A 30-year-old female arrived for a comprehensive eye examination. She was a new patient to our practice. Her chief complaint was that her vision wasn’t great in low light levels, such as when driving in the evening, but she stated that there was probably nothing that could be done about that.
The patient’s entering visual acuities wearing daily disposable contact lenses with a power of –3.25D in both eyes were OD 20/20-2, OS 20/20-2, and OU 20/20-1. An over-refraction revealed OD +0.25 –0.50 x 180, 20/20; OS +0.25 –0.50 x 180, 20/20; and OU 20/15. The patient’s habitual contact lenses fit very well. Anterior and posterior segment evaluation was unremarkable.
The patient’s manifest refraction when the contact lenses were removed was OD –3.00 –0.50 x 180, 20/20 and OS –3.00 –0.50 x 180, 20/20. Interestingly, during the refraction, when testing for the astigmatic power, the patient went back and forth between the –0.50D and the –0.75D cylinder powers during the Jackson cross-cylinder (JCC) power check of the refraction for both eyes. When the JCC was removed and the patient was asked whether either –0.50D or –0.75D of astigmatism correction looked clearer, she reported that they were almost identical but that –0.50D was slightly better. The patient provided the same response when the over-refraction was performed over the contact lenses that she was wearing.
What to Do with the Uncorrected Astigmatism?
It was clear that the uncorrected astigmatism was at least contributing to the visual issues that this patient was experiencing. Interestingly, her refractive astigmatism was just below the accepted –0.75D minimum that we typically think to correct with toric contact lenses.
In our practices, we typically do not hold off on correcting this level of astigmatism; we simply present both options to patients and let them decide. One way to do this is to show them the vision through the manifest refraction with –0.75D of cylinder at the appropriate axis compared to with no astigmatism correction. Additionally, we can demonstrate the astigmatism correction over spherical contact lenses and ask patients which one is clearer: with the –0.75DC or without.
Using handheld trial lenses, we demonstrated for our patient the –0.75D of astigmatism correction at the appropriate axis over her contact lenses, and she preferred the –0.75DC correction compared to no correction. The patient was fit with daily disposable lenses with the following power: –3.00 –0.75 x 180 OD and OS. She was given five pairs of lenses and was instructed to return three days later for follow up.
When the patient returned, she said that she couldn’t believe how clear her vision was, particularly in low light levels. She purchased a year’s supply of toric contact lenses.
Oftentimes, we may unintentionally dismiss certain patients from improved visual quality with toric lenses because their astigmatism falls below the minimum parameters available. Some of these patients will have improved vision with toric contact lenses even if the cylinder is greater than what is required. If not correcting low levels of uncorrected astigmatism is the new norm, we don’t want to be normal. CLS