The effect of simulated cataract light scatter on retinal vessel oximetry

Abstract

To assess the impact of light scatter, similar to that introduced by cataract on retinal vessel blood oxygen saturation measurements using poly-bead solutions of varying concentrations.Eight healthy, young, non-smoking individuals were enrolled for this study. All subjects underwent digital blood pressure measurements, assessment of non-contact intraocular pressure, pupil dilation and retinal vessel oximetry using dual wavelength photography (Oxymetry Modul, Imedos Systems, Germany). To simulate light scatter, cells comprising a plastic collar and two plano lenses were filled with solutions of differing concentrations (0.001, 0.002 and 0.004%) of polystyrene microspheres (Polysciences Inc., USA). The adopted light scatter model showed an artifactual increase in venous optical density ratio (p=0.036), with the 0.004% condition producing significantly higher venous optical density ratio values when compared to images without a cell in place. Spectrophotometric analysis, and thus retinal vessel oximetry of the retinal vessels, is altered by artificial light scatter.

The effect of vitreomacular and cataract surgery on oxygen saturation in retinal vessels

“…Previous reports have shown that the measurement of arterial and venous retinal oxygen saturation tended to be lower in images of poor quality 16,17. To minimize the effects of cataract in this study, we excluded 26 patients, whose “image quality” was <6.0 before surgery.…”

Preoperative and postoperative measurements of retinal vessel oxygen saturation in patients with different grades of cataracts

“…In vivo , Patel et al. () introduced an additional plano lens filled with a polybead solution that simulated light scatter to mimic the changes in lens morphology. The light scatter model used in this study incorporated polybead microspheres, mimicking a forward light scatter similar to that produced by the ultra‐structural features of human lens fibre cells (Costello et al.…”

The influence of simulated cataract on retinal vessel oximetry measurements

“…We previously explored the effects of scatter on dual‐wavelength oximetry (Patel et al. ) and were able to demonstrate that simulated light scatter alters retinal vessel oximetry parameters. One of the limitations of this study was the small numbers of participants, vessels assessed and image size due to the optical set‐up.…”

“…Vessel saturation calculations depend on the absorption spectra, which in turn can be affected by light scatter, media opacity and illumination (Heitmar & Cubbidge ; Patel et al. ). We have previously explored the influence of light scatter using a polybead model (Patel et al.…”

“…We have previously explored the influence of light scatter using a polybead model (Patel et al. ), demonstrating that vessel oxygen parameters are altered depending on the amount of forward light scatter introduced. Unfortunately, this experiment was limited to explore only the effect of light scatter.…”