The Contact Lens Exam

Use Demonstrations to Educate Astigmatic Patients

the contact lens exam

Use Demonstrations to Educate Astigmatic Patients


Educating the patient is one of the most vital components of any exam. Patients who understand their conditions place greater importance on caring for their eyes. This translates into better compliance with care products, lens replacement and maintaining appointments; all of which promotes a healthier visual system and produces better patient outcomes.

Revisit Old Jargon

In my 12 years of practice, I've found that some of the most ill-informed patients are those with astigmatism. First, many think that they have a "stigmatism" — presumably some phantom growth inside the eye. Many have been told their eye is shaped like a football. When I ask them if they know what this means, they invariably shrug their shoulders.

To remedy this confusion, I take a different approach to the way I explain astigmatism. First, I tell patients that astigmatism is a description for the type of vision correction they need, similar to nearsightedness or farsightedness. However, in the case of astigmatism each individual eye requires a correction with two separate focal points. I usually supplement this point by using my hands to demonstrate the position of two far points of a myopic astigmat in front of my own eye. While this demonstration is rather basic, it provides patients with an understanding of why they need a lens with two different focal points to fully correct their vision.

Illustrating the Visual Impact

To demonstrate the visual effects of a toric lens, I often use two spectacle trial lenses from my loose diagnostic lens set. First, I hold up a –3.50D spherical lens between me and the patient and rotate the lens 360 degrees to show that no distortion occurs because the lens has the same power throughout the lens surface. Then I repeat the demonstration to show the distortion effect of a –3.50D cylindrical lens as it rotates.

This simple visual exercise also emphasizes that lens designs must incorporate stabilization features to provide consistent vision correction without fluctuations.

Another important element of astigmatic lens correction is the impact these lenses have on corneal health. The differential areas of thickness that are required to stabilize the visual effect of the lenses can decrease the oxygen transmission to the eye. Just like my previous examples, I feel that a visual demonstration has the most impact on patients. For this purpose, I use the Vistakon Eye Model (Figure 1). I place one of the demo contact lenses on the clear cornea to show how it can block the oxygen in the air from reaching the corneal surface in full concentration. Then I switch to the cornea that demonstrates pannus to explain the long-term effect if lenses are overworn or are not of high enough oxygen transmission.

Figure 1. The Vistakon Eye Model for visual demonstrations.

Educated Patients Know Best

Patients who understand their condition are more likely to make decisions that will promote better visual outcomes. Education also results in a higher level of patient trust, which enhances compliance with your treatment plan. CLS

Dr. Nixon is an associate professor of clinical optometry and the extern coordinator at The Ohio University College of Optometry. He is also in a group private practice in Westerville, Ohio.