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Does lens densitometry predict ultrasound energy in manual and femtosecond laser-assisted phacoemulsification cataract surgery?

Poster Details

First Author: M.Ryan USA

Co Author(s):    M. Pyfer   Q. Zhang                 

Abstract Details


To determine if measurements of lens density taken with scheimpflug imaging correlate with total phacoemulsification energy used in standard manual or femtosecond laser-assisted cataract surgery


Private practice affiliated with Wills Eye Hospital in Philadelphia, PA USA.


This is a retrospective review of 90 eyes that underwent cataract extraction with manual cataract surgery (MCS) or femtosecond laser-assisted surgery (FLACS). Cases were performed by one surgeon using the same technique and equipment. All eyes underwent lens densitometry via schiempflug imaging using Pentacam HR (Oculus, Germany) prior to surgery. Average and maximum lens opacity were recorded as percent values. Intraoperative phacoemulsification energy was recorded as cumulative dissipated energy (CDE) in %-sec for each case. Lens density measures were correlated with CDE using spearman rank-order statistics.


Mean (± standard deviation) of average lens opacity was 11.8% (± 1.6) and 12.5% (±1.8) for FLACS and MCS groups respectively. Mean maximum lens opacity was 39.3% (± 16.8) for FLACS and 37.7% (±13.9) for MCS. Mean CDE was 1.45 (±1.34) for FLACS and 6.99 (±5.02) for MCS. Maximum CDE was 5.68 for FLACS and 25.27 for MCS. In MCS, CDE was positively correlated with average lens opacity (R=0.34, P= 0.024) and maximum lens opacity (R=0.32, P = 0.031). In FLACS, CDE did not correlate with average lens opacity (R =-0.18, P=0.26) or with maximum lens opacity (R= -0.14, P=0.41).


FLACS decreased mean and maximum CDE compared with MCS. Scheimpflug imaging measures of average and maximum lens opacity performed similarly as measures of cataract density. Our findings demonstrated lens density positively correlates with CDE in MCS. However we found that this relationship was eliminated in FLACS, where CDE showed a trend towards negative correlation with lens density. This suggests that FLACS fundamentally alters the effect of lens density on intraoperative parameters in cataract surgery. This has implications for intraoperative planning and patient risk stratification. It also suggests that measures of surgical efficiency in MCS may not apply in FLACS.

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