Hi, Thanks for writing in to us. Optic neuritis is an inflammation of the optic nerve which carries impulses from the eye to the brain through the optic tract. This is usually a limited condition and is treated with steroids. Brain tumors are of many different types and categories. Most benign tumors grow very slowly and stay stable for years before they cause symptoms. In contrast malignant or cancerous tumors grow violently and it might take 3 to 6 months for them to grow into a mass of cancer cells. In conclusion, a tumor is slow growing if it takes more than a year or two to double its size and is a fast growing it there is double in tumor volume over 3 to 6 months. You likely do not have a brain tumor.