Types of Home Tonometers: A Comparative Guide

The Glaucoma Research Foundation says that over three million Americans and more than 80 million people worldwide have glaucoma. Half of these people do not even know they have it. This group of eye conditions leads to optic nerve damage and vision loss.

Glaucoma is the second leading cause of vision loss worldwide. Unfortunately, its symptoms are subtle. People often overlook or ignore them until they damage the optic nerve.

Early detection is crucial. When doctors find glaucoma early, they can manage it well. This can slow down or even stop its progression.

Many factors cause glaucoma, but elevated intraocular pressure (IOP) is usually the main culprit. Luckily, with careful monitoring, we can manage and adjust IOP. This shows how important home tonometry is, not just for early detection.

In this guide, we will discuss home tonometers, covering the different types and how to choose the right one for you. This will help you manage your IOP easily and consistently.

What are Home Tonometers?

Tonometry is a quick and simple procedure used to detect changes in eye pressure in glaucoma patients. However, traditional tonometry usually requires a visit to the doctor’s office, which can be time-consuming, inconvenient, and stressful.

For all its benefits, clinical tonometry has its downsides. The main downside is the frequency of IOP checks. Glaucoma patients usually get IOP measurements three or four times a year.

IOP varies greatly in eyes without glaucoma and is even broader in glaucomatous eyes. The frequent use of clinical tonometry creates a greater need for more frequent IOP measurements. Daily IOP checks would help doctors and ophthalmologists fully assess a patient’s IOP and decide the best way to manage it.

That’s where home tonometry comes into play. Home tonometers are devices that measure eye pressure, and patients can measure their own IOP in the comfort of their homes.

They touch the eye with a small, cushioned probe that applies pressure. The device measures and records the IOP readings.

Home tonometry devices are portable. They let glaucoma patients measure their eye pressure more often and consistently. This is important for spotting problems early. Early detection helps prevent permanent damage to the eye nerve.

Not all self-tonometers have the same quality, and not all types suit specific eye conditions. Below is a breakdown of each type of home tonometer.

Rebound Tonometers

Rebound tonometry is used for home monitoring of IOP without an anesthetic or fluorescein. Obbink and Weigersma conceptualized it in the 1960s, but clinicians didn’t widely adopt it then.

Dr. Antti Kontiola improved the idea in the 1990s. He developed modern rebound tonometry, which led to the iCare tonometer. A useful and successful device for measuring IOP without needing an anesthetic exists.

Even with Dr. Kontiola’s improvements, the main mechanics of rebound tonometry remain the same. The system speeds up a probe, which rebounds from the cornea. Researchers then use the measurements to find the IOP data.

High IOP makes the cornea firmer, reducing contact between the cornea and the probe and increasing the probe’s speed after contact.

Many studies compared rebound tonometry to Goldmann applanation tonometry (GAT). They found that rebound tonometry measurements are usually within five mmHg of GAT.

The main benefits of home rebound tonometers are their portability and ease of use. This type of measurement doesn’t require an anesthetic, and it is usually more affordable than other home tonometers. It works well for most patients, including those with corneal irregularities.

iCare HOME2 Tonometer is a good example of a product. They are great for home and clinical use. Both provide fast and effective home use for glaucoma patients who need regular IOP monitoring. They require no specialized skills or anesthetic use and can deliver reliable measurements for clinical use.

The iCare HOME 2 Tonometer has a tilt sensor, which lets you measure patients vertically and horizontally. This is important for measuring daily IOP. The device also relies on more advanced measuring algorithms and features cloud connectivity.

However, rebound tonometers do have certain drawbacks. They are not as accurate as applanation tonometers. They can also have user errors from improper use and eye movement.

Applanation Tonometers

Applanation tonometers rely on Goldmann applanation tonometry, which is the benchmark by which IOP is interpreted in patients with glaucoma and ocular hypertension. The main idea of applanation tonometry is simple. The statement connects the pressure inside a sphere to the force required to flatten it.

The IOP is determined by measuring the force required to flatten a small, defined cornea area. This usually requires applying a topical anesthetic and fluorescein to the ocular surface.

The main benefits of applanation tonometers are their high accuracy and reliability. Corneal thickness does not affect these measurements, so ophthalmologists prefer these devices for managing glaucoma.

An example of a great applanation tonometer is the KOWA HA2 Hand-Held Applanation Tonometer. Doctors mainly use this device in clinics. However, with proper training, users can also use it for self-tonometry at home.

This is also a drawback, as patients must learn how to operate the device. Additionally, applanation tonometers aren’t suitable for patients with corneal abnormalities, such as small palpebral fissures, edema, surface irregularities, and band keratopathy. They also tend to be on the higher end of the price spectrum.

Other Emerging Technologies

Traditional tonometry is important and effective in eye care. It is also a minimally invasive procedure. An anesthetic may or may not be needed depending on the tonometer used.

However, other emerging technologies are even less invasive than current methods. In 2016, the Food and Drug Administration (FDA) approved contact lens sensors allowing 24-hour eye monitoring.

These single-use silicone contact lenses come in different sizes and curves. They have built-in strain gauges and a microchip that records and processes over 86,000 data points in 24 hours.

Someone sends these to a computer or a smart device (iOS or Android) using Bluetooth for further interpretation. However, even though the devices show good reproducibility, they still need more testing and research. They must complete this step before being entirely used in clinical practice.

Choosing the Right Tonometer

Not all home tonometers are the same, and not all are best suited for different eye conditions. However, choosing the right tonometer can be overwhelming, especially if you’re unsure what to look for.

In this section of your guide, we’ll provide the knowledge necessary to make an informed purchasing decision. We recommend you talk to your healthcare provider or eye care professional first. They can help you find the best device for your needs.

Factors to Consider

Here are some of the most important factors to consider when choosing a home tonometer device:

• Ease of use: Most home devices are easy to use. Ensure you know the basic functions and understand how to use them to measure your IOP correctly. The iCare HOME2 home tonometer is exceptionally easy to use, making it suitable for patients of all ages.
• Accuracy: While application devices feature benchmark accuracy, rebound devices may overestimate or underestimate the readings. However, these are often well within their error margins, making measurement errors clinically irrelevant.
• Cost: Home tonometry is a cost-effective way to measure and manage your IOP. However, the initial cost of a home tonometer can be hard for patients with limited financial resources to afford. Some devices might require periodic calibration or maintenance, which adds to the cost of ownership.
• Lifestyle and individual needs: Different home tonometers work better for different patients. Each type has its benefits and drawbacks. Make sure you choose a device that best fits your glaucoma care needs.
• Recommendations: The best way to choose a home tonometer is to talk to your doctor or eye care expert.

Importance of Consulting Your Doctor

Your eye doctor is best familiar with your glaucoma and any accompanying conditions affecting your eyes. It is important to talk to your doctor before buying a home tonometer. This way, you can get a device that suits your condition and needs.

Relying only on online guides to make your buying decision can be risky. You may choose a tonometer that is not right for your eye condition, measurement needs, or experience level. Always consult your eye care professional for the best advice.

Endnote

The type of home tonometers you use will vary based on your eye condition. Applanation tonometers are extremely accurate. However, they need an anesthetic and are not helpful for patients with corneal problems.

Rebound tonometers are not as accurate but exceptionally easy to use. They are also minimally invasive and do not need anesthesia. Talk to your doctor about home tonometry to maintain your eye health. Also, visit our tonometer category to see our quality tonometers.