Grass seed season is upon us, and in general practice an ocular grass seed should always be suspected when a patient has a unilateral purulent ocular discharge (see Image). They commonly find their way into the dorsal or ventral conjunctival fornix, or behind the nictitans (third eyelid) and secondary corneal ulceration is often seen. Less commonly they can find their way into the tear duct, again leading to a unilateral purulent discharge. Without specialist expertise and experience grass seeds in these locations can be very hard to find and/or remove. We suggest any eye with an unexplained purulent discharge is referred to VOR for specialist assessment and to rule out an undetected grass seed.
In some cases, a grass seed can migrate into the retrobulbar region (orbit) and produce ongoing retrobulbar cellulitis. This should be suspected when a presumed retrobulbar infection fails to respond to oral drainage and/or systemic antibiotics. Worse still, some grass seeds end up penetrating and entering the posterior segment of the globe, leading to destructive panophthalmitis. This should be suspected with a severe progressive medically unresponsive unilateral uveitis. The presence of an intraocular grass seed in a cloudy, highly inflamed eye can usually be confirmed with ocular ultrasonography, but such eyes usually require enucleation.