The invention relates to a method of indexing image data comprising the steps of acquiring image data representing a series of images, acquiring manually provided user cues for designating ones of the images, and indexing the image data in association with the manually provided user cues. Battery pack chargers include one or more key tabs in a door and rectangular guide tabs to differentiate rechargeable battery packs that can be safely charged. Also include methods of treating or preventing diseases or conditions, such as ocular diseases or conditions. The method then receives by the error handling module a completion signal from the error data management module, and provides an error signal from the error handling module to a support center.