Hemeralopia: Definition, Causes, Symptoms, Treatment and Prevention

It can be defined as the insufficient adjustment of the eyes to bright or glaring light.

The word hemeralopia (from the Greek ημέρα Hemera, “day,” and αλαός alas, “blindness”) is the inability to see clearly in bright light and is the exact opposite of nyctalopia (night blindness), the inability to see clearly with low light.

Hemera was the Greek goddess of the day, and Nyx was the goddess of the night. However, it has been used in the opposite direction by many non-English speaking physicians.

It can be described as an insufficient adaptation to bright light. This poor adjustment to the brilliant light phenomenon is known as “heliophobia” and “day blindness.”

In hemeralopia, daytime vision worsens, characterized by photo aversion (aversion/avoidance of light) rather than photophobia (eye discomfort/pain in the morning), typical of eye inflammations.

Night vision remains unchanged mainly due to the use of rods as opposed to cones (during the day), which are affected by hemeralopia and, in turn, degrade the daytime optical response.

Therefore, many patients feel that they see better at dusk than during the day.


When someone suffers from hemeralopia, their vision during the day is detracted. This is followed by photo aversion or aversion to bright light rather than photophobia, which is the fear of bright light.

A person’s vision remains unaltered mainly as an individual’s eyes rely on the rods at night rather than the cones used during the day.

These cones are affected by hemeralopia, which hinders the daytime optical response. This is precisely why many patients report that they see better after sunset than during the day.

Causes of hemeralopia

Hemeralopia is known to occur in various ocular conditions. Cone dystrophy and Achromatopsia, which affect the cones in the retina, and the antiepileptic drug trimethadione are typical causes.

Hereditary: Hemeralopia is a rare type of eye dies that is primarily hereditary. It prevents the patient from being able to see clearly in bright light or during the day.

Other Eye Conditions: It is caused by various eye conditions such as cone dystrophy and Achromatopsia.

Cone dystrophy is known to be an eye disorder that is also inherited. It takes place due to the loss of proper cone cells and the photoreceptors that one depends on for color and central vision.

On the other hand, Achromatopsia is a non-progressive disorder that causes a lack of color vision, high sensitivity to light, nystagmus, and decreased vision. It also implies the absence of functional cones in the retina.

In rare cases, you can have eye complications such as hemeralopia, pigmentary chorioretinitis, optic atrophy, or retinal / iris coloboma, which severely affect the person’s vision.

Yet another cause of hemeralopia is a unilateral or bilateral postchiasmatic brain injury. This can also cause concomitant nyctalopia.

Medications: An antiepileptic drug, Trimethadione, can also cause hemeralopia in some cases.

Adie SyndromeAdie Syndrome is also a known cause of hemeralopia. It is a neurological disorder seen mainly in women with absent knees or even altered sweating.

Adie’s pupil, which does not contract in response to light; aniridia, which is the absence of the iris; and albinism, where the iris is poorly pigmented, can also cause this.

Aniridia and Albinism: Two other plausible causes can arise from the condition of aniridia and albinism.

Aniridia is the absence of the iris, and this condition may be congenital or may be due to an injury involving penetration. On the other hand, albinism is primarily a genetic disorder that lacks pigmentation in the skin, hair, and eyes.

Cataracts: in the central cataract of an older individual that involves fogging / opacity of the eye lenses, which is responsible for scattering light before it reaches the retina. This leads to hemeralopia and photo aversion in its early stages.

Cancer-associated retinopathy: A severe hemeralopia caused is cancer-associated retinopathy. This particular syndrome is especially seen when specific cancer cells become responsible for producing antibodies that act against components of the retina.

Cohen’s Syndrome: Also known as Pepper’s Syndrome, it is a genetic condition. This is seen in people suffering from obesity and mental retardation.

It is also seen in cases of craniofacial dysmorphia, which occurs due to the 8q22-23 mutation. This, on several rare occasions, can lead to hemeralopia.

What are the symptoms of hemeralopia?

The main symptom of hemeralopia is the inability to see in bright lights or during the day and see in dim lights or at dusk.

In the dark, twilight, in low light conditions, people with hemeralopia experience poor vision. Yet, at the same time, under normal lighting conditions, these same people see well enough.

Symptoms of this disease begin to manifest themselves even in early childhood. Children in poor lighting conditions lose their spatial orientation; they no longer distinguish colors and see objects around them.

The diagnosis is based on the clinical picture, the results of the laboratory tests, and the personal complaints of the patients.

Treatment and management of hemeralopia

At the moment, there is no well-defined cure for hemeralopia.

