The orthoptic slit lamp.

Recently we presented our concept of "videography with the slit lamp," which provides an imaging solution for nearly every pathological finding in ophthalmology. This paper deals with the changes that must be made to prepare the slit lamp for documenting squint. To achieve this goal we propose: 1. Changes in the observation system: minus lenses in front of the objective of the slit lamp to achieve a sharp image of both eyes (eg, -8 diopters [dpt] if the patient sits at a distance of 50 cm). 2. Changes in the illumination system: minimizing the narrowed angle between illumination and observation axis by holding a "recentration" prism of 14 dpt horizontally in front of the slit light. This procedure creates equally sufficient illumination of the patient's face and central corneal reflexes. 3. Recording clinical findings with a digital recorder. This enables us to identify binocular eye positions, which sometimes last only part of a second, eg, in latent or intermittent strabism. 4. Visualizing clinical findings by using Microsoft PowerPoint® to build up 9-gaze composites or adjust corneal reflexes on subsequent foils. Changes in binocular eye positions (eg, after surgery, but also during diagnostic covering) can be made visible by flickering between the foils to compare.