Nyctalopia. Or night blindness is a symptom of something else such as myopia or malnutrition it is treated based on the cause. It is the inability to see at night or in low light environment.
Can be treatable. Nyctalopia can be caused by a number of things. A few are birth defects, vitamin a deficiency, medications, glaucoma, diabetes, cataracts, severe near sightedness, retinitis pigmentosa, and refractive surgery (eg. Lasik). There are other causes (some untreatable) but of the ones listed above the only untreatable causes are birth defects and retinitis pigmentosa. Treatable not same as curable.
Yes find the reasons. “photophobia or light sensitivity is a common eye complaint. It can result from several different conditions and in most cases is easily treatable when you find the cause. Treatment for night blindness will depend on its cause. Treatment may be as simple as a new prescription for your eyeglasses or switching glaucoma drugs, or it may require surgery if it's the result of cataracts.
Is true that ox liver cures night blindness and cod liver oil and sunshine can help to cure rickets?
No and yes. Night blindness (nyctalopia) is usually associated with rp (retinitis pigmentosa) and we have no treatment available. Rickets are caused by a vitamins d deficiency best treated with vitamin d supplements and sunshine which activates the vitamin d. Cod liver oil is a good source of vitamin d.