RGP insights

Diagnosing Post-PK 'Contact Lens Problems'

LORETTA B. SZCZOTKA,OD MS
FEBRUARY 1998

Even many years after penetrating keratoplasty (PK), patients may still be at risk for surgical complications which can be difficult to distinguish from contact lens related problems. Patients often first present to the contact lens practitioner with any new ocular complaints such as recent onset RGP intolerance, decreased visual acuity, or ocular

Patients who develop post-PK complications often visit the contact lens practitioner first with any new ocular complaints such as recent onset RGP intolerance, decreased visual acuity, ocular pain or redness. Here are two common surgical complications that patients frequently first attribute to contact lens wear.

Loose and Broken Sutures

Contact lens wear can begin as early as three months postoperatively, so sutures are often present when the first lens is dispensed. Most surgeons believe that remaining sutures are not a contraindication to RGP fitting as long as they are completely covered by epithelium, all knots are buried and suture removal is not planned soon thereafter.

The first symptom of a loose or broken suture is often contact lens intolerance, which patients usually attribute to a faulty lens. Classic signs and symptoms of exposed sutures include: foreign body sensation or pain, photophobia, papillary hypertrophy, conjunctival injection, epithelial erosions, dellen formation, corneal vascularization and occasionally iritis, which may lead to graft rejection.

Loose or broken sutures require prompt removal to avoid a nidus of infection, a target for mucus accumulation or a stimulus to neovascularization. The surgeon may remove all or some of the sutures, depending on the suturing technique, the time elapsed after surgery and the ocular status. Suturing techniques include: single or double running sutures, interrupted sutures and combination interrupted and running sutures. If a continuous suture is affected, removal is based on the extent of wound healing and if additional sutures will support the wound. If there are exposed loops or knots but the wound isn't completely healed, the surgeon may remove the exposed portion only.

Graft Rejection

Allograft rejections are usually not attributed to contact lens wear, but being aware of the signs of early graft rejection can help prevent graft failure. The three most common classifications of graft rejection are epithelial rejection, subepithelial infiltrates and endothelial rejection. Epithelial rejection is characterized by an elevated epithelial rejection line that stains with fluorescein. Subepithelial infiltrates are usually 0.2mm to 0.5mm in diameter and are randomly distributed immediately below Bowman's layer in the donor tissue. Endothelial rejection usually presents with conjunctival hyperemia, an anterior chamber reaction, keratic precipitates and graft edema. The pathognomonic endothelial rejection line (Khodadoust Line) advances from the periphery of the graft and moves centrally. Stromal edema often results in the areas of the graft through which the endothelial rejection passes.

True Contact Lens Complications

The most common contact lens complications include chronic epithelial staining, epithelial defects, lens adherence, microcystic edema, chronic neovascularization, lens deposits and solution sensitivity. Monitor patients closely at least every six months after contact lens fitting, especially because many early complications may be asymptomatic due to reduced corneal sensitivity.

References are available upon request to the editors. To receive references via fax, call (800) 239-4684 and request document #33.

Special thanks to Jonathan Lass, M.D., for review of this article.

Dr. Szczotka is an assistant professor at Case Western Reserve University, Department of Ophthalmology and director of the Contact Lens Service at University Hospitals of Cleveland.