What is the purpose of splitting prescribed prism?

Splitting prescribed prism is primarily done to balance the thickness and weight of the lenses. When prism is prescribed in lenses, it can lead to variations in lens thickness that might not only affect aesthetics but also comfort during wear. By splitting the prescribed prism between the two lenses, the overall thickness can be reduced, leading to lighter lenses and improved cosmetic appearance without compromising the intended visual correction. This method helps to distribute the weight more evenly across both lenses, making them more comfortable for prolonged use.

The other answers focus on outcomes that are not the primary goal of splitting prism. Increasing lens thickness would generally be counterproductive, while enhancing visual acuity is typically achieved more through precise lens prescriptions rather than modifying thickness. Altering lens prescriptions might be a separate consideration but is not the purpose of splitting prism itself.