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Purpose.
Accommodation is a dioptric change in power of the crystalline lens resulting from ciliary muscle contraction that leads to an increase in lens surface curvatures and thickness and changes in the position of lens surfaces. Previous studies have used A-scan ultrasound to measure changes in the position of lens surfaces with voluntary accommodation, but have not simultaneously measured the change in refraction. The goal of this study is to simultaneously measure and correlate refractive and biometric changes in the lens during voluntary accommodation in humans.
Methods.
Refraction was measured off-axis in the right eye and biometry on-axis in the left eye simultaneously during voluntary accommodation in 22 human subjects between the ages of 21 and 30 years (mean ± standard deviation: 25.8 ± 2.3 years). Subjects viewed a distant target and four near targets spanning the full accommodative range available to evaluate refraction and lens surface position at each accommodative state.
Results.
Maximum objectively measured accommodative amplitude of all subjects was 5.64 ± 0.21 D (mean ± standard error of mean). Biometric and refractive changes during accommodation were linearly correlated. The mean ± standard error of mean decrease in anterior chamber depth was 0.051 ± 0.008 mm/D, increase in lens thickness was 0.067 ± 0.008 mm/D, and increase in anterior segment length was 0.017 ± 0.005 mm/D during accommodation. There was a net anterior movement of the lens center of 0.017 ± 0.005 mm/D.
Conclusion.
Anterior chamber depth, lens thickness, and anterior segment length change linearly with refraction during accommodation. Per-diopter changes in the lens were greater in the current study compared with previous studies in which only accommodative demand was measured, which overestimates the accommodative response.
Such a nice optician. My grandson is only 4 and needs glasses. We were so sad, but he explained the issues, and we will follow up as he suggested.
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Dr. Zurcher has gone above and beyond what any other eye doctor has ever done to figure out what is going on with my eyes. Very happy with American Family Vision.
Family Vision Clinic changed our lives! My daughter was frequently car sick, and she was getting headaches every day, often painful enough that they brought her to tears. We saw a string of doctors and therapists, but we made no progress. Finally, we found Dr. Levi Zurcher and his eye therapist Rain. After ten weeks of eye therapy my daughter no longer gets headaches, and she no longer gets car sick. Daily tears are a thing of the past. I really can’t say enough about this clinic. It was fascinating to watch Dr. Zurcher work. For the first time, someone who knew what they were doing was intently studying my daughter, really trying to figure out all of her eye issues, and his therapist Rain is one of the most patient and lovely people that I’ve ever had the good fortune to meet. We’re finished with eye therapy—yay!—and I have switched to American Family Vision Clinic for all of my family’s other eye health needs.
Very professional, yet kind and helpful. They do what they can to make the appointment comfortable. I was running a bit late, I made sure ti call. They were able to switch me with a patient who was already there, they treated me with respect, and helped my son have confidence by getting him the eye care he needed that day. Thank you so much! Would recommend to anyone. It's a blessing that they care enough to work with people who have all different types of insurance from work to state coverage.
The staff is friendly. The Doc is very knowledgeable. The office is family friendly and everyone is so patient with the little ones.
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