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Thygeson's Superficial Punctate Keratitis
(Thygeson's SPK or TSPK)
First described: Phillips Thygeson. "Superficial Punctate Keratitis". Journal of the
American Medical Association, 1950; 144:1544-1549.
Signs and Symptoms:
Symptoms are minimal, typically these include discomfort such as burning or irritation,
foreign body sensation, mild degrees of tearing, and photophobia (light sensitivity). There
will occasionally be minor decreases in visual acuity.
The typical appearance of the cornea shows numerous superficial lesions that will
stain with fluorescein or rose bengal dye. The epithelium may be eroded. Lesions may be
round, oval or star shaped, they consist of a conglomerate of tiny grey-white dots that are
slightly raised. Individual lesions are transient and usually are randomly scattered over
the central part of the cornea.
During inactive stages of
TSPK, lesions can
disappear; can be flat, grey
dots that do not stain; or
can appear stellate (star
shaped). The conjunctiva
may be mildly red and
swollen; tiny hair-like
filaments may be present;
and corneal sensation is
generally normal to slightly
decreased. (Arffa, p. 323)
Etiology
The cause of TSPK is unknown but viral or immune mechanisms have been suggested.
"A viral cause has been proposed based on the absence of bacteria and other infectious
agents, the resistance of the disease to antibiotics, and features that are said to resemble
the lesions of measles and adenoviral infections." (Leibowitz, p.461) However, it should
also be noted that the disease is unresponsive to antiviral agents as well. One author also
notes that the role of the immune mechanism is suggested by the presence of white blood
cells in the conjunctiva and corneal epithelium, "by the extended course of the disease, by
the therapeutic efficacy of topical corticosteroids," and by the presence in some
individuals of an antigen called HLA-DR3. (Leibowitz, p.461)
Natural History
TSPK tends to have a chronic recurrent course with asymptomatic periods during which
both corneas are clear interrupted by episodes of blurred vision and minor eye irritation.
One remarkable feature is the absence of any accompanying conjunctivitis. Keratitis is
variable with remissions and exacerbations for several years until it resolves
spontaneously, usually without serious sequellae. (Gock, 1995) "Individual attacks
generally last 1 to 2 months, go into remission for 4 to 6 weeks, and the recur; the time
course is variable. Usually after 2 to 4 years, the disease resolves without sequelae."
(Arffa, p.323) However, rare cases have been reported to persist for as long as 20 years. It
is thought that steroid use is involved in causing persistence of the disease (see treatment,
below).
Treatment
Treatment is only indicated if the patient suffers with significant decreased vision and/or
light sensitivity or pain to be worth the risks of treatment: development of glaucoma
(especially if there is a family history of glaucoma) or cataract (higher doses of steroids
for long periods) or the possibility of prolonging the TSPK itself..
Lubricant eye drops alone may occasionally relieve symptoms.
The keratitis usually improves with low-dose topical corticosteroids (0.12% prednisone
or equivalent 2 to 3 times per day for a few days up to 2 weeks as recommended by
Arffa, p. 323. Leibowitz et al., recommend that acute episodes be treated aggressively
with topical steroids and then tapered and discontinued over a 3 to 4 week interval.) It
should be noted that "steroids may prolong the condition and have the risk of
complications in an essentially benign disease." (Gock, p.76). Complications such as
ocular hypertension and cataracts are associated with extended use of topical
corticosteroids. However, the use of steroids may be warranted in patients who are
significantly disabled by the condition
Therapeutic soft contact lenses have been used successfully to treat the condition but the
treatment must be for an extended period of time. One of the first reports was by
Goldberg, et al. who noticed that patients whose eyes had been bandaged or patched for
24 hours showed considerable symptomatic relief. This prompted a trial period of
therapeutic soft contact lenses in the patients resulting in "almost complete resolution of
the lesions and dramatic almost immediate relief of discomfort." (Goldberg, p.23) It has
been postulated that soft contact lenses "improve symptoms by improving the optical
quality of the cornea, and cover the elevated corneal lesions and nerves that are
constantly in friction with the conjunctiva during blinking. The effect would break a
vicious cycle by decreasing lacrimation (tearing) that is associated with hypotonic (low
salt content) tears that may contribute to local epithelial edema (swelling)." (Tabbara, p.
77) Soft contact lenses may simply protect the cornea and thus the lesions from exposure
and friction.
Outcome/Prognosis
The visual outcome of TSPK is generally good, although some individuals have
experienced slightly reduced visual acuity.
Bibliography
Gock G, Ong K, McClellan K. A classical case of Thygeson's superficial punctate
keratitis. Australian and New Zealand Journal of Ophthalmology. 23(1):76-77, 1995.
Goldberg DB. Schanzlin DJ. Brown SI. Management of Thygeson's superficial punctate
keratitis. American Journal of Ophthalmology. 89(1):22-24, 1980.
Tabbara KF, Ostler HB. Dawson C, Oh J. Thygeson's superficial punctate keratitis.
Ophthalmology. 88(1):75-77, 1981.
Thygeson's Superficial Punctate Keratitis. In Arffa RC. Grayson's Diseases of the
Cornea, 4th ed. Mosby, 1997, pp. 323-329.
Thygeson's Superficial Punctate Keratitis. In Leibowitz HM, Waring GO. Corneal
disorders: clinical diagnosis and management, 2nd ed. Saunders, 1998, pp. 460-461.
Van Bijsterveld OP. Mansour KH. Dubois FJ. Thygeson's superficial punctate keratitis.
Annals of Ophthalmology. 17(2):150-153, 1985.
reviewed January, 1999, by John E. Sutphin, Jr., MD, Cornea and External Diseases,
Department of Ophthalmology and Visual Science, University of Iowa.