Please explain what are some symptoms for gradual blindness?

In Eye of beholder: Vision is divided into central and peripheral types. Symptoms of central visual problems include blurriness/fuzziness of objects despite best efforts to focus on them down the center. Trouble seeing things to the side or bumping into things may signal trouble in the periphery. Flashes of light, dulling of colors, inability to correct vision with glasses and failing night vision are other symptoms.