Surgical intervention and accommodative responses, II: forward ciliary body accommodative movement is facilitated by zonular attachments to the lens capsule.
OBJECTIVE
To determine the role of the lens and the lens capsule in the three-dimensional architecture of the ciliary muscle at rest and during accommodation, in live rhesus monkeys and in histologic sections, by removing the entire lens, or only the lens nucleus and cortex, while leaving the posterior capsule in place.


METHODS
In 15 rhesus monkey eyes, aged 6 to 27 years, accommodation was induced by central stimulation of the Edinger-Westphal nucleus before and after intra- or extracapsular lens extraction (ICLE, ECLE). Forward ciliary body movement and ciliary body width were measured by ultrasound biomicroscopy (UBM, 50 MHz). The monkeys were then killed, the eyes were examined morphologically in 1-microm sections, and the shape of the ciliary muscle was compared with that obtained from UBM images.


RESULTS
The shape of the ciliary muscle in eyes undergoing ECLE (n = 5) did not differ from that in control eyes. In contrast, after ICLE (n = 10), accommodative forward ciliary body movement (P < 0.01) and thickness were decreased (P < 0.001), length was increased (P = 0.058), and the inner apex was located more posteriorly than in control eyes (P < 0.005). Histologic and in vivo data were similar and showed that the ciliary muscle maintained its triangular shape only if the lens capsule (with or without the lens substance) was present.


CONCLUSIONS
The posterior lens capsule and anterior zonular attachments facilitate forward accommodative ciliary body movement. Lens substance extraction procedures that leave the posterior capsule intact, similar to those used clinically, do not affect the capsule/zonular/muscular system movements, an important finding for accommodating intraocular lens development.
Wasilewski
Rainer
R
Department of Anatomy, University of Erlangen-Nürnberg, Erlangen, Germany.
McDonald
Jared P
JP
Heatley
Gregg
G
Lütjen-Drecoll
Elke
E
Kaufman
Paul L
PL
Croft
Mary Ann
MA
D000065:Accommodation, Ocular / Q000502:physiology*; D000375:Aging / Q000502:physiology; D000818:Animals; D019923:Capsulorhexis / Q000379:methods; D002924:Ciliary Body / Q000000981:diagnostic imaging / Q000502:physiology*; D004558:Electric Stimulation; D005260:Female; D032801:Iridectomy; D007903:Lens Capsule, Crystalline / Q000502:physiology* / Q000648:ultrastructure; D007908:Lens, Crystalline / Q000502:physiology* / Q000601:surgery* / Q000648:ultrastructure; D008022:Ligaments / Q000000981:diagnostic imaging / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D033401:Microscopy, Acoustic; D009130:Muscle, Smooth / Q000502:physiology; D018918:Phacoemulsification / Q000379:methods