Your eye is filled with a gel-like substance called vitreous, which lies in front of the macula. As you age, the vitreous gel shrinks and pulls away from the macula, usually with no negative effect on your sight. In some cases, however, the vitreous gel sticks to the macula and is unable to pull away. As a result, the macular tissue stretches. After several weeks or months the macula tears, forming a hole.