Premium
An optical explanation of the entoptic phenomenon of ‘clouds’ in posterior vitreous detachment
Author(s) -
Serpetopoulos Christos N.,
Korakitis Romylos A.
Publication year - 1998
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1046/j.1475-1313.1998.00387.x
Subject(s) - opacity , optics , physics , eclipse , shadow (psychology) , retina , photopic vision , pupil , penumbra , astrophysics , medicine , psychology , ischemia , cardiology , psychotherapist
Summary The purpose of this work is to investigate in detail the optics of the shadow cast by vitreous opacities and its effects in the perception of related entoptic phenomena. The optics of the eclipse has been used as a model. The various parameters affecting the shadow, i.e. the diameter of the opacity, its distance from the retina and the overall distance between the pupillary plane and the retina, have been taken into account in the calculations. A mathematical function has been derived and curves defining the density of the penumbra have been plotted for various distances of an opacity from the retina. An area of uniform partial illumination of the retina behind the opacity has been defined, outside of which the density of the penumbra falls rapidly. It is concluded that the sensation of ‘cloud’ or ‘smoke’ reported by the patient stems from this uniform area of penumbra behind the opacity, whose extent depends on the above mentioned parameters. Thus, the optics of the eclipse explains this entoptic phenomenon. Of course, ‘clouds’ can also be due to semi‐transparent vitreous floaters.