We thank the authors Ashish et al for their interest in our publication. We first described our 3D printed smartphone-based indirect ophthalmoscopy adapter design in 2014,1 and this Retina publication reports on a subsequent iteration of this adapter as a tool to screen for diabetic retinopathy in the United states.2 We have subsequently published a large user feasibility study in India.3 Ashish et al have also created an adapter that converts a smartphone into an indirect ophthalmoscope to capture posterior segment photographs that is one of several such efforts.4–8 We are very pleased that there is a growing body of investigators developing and validating the clinical utility of these and other smartphone-based tools for clinical documentation and applaud these efforts to move the field of ophthalmology into the digital age.
We would like to use this letter to note some key considerations for this nascent field. First, ophthalmoscopy of any kind requires the passage of light through a condensing lens and onto a patient's retina. This has implications on both patient safety (e.g., phototoxicity) and image quality. As Ashish et al point out, the light-emitting diode (LED) light source on the HTC phone was in some cases believed to be overly bright and required attenuation with tissue paper. This highlights the importance of understanding and documenting the nature of the light source being used, especially with the wide variety of phone models constantly coming to market. Using the ISO 15004-2:2007 standard for optical radiation safety as a guide, we evolved our original design from using a phone's internal LED light source1 to one that uses an adjustable, external LED2 present in the final commercial version launched in 2015 (Paxos Scopeby Digisight Technologies). Currently, it is designed to be coupled to nearly any user-owned phone. Second, as adapters are regulated medical devices, they must be manufactured with quality assurance and appropriate system design controls.
Finally, a critical consideration is having a secure HIPAA+compliant way of storing and transmitting sensitive patient information collected on smartphones. Recent data security breaches at major hospitals have only highlighted the importance of vigilance in the digital age.9,10 In our study, we used Digisight's HIPAA-compliant iPhone application (now Paxos) as an integrated system to collect information from other portions of the eye examination (i.e., visual acuity) and the patient's fundus photographs. Photographs taken through the application were transmitted directly to secured Digisight servers and not stored locally on the smartphone. The data were then viewable through a secured cloud server.
There are certainly other considerations related to the ease, quality, safety, and security of fundus imaging that merit further discussion. We thank the editors for the opportunity to respond to the work that Ashish et al and others are doing with smartphone fundus photography to improve patient care.