Digital mobile telephones and interference of ophthalmic equipment

Aim To assess the effect of mobile telephone electromagnetic interference on electronic ophthalmic equipment. Methods Prospective audit with mobile telephones placed at distances of 3m, 1 m, and 30 cm from, and in contact with, electronic ophthalmic equipment. Any interruption or cessation of the function of the ophthalmic device was assessed with the mobile telephones in standby, and in dialling or receiving modes. Any alterations of displayed digital figures or numbers were also assessed. Results A total of 23 electronic ophthalmic devices in two hospital ophthalmology outpatient departments were evaluated. All six mobile telephones used, and 22 (95.7%) of the 23 ophthalmic equipment evaluated had the Conformite Europeene (CE) mark. No device showed any interruption or cessation of function. There were no alterations of displayed digital figures or numbers. The only effect of any kind was found with four instruments ( 1 non-CE marked), where there was temporary flickering on the screen, and only occurred when the mobile telephones were dialling or receiving at a distance of 30 cm or less from the instruments. Conclusion This study shows that among the electronic ophthalmic devices tested, none suffered failure or interruption of function, from mobile telephone interference. Although not comprehensive for all ophthalmic equipment, the results question the need for a complete ban of mobile telephones in ophthalmic departments. It highlights the need for a controlled, objectively measured study of the clinically relevant effects of mobile telephones in the ophthalmology outpatient setting.