Corneal foreign bodies are a common complaint confronting Emergency
Physicians and account for approximately 35 percent of all eye injuries
seen.1 Many objects have been implicated as a source of
corneal foreign bodies including, but not limited to: glass, metal,
wood, dirt, dust, insects, and plant particles.1 The majority
of ocular foreign bodies require prompt removal. More than 75 percent
of retained foreign bodies present on the eye surface are corneal
in nature, and if left in place for more than 3 days will
result in a keratitis.2
The prevailing symptom that forces patients to seek treatment
is the sensation of an ocular foreign body or simply the pain associated
with the foreign body. A variety of techniques exist for removal
of ocular foreign bodies. A discussion of each of these techniques
is necessary to determine the proper technique for a given situation.
Many foreign bodies are diverted from the surface of the eye
by the rapid blinking action of the eyelids and the eyelashes. A
foreign body may not necessarily lodge itself into the cornea or
the surrounding scleral surface if it is able to get past the eyelids
and eyelashes. It may be washed to the inner canthus by a combination
of blinking and tear flow. The foreign body may occasionally be
carried away via drainage through the lacrimal ducts.2 Objects
that resist these means of diversion may be found in the upper or
lower fornices, the channels created by the fold of the inner surfaces
of the eyelids in communication with the conjunctival surface of
the eye. The foreign body in the upper fornix is typically found
lodged in the subtarsal groove on the inner surface of the upper
eyelid, inferior to the tarsal plate.2 Foreign bodies may
also travel deeper into the respected fornices where they may be
difficult to find. Foreign bodies may lodge themselves into the
surface of the conjunctiva overlying the sclera or into the cornea
itself, which obviously carries the most risk of serious injury
or permanent scarring.
The cornea is only millimeters thick. It is comprised of five
layers (from outer to inner layer): epithelium, Bowman’s
membrane, stroma, Descemet’s membrane, and the endothelial
layer that lies directly over the anterior chamber.3 The
surface epithelium itself has five layers of squamous cells.
Most superficial corneal foreign bodies become embedded in this
layer and do not result in scarring. Bowman’s membrane
has no regenerative capacity, and if injured, may result in scarring
and permanent injury.4 Foreign bodies that violate Bowman’s
membrane are considered deep corneal injuries. The stroma is composed
of collagen and accounts for the largest portion of the cornea.
Descemet’s membrane is a basement membrane that can be
regenerated if injured. The final component of the cornea is the
endothelial layer that is composed of a single
row of cuboidal cells that can regenerate if damaged.
Healthy cells adjacent ...