Christmas tree cataract
A descriptive term for a cataract containing highly refractile multicoloured “needles” crisscrossing the fibres of the deep cortex of the lens, which has been fancifully likened to a Christmas tree covered with glittering doo-hickies*. The needles’ colours vary according to the angle of incident light, and in retroillumination reveal only a dim outline of the cataract, suggest that the Christmas tree cataract is a diffractive phenomenon.
*It’s a bit of a stretch, but these guys probably don’t get out much
Analysis of these cataracts by scanning EM, energy-dispersive x-ray and Raman microanalysis concluded that the needles were probably composed of cystine and the result of age-related breakdown of crystals induced by elevated calcium levels.
Synonym Congenital spear cataract
Reference Invest Ophthalmol Vis Sci 1993;34:3489-3496