Objective quantification of lens nuclear opacities using swept-source anterior segment optical coherence tomography

Abstract

Background/aims: The primary objective is to quantify the lens nuclear opacity using swept-source anterior segment optical coherence tomography (SS-ASOCT) and to evaluate its correlations with Lens Opacities Classification System III (LOCS-III) system and surgical parameters. The secondary objective is to assess the diagnostic performance for hard nuclear cataract.

Methods: This cross-sectional study included 1222 patients eligible for cataract surgery (1222 eyes). The latest SS-ASOCT (CASIA-2) was used to obtain high-resolution lens images, and the average nuclear density (AND) and maximum nuclear density (MND) were measured by a custom ImageJ software. Spearman's correlations analysis was used to assess associations of AND/MND with LOCS-III nuclear scores, visual acuity and surgical parameters. The subjects were then split randomly (9:1) into the training dataset and validating dataset. Receiver operating characteristic curves and calibration curves were constructed for the classification on hard nuclear cataract.

Results: The AND and MND from SS-ASOCT images were significantly correlated with nuclear colour scores (AND: r=0.716; MND: r=0.660; p<0.001) and nuclear opalescence scores (AND: r=0.712; MND: r=0.655; p<0.001). The AND by SS-ASOCT images had the highest values of Spearman's r for preoperative corrected distance visual acuity (r=0.3131), total ultrasonic time (r=0.3481) and cumulative dissipated energy (r=0.4265). The nuclear density had good performance in classifying hard nuclear cataract, with area under the curves of 0.859 (0.831-0.886) for AND and 0.796 (0.768-0.823) for MND.

Conclusion: Objective and quantitative evaluation of the lens nuclear density using SS-ASOCT images enable accurate diagnosis of hard nuclear cataract.

Keywords: lens and zonules.

Figure 1

Flow diagram. LOCS-III, Lens Opacities Classification System III.

Figure 2

Scatter plots showing the correlations of SS-ASOCT nuclear density quantitated by ImageJ software in pixel intensity units with LOCS-III scores (n=1099). (A) Maximum nuclear density versus NC score; (B) maximum nuclear density versus no score; (C) average nuclear density versus NC score; (D) average nuclear density versus no score. NC, nuclear colour; NO, nuclear opalescence; LOCS-III, Lens Opacities Classification System III; SS-ASOCT, swept-source anterior segment optical coherence tomography.

Figure 3

Receiver operating characteristic (ROC) curve and calibration curve for diagnosis of hard nuclear cataract (LOCS-III NO score ≥5.0) in training dataset (n=1099). (A) The ROC curve showing excellent discriminative power of AND and MND for diagnosing hard nuclear cataract. (B) The calibration plot showed good calibration between the observed and predicted proportion of hard nuclear cataract. AND, average nuclear density; AUC, area under the curve; LOCS-III, Lens Opacities Classification System III; MND, maximum nuclear density; NO, nuclear opalescence.