this type of glaucoma is a genetic chronic disease and it usually affect elderly people in this type intra ocular pressure increase slowly and gradually reaching 20 mmHg or higher and the normal range is 14-16 mmHg so cornea of the eye swell without any pain so patient does’t recognize that their is a problem and the eye is begin to loss it’s vision and this loss is irreversible due to formation of blind spot that become larger and developed in the area of eye vision first around outer peripheral field of vision then it develop at the center of eye vision.
2-Normal Tension Glaucoma
this type of glaucoma characterized by normal intra ocular pressure so it also called low-tension glaucoma.But progressive optic nerve cell destruction and visual loss occur due to insufficient blood flow to the optic nerve which lead to death of this nerve that responsible for carrying visual information impulses to the brain. so decreases intra ocular pressure is dangerous also.
this type of glaucoma is the most popular type as it is an inherited disease that the anterior chamber of the eye is smaller than normal range.so the migration of aqueous humor to the lens is reduced,increasing intra ocular pressure and forced trabecular meshwork against eye lens resulting in further angle narrowing and blocking drainage.
in this type of glaucoma Intra ocular pressure increases suddenly and with fast rate unlike closed angle glaucoma it increases slowly and gradually.As a result of this sudden increase it will cause intense pain in the eye,Swelling of cornea, blurred vision also nausea and vomiting.
this is a type of open angle glaucoma but it affect teenage.it is due rubbing of eye’s pigment layer to the lens causing shedding with aqueous humor leading to blockage of pores of trabecular meshwork tissues so intra ocular pressure increased.