Managing Thygeson's Superficial Punctate Keratitis
BY WILLIAM L. MILLER, OD, PHD, FAAO
Thygeson's Superficial Punctate Keratitis (TSPK) was initially described more than half a century ago, yet our understanding of its etiology has not progressed greatly over this time. Most common suggestions regarding its cause point to either an immune or viral mechanism. It has also been shown that the antigen HLA-DR3 is present in some patients who have TSPK.
Signs and Symptoms
TSPK is typically a transient, bilateral condition that causes superficial punctate areas of staining under which lie coarse, gray epithelial opacities. Although bilateral, the condition can be asymmetric or may start in one eye first. The opacities tend to be round and/or stellate, slightly elevated, and are randomly scattered throughout the central and paracentral cornea (Figure 1). Discomfort varies, with many experiencing moderate irritation. Most TSPK patients also complain of photophobia and epiphora.
Figure 1. Opacities in Thygeson's Superficial Punctate Keratitis.
TSPK is non-contagious, but in some cases it may be confused with infiltrates caused by viral entities. Most TSPK patients experience periods of quiescence between active bouts of the disease that can last for weeks, months, and in some cases years. As with discomfort, visual acuity may be variable, ranging from normal to moderately reduced depending on the amount, location, and density of the opacities.
Other conditions can mimic TSPK especially in its early stages. One more common condition is epidemic keratoconjunctivitis, from which TSPK can be differentiated based on its longer duration and the elevated nature of the opacities. Other entities that may mimic TSPK include Herpes simplex and zoster, neurotrophic keratitis, staphylococcal/seborrheic keratitis, exposure keratopathy, and vernal keratitis.
Management options for TSPK depend largely on the visual acuity reduction and severity of discomfort. Although some believe the condition to be viral in origin, antiviral medications do not provide symptomatic relief or decrease the disease progression. In mild cases, patients can be treated with tear supplements. However, moderate-to-severe cases may benefit from topical steroid application. Pred Forte (Allergan) can be administered q.i.d. in a pulsed mode; however other steroid medications such as Lotemax and Alrex (both Bausch & Lomb) can be used in a similar dosing pattern if there is concern about steroid side effects. If prescribing the steroid medication for longer than one week, it may be prudent to taper the dose to prevent a quick rebound recurrence of TSPK. There has also been some suggestion that a topical steroid prolongs the course of the disease; however, these same reports also illustrate the positive effects of topical steroids in reducing patient symptoms as a result of the anti-inflammatory activity.
Another possible therapy is cyclosporine 0.05% (Restasis, Allergan), which has been advocated to decrease the course of the condition and to provide symptomatic relief. This may illustrate the possible connection to the immune aspect of TSPK. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #169.
Dr. Miller is an associate professor and chair of the Clinical Sciences Department at the University of Houston College of Optometry. He is a member of the American Optometric Association and serves on its Journal Review Board. You can reach him at firstname.lastname@example.org.