Britney Spears has explained her penchant for wearing sunglasses after dark - she has a case of pink eye. Ex-husband Kevin Federline wore an eye-patch to cover his eye infection when he appeared in court to battle Spears over child custody details earlier this month (Oct07), and now the singer has come down with the same ailment. She told paparazzi catching her leaving Los Angeles' Van Nuys police station, where she was booked on a hit and run charge on Monday night (15Oct07), that she was wearing dark glasses to cover up her bad eye. She said, "It's really bad." Sources claim this is why she refused to let snappers take her photo when she arrived at court on Thursday (11Oct07), and then insisted on keeping sunglasses on as she addressed Los Angeles Superior Court Commissioner Scott Gordon, who is overseeing her child custody battle. Spears has since been spotted out and about at night in Hollywood, wearing her dark glasses; she was wearing a pair when she reversed into a paparazzi's car while parking outside a Hollywood party on Saturday (13Oct07). Pink eye is a form of conjunctivitis caused by the same types of bacteria that cause the sexually transmitted diseases chlamydia and gonorrhoea.