Hemeralopia: Definition, Causes, Symptoms, Treatment and Prevention

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

The word hemeralopia (from the Greek ημέρα hemera, “day”, and αλαός alaos, “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 insufficient adaptation to bright light. This phenomenon of poor adjustment to bright light is also known as “heliophobia” and “day blindness.”

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

Night vision remains largely unchanged 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 photoaversion or aversion to bright light rather than photophobia, which is the fear of bright light.

A person’s vision remains largely unaltered 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 exactly 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 in nature. Prevents the patient from being able to see clearly in bright light or during the day.

Other Eye Conditions : It is known to be 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, as well as the photoreceptors that one depends on for color and central vision.

Achromatopsia, on the other hand, is a non-progressive disorder that causes 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 have a serious effect on the person’s vision.

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

Medications : An antiepileptic drug Trimethadione can also be a cause of hemeralopia in some cases.

Adie Syndrome : Adie Syndrome is also a known cause of hemeralopia. It is a neurological disorder that is 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 actually the absence of the iris and this condition may be congenital or it may be due to an injury involving penetration. On the other hand, albinism is primarily a congenital disorder that involves a lack of 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 photoaversion in its early stages.

Cancer-associated retinopathy : A serious cause of hemeralopia is cancer-associated retinopathy. This particular syndrome is especially seen when certain cancer cells become responsible for the production of 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 be able to see in dim lights or at dusk.

In the dark, twilight, in low light conditions, people with gemeralopia 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 cause of hemeralopia is 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 in nature, its treatment can be much more complicated. Therefore, it is always highly recommended to properly assess your visual condition before undergoing any kind of medical treatment.

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

In more extreme situations, special eye drops and light-filtering lenses are proposed, but only after they have been properly 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 special 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.

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

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

How to prevent hemeralopia?

There are certain steps and healthy habits that can be taken to have a well-protected vision. As there are a number of deficiencies that can lead to day blindness or night blindness, it is essential to take them into account.

Good diet to prevent hemeralopia

The first thing to keep in mind as you continue your efforts to gain 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 choice 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 is helpful in fighting 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.

There are several short wave and long wave rays that travel through sunlight and can be corrosive to your vision. Ultraviolet rays and UVB rays can induce radiation that leads to cataract 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 of the eyes can put a certain amount of stress on the retina and can lead to hemeralopia.

Using electronic devices for a long and constant period of time can cause dry eyes. This means that 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 when it comes to blindness of any kind, including hemeralopia. Smoking leads to the production of cyanide which mixes in a blood stream.

This can damage your eyes and lead to conditions like hemeralopia, cataracts, and dry eyes. If carried out on a regular basis 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 that is recommended more frequently by various doctors and eye specialists is to have regular and constant eye exams.

Getting regular eye exams can actually help protect your eye from getting serious 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 always 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.