Night Blindness and it different causes.

1. Night Blindness
(Nyctalopia)
By Kevin J Ambadan

2. Definition
Derived from Greek words: nykt = ‘night’
& alaos = ‘blindness’
It is a condition in which it difficult or
impossible to see in relatively low light.
Symptom of several eye diseases.

3. Etiology
Night Blindness may exist from birth or be caused by
injury or malnutrition (for example, vitamin A
deificiency).
Causes:
• Vitamin A deficiency
• Retinitis Pigmentosa & other tapetoretinal
degenerations
• Congenital night blindness
• Pathological myopia
• Peripheral cortical cataract & Corneal
opacities
• Advanced Primary open angle glaucoma

4. Vitamin A Deficiency
Inhibits the production of rhodopsin (the eye
pigment responsible for sensing low light
situations) found in the retina, composed of
retinal (active form of Vitamin A)
The decreased amount of rhodopsin in the
eye implies that there is inadequate retinal to
bind to opsin. Therefore, night blindness
results.

5. Retinitis Pigmentosa
A disorder in which the rod cells in the retina
gradually lose their to respond to the light.
Patients suffering from this genetic condition
have progressive nyctalopia and eventually
their daytime vision may also be affected
(Hamarlopia).

6. Congenital Stationary
Night Blindness
It is a rare X-linked non-progressive retinal
disorder.
Caused by malfunction in neurotransmission
from rods to bipolar cells in the retina.
Also known as Oguchi’s disease.

7. Peripheral Cortical
Cataract
The outer area of the retina is made up of
more rods than cones.
As rods are responsible for vision in dim light,
loss of peripheral vision often results in night
blindness.

8. Treatment
TREAT THE UNDERLYING CAUSE!!!!
The treatment method depends on the cause
of the night blindness:
• Vitamin A deficiency - treated by giving
Vitamin A supplement
• Retinitis Pigmentosa – not completely
curable, but the rate of progression of this
disease can be reduced by intake of vitamin
A supplements and surgeries (retinal
transplant)

9. Treatment
• Myopia – use of corrective glasses or
lenses or refractive surgery
• Glaucoma – switching of glaucoma
medicines may help
• Peripheral Cataract – Cataract surgeries
• Oguchi’s Disease – incurable

10. The end