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CONTACT LENS CASE REPORTS

SOMETIMES FITTING LENSES IS LIKE HITTING A MOVING TARGET

Our patient is a 69-year-old retired professional clay target shooter who has spent a great deal of his life developing the visual and motor skills required to be successful in his profession. To that end, he has won hundreds of trophies, medals, and ribbons in world shooting competitions (Figure 1).

His optical journey began in his early 20s with the onset of bilateral myopia and astigmatism that was first corrected with spectacles (which proved less than optimal in his profession) and then with toric soft contact lenses. As the toric soft lenses failed to provide the visual quality and consistency required to identify a target moving at 70 miles per hour, he underwent bilateral laser-assisted in situ keratomileusis (LASIK) surgery in 2004. The surgeries were an anatomic success in that he was able to see 20/15 without correction in both eyes. However, 10 years post-op, he noticed a gradual change in his vision as he developed additional myopia and astigmatism in both eyes.

Figure 1. The patient in a professional shooting competition.

It was at that time that he was referred to our Specialty Lens Clinic for a scleral lens evaluation. We fitted him with 16.5mm scleral lenses: OD 4,000µ sagittal height (sag), 8.44mm base curve (BC), –0.75D power and OS 4,000µ sag, 8.44mm BC, –1.00D power. He was then able to clearly see 20/15 in both eyes. During his follow-up visits, the patient would continually remark about the quality and stability of his vision and in his ability to perceive moving objects in space. However, as with many patients wearing scleral lenses, his vision was “not perfect.” So, we performed numerous cylindrical over-refractions, which failed to uncover any residual astigmatism.

The real visual breakthrough for the patient occurred two years ago when we began our work with aberration-correcting optics on the anterior surface of scleral lenses. These are non-linear aspheric optics designed to eliminate the peripheral power changes associated with all minus- and plus-powered contact lenses.

Figure 2 shows the power profiles of the –0.75D right and the –1.00D left lenses, with and without the aberration-correcting optics. While the impact of these unique optics will be greater with higher-powered lenses (as described in last month’s Case Report), this patient found a remarkable increase in both his foveal acuity and his peripheral acuity.

Figure 2. The power profiles of both the –0.75D right and the –1.00D left lenses, without the aberration-correcting optics (black line) and with the aberration-correcting optics (red line).

Incorporate Different Optics

There are always some scleral lens patients who report less clarity in their vision as compared to with other optical modalities. Historically, we have addressed these unique optical challenges with careful residual cylinder over-refractions. Today, we also have the option of incorporating anterior-surface aberration-correcting optics.

The patient said: “My traditional scleral lenses produced better peripheral awareness than any contact lens I have ever worn. However, the aberration-free lenses provided an even greater level of peripheral awareness and an even higher degree of peripheral clarity. I can comfortably wear the lenses 12 to 14 hours in all of the unique outdoor environments present in professional shooting competitions. The lenses are fabulous under low light situations such as dusk and on cloudy days.” CLS

The authors wish to thank Mike Johnson at Art Optical for his assistance with the lens aberration graphs.