green spinach and other forms of salad are primary choice in maintain your vision. Brightly colored and highly leafy vegetables provide your body with nutrients such as lutein as well as zeaxanthin, which benefits your vision to a large extent. Vitamin A, which is found in abundance in carrots and sweet potatoes, are a delicacy for the health of your eyes. They give the necessary boost which is required by your eyes. Also, keep in mind that fruits such as strawberries and mangoes carry Vitamin C, which is useful in combating eye diseases. Several types of fresh water fishes are recommended by most dieticians as they provide omega 3s in large proportions.

Avoid Sun Exposure To Prevent Hemeralopia

When it comes to eye sight, bright sunlight is something to watch out for. Your every day exposure to sunlight might be putting your vulnerable eyes to more than just a warm sunny day. There are several short wave and long wave rays that travel through sunlight which may prove corrosive for your vision. UVA rays and UVB rays can induce radiation that leads to cataract and macular degeneration. The best way to protect your eyes from incurring any harm from these rays is by using a sunglass each time you take a walk in the sun.

Keep Your Eyes Lubricated To Prevent Hemeralopia

In several occasions, the drying up of the eyes can exert certain amount of stress on the retina and can lead to Hemeralopia. The use of electronic devices for a long and consistent period of time can lead to dry eyes. This means that the moist mucus layer on top of your iris have dried making your eyes feel itchy and disturbed. Eye drops to keep them moist and protected are recommended to keep them safe from harm and to prevent Hemeralopia.

Quit Smoking To Prevent Hemeralopia

Smoking also puts you at high risk when it comes to blindness of any kind including Hemeralopia. Smoking leads to the production of cyanide that mixes into one blood stream. This can cause damage to your eyes and lead to conditions like Hemeralopia, cataract and dry eyes. If carried on a regular basis may also lead to macular degeneration. This could permanently destroy the vision at the centre of your eyes.

Get Regular Eye Exams To Prevent Hemeralopia

One other prevention which is most often recommended by several medical practitioners and eye specialists is to have regular and consistent eye checkups. Undergoing regular eye exams can actually help you protect your eye from incurring any severe eye diseases including Hemeralopia in the future. There are several varieties of problems which you can prevent in advance. Issues like glaucoma and diabetic eye diseases can be tracked and dealt with on time. Regular visits to your eye specialist can ensure you healthy on time treatment for your eyes.


As you already know, day blindness or Hemeralopia can be caused by several varying conditions. Presently it has no definite form of treatment and its cause must always be assessed individually. There are also many precautions one can bring under measure in order to keep their eyes healthy and well protected from Hemeralopia. Regularly knowing about the requirement of your eyes can present you with even more healthy vision overtime.


  1. “Hemeralopia.” Genetic and Rare Diseases Information Center. https://rarediseases.info.nih.gov/diseases/6417/hemeralopia
  2. “Hemeralopia (Day Blindness).” American Academy of Ophthalmology. https://www.aao.org/eye-health/diseases/hemeralopia-day-blindness
Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 29, 2023

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