Long-term eye movement recordings with a scleral search coil-eyelid protection device

The search coil technique is regarded as the gold standard in eye movement recordings. The manufacturers of scleral search coils (SSC) do not recommend using them longer than 30 minutes. The temporal limitations result from potential cornea damage and from irritations of the lid margins and palpebral conjunctiva which subjects perceive as unpleasant. Here we introduce a new coil-eyelid protection device (CEPD) which allows recording intervals up to 2 hours with considerably reduced discomfort. Ophthalmic examinations and saccade recordings were used for comparison with the conventional SSC recording technique. In three experiments subjects were examined using SSCs with a commercially available cornea bandage lens on top of the search coil up to 120 minutes recording time. Ophthalmic testing revealed no apparent harmful effects on eyes or lid surface. Saccade parameters (main sequence) remained unchanged comparing SSC and CEPD recordings. Subjects rated less discomfort by using the CEPD. For the first time we show that SSC recordings can be extended over about 120min without hazard to the eye, when using an eyelid protection lens. This advanced method allows new applications like eye movement recordings during sleep (rapid eye movements) or perceptional or motor learning tasks, e.g. saccade adaptation paradigms.