What does optics teach us about myopia?

A proud County Mayo man, a passionate advocate of optics, and most of all a warm-hearted, caring and kind person with students, colleagues, family, and friends. Such was Prof. Seán (John) Sheridan, an amazing colleague and friend with whom I shared many memorable moments in University College Dublin (UCD) over the past 15 years. Although we were in different departments, he in Engineering and I in Physics, we were always closely connected in our research and teaching. He always went the extra mile to help students, take part in outreach, to meet up to discuss science and for a friendly chat and a healthy laugher. Eight years before me, in 2000, Seán had arrived to UCD from Dublin Institute of Technology (now Technological University Dublin), with a very strong optics background having worked with scientists such as Colin Sheppard and William Rhodes. Seán was keen on applying optics to real-world problems and with an entrepreneurial spirit he explored commercial opportunities. A decade ago, he became interested in the optics of the eye, and more particular the optics of the animal eye, when he got involved with horse breaSPIEding and a spin-out company Equilume on the development of a blue-light mask that alters the breeding season for horses. He also co-developed a highly sensitive device to measure ocular movement as indicator of brainstem activity. He was familiar with my own work on vision and photoreceptors, and some of our last communications were on the topic of myopia. We had agreed to meet up with the CTO of Equilume, Dr Barbara Murphy, to discuss related matters in November 2022. This was just after I had returned from a conference trip to Recife, Brazil, and he had recovered from a recent and successful eye-squint surgery. Seán also had high myopia and aimed for cataract surgery by the end of the year with the hope of improving his eyesight. Sadly, just one-week later Seán passed away unexpectedly before we got the chance to meet again. In this contribution, I will review some of my optics background, and activities, that I shared with Seán, and discuss in some depth what optics may teach us about myopia.