Contact tonometry is similar to non-contact tonometry with the obvious difference- contact tonometry comes in direct contact with the eye.
In developing countries, contact tonometry poses a greater cultural issue. Dilation and numbing drops are not highly accepted, which turns people away from wanting to get tested for glaucoma. As discussed in the last post, glaucoma undiagnosed will cause irreversible blindness.
Like non-contact tonometers, contact tonometers are very expensive. Most are sold for close to $4,000. Non-portable ones are even more expensive.
So at this point you might be wondering, why would anyone need a contact tonometer over a non-contact tonometer? The largest draw to a contact tonometer is the accuracy. Non-contact tonometers are not nearly as accurate as contact ones.
CorneaPressure applied by a contact tonometer
Contact tonometers measure IOP by applying direct pressure onto the cornea. In order to come in direct contact with the eye dilation and numbing is required. This is not desirable in developing countries, but it is necessary for a contact tonometer to measure the IOP. Most tonometers are calibrated to measure in millimeters of Mercury (mmHg).
Have you ever wondered what that device is at the eye doctor that puffs air into your eye? More importantly, have you ever wondered what it does?
Non-contact tonometers are one way to test for glaucoma. As the name suggests, these tonometers don’t make contact with the actual eye. Instead, a puff of air is used to flatten the cornea so the IOP can be measured.
Non-contact tonometer in Nepal.
This is useful in places where sanitation might be an issue since the risk of passing along an infection from one person to the next with a non-contact tonometer is essentially non-existent. Non-contact tonometers, like the ones pictured above and below, are also useful for being able to screen large masses of people in a short period of time. A tonometer like the one below is able to screen someone in under a minute. Since the eye is not coming in direct contact with the device, no dilation or numbing is required to perform the test. This also cuts down on the total time required to determine the IOP. In developing countries, numbing and dilating your eyes is not ideal, which is what makes non-contact tonometry so appealing.
Non-Contact Tonometer
The main issues with non-contact tonometry are the accuracy and the cost. These devices are not very accurate and the one pictured above is almost $7,000, which is a common price point for non-contact tonometers. In developing countries, it is very unlikely that a doctor would be able to afford one of these. People have to travel far and wide to have their IOP measured due to how expensive these devices are.
Since glaucoma is irreversible, early diagnosis is crucial, especially in developing countries where sight is survival. Typically, there are no warning signs until you already have significant vision loss. Creating new ways to make non-contact tonometers useful and readily available in developing countries will make a dramatic impact on people’s quality of life and life span.
A human being can survive almost anything, as long as he sees the end in sight.
By now you’ve probably guessed what’s coming up next… Contact tonometry. Be sure to check back in to find out how contact tonometry can be useful in developing countries all over the world.
Clarity Design is very enthusiastic about the opportunity to utilize our design and manufacturing services for a humanitarian purpose. With the goal of helping others, especially those in developing countries, we have teamed up with the Himalayan Cataract Project to help eradicate curable and preventable blindness.
First, let’s dig into some background information on this life-changing organization and the people behind it.
The goal of the Himalayan Cataract Project, in short, is to provide affordable, high-quality, sustainable eye care to the developing world. The HCP has built infrastructures and eye care facilities, trained and educated local eye care teams, and performed countless surgeries to bring sight back to people all over the world. In 2013 alone, the HCP helped over 670,000 patients and performed 60,017 surgeries.
For the majority of people in the developing world, sight is survival. In Kalimpong, India, a woman’s sight is restored with the help of the HCP.
The Himalayan Cataract Project was started by two ophthalmologists with a mission- a mission to cure blindness.
Dr. Sanduk Ruit (left) and Dr. Geoff Tabin (right) at a rural eye camp. They are able to perform a cataract surgery replacing a lens in 7 minutes for $20.Dr. Ruit (left) educating others on his cataract surgery techniques.
Dr. Sanduk Ruit, Co-Founder of HCP, was the first Nepali doctor to perform cataract surgery with intraocular lens implants. He also pioneered a method for delivering high-quality microsurgical procedures in remote places. His work has not gone unrecognized as he has received some of the highest attainable awards in the area of international health.
Dr. Geoff Tabin, Co-Founder of HCP, is a Professor of Ophthalmology and Visual Sciences as well as the Director of International Ophthalmology at the John A. Moran Eye Center. He dedicates a significant amount of time working in Nepal and throughout the Himalayas.
“My partner Dr. Sanduk Ruit and I have vowed to work to eliminate all preventable and treatable blindness from the Himalayan region in our lifetime, a goal more audacious than setting out to make the first assent of the East Face of Mount Everest.” -Dr. Geoff Tabin
To learn more about this amazing organization and how you can be a part of the movement to cure blindness go to the Himalayan Cataract Project website.
To find out how Clarity Design is involved with the HCP and what we are doing to help cure blindness, keep checking back for more posts. You can also follow us on Facebook, Instagram, or Twitter (@ClarityDesign_) for more information.
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