Unlike many other eye diseases, diagnosing glaucoma is not as straightforward as discovering a single red flag inside the eye. For instance, cataracts are often easily found when a doctor examines your eye with an ophthalmoscope or slit lamp, and can sometimes even be outwardly noticeable as a grey haze seen through the pupil (covering the eye implies cataract is a surface growth that is “scraped off” which is not true but a popular perception among the public).

The diagnosis of glaucoma, on the other hand, involves assessing the structure and function of the optic nerve and distinguishing damage from natural differences in nerve appearance. Ophthalmologists will analyze multiple different factors of your eye health—such as corneal thickness, intraocular pressure, and anatomy of the optic nerve—to reach a solid decision. Testing equipment goes a long way to make this possible.

It is crucial to understand that the way in which glaucoma nerve damage occurs varies drastically from most eye conditions. Glaucoma often begins by impacting peripheral vision in a slow and sneaky way. A person may have “20/20 vision” with or without glasses yet may have already lost the majority of their peripheral vision without noticing it. Since this damage is permanent and irreversible, early diagnosis is imperative. The goals of glaucoma treatment involve slowing or stopping such damage to ensure a person can maintain excellent vision throughout their life. Different aspects of the diagnosis and exam for glaucoma are discussed in more detail below. 

Because glaucoma begins by hindering your peripheral vision most of the time, eye doctors and ophthalmologists will often test this with a visual field test. A visual field machine will flash lights of varying brightness across different quadrants of your peripheral vision — testing the extent of your visual field — and typically requires you to press a button every time you detect one. After viewing the results, an eye doctor can see which areas of your peripheral vision might be weaker than expected. These tests are usually repeated every 6-12 months in order to ensure no additional changes are occuring.

Intraocular Pressure (IOP)

While the back part of each eye contains a gel-like substance called vitreous, the front part of the eye is filled with a water-like substance called aqueous humor. This fluid maintains the nutrition and oxygen needs of the front of the eye and its clarity helps light travel clearly to the rest of the eye’s structures. This fluid is made in the ciliary body and exits through an outflow system in the front of the eye. The resistance to outflow of fluid through this system determines the pressure inside the eye, or the intraocular pressure (IOP). The nerve damage which occurs with glaucoma is known to be sensitive to eye pressure and therefore the lower the IOP, the lower the risk of progressive nerve damage. 

Whenever you receive a comprehensive eye exam, either a technician or your eye doctor will usually measure your IOP via an “air puff” or by gently tapping your eyes with a special tonometer device.  Most people’s IOP will be in the range of 10-21 mm Hg. Glaucoma can occur at any eye pressure and your doctor will set a goal, or target IOP, based on your personal risk factors.

One of the points of interest an eye doctor will grade is your optic nerve, a small nerve head at the back of your eye which is directly attached to the brain. This is where the sensory information your eye picks up travels via electrical impulses for your brain to comprehend. Glaucoma causes damage to the optic nerve, which in turn messes up the images your brain perceives. If IOP is higher than the nerve tissue tolerates, the nerve fibers in the optic nerve can die off, resulting in decreasing vision.

Each optic nerve looks like a small donut in the back of the eye with an empty space in the center. In this analogy, the donut hole is known as the cup and the donut is the disc (or optic nerve head). The ratio of the cup to the disc is assessed and often documented in the chart as the cup-to-disc ratio, or CDR. As nerve damage progresses, the cup enlarges and this ratio increases.

The nerve is also assessed with an imaging machine which directly measures the thickness of this tissue and can monitor for change over time.

By taking a look at the whole picture and accurately assessing your visual field, IOP, CDR, and more, an eye doctor can add up the evidence to determine whether you might be susceptible to developing glaucoma — or how far along it has already progressed.

But glaucoma drops can be pricey, and eye drop bottles are already designed to output too much solution for the eyes to take advantage of. That means excess is often wasted, requiring a trip to the pharmacy much sooner than necessary.

Looking for a way to streamline your glaucoma treatment? Our Nanodropper Adaptors are designed to screw onto your bottle and minimize the size of the drops you squeeze out. This saves you money, reduces waste, and decreases the risk of systemic side effects. Visit our store page to see how you can revolutionize your eyedrop regimen!

This article has been reviewed by a medical professional. Please consult your eye doctor for medical advice.