Herpes simplex keratitis is a leading cause of corneal opacification in the United States, other industrialized countries, and developing nations throughout the world. An estimated 450,000 people in the United States can develop recurrent episodes of the disease and about 46,000 episodes of HSV eye infection every year. Herpetic eye disease is the most common infectious cause of corneal blindness in this country.

Despite the availability of antiviral agents that are effective in treating herpes simplex epithelial keratitis, inflammation in the corneal connective tissue and iris that can lead to corneal scarring and visual impairment develops in many patients. Prior to the HEDS-I trials, the role of topical corticosteroids in the management of HSV stromal keratitis was uncertain; some animal and human studies suggested there was a benefit to treatment whereas others suggested harm. The value of adding an oral antiviral agent to treatment with topical corticosteroids and topical antivirals also was unknown.

The HEDS-I trials were developed to assess the efficacy of topical corticosteroids and oral acyclovir in treating HSV stromal keratitis and iridocyclitis.

HEDS-I consisted of three randomized, placebo-controlled trials. The organizational structure consisted of a data coordinating center and eight clinical centers.

All patients received the topical antiviral trifluridine as prophylaxis against recurrences of HSV epithelial ulceration. Patients were evaluated weekly for 10 weeks, every other week through week 16, and again at 6 months. The primary outcome was the time to development of preset criteria for treatment failure during the 16-week period of examination. Protocol-specific descriptions of the three trials follow.

Herpes Stromal Keratitis, Not on Steroid Trial (HEDS-SKN): Patients with active HSV stromal keratitis who had not used a topical corticosteroid in the preceding 10 days were randomized to treatment with topical prednisolone phosphate drops or topical placebo drops. A treatment schedule, starting with 8 drops a day of 1 percent prednisolone phosphate for 7 days, was progressively decreased over 10 weeks in such a way that patients received 1 drop per day of 1/8 percent prednisolone for the last 3 weeks of treatment. Placebo drops were given by the same schedule.

Herpes Stromal Keratitis, on Steroid Treatment (HEDS-SKS): Patients with active HSV stromal keratitis who already were being treated with a topical corticosteroid were randomized either to oral treatment with 200 mg acyclovir capsules (400 mg five times daily) for 10 weeks or to the identical dose of placebo capsules. Patients also received topical prednisolone phosphate in the dosage schedule described above for the SKN trial.

Herpes Simplex Virus Iridocyclitis, Receiving Topical Steroids (HEDS-IRT): Patients with active HSV iridocyclitis were randomized either to oral treatment with 200 mg acyclovir capsules (400 mg five times daily) for 10 weeks or to the identical dose of placebo capsules. Patients also received topical prednisolone phosphate in the dosage schedule described above for the SKN trial.