Long-term research investigates the causes of high ocular pressure, its risk factors, and available therapies.
Glaucoma is the most prevalent global cause of permanent blindness and is sometimes referred to as “the silent thief of sight.” High eye pressure harms the optic nerve, taking away first peripheral vision (what you see at the outside corners of your eyes), and then central vision (what you see when looking straight ahead). Usually, no symptoms are present until vision loss happens.
The only known way to stop or slow glaucoma is to lower excessive eye pressure. But is medical intervention necessary for everyone with elevated ocular pressure? Although it doesn’t yet have the full answer, significant long-term research offers some hints.
Is glaucoma a condition that affects all people with excessive eye pressure?
Three million Americans are thought to be affected by glaucoma, of whom half are unaware of their condition. When someone has high eye pressure, an ophthalmologist can do a thorough eye exam to establish if they already have glaucoma or are at risk for acquiring it in the future (ocular hypertension). Some individuals with high eye pressure may never develop glaucoma, according to findings from the long-running Ocular Hypertension Treatment Study (OHTS).
We continue to learn more about persons with high ocular pressure, their risk of getting glaucoma, and if they can take drugs to prevent glaucoma thanks to the multicenter, randomized clinical study known as OHTS, which was started in 1994.
A heterogeneous sample of 1,636 ocular hypertension patients from 22 sites throughout the US was enlisted by the researchers. Participants were randomized to begin early pressure-lowering eye drops (medication group) or careful observation to study glaucoma prevention (control group).
In the pharmaceutical group, 4.4% of patients had glaucoma at five years, versus 9.5% in the control group. This indicates that early usage of prescription eye drops helps persons with ocular hypertension postpone more than 50% of glaucoma occurrences.
It was determined whether commencing treatment later may still postpone glaucoma during subsequent stages of the research by giving the control group access to ocular pressure-lowering drugs; it did. By the age of 20, 42% of those using medication had acquired glaucoma, compared to 49% of those in the control group. The researchers were unable to assess the 20-year risk decrease between the initial beginning groups due to the trial no longer being randomized, though.
The study’s participants were who?
Considering that minorities have traditionally been underrepresented in clinical trials, a significant number of research participants (25%) were Black. The remaining participants were mainly of Caucasian ethnicity. 40 to 80 years of age were represented (the average was 55). All of the individuals’ eye tests, vision, and open-angle eye anatomy were normal, except for ocular hypertension. None of them already had glaucoma.
Has the timing of glaucoma treatment been altered as a result of this research?
According to the five-year statistics, Black persons appeared to have a greater rate of glaucoma than those of other races. When the researchers took into account crucial factors including age, corneal thickness, an indicator known as the size of the optic nerve cup, and the results of the initial peripheral vision test, the apparent difference vanished.
It became discovered that glaucoma risk depended on a mix of exam results rather than just ocular pressure and race. This knowledge aids medical professionals in assessing whether an individual with ocular hypertension has a low, medium, or high risk of developing glaucoma. Knowing this might aid individuals in deciding when to start utilizing prescription eye drops to either stop vision loss in its tracks or delay its progression.
What are the shortfalls of this extensive research?
Several restrictions apply to the study:
- It is typical for trial participants to adhere to their medication and visit schedules better than non-participants, which may lead to real-world glaucoma rates that are greater than those observed in either research group.
- The initial five years of the OHTS were randomized, but in subsequent phases, both groups were eligible to receive ocular pressure-lowering drugs.
- With novel diagnostic procedures like ocular coherence tomography and recently identified risk factors like corneal hysteresis, glaucoma diagnosis has improved over time. This may strengthen the case for cautious waiting as a viable choice for those who, due to several circumstances, have a decreased chance of developing glaucoma.
The findings of the study do not, of course, apply to those who already have glaucoma or other eye problems or who have narrow-angle eyes.