![]() ![]() 1 It was also helpful in cases where significant media opacities existed, where-if the illumination of a closed eye induced shadows-it correlated with good retinal and macular function. Screening ApplicationsIn the late 1990s, the application of this afterimage was used clinically to grossly measure potential acuity, as patients’ lack of perception of their vessels correlates highly with poor macular function and markedly reduced acuity. Here, entoptic phenomenon is perceived as vitreous floater secondary to posterior vitreous detachment. ![]() 2 In fact, it is this observation, which led to the conclusion that there must be a rapid mechanism of image creation and erasure as the foundation of normal visual processing. 1 It differs from a real image, particularly in that it does not track with eye or retinal movement due to the direct and constant relationship with the photoreceptor layer. HistoryEntoptic phenomena were first described by Johann Purkinje in the early 1800s, to describe the fleeting, black afterimage of retinal vasculature, later coined the ‘Purkinje tree.’ 1 This phenomena occurs due to the location and pattern of the branching retinal vascular ‘tree’ in front of the photoreceptor layer, casting a shadow that is only induced when the anterior segment of the eye is illuminated. This month, let’s evaluate what significance, if any, these reflections hold to us as eye care practitioners. ![]() 1,2 The presence or absence of different entoptic phenomena can raise red flags for posterior and anterior abnormalities, and even refractive and convergence conditions-making them potential markers of disease presence and progression. Oftentimes, when our patients are sitting behind the slit lamp during a routine examination, we hear them cry, “Wow, I can see the reflection of my blood vessels!” The image that appears to them is an instance of entoptic phenomena (EP), a phrase derived from the Greek words ‘inside’ and ‘light’ or ‘vision’, which describes the ability of an individual to perceive substances endogenous to their own eye, such as retinal vessels or vitreous opacities. ![]()
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