Abstract
Purpose: :
To evaluate the mechanical properties of the lens capsule bag with or without zonular tension in order to better understand the dynamics of the capsular bag during accommodation in the aphakic eye.
Methods: :
Six fresh human donor eyes, ages 60 to 68 years, were studied (approximately 72 hours postmortem) and white–to–white diameter, equatorial diameter and axial length were measured. Following removal of the cornea and iris, the natural lens diameter was measured. A continuous curvilinear capsulorrhexis (CCC) was performed and the lens was removed by phacoemulsification and irrigation/aspiration. The capsulorrhexis and the lens capsule bag diameter were measured in two axes before and after lens extraction and cutting one–fourth, one–half and all of the zonules. All measurements were performed under microscopic view using digital calipers with an accuracy of ±0.01 mm.
Results: :
The white–to–white corneal diameter ranged from 11.03 to 12.42 mm, equatorial diameter was 22.67 to 23.90 mm and axial length was 22.76 to 24.50 mm. The mean natural lens diameter was 9.80 mm. The mean lens capsule bag diameter increased following lens extraction to 10.20 mm. Following zonular removal, the mean isolated lens capsule bag diameter decreased to 9.12 mm. Thus, without zonular attachment, the isolated capsular bag diameter decreases to less than its natural crystalline lens size.
Conclusions: :
To our knowledge, this is the first human donor eye study to assess the lens capsule bag elasticity with and without mechanical interaction of the zonules. The aged human eye lens capsule bag retains its elasticity and integrity as demonstrated by a decrease in lens capsule diameter following release of zonular tension. This may have relevance in understanding the ability of the aged lens capsule to facilitate accommodation in the pseudophakic eye.
Keywords: crystalline lens • presbyopia