Why does Tay Sachs disease present with a cherry red macula?

Tay Sachs disease is a genetic disorder caused by a deficiency of the enzyme Hexosaminidase A (Hex-A), leading to the accumulation of GM2 gangliosides, particularly in neural tissues. The cherry red spot in the macula is a characteristic finding in this condition and arises due to the contrast between the pale retina, where there is a significant loss of neurons and ganglion cells, and the intact underlying choroidal blood vessels, which appear as a red spot against the pale background.

As the gangliosides accumulate, they cause neurodegeneration and a reduction in the retinal ganglion cells. This loss is most pronounced in the fovea where photoreceptors are densely packed, and thus the foveal area appears pale, creating the "cherry red spot" effect when viewed against the blood vessels that remain intact and visible within the macula region.

This distinct macular appearance is a classic clinical finding in Tay Sachs disease and can help differentiate it from other conditions that may present with similar neurological symptoms. The other answer choices do not account for this specific pathophysiological change leading to the cherry red spot.