One of the questions we are continuously asked here at Smart Vision Labs is “How accurate is the SVOne in comparison with the autorefractor I am using now?” This is a critically important question.The SVOne has to be easy and accurate for ODs to choose our device to take with their team a mission in the developing world. And, although we know from our own testing that the SVOne is extremely accurate, we also recognize it is important for people to see how this handheld autorefractor performs in the field.
With this in mind Luke Burchell, a Smart Vision Labs team member in Guatemala who practiced with the SVOne for only a day, popped the SVOne in his knapsack and hopped on a bus. After his 40-hour ride through southern Mexico he met up with the Volunteer Optometric Services to Humanity (VOSH) chapter from Illinois working in Oaxaca. The goal, apart from serving those in need on the campaign days, was to see how the SVOne performed alongside another high-quality handheld autorefractor.
So how did it go? It went very well. In short, the SVOne matched and then beat the handheld autorefractor being used. Let me explain how we know this.
First we wanted to see was if and how the SVOne “matched” the results of the other handheld autorefractor. Did we get similar results? Yes: the average difference for sphere and cylinder between the two technologies was less than a half diopter. Out of 84 eyes, 24 readings were the same, in 21 cases there was a difference of a quarter diopter, and in 10 cases there was a difference of a half of a diopter. This trend in differences continued downward. What this means is that in 54% of the cases the results were exactly the same or had a difference a quarter diopter and a combined 65% of the time we had a difference of a half of a diopter or less. This passed our match test with regards to diagnostic output.
The big question we wanted to know is: When looking at the final glasses prescription given by the optometrists on site, which technology came closest, most often? When compared side by side, which technology could get closest to the prescription that the clients actually needed? More often, it was the SVOne. When we looked at the spherical equivalent of the glasses that were actually prescribed for patients and compared that to the spherical equivalents of the other autorefractor and of the SVOne, the SVOne performed better. With 32 data points (16 pairs of glasses provided), the SVOne “won” 20 times and the other autorefractor won 12 times. In addition, even when the other autorefractor won the win was by an average of less than a quarter diopter.
In conclusion, is the SVOne economical? Yes. Is it portable? Yes. Does the battery last longer than other technologies? Most definitely it does. And, getting back to the big question—“Does it perform well compared to commonly used handheld autorefractors?” — the data says that it does. This is especially true with children. Given the open-field nature of the device, the SVOne overcomes the accommodation issues that are so prevalent when testing young eyes.
Interested in learning more about taking the SVOne on your mission in the developing world? Reach out to Brad at firstname.lastname@example.org. Let’s help change the world together.