More insight into eye disease glaucoma

Why is this insight so important?

“Because once damage is caused by glaucoma, it is irreversible. But with the right treatment — eye drops, laser treatment, or surgery — you can slow its development. So the sooner you make the diagnosis, the better the perspective for the patient.”

Back again: what exactly is glaucoma?

“A damage to the optic nerve, which gradually makes your vision worse. That starts at the edges of your field of view, but can spread to the center. Glaucoma can eventually lead to blindness. Fortunately, that rarely happens in the Netherlands.”

How does the problem arise?

“We don’t yet know exactly what causes glaucoma, but we do know that it has to do with too high eye pressure. Fluid is constantly being produced in your eyes. If more of that aqueous humor, as it is officially called, is produced than is discharged, the pressure rises and damage can occur.”

Is glaucoma common?

“Yes. About two in a hundred people over the age of 45 have this eye disease. In 2019 — the most current measurement — there were an estimated 328,200 people with glaucoma known to the general practitioner. In comparison, there were about 386,500 cases of the much more famous eye disease cataract in 2019. By the way, the vast majority of glaucoma patients are over 60; the risk increases with age.”

What do patients notice?

“That’s the treacherous thing: nothing for a long time. In the first years, glaucoma — apparently — usually does not cause any symptoms. That’s because you don’t feel it when you have increased eye pressure. Moreover, if you have a defect in one eye, the other eye will make up for it. Furthermore, your brain is smart enough to fill in the pieces that you no longer see. This explains why patients often don’t notice anything for a long time. As doctors, we also learn that during our studies. Real complaints only come later, when the field of view is drastically reduced. Patients then, for example, start bumping themselves more often, or they notice things in their environment less quickly.”

You say they don’t seem to have any symptoms at first. What Do You Mean By That?

“Groningen ophthalmologist Nomdo Jansonius heard from his glaucoma patients that their vision deteriorated under certain lighting conditions. In very bright light, but especially in the dark. He asked me to find out what this is in a PhD research. First, I had 400 participants fill out questionnaires about how well they could see in different conditions. In optimal light — outside on a cloudy day — there were hardly any differences. But in the dark, patients with glaucoma did indeed have more problems seeing than people with healthy eyes.”

In their own words.

“Correct. However, I then measured those differences objectively in the laboratory, using welding goggles with light filters. This allowed me to change the lighting conditions very gradually, from full sunlight on a bright summer day to a cloudy night without a moon. What seems? The eyes of people with and without glaucoma can adapt equally quickly to changing light conditions. But on some other factors that determine how well you can see, such as the contrast sensitivity of your eyes, glaucoma patients scored worse under all circumstances.”

What does that mean in practice?

“Simply put, people with glaucoma have less spare capacity. As a result, when it gets darker, they fall faster through the critical lower limit. While people with healthy eyes can still see well, people with glaucoma can no longer see that. To do the same things in the dark, glaucoma patients need three to ten times more light. In short: even in the early phase of their illness they do have symptoms. Only we have never made the link between these specific complaints and glaucoma before. I spread that message in as many places as possible, for example at lectures for ophthalmologists.”

You have also conducted public research.

“That was great fun! As a researcher, I think it is important to translate my data from the laboratory into practice. A few years ago, about two thousand people took to the streets after sunset during the Weekend of Science. Together they have taken more than 7000 measurements for my research. Using a special app on their smartphone, they were able to measure the amount of light on the ground in front of them (this app no ​​longer exists, ed.). At the same time, they indicated in the app how much difficulty they had in walking normally in the dark, ie without bumping or tripping. This study also showed that participants with an eye disease – not only glaucoma, but also cataracts, for example – had more difficulty seeing as it got darker than people with healthy eyes.”

Should opticians also start testing their customers in the dark from now on?

“That probably doesn’t make much sense. After all, the deterioration of vision in glaucoma occurs across the board, in both dark and light conditions. In addition, an optician mainly focuses on the vision in the center of the eye. And that is usually less affected in glaucoma. More importantly, opticians measure their customers’ eye pressure at every visit. That is still the best way to detect glaucoma at an early stage. If you do not receive such an investigation as standard, ask for it. Or go to another optician, or to an optometrist.”

What’s the difference between those two?

“An optician measures visual acuity, with the aim of determining whether you need glasses or contact lenses. In addition, he can also measure the eye pressure. It is not a protected profession. So there are qualified and non-certified opticians. An optometrist is a licensed healthcare professional who has completed a four-year college degree. He examines the health of the eyes and detects any abnormalities and diseases. An optometrist also measures glasses and contact lenses. Treatment of eye diseases is reserved for an (ophthalmologist) doctor. About 30 percent of the optometrists work in a hospital, the rest at an optician or in their own practice. You can visit the last two without a referral. Sometimes they also have special consultation hours for checks for eye abnormalities, for example for glaucoma or diabetes patients.”

Would it make sense if opticians, optometrists and ophthalmologists started using such special welding glasses?

“Based on the research I’ve done, no. However, I only looked at a few aspects of vision. There are more. For example, how eyes react when perceiving movement. Glaucoma patients may have more difficulty adjusting their eyes accordingly. Other Groningen scientists are now researching this. Yet another follow-up study is looking at whether you might be able to detect glaucoma simply by asking people if they can see anything outside on a dark night without a moon. If that really turns out to be a reliable indicator, we might eventually be able to conduct population screening for glaucoma relatively easily and cheaply.”

Does it make sense to test yourself by going outside on a dark night?

“That is difficult, because it is difficult to compare your own view with that of someone else. But if you notice that your vision is deteriorating in the dark, it is certainly a good idea to have your eye pressure measured. I would also if you are over 40 and one of your parents, children, siblings or grandparents has glaucoma. The condition is hereditary. If necessary, the optician can refer you to an optometrist or ophthalmologist. That is really worth it, because if glaucoma can be treated at an early stage, patients often have little trouble with it during their lives.”

on www.questionaandeoogarts.nl There are useful sample questions about (among other things) glaucoma, which you can ask when visiting an ophthalmologist.

Medications for glaucoma: there is something to choose

Once glaucoma has been diagnosed, patients often receive medication in the form of eye drops to lower eye pressure. There are many different types. Which one is most suitable for you depends, among other things, on the type of glaucoma, the level of the eye pressure and whether you also have other eye conditions (such as cataracts).

on www.apotheek.nl Under ‘glaucoma’ you will find an overview of the different medicines and how they work.

Tips for use

• Eye drops also reach the rest of the body via the tear duct in the eye. There they can give side effects. Pharmacists therefore advise to close the tear duct for a minute after the drip. You do this by pinching your nose at the level of the inner corner of your eye with your thumb and forefinger. This prevents the active substance from entering the blood.
• Do you find it difficult to get the drops in the eye? Then ask the pharmacy for an eye drop aid. This is a container that makes it easier for you to put drops into the eye. The pharmacist can also check that you are dripping properly.
• Most eye drop bottles have a shelf life of one month after opening. You can note on the packaging when you have opened it.

This article previously appeared in Plus Magazine June 2021. Want to subscribe to the magazine? You can do that in an instant!