Generality
Hemeralopia - also known as night blindness - is a disorder characterized by difficulty seeing at night and in low light or twilight conditions.
Basically, we can distinguish two different types of emeralopia:
- The hereditary and congenital form, also known as congenital emeralopia or congenital stationary night blindness;
- The acquired form, an example of this particular form of emeralopia is constituted by emeralopia in pregnancy.
Causes
The causes of emeralopia can be of different origin and nature.
The cause of hereditary and congenital hemeralopia lies in an alteration in the structure and functionality of rods (photosensitive cells, otherwise called photoreceptors, which are found in the retina and which are responsible for vision in low light conditions).
On the other hand, in most cases the acquired emeralopia is caused by a dietary deficiency of vitamin A (or retinol, if you prefer), a fundamental molecule in the synthesis of rhodopsin (glycoprotein that is found on the membrane of rods and which covers a role of primary importance in the molecular mechanism of vision). The deficiency of vitamin A, in turn, can be caused by an insufficient intake with food, or by a lack or reduced absorption at the intestinal level.
In other cases, however, hemeralopia may be the symptom of other diseases, such as cataract, age-related macular degeneration, glaucoma, retinitis pigmentosa, optic neuritis, diabetic retinopathy, retinoblastoma, liver disease, thyrotoxicosis, myopia and Refsum disease.
Symptoms
As stated above, hemeralopia consists of vision difficulties in low light conditions and can sometimes be the symptom of a basic pathology.
However, in association with this disorder - in addition to the difficulty of retinal adaptation to external luminosity - it is not uncommon for other symptoms to appear, such as dry eyes and headaches.
Treatment
The treatment of hemeralopia may be different depending on the cause that caused it.
Therefore, if hemeralopia is caused by a deficiency of vitamin A, it is necessary to intervene with a therapy aimed at bridging this deficit in the patient.
If, on the other hand, hemeropia is caused by basic pathologies, the treatment that the doctor decides to undertake will be aimed at treating the primary cause that led to the onset of night blindness.
As for the congenital form of emeralopia, instead, unfortunately at the moment there is no cure able to solve this pathology.