The causes of this eye condition are so numerous and diverse that it is difficult to determine a cure without knowing the exact cause or condition. If the reason for hemeralopia is a cataract, removal of the cataract is possible in the early stages through surgery prescribed by a doctor.

On the other hand, if hemeralopia is more genetic, its treatment can be complicated. Therefore, it is always highly recommended to assess your visual condition before undergoing medical treatment properly.

In general, blind people are advised to keep their eyes well protected from bright light all day. In this case, wearing specialized sunglasses or glasses allows one to do just that.

Special eye drops and light-filtering lenses are proposed in more extreme situations, but only after being correctly checked by an eye doctor.

Such glasses have lenses in which the passage of light has been suitably adjusted according to the requirements of the patient suffering from hemeralopia.

In this disease, a unique role is given to preventive measures: treatment of concomitant ophthalmic diseases and proper rational nutrition. Treatment of night blindness is primarily aimed at eliminating the disease-causing the bleeding.

Recommended list of products for bleeding patients:

 Rich in vitamin A. Milk, cheese, egg yolks, cod liver and butter, carrots, green onions, spinach, etc.

 Provitamin A. Peaches, apricots, currants, cherries, blueberries, and blackberries are rich in provitamin.

 Locally attributed to the use of eye drops – 5% solution melanotsitostimuliruyuschego hormone – intermedin. Riboflavin is prescribed in doses – of no more than 0.02 g per day. In addition to nutrition saturated with vitamins, unique complexes of vitamins A, B2, PP, and C are assigned.

How to prevent hemeralopia?

There are specific steps and healthy habits that can be taken to have a well-protected vision. As several deficiencies can lead to today’s blindness or night blindness, it is essential to consider them.

A good diet to prevent hemeralopia

The first thing to keep in mind as you continue your efforts to gain a healthier vision is to follow a healthy diet. There are several types of protein that you can customize your diet with.

Your food affects your health. Bright green spinach and other forms of salad are the top choices for maintaining your vision.

Brightly colored, tall leafy greens provide your body with nutrients like lutein and zeaxanthin, which greatly benefit your vision.

Vitamin A, found in abundance in carrots and sweet potatoes, is a delicacy for your eye health. They give the necessary boost your eyes require.

Also, keep in mind that fruits like strawberries and mangoes contain vitamin C, which helps fight eye diseases.

Most dietitians recommend several types of freshwater fish, as they provide omega 3 in large proportions.

Avoid sun exposure to prevent hemeralopia.

When it comes to eyesight, bright sunlight is something to watch out for. Your daily exposure to sunlight could be putting your vulnerable eyes on more than just a warm sunny day.

Several short waves and longwave rays travel through sunlight and can be corrosive to your vision. Ultraviolet and UVB rays can induce radiation that leads to cataracts and macular degeneration.

The best way to protect your eyes from any damage from these rays is to wear sunglasses every time you go for a walk in the sun.

Keep your eyes lubricated to prevent hemeralopia.

At various times, drying the eyes can put a certain amount of stress on the retina and lead to hemeralopia.

Using electronic devices for a long and constant period can cause dry eyes. The wet layer of mucus on top of your iris has dried, making your eyes feel itchy and irritated.

Eye drops to keep them moist and protected are recommended to protect them from damage and prevent hemeralopia.

Quitting Smoking to Prevent Hemeralopia

Smoking also puts you at high risk of the blindness of any kind, including hemeralopia. Smoking leads to the production of cyanide which mixes in the bloodstream.

This can damage your eyes and lead to conditions like hemeralopia, cataracts, and dry eyes. If carried out regularly, it can also lead to macular degeneration. This could permanently destroy the vision in the center of your eyes.

Get regular eye exams to prevent hemeralopia.

Another prevention recommended more frequently by various doctors and eye specialists is regular and constant eye exams.

Getting regular eye exams can help protect your eye from getting severe eye diseases, including hemeralopia, later in life.

There are several types of problems that you can prevent beforehand. Issues like glaucoma and diabetic eye diseases can be tracked and treated early.

Regular visits to your eye specialist can ensure timely healthy treatment for your eyes.


As you already know, day blindness or hemeralopia can be caused by several variable conditions. It currently has no defined form of treatment, and its cause must continually be assessed individually.

There are also many precautions that one can put in place to keep their eyes healthy and well protected from hemeralopia. Knowing regularly about your eye requirement can present you with even more hours of healthy vision.


People with hemeralopia can benefit from sunglasses. Whenever possible, ambient lighting should be adjusted to a comfortable level. Light filter lenses seem to help people who report photophobia.

Otherwise, treatment is based on identifying and treating any underlying disorders.