Achromatopsia is a hereditary condition where the cones in the eye have not developed properly, resulting in reduced color perception and light sensitivity. There are two main types: rod monochromatism, which is the most common and causes color blindness, and blue cone monochromatism, which results in the loss of red and green cones. Achromatopsia causes low visual acuity, especially in bright light, nystagmus, and photophobia, though symptoms may lessen with age. Electrodiagnostic testing can help diagnose this non-progressive condition.

1. Jaival Sheth
T.Y. B. Optom

2. CONTAINS
Definition
Etiology
Visual Acuity & Visual Fields
Ocular Signs & Symptom
Adjunct Testing
Prognosis

3. Achromatopsia is a hereditary condition in which
the cones have not developed properly.
There are two types of Achromatopsia.
1. Rod monochromatism (color blindness)
2. Blue cone monochromatism (loss of red & green
cones)

4. Rod monochromatism is the most common form of
Achromatopsia and is transmitted as an autosomal
recessive trait.
Blue cone monochromatism is transmitted as an X
– linked recessive inherited pattern & Symptoms
tend to be milder than with rod monochromatism.

6. This hereditary condition is found in 3 of 1,00,000
males.
Occurrence in females is slightly less.
In normal eyes there are 6 million cone cells and
100 million rod cells.
Achromatopsia is a genetic disease in the eyes and
it is not infectious. This disease can’t be spread.

7. Distance visual acuity ranges from 6/18 to 6/60.
Vision is somewhat better at near distances and in
dim illumination and worse in bright illumination.
Visual fields are usually normal but can be slightly
constricted.
Particularly to colors.

8. Achromatopsia, results in reduced central acuity
in bright ligh, pronounced decrease in color
perception, and photophobia.
Pendular nystagmus also results from the
diminished acuity and may decrease at near.
Nystagmus & Photophobia may diminish after the
age of 15 years.

9. Pupils react sluggishly to light and paradoxical
responses have been reported during dark
adaptation.

10. Electrodiagnostic testing reveals normal electro-
oculogram (EOG) and scotopic.
Electroretinogram (ERG) responses and subnormal
photopic ERG rsponses.
Color testing, with a D-15 test or Nagel
anomaloscope, is helpful in diagnosing this
condition.

11. Blue monochromat plates can be used to
distinguish rod monochromatism from blue
monochromatism.
Fluorescein angiography (FA) may show mild
hyper-fluorescence when disturbance of RPE is
present.

12. The prognosis for rod monochromatism is favorable
beacause it is a non-progressive condition.
Nystagmus and photophobia may decrease by mid
teenage years; however, diminished central acuity
remains.