Does lens influence green component in short 450 nm color autofluorescence? A cross-sectional study in heathy Caucasian population

Abstract

Purpose : Short wavelength 450 nm color fundus autofluorescence (cFAF) has recently been introduced based on a confocal light-emitting diode (LED) fundus imaging system with an emission detector between 500 and 750 nm. Both green and red emission fluorescent component (GEFC and REFC respectively) can be subtracted and analyzed. The purpose of this study is to investigate influence of lens in GEFC.

Methods : 43 healthy Caucasian subjects were enrolled in this cross-sectional study. cFAF was obtained following pupillary dilation using short wavelength 450 nm EIDON cFAF (CenterVue, Padua, Italy). Images acquisition was completely automatic, therefore 1 image per eye was obtained after auto-focus procedure. In 19 subjects 2 images per eye were acquired after one-minute interval time in order to calculate reproducibility data. At a later time, we enrolled 10 patients affected by cataract and we acquired cFAF images before and 1 week after cataract surgery. All images were obtained in a single exposure and only original color images based of both green and red channel were analyzed.
Images with adequate quality were exported and then imported into a publicly available image processing software (ImageJ 1.49v; National Institutes of Health) allowing red, blue and green channel splitting function. As cFAF does not contain any blue component, only subtraction from red to green was made in order to obtain exclusively the GEFC.
Statistical analysis was conducted using linear regression model. Test-retest agreement was calculated using Pearson Correlation Coefficient (PCC). A paired t-test was performed in order to determinate differences in retinal GEFC before and after cataract surgery.

Results : The right eye of 39 phakic healthy subjects (mean age 40.3, SD±17.3, range 18-75) was included in the analysis. Test-retest reliability in 19 eyes was significantly high (PCC= 0.99). Regression analysis did not show any significant correlation between age and GEFC in healthy subjects (R²=0.06 p=0.13), however, t-test showed a statistically significant GEFC decrease after cataract surgery (p<0.05).

Conclusions : Green emission fluorescent component in not influenced by age in a phakic population, however it appears to be affected by presence of either lens or intraocular lens based on phakic/pseudophakic data. Further cFAF study should consider lens interaction in GEFC estimation.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.