Purpose: To report the correlation of features of cataracts graded by the Lens Opacities Classification System, version III (LOCS III), with phacoemulsification energy expenditure and the balanced salt solution (BSS) volume used during cataract surgery.
Setting: Wolfe Clinic, Marshalltown, Iowa, USA.
Methods: This was a retrospective review of 2364 cases operated on by a single surgeon from January 1998 to July 2000 in which the cataract had been graded at the slitlamp using the 4 grading scales of the LOCS III: nuclear opalescence (NO), nuclear color (NC), cortical cataract (C), and posterior subcapsular cataract (P). Polynomial best-fit lines were derived using regression analysis correlating the 4 preoperative LOCS III characteristics with 3 intraoperative observations: machine-measured phacoemulsification time, mean power expenditure, and BSS volume.
Results: As determined by best-fit lines and their coefficient of determination (R(2)), there were exponential relationships between machine-measured phacoemulsification time and the degree of NC (R(2) = 0.48) and NO (R(2) = 0.40). Trends existed between NC and NO and the amount of BSS used (R(2) = 0.08 and R(2) = 0.07, respectively). No relationships were observed between the LOCS III classes of cataract, C and P, at any intraoperative observation.
Conclusions: Exponentially, greater phacoemulsification energy was required as NC and NO increased. The LOCS III cataract grading system enhanced the ability to estimate ultrasonic energy expenditure and BSS volume use during phacoemulsification. Preoperative LOCS III cataract classification can help to create a more formally organized, integrated, customized operative plan.