Anatomical and optical origins of negative dysphotopsia

Abstract

Negative dysphotopsia (ND) is a complaint after, an otherwise uneventful, cataract surgery with intraocular lens (IOL) implantation. It is generally described as a shadow in the temporal peripheral visual field. Approximately 3% of the patients suffer from this condition and complaints range from mild visual field defects to a significant loss of peripheral vision that disturbs daily life. Originally, this condition was poorly understood as conventional ophthalmic techniques are not designed for a comprehensive evaluation of the peripheral vision. In the last years, however, a combination of dedicated anatomical measurements and optical ray tracing simulations have revealed the cause of ND and proposed different treatments.In this presentation the basic principles of ray tracing of the eye will be presented, followed by the main results of the ESCRS vRESPOND study. In this study, a detailed anatomical assessment of the pseudophakic population with and without ND was made. The distinct differences between both groups, such as a smaller (p = <0.01) and more decentered (p < 0.01) pupil and an increased temporal‐tilted iris (p < 0.01), will be discussed. Interestingly, high‐resolution ocular MRI revealed that the in‐the‐bag IOL position and retinal shape did not differ significantly between both groups. The impact of these differences on the patient's peripheral vision will be shown through ray tracing simulations. First the optical origin of the shadow, caused by light rays missing the IOL, will be presented, followed by a quantitative analysis of the effect the different anatomical and IOL‐design parameters on the severity of this shadow. At the end of the presentation, the optical rationale behind some of the treatments of ND will be discussed.