Articles about Eye Health and Disease 2002
Ocular Hypertension Medication
Delays or Prevents the Onset of Glaucoma
(From The Ocular Hypertension Treatment Study Group, Arch
Ophthalmol. 6/2002;120:701-713.)
Primary open-angle glaucoma is one of the leading causes of blindness
in the United States and worldwide. It is estimated that more than 2.5
million people in the United States have glaucoma, and that more than
130,000 people are legally blind from the disorder. Less than 50% of those
with peripheral vision loss from glaucoma have received an appropriate
diagnosis or treatment. (For more information about glaucoma in general,
go to Glaucoma).
Three to six million people in the United States are at increased risk
for developing vision loss from glaucoma due to having an increased eye
pressure (intraocular pressure, or IOP). It has not been previously known
the best course of action to take in people who have an abnormally high
IOP (i.e. Ocular Hypertension), yet do not have any apparent damage from
the elevated pressure, such as developing blind spots in the peripheral
vision (i.e. Glaucoma). The study discussed here looked at this issue, in
order to determine the safety and effectiveness of using eyedrop
medication to delay or prevent glaucoma in those who have an elevated IOP,
but no apparent damage from glaucoma.
In this randomized clinical trial, a total of 1636 participants with no
evidence of damage from glaucoma but with an elevated eye pressure between
24 and 32 in one eye and between 21 and 32 in the other eye were enrolled
(normal eye pressure is generally 21 or below). The participants
were randomized to either an observation group (no treatment) or a
treatment group with commercially available glaucoma eye drops (to lower
eye pressure). The goal in the medication group was to lower the IOP
by 20% or more, and to reach an IOP of 24 or less. Other
characteristics of the study included:
-
Age range from 40 to 80 years.
-
Enrollment was continued to include at least 400 African Americans.
-
The study was conducted at 22 clinical centers.
-
1692 individuals attempted to enroll but were rejected for a variety
of reasons, including poor visual acuity, unreliable test results,
abnormalities in the optic nerve appearance, inability to obtain clear
photographs of the optic nerve, and IOP outside of the specified
range.
-
The average follow-up time was 72 months for African Americans, and
78 months for other participants.
During the study period, follow-up visits were scheduled every six
months. Visual field testing to check for glaucoma blind spots was
conducted at every visit, along with the checking of eye pressure, and an
eye examination. Dilation was performed annually along with
photographs of the optic nerve. In the treatment group, medications
were added or changed in order to achieve the desired reduction in eye
pressure. The IOP goal was met at 87% of the scheduled follow-up
visits. By 60 months, nearly 40% of those in the treatment group
required 2 or more medications to successfully lower the IOP (more so in
African Americans than in the other groups).
During the course of the study, the IOP dropped an average of 22.5% in
the treatment group, compared to 4% in the observation group. At 60
months, the cumulative chance of developing glaucoma in the treatment
group was 4.4%, compared to 9.5% in the observation group, which was a
statistically significant difference. There was little evidence of
any increased ocular or bodily risk associated with using the glaucoma
eyedrop medications. An eye was felt to have developed glaucoma if
there was repeatable deterioration in the peripheral vision typical for
glaucoma, or if there were changes in the optic nerve photographs
characteristic of glaucoma.
Thus, this study indicates that lowering eye pressure using glaucoma
eye drops may significantly delay or prevent the development of glaucoma
damage to the eye before it has begun. The treatment of elevated IOP
alone, with no damage yet occurring, is a departure from the normal
treatment strategies that most ophthalmologists have used in the past,
making this study's findings very significant.
Return to the Eye News Index
of Articles Page
What's New at 