This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Glaucoma, Subject name: Ophthalmology
A 75 year old patient presents with deterioration of vision. On examination the pupillary reflex is observed to be sluggish and the intraocular pressure is normal. Optic disc evaluation shows a large and deep cup and paracentral scotomas. The most likely diagnosis is: 
Select and explain. 
A. Primary Narrow angle glaucoma, B. Normal Tension Glaucoma, C. Neovascular Glaucoma, D. Absolute Glaucoma
B: Normal Tension Glaucoma
Answer: B: Normal Tension Glaucoma 
Explanation: Ans. (b) Normal Tension GlaucomaRef: Kanski 7/e, p. 346; Yanoff 3/e, p. 1159Glaucomatous cupping (large and deep cup) along with glaucomatous visual field defects (paracentral scotomas are the most frequent) in patients with normal intraocular pressure suggests a diagnosis of Normal Tension Glaucoma (NTG).