Day Blindness Causes, Symptoms, Treatment, Ayurveda Understanding

Article by Dr Raghuram Y.S. MD (Ay) & Dr Manasa, B.A.M.S
Day blindness is a condition wherein the patient is unable to see clearly in daylight. This condition is exactly opposite of Nyctalopia – night blindness wherein the patient is unable to see clearly at night or dim light. Hemeralopia is a Greek word which means ‘day blindness’. The word Hemeralopia is made up of two terms – Hemera – day, Alaos – Blindness. Other name – Heliophobia.

Day Blindness is also defined as a syndrome of impaired vision in good illumination associated with almost normal vision in the dark or dim light. This condition can be divided into 3 groups –
Associated with central opacities of cornea and lens
Associated with macular degeneration or toxic anmblyopia
Congenital day blindness
Read – Eye Diseases Causes, Pathogenesis, Symptoms, Treatment, Herbs

Predominant symptoms of Day Blindness

Daytime vision gets worse
Photo-aversion
Dislike towards light / person tries to avoid light against photophobia wherein there is pain or discomfort of the eye (this is typical of eye inflammations)
Night time vision is unchanged, patients see better at evening / night in comparison to the daytime
Read – Nakulandhya / Nakula Drishti Meaning, Symptoms, Treatment

Causes

This condition happens in many eye conditions. The typical causes for Hemeralopia are –
Cone dystrophy – The term describes a group of rare eye disorders that affect the cone cells of the retina. This can cause symptoms including decreased visual acuity, decreased color perception and increased sensitivity to light (photophobia).
Achromatopsia – means partial or total absence of color vision, those with complete achromatopsia cannot perceive any colors. They can see only black, white and shades of gray. In incomplete achromatopsia the person will retain color discrimination to some extent and is milder form of the disease.
Antiepileptic drug trimethadione
Adie’s pupil – pupil which fails to constrict in response to the light
Aniridia – absence of iris
Albinism – defective pigmentation of the iris
Central cataracts – in adults
Cancer Associated Retinopathy (CAR)
Cohen syndrome / Pepper Syndrome
Unilateral or bilateral post-chiasmatic brain injury
Read – Corneal Opacities – Causes, Symptoms, Preventive, Treatment

Management

Sunglasses may benefit people having hemeralopia. Environmental illumination shall be adjusted to a comfortable level. If there is photophobia, light filtering lenses would help. Most often treatment relies on identifying and treating the underlying disorder.

Research

Researchers in Israel in 2009 identified a herd of Awassi sheep which were day blind but could see at night, in low light conditions. Hereditary Achromatopsia or Day Blindness is caused by a genetic mutation. This can afflict human beings too. It mainly afflicts the children born out of marriages between close relatives. The US FDA in 2015 approved clinical trials of gene therapy for day blindness developed in Israel by members of a team that identified and treated the blind sheep in 2009. It is already being used in several US medical centers. (read more)

Prof Ron Ofri of Hebrew University’s Koret School of Veterinary Medicine is quoted saying ‘Less than 10 years after we first discovered the vision impaired herd we began human clinical trials. This marks a wonderful feat in ovine-to-human and research-to-cure efforts”. The research papers wherein other partners of Prof Ron took active part in was published in Human Gene Therapy. In cooperation with Prof. William Hauswirth, Dept of Ophthalmology, University of Florida – Ofri and his colleagues began gene therapy trials for the day-blind sheep. A virus carrying a normal copy of missing gene was injected to affected sheep. When this was done the sheep regained their day vision. Those sheep which were not treated remained visually impaired. Interestingly the oldest surviving sheep from the original study had still maintained daytime vision by the time the human studies were started.

Relation with consanguineous marriages – In Israeli cities like Jerusalem, Hereditary achromatopsia is of special concern. Day blindness is estimated to affect 1 in every 5,000 people in certain populations mainly due to consanguineous marriages. (Read more)

Ayurveda Understanding of Day Blindness

A condition named ‘Pitta Vidagdha Drishti’ which means ‘vision destroyed by vitiated pitta’ has been compared to day blindness.

Click to Consult Dr Raghuram Y.S. MD (Ayu)