A 68-year-old man from Delhi presents with progressive blurring of vision over 3 years. He reports difficulty with night driving and glare from headlights. On examination, visual acuity is 6/18 in both eyes. Slit-lamp examination reveals a brown discoloration of the lens nucleus with preserved clarity of the cortex. The patient denies any history of trauma, uveitis, or systemic disease. What is the most likely type of cataract?