This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lens, Subject name: Ophthalmology
A 55 years old patient complains of decreased distance vision however he will now does not require his near glasses for near work,the most likely cause is 
Select and explain. 
A. Posterior subcapsular cataract, B. Nuclear sclerosis, C. Zonular cataract, D. Anterior subscapular cataract
B: Nuclear sclerosis
Answer: B: Nuclear sclerosis 
Explanation: Nuclear sclerosis causes mild increase in the refractive index of the lens and hence the refractive power of the lens increases it leads to improvement in the near vision