Abstract
Purpose: :
To determine correlation of subjective nuclear sclerotic cataract (NSC) grading and intraoperative cumulative dispersed energy (CDE) during phacoemulsification.
Methods: :
Retrospective analysis of data from 279 operations conducted at the VA Medical Center in Nashville, TN. Before each operation, cataracts were subjectively assigned nuclear sclerotic density grades on a scale of 1 to 4, with most cataracts assigned single-digit grades and some assigned hemi-grades such as 1.5 or 2.5. Cumulative dispersed energy (CDE), or amount of phacoemulsification ultrasound energy required to remove the cataract, was recorded intra-operatively.
Results: :
Out of 279 cataracts operated upon, 267 were assigned subjective density values using single-digit grades and 12 were assigned using hemi-grades. Incrementally increasing NSC grades & hemi-grades exhibited a stepwise increase in average CDE as well as variation in CDE, but with moderate correlation to CDE average (R2 = 0.75) and weak correlation to CDE variation (R2 = 0.61). With elimination of hemi-grading data, incrementally increasing NSC single-digit grades alone showed a stronger correlation to CDE averages (R2 = .88) and variation (R2 = 0.96). Successively increasing NSC hemi-grades alone did not exhibit stepwise increases in average CDE or variation in CDE, with the weakest correlation to CDE averages (R2 = 0.62).
Conclusions: :
Data reveals a stepwise incremental increase in average CDE with increasing NSC grades, indicating that subjective NSC grading is a reliable clinical means of predicting cataract density before an operation. However, higher subjective NSC grades also correspond to greater variation in CDE values. This pattern of incremental increase was not observed with NSC hemi-grading alone, and more data is needed to explore potential relative inaccuracy of NSC hemi-grading and the causes thereof.
Keywords: cataract • anatomy • training/teaching cataract surgery