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Mary Ann Croft, Jared McDonald, T Michael Nork, Gregg A Heatley, Paul L Kaufman; ACCOMMODATIVE LENS EQUATOR POSITIONING AND CILIARY MUSCLE (CM) AND CILIARY PROCESS’ (CP) AREA IN THE AGING EYE. Invest. Ophthalmol. Vis. Sci. 2020;61(7):5137.
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The accommodative forward movement of the lens equator is significantly related to accommodative amplitude [Croft, Kaufman; IOVS 2013]. Our goal was to determine if the lens equator position in the resting or accommodated eye is dependent upon resting CM area and/or the CP area in human subjects of varying ages.
The eyes of 12 human subjects (aged 19-65 yrs) were studied. Ultrasound biomicroscopy (UBM; 50 MHz, 35 MHz) images were collected in the region of the lens/capsule and ciliary body following 1 drop of 5 % homatropine to induce disaccommodation and following 2 drops of 4% pilocarpine to induce maximum accommodative responses.
CM Area: The homatropinized (HOM) or pilocarpinized (PILO) A/P (anterior/posterior) lens equator position was unrelated to the amount of resting CM area. However, the centripetal (medial/lateral; ML) position of the resting (HOM) lens equator with respect to the scleral spur was related to the amount of resting (HOM) CM area (slope= - 0.28 ± 0.11 mm/mm2 ; p=0.039); the larger the CM area, the shorter the ML distance between the lens equator position and the scleral spur.CP Area: In the pilocarpinized eye, the A/P lens equator position with respect to the scleral spur tended to be related to the amount of resting CP area (slope = -0.61 ± 0.26 mm/ mm2; p=0.064); the larger the resting CP area, the less forward (more unaccommodated) was the AP lens equator position. Further, there was a significant relationship between the accommodative A/P forward movement of the lens equator position and the amount of resting CP area (slope= - 0.86 ± 0.15 mm/mm2 ; p<0.002); with increased resting CP area, the less was the accommodative forward movement of the A/P lens equator position.In addition, there was a significant relationship between ML lens equator position in the PILO eye and the amount of resting CP area (slope= - 0.72 ± 0.28 mm/mm2; p=0.048); the smaller the resting CP area, the greater the ML distance between the scleral spur and the lens equator.
At rest and during accommodation the lens equator position is dependent upon resting CP area (which increases with age). Maintaining the size/area of the CPs as seen in the young eye may be important to accommodative amplitude as we age - at least in part. Results of the CM and CP coordinates that define their shape and how they relate to accommodation will be discussed.
This is a 2020 ARVO Annual Meeting abstract.
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