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Researchers find ciliary muscle ring diameter correlates with myopic refractive error
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Within the adult eye, refractive error is significantly correlated with the anterior equatorial dimensions, according to Kathryn Richdale, OD, PhD, FAAO, and colleagues in Optometry and Vision Science.
Researchers used ultrasonography, phakometry, keratometry, pachymetry, interferometry, anterior segment optical coherence tomography and high-resolution MRI on the right eyes of 91 adults, according to the study. Most participants were white (76%) and female (57%) with an average enrolled age of 40.5 years. Patients had a broad range of refractive errors, from -10.90 D to +1.75 D, with slightly more than half being myopic.
The maximum subjectively measured accommodative amplitude declined about 0.6 D per year of age, according to the study.
The researchers found that, with age, crystalline lens thickness increased at 0.03 mm/year, and anterior curvature steepened 0.11 mm/year. Furthermore, lens equivalent refractive index decreased by 0.001/year.
Richdale and colleagues reported no relationship between refractive error and accommodative amplitude.
, the following measurements increased: axial length by 0.37mm/D, vitreous chamber depth by 0.34 mm/D, vitreous chamber height by 0.09 mm/D and ciliary muscle ring diameter by 0.10 mm/D, according to researchers. Steepening of both the cornea and anterior lens surface was associated with increasing myopia.
Lens equatorial diameter significantly decreased with accommodation and increased with myopic refractive error, they reported.
“Although the lens continues to grow in all dimensions with age, it is likely that the equatorial diameter growth is canceled by the inward movement of the ciliary muscle, which allows the lens to further shorten in diameter and thicken with age,” the researchers wrote.
According to the researchers, this is the first study to demonstrate the correlations of larger ciliary muscle ring diameter with myopic refractive error.
Accommodating IOLs may need to be available in more than one diameter to allow maximum benefit, they concluded. – by Abigail Sutton
Disclosure: The researchers reported no relevant financial disclosures.
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