Suggest Treatment For Discomfort In The Abdomen And Dark Colored Stool Discharge

hello iam Doctor muayad from iraq ,my father undergo from optic nerve atrophy result from increase intraocular pressure for 20 years duration and he lost his vision now he control on pressure [on normal level] by medication ,my father age is 55 years old and he donot undergo from any associated diseases ,Is there treatment and improve my father vision or not ,permenent or temporarily ,how long duration this treatment ,how cost me .

my father name is salam majeed hashim

please respond me quickly