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Ocular Hypertension Treatment Study (OHTS)

Purpose | Background | Description | Patient Eligibility | Recruitment Status | Current Status | Results | Publications | Resource Centers | NEI Representative

Purpose

Background

Glaucoma is one of the leading causes of blindness in the United States and other industrialized countries. It is estimated that 2 million people in the United States have glaucoma and that 80,000 of these individuals are legally blind from the disease. Among African Americans, glaucoma is now recognized as the leading cause of blindness.

Elevated intraocular pressure (IOP), a common condition affecting 3 to 6 million people in the United States, is thought to be the leading risk factor for development of open-angle glaucoma. There is no consensus that medical reduction of intraocular pressure prevents or delays the onset of visual field and/or optic nerve damage in ocular hypertensive subjects.

Despite the lack of convincing evidence for the efficacy of medical treatment in ocular hypertension, approximately 1.5 million glaucoma suspects in the United States are being treated with costly ocular hypotensive medications that carry the potential for serious and even life-threatening side effects.

Clearly, there is a need for a well-controlled clinical trial to determine whether medical reduction of IOP can prevent or delay the onset of glaucomatous damage in ocular hypertensive subjects. Only then can clinicians and patients make rational choices and health care planners ensure that limited medical resources are being allocated in a safe and cost-effective manner.

Description

The Ocular Hypertension Treatment Study (OHTS) is a long-term, randomized, controlled multicenter clinical trial. Ocular hypertensive subjects judged to be at moderate risk of developing primary open-angle glaucoma are randomly assigned to either close observation only or a stepped medical regimen. Medical treatment consists of all commercially available topical antiglaucoma agents.

After completion of baseline measures (IOP, visual fields, disc photos) and randomization, the subjects are followed for a minimum of 5 years with automated threshold central static perimetry (Humphrey program 30-2) twice yearly and stereoscopic optic disc photographs once yearly. Study end points are reproducible visual field loss and/or progressive optic disc damage in either eye of a patient. All visual fields and optic disc photographs are read in a masked fashion in Reading Centers.

In the 1991 Baltimore Eye Survey, African Americans were shown to have a prevalence of open-angle glaucoma four to five times higher than whites. Given this high prevalence of glaucoma in the African American population, it is important to recruit and follow an adequate sample of African American subjects in the trial (approximately 25 percent of the total patient sample).

At the conclusion of this study, practitioners should be able to make reasonable estimates of risk for individual ocular hypertensive patients and to determine which ocular hypertensive individuals are most likely to benefit from early prophylactic medical treatment.

Patient Eligibility

Men and nonpregnant women between the ages of 40 and 80 with IOP greater than or equal to 24 mm Hg but less than or equal to 32 mm Hg in at least one eye and IOP greater than or equal to 21 but less than or equal to 32 mm Hg in the fellow eye, as well as normal visual fields and optic discs are eligible for the trial. Patients presenting with best-corrected visual acuity worse than 20/40 in either eye, previous intraocular surgery, a life-threatening or debilitating disease, secondary causes of elevated IOP, angle-closure glaucoma or anatomically narrow angles, other diseases that can cause visual field loss, background diabetic retinopathy, optic disc abnormalities that can produce visual field loss or obscure the interpretation of the optic disc, or unwillingness to undergo random assignment are excluded from the trial.

Patient Recruitment Status

Completed. Recruitment of non-African American patients closed in December 1995; recruitment of African American patients closed in June 1996.

Current Status of Study

Ongoing.

Results

In univariate analyses, baseline factors that predicted the development of primary open-angle glaucoma (POAG) included older age, race (African American), sex (male), larger vertical cup-disc ratio, larger hoizontal cup-disc ratio, higher intraocular pressure, greater Humphrey visual field pattern standard deviation, heart disease, and thinner central corneal measurement. In multivariate analyses, baseline factors that predicted POAG included older age, larger vertical or hotrizontal cup-disc ratio, higher intraocular pressure, greater pattern standard deviation, and thinner central corneal meaturement.

