Current Management of Ocular Hypertension

Hilary Grissom; Mary E. Smith, MPH, RDMS; Peter A. Netland, MD, PHD

Disclosures

Compr Ophthalmol Update. 2004;5(2) 

In This Article

Abstract and Introduction

Our purpose is to update the comprehensive ophthalmologist about the results of the Ocular Hypertension Treatment Study and the current clinical management of ocular hypertension. In the Ocular Hypertension Treatment Study, after 60 months, the probability of progressing to primary open-angle glaucoma was 9.5% in the observation group and 4.4% in the treatment group. Approximately half of the patients who progressed showed changes of the visual field, whereas the other half showed disk changes, demonstrating the importance of both visual field and disk monitoring. Pachymetry is now recognized as a useful clinical measurement in ocular hypertension patients. In addition to thinner corneal measurement, the Ocular Hypertension Treatment Study identified other risk factors for progression of ocular hypertension to primary open-angle glaucoma, including older age, higher intraocular pressure, large cup-to-disk ratio, and an elevation of pattern standard deviation of the visual field. In practice, the clinician and the patient evaluate these risk factors for progression to primary open-angle glaucoma and individualize treatment, if needed, for the patient.

Ocular hypertension is a term used to describe intraocular pressure (IOP) greater than two standard deviations above the mean, above 21 mmHg by population studies (mean = 16 mmHg, normal range 10-21 mmHg), in the absence of optic nerve damage or visual field loss. However, 5% of all patients are found to have IOP above 21 mmHg (10% of patients over 40).[1] Practitioners have struggled with the decision to treat these patients, who are referred to as ocular hypertensives or glaucoma suspects. Criteria were lacking to distinguish those patients who are at a higher risk for progression to primary open-angle glaucoma (POAG) from those who will not progress to POAG without intervention.

The Ocular Hypertension Treatment Study (OHTS) examined those patients at moderate risk for progression to POAG because this group represents the most clinical uncertainty.[2] Prior to the OHTS, practitioners had limited information and were often unable to give patients definitive advice as to their relative risk and probable outcome. The findings of the OHTS have improved the evaluation and treatment of these patients.

The OHTS has shown that topical ocular hypotensive medications are effective in preventing visual field loss and optic disk deterioration in select individuals with IOP between 24 mmHg and 32 mmHg in at least one eye and a pressure between 21 mmHg and 32 mmHg in the other eye. Although these parameters adequately examined the target group of ocular hypertension patients at moderate risk, the values used in the study did exclude certain ocular hypertensives who may or may not have responded differently to treatment compared with the study population.

Major risk factors targeted by the OHTS to be predictive of progression of ocular hypertension to POAG are older age, higher IOP, increased vertical and horizontal cup-to-disk ratio, elevated pattern standard deviation of the visual field, and thinner central corneal measurement. Pattern standard deviation represents the homogeneity of any visual field abnormality. It is small if all locations in the visual field deviate from normal by the same amount, and a minimal value represents the expected variability of testing. The patter n standard deviation becomes larger when field loss is more marked in some locations than in others.[3] Corneal thickness in particular has emerged as a major factor in predicting later progression to POAG.

In an earlier article, we provided a review of ocular hypertension and early POAG.[4] Our purpose is to update the comprehensive ophthalmologist about the current clinical management of ocular hypertension.

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