your father is having black cataract in right eye and left eye is having retinal degeneration
The treatment option available is by cataract surgery
for right eye. Cataract surgery can restore vision in his right eye and he may be able to see following surgery. Black cataract is hard cataract hence requires more energy during phacoemulsification
surgery, which is the treatment of choice for cataract surgery as of now. With the availability of the recent machines the treatment will not be a problem and post operative complications are minimal. He can undergo cataract surgery.