Using corticosone like flovent inhaler can cause loss of vision?

Yes. Steroids used chronically have been associated with cataract formation. You should see your eye doctor. Also steroids can cause elevation in blood sugar and this leads to fluid shifts that can cause blurring vision. You should have your blood sugars checked to rule out diabetes.
Possibly. Prolonged use of corticosteroid medications can result in the development of glaucoma, a potentially blinding condition. Nasal steroid medications can be absorbed into the blood stream and over time affect the eyes. If there is prolonged need for steroids and a family history of glaucoma, a complete eye examination would be highly recommended.
Possibly. Infrequently, an inhaled corticosteroid can elevate the intraocular pressure and lead to glaucoma. Untreated glaucoma causes loss of vision, but regular check ups with your eyemd can detect this problem and prevent the damage. I have been following many patients on Flovent and similar medications and if the iop goes up, we manage it sucessfully with no loss of vision.
Cataract? The use of any steroid for a long period of time can cause cataracts to form, in addition to increased eye pressure. I would recommend seeing your ophthalmologist.
In a way.... Long term use of moderate doses of fluticasone/flovent is associated with an increased risk of cataract formation. Daily use of the drug can be associated with reversible blurring of the vision. In low to moderate doses the drug is very safe and has a very low incidence of visual side effects.