During the course of the study, the mean ±SD reduction in IOP in the medication group was 22.5 percent ±9.9 percent. The IOP declined by 4.0 percent ± 11.6 percent in the observation group. At 60 months, the cumulative probability of developing POAG was 4.4 percent in the medication group and 9.5 percent in the observation group. There was little evidence of increased systemic or ocular risk associated with ocular hypotensive medication.

Topical ocular hypotensive medication was effective in delaying or preventing onset of POAG in individuals with elevated IOP. Although this does not imply that all patients with borderline or elevated IOP should receive medication, clinicians should consider initiating treatment for individuals with ocular hypertension who are at moderate or high risk for developing POAG.

Publications

Palmerg P: Answers from the Ocular Hypertension Treatment Study (editorial). Arch Ophthalmol 120: 829-830, 2002.

Kass MA, Heuer DK, Higginbotham EJ, Johnson CA, Keltner JL, Miler JP, Parrish II RK, Wilson MR, Gordon MO, for the Ocular Hypertension Treatment Study Group: The Ocular Hypertension Treatment Study: A Randomized Trial Determines that Topical Ocular Hypotensive Medication Delays or Prevents the Onset of Primary Open-Angle Glaucoma. Arch Ophthalmol 120: 701-713, 2002.

Gordon MO, Beiser JA, Brandt JD, Heuer DK, Higginbotham EJ, Johnson CA, Keltner JL, Miller JP, Parrish II RK, Wilson MR, Kass MA, for the Ocular Hypertension Treatment Study Group: The Ocular Hypertension Treatment Study: Baseline Factors that Predict the Onset of Primary Open-Angle Glaucoma. Arch Ophthalmol 120: 714-720, 2002.

Keltner JL, Johnson CA, Quigg JM, Cello KE, Kass MA, Gordon MO, for the Ocular Hypertension Treatment Study Group: Confirmation of visual field abnormalities in the Ocular Hypertension Treatment Study . Arch Ophthalmol 118: 1187-1194, 2000.

Kass MA: The Ocular Hypertension Treatment Study. J Glaucoma 3: 97-100, 1994.


Resource Centers

Chairman's Office
Michael A. Kass, M.D.
Washington University
Department of Ophthalmology and Visual Sciences
660 South Euclid, Campus Box 8096
St. Louis, MO 63110
Telephone: (314) 362-5713
Fax: (314) 362-3725

Vice Study Chair
Dale K. Heuer, M.D.
Medical College of Wisconsin
Department of Ophthalmology
925 North 87th Street
Milwaukee, WI 53226-4812
Telephone: (414) 456-7915

Eve J. Higginbotham, M.D.
Maryland Center for Eye Care
Department of Ophthalmology
419 West Redwood, Room 580
Baltimore, MD 21201
Telephone: (410) 328-5929

Richard K. Parrish, II, M.D.
University of Miami
McKnight Vision Research Center
5th Floor
1638 NW 10th Avenue
Miami, FL 33136
Telephone: (305) 326-6389

Data Coordinating Center
Mae O. Gordon, Ph.D.
Washington University
Department of Ophthalmology and Visual Sciences
Division of Biostatistics
660 South Euclid, Campus Box 8203
St. Louis, MO 63110
Telephone: (314) 362-3716
Fax: (314) 362-0231

Optic Disc Reading Center
Richard K. Parrish, II, M.D.
University of Miami
McKnight Vision Research Center
5th Floor
1638 NW 10th Avenue
Miami, FL 33136-1015
Telephone: (305) 326-6385

Visual Field Reading Center
John L. Keltner, M.D.
University of California, Davis
Department of Ophthalmology
4860 Y Street, Suite 2400
Sacramento, CA 95817

NEI Representative

Donald F. Everett, M.A.
National Eye Institute
National Institutes of Health
Suite 1300
5635 Fishers Lane MSC 9300
Bethesda, MD 20892-9300
USA
Telephone: (301) 451-2020
Fax: (301) 402-0528
Email: deverett@nei.nih.gov

 

Last Updated: 6/13/02



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