Comparability of subjective and objective measurements of nuclear density in cataract patients

Purpose: To evaluate the relationship between subjective and objective measurements of lens density and the energy of phacoemulsification. Setting: University Eye Clinic, Maastricht University Medical Centre, Maastricht, the Netherlands. Design: Cross-sectional study. Methods: The study population included 69 patients. Nuclear opalescence (NO) was graded with the Lens Opacities Classification System III (LOCS III). Thereafter, lens density was measured objectively with Scheimpflug imaging, anterior segment optical coherent tomography and spectral fundus reflectometry (SFR). Cumulative dissipative energy (CDE) and total ultrasound time (US t.t.) of the phacoemulsification were noted. The relationship between the different measurement techniques and energy of phacoemulsification was assessed using Spearman's correlation coefficients. Results: We found moderate to strong correlations between LOCS III and objective measurements of the lens density (rho's from 0.53 to 0.78, p < 0.05) and a moderate correlation between three objective measurement techniques (rho's between 0.29 and 0.57, p < 0.05). There was a moderate correlation between CDE, US t.t. and lens density measurements (rho's from 0.29 to 0.55, p < 0.05), and the highest correlation was found between CDE and NO scores. Exclusion of patients with advanced cortical and posterior subcapsular opacities improved the correlation between SFR and lens density measurements but not the correlation with the energy of phacoemulsification. Conclusion: Lens Opacities Classification System III has shown the highest correlation with phacoemulsification energy and may be a preferred technique for prediction of use of phacoemulsification energy. Advanced cortical and posterior opacities may interfere with the quality of objective measurements but do not affect the correlation between lens density measurements and phacoemulsification energy.