Abstract
Purpose :
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.
Methods :
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.
Results :
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.
Conclusions :
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.