Influence of lens opacities and cataract severity on quantitative fundus autofluorescence as a secondary outcome of a randomized clinical trial

Abstract

The aim of this study is to investigate the impact of age-related lens opacities and advanced cataract, quantified by LOCS III grading, on quantitative autofluorescence (qAF) measurements in patients before and after cataract surgery. Images from a randomized controlled trial evaluating the impact of femtosecond-laser assisted cataract surgery (FLACS) on retinal thickness were analyzed post-hoc. One-hundred and twenty eyes from 60 consecutive patients with age-related cataract were included and assessed with qAF and optical coherence tomography (OCT) before, 1, 3 and 6 weeks after cataract surgery (randomized 1:1 to FLACS or phacoemulsification). LOCS III grading was performed before surgery. Pre- to post-surgical qAF values, as well as the impact of LOCS III gradings, surgery technique, gender, axial length and age on post-surgery qAF values was investigated using generalized linear mixed models. For this analysis, 106 eyes from 53 patients were usable. No difference in qAF was found between FLACS and phacoemulsification (p > 0.05) and results were pooled for the total cohort. Mean pre-surgical qAF was 89.45 ± 44.9 qAF units, with a significant mean increase of 178.4-191.6% after surgery (p < 0.001). No significant difference was found between the three follow-up visits after surgery (p > 0.05). Higher LOCS III cortical opacity quantifications were associated with a significantly greater increase in qAF after surgery (estimate: 98.56, p = 0.006) and nuclear opacities showed a trend toward an increased change (estimate: 48.8, p = 0.095). Considerable interactions were identified between baseline qAF and cortical opacities, nuclear opacities and posterior subcapsular opacities, as well as nuclear opacities and cortical opacities (p = 0.012, p = 0.064 and p = 0.069, respectively). Quantitative autofluorescence signals are significantly reconstituted after cataract surgery and LOCS III gradings are well associated with post-surgical qAF values. Careful consideration of age-related lens opacities is vital for the correct interpretation of qAF, especially in retinal diseases affecting the elderly.ClinicalTrials.gov Identifier: NCT03465124.

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1

Quantitative autofluorescence (qAF) imaging of a 64.9 years old, male participant before (A + C) and 6 weeks after (B + D) cataract surgery. qAF8 was quantified as the mean of the middle 8-segment ring of the Delori-pattern (red pattern). The top row shows the left eye with a LOCS III grading of (NO = 2/NC = 2/C = 1/P = 1) and the bottom row shows the right eye of the same patient with a LOCS III grading of (NO = 3/NC = 3/C = 2/P = 3). Images were acquired and analyzed with the Heidelberg Eye Explorer (HEYEX) Version 1.9.10.0 (Heidelberg Engineering, Heidelberg, Germany).

Figure 2

Flow diagram of patients randomized into either femtosecond-laser assisted cataract surgery (FLACS) or phacoemulsification. Because each patient received FLACS in one and phacoemulsification in the other eye, the numbers of eyes do not differ between the two treatment arms.

Figure 3

Course of quantitative autofluorescence (qAF) before and after cataract surgery demonstrated by the mean and 95% confidence intervals. qAF assessment was performed before cataract surgery (week 0) and at week 1, 3 and 6 after surgery.