![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKTfD78cwoqRsIkAJ6ME3vFj3KXqEpyYc6CkedyL0dlIGwIEdSGwjT1VN6wG55BJlTetxYcWE3JsgmwS0TDpVcRW_zWuLqfhmtbT3SaAyS6EI7gOQ4YAUK_5y_QTvG7n7-V-tB_O_RzXw/s400/eyes_horners2.jpg)
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkO0DlH8_tL3A3EqXlXn5HdNinIOMsahfEsjWllF4UKIrCPxFzxcKLShvNDN-T4IZtbXI8y2MZfRvw5_Mni9Fz1xfKrP4pnJH2orCPIqGznRQJA6IZkRWpuZs0SEDiyfCXOw8FWd_GQ3Y/s400/head_horners4.jpg)
Loss of sympathetic nervous system input to (in this case) right eye.
Note that right pupil is smaller than left. Also that right eyelid covers a greater portion of eye than on left
(known as ptosis). The etiology in this case was due to tumor infiltrating the sympathetic chain.