Pterygium Surgery Expert Witness

Pterygium excision is often described to patients as a minor procedure. It generates claims for three reasons: the growth frequently comes back, patients often expect a cosmetic result the operation cannot guarantee, and the drug used to prevent recurrence can, in rare cases, damage the eye severely.

Technique is a choice, and the choice is reviewable

There are several accepted ways to close the area left after the pterygium is removed, and they do not perform equally:

• Bare sclera excision leaves the area uncovered. It is the simplest method and carries the highest recurrence risk, reported as upwards of 80 percent in some series.
• Conjunctival autograft covers the area with a patch of the patient’s own conjunctiva, secured with sutures or tissue adhesive. A Cochrane review found a lower risk of recurrence at six months with conjunctival autograft than with amniotic membrane.
• Amniotic membrane graft uses processed donor tissue and is often chosen when the patient’s own conjunctiva must be preserved, for example before possible glaucoma surgery.
• Mitomycin C, an antimetabolite drug applied during surgery, lowers recurrence. The American Academy of Ophthalmology’s technology assessment found that autograft or mitomycin C reduced recurrence compared with bare sclera excision in most studies, and that the data were insufficient to name one adjuvant as superior.

The standard of care therefore does not dictate a single technique. It does require that the surgeon’s choice be reasonable for the eye in question, and a surgeon who chose bare sclera excision without any adjunct should be able to explain why.

Recurring claims

• Recurrence. The most common complaint and, standing alone, the weakest. Recurrence happens with every technique. The analysis looks at whether the method chosen was reasonable, whether postoperative inflammation was controlled, and whether the risk was disclosed.
• Mitomycin C complications. A published series of ten patients documented severe secondary glaucoma, corneal edema, corneal perforation, sudden cataract and incapacitating pain after topical mitomycin C, with vision of 20/200 or worse in five eyes. The authors urged the lowest possible concentration for the shortest time. Scleral thinning and melting can appear long after the operation. The operative note should record the concentration, the exposure time and the irrigation afterward.
• Double vision. A pterygium on the nasal side lies directly over the medial rectus muscle. Injury to the muscle, or scarring that tethers the eye, can restrict movement and cause diplopia. Preoperative motility findings matter, because a large or recurrent pterygium can restrict movement before any surgery.
• Graft problems. Graft dehiscence, retraction, loss, or an inverted graft, and the adequacy of follow-up when they occurred.
• Missed tumor. Ocular surface squamous neoplasia, a tumor of the conjunctiva and cornea, can look like a pterygium. In a review of 2,005 excised pterygia at one institute, 1.7 percent contained this tumor, and more than half of those were not suspected before surgery. Failure to send the excised tissue for pathology, or to act on the report, is a recurring allegation.
• Steroid response. Weeks of postoperative steroid drops can raise eye pressure. Whether pressure was checked during the taper is a simple question the chart answers.
• Expectation and consent. Persistent redness, a visible graft edge, induced astigmatism and recurrence are foreseeable. Whether they were explained is addressed at Informed Consent in Eye Surgery.

The records that matter

The preoperative examination should establish why surgery was indicated: growth toward the visual axis, induced astigmatism, restricted eye movement, chronic inflammation or appearance. Photographs or a drawing with measurements fix the size and location. The consent form should mention recurrence and, if mitomycin C was planned, its off-label use and risks. The operative note, the pathology report and each postoperative visit with pressure measurements complete the picture.

Causation, sun exposure and work

Because ultraviolet exposure is the major recognized contributor to pterygium formation, outdoor workers sometimes claim the condition as an occupational disease. The medical questions are whether the work involved sustained sun exposure, how that compares with a lifetime of exposure outside work, and whether the pterygium predated the employment. In California, the evaluator must then apportion permanent disability between industrial and non-industrial causes with the reasoning shown, as described at Apportionment in Ophthalmic Injury Claims. Dr. Shomer addresses these questions as a Qualified Medical Evaluator and as a retained expert. See also Workplace Eye Injuries.

Damages and the measurable deficit

Most pterygium complications leave acuity intact and the dispute concerns comfort, appearance, double vision or astigmatism. These are measurable: corneal topography documents induced astigmatism, prism measurements document misalignment, and photographs document appearance. Where vision is lost, the rating follows the methods described at Visual Disability Evaluation.

Frequently Asked Questions

Authorities Cited

Primary sources referenced on this page. Links open the source on the publisher’s or agency’s site.

• Clearfield E, Muthappan V, Wang X, Kuo IC. Conjunctival autograft for pterygium. Cochrane Database Syst Rev. 2016;2:CD011349
• Kaufman SC, Jacobs DS, Lee WB, Deng SX, Rosenblatt MI, Shtein RM. Options and adjuvants in surgery for pterygium: a report by the American Academy of Ophthalmology. Ophthalmology. 2013;120(1):201-208
• Rubinfeld RS, Pfister RR, Stein RM, et al. Serious complications of topical mitomycin-C after pterygium surgery. Ophthalmology. 1992;99(11):1647-1654
• Oellers P, Karp CL, Sheth A, et al. Prevalence, treatment, and outcomes of coexistent ocular surface squamous neoplasia and pterygium. Ophthalmology. 2013;120(3):445-450
• California Labor Code section 4663 (apportionment of permanent disability to causation)