Cone dystrophies

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Symptoms

The two most common initial symptoms in cases of cone dystrophy are blurred vision and photophobia. Once vision has declined to a level of 6/12 to 6/18, colour vision may be severely affected. Red-green colour vision defects are most commonly seen. Vision loss may well commence in the first decade of life, declining slowly to around 6/60 by the third or fourth decade. Some patients are quite sensitive to glare and will complain of difficulty adjusting to changing light levels. Some difficulty with night vision is usually present in cases of rod-cone degeneration, with this sub-type carrying the worse overall prognosis for vision.