Online Photo Diagnosis

By William Townsend, OD, FAAO

The unusual pigmentation seen in this photograph resulted from an accident that occurred when the patient was a teenager. He was in class when a classmate threw a pencil across the room. It struck the patient's eye, point first, and penetrated the conjunctiva but not the underlying sclera. According to the patient, the injury was treated with a topical antibiotic. The wound healed, but residual grains of graphite remain trapped beneath the conjunctiva many years later. The patient denied any pain, discomfort or inflammation related to the graphite deposited beneath his conjunctiva.

Penetrating pencil injuries in and around the eyes are not rare events. Graphite, a form of carbon used in pencil lead, appears to be relatively nontoxic. Graphite is an allotrope of carbon that is ground into a very fine powder and mixed with a small amount of clay binder to form the “lead” in pencils.

Dinakaran and Noble¹ reported the case of a 5-year-old boy who fell on a pencil, which passed through the upper eyelid, the roof of the orbit, and into the cortex adjacent to the lateral ventricle. The pencil was removed before they evaluated the corresponding path of the pencil. Remnants of pencil lead identified by the CT scan were left in place, and after 1 year of observation without complications, the patient was dismissed.

Hamanaka et al² reported the case of an 8-year-old boy who presented with a penetrating corneal injury and an intraocular foreign body composed of graphite pencil lead. Initially, the injury was treated with lens extraction and suturing of the corneal wound. Two days later the patient presented with endophthalmitis and was treated with removal of the foreign bodies and vitrectomy. Cultures of the vitreous were negative for bacteria, but analysis of the vitreous revealed low levels of aluminum, a constituent of pencil lead and a substance known to be toxic.

Honda and Asayama³ evaluated a young man who, at the age of 5, sustained a penetrating pencil injury. After the wound was repaired, the surgeon noted a piece of broken graphite pencil lead in the vitreous cavity. During a 6-year follow-up period, there was no infection, inflammation or necrosis. The authors noted that, unlike black pencil leads made from graphite and additives, colored pencil leads can evoke a dramatic immune response inside the eye.

In our patient's case, there was no long-term threat to vision or discomfort associated with his injury. Any potentially penetrating injury should be carefully evaluated for Seidel sign and any other indication that the globe has been pierced. This case also demonstrates that some materials can remain in contact with the eye without causing infection or inflammation.

References

1. Dinakaran S, Noble PJ. Silent orbitocranial penetration by a pencil. J Accid Emerg Med. 1998;15:274-275.
2. Hamanaka N, Ikeda T, Inokuchi N, Shirai S, Uchihori Y. A case of an intraocular foreign body due to graphite pencil lead complicated by endophthalmitis. Ophthalmic Surg Lasers. 1999;30:229-231.
3. Honda Y, Asayama K. Intraocular graphite pencil lead without reaction. Am J Ophthalmol. 1985;99:494-495.