# Active-fluidics versus gravity-fluidics in uncomplicated cataract surgery: using optical coherence tomography angiography to estimate early changes in macular and optic disc microcirculation

## TL;DR

This study compares two cataract surgery techniques using OCTA to assess early effects on retinal and optic disc blood flow, finding that one method better preserves microcirculation.

## Contribution

The study introduces OCTA as a tool to detect early microcirculation changes in cataract surgery and identifies AFS as a potentially safer technique for preserving retinal vasculature.

## Key findings

- The GFS group showed significantly lower macular vessel density at 24 hours post-surgery compared to the AFS group.
- Seven days after surgery, the GFS group had higher retinal nerve fiber layer thickness and lower vessel density in specific quadrants compared to the AFS group.
- The AFS system appears to better protect retinal and optic disc microcirculation during cataract surgery.

## Abstract

To compare, using optical coherence tomography angiography (OCTA), the earliest changes and damages to macular and optic disc microcirculation after active-fluidics system (AFS) and gravity-fluidics system (GFS) procedures in uncomplicated cataract surgery.

We included 42 eyes affected by uncomplicated cataracts and divided them into two groups: 21 eyes were randomly assigned to an AFS group and 21 eyes were randomly assigned to a GFS group. Expert examiners performed OCTA 30 ± 10 min before surgery (T0), 30 ± 8 min after surgery (T1), 24 ± 2 h after surgery (T2) and 7 days after surgery (T3).

No significant differences at T1 were detected between the groups. At T2, eyes in the GFS group exhibited a whole macula deep capillary plexus vessel density of 37.9 ± 5.8%, which was significantly lower than that of the eyes in the AFS group (42.2 ± 5.7%; p = 0.048). At T3, eyes in the GFS group exhibited a significantly higher retinal nerve fibre layer thickness in the nasal (p = 0.020) and inferior (p = 0.045) quadrant, and a significantly lower peripapillary vessel density in the inferior quadrant of the papilla (p = 0.036) compared with eyes in the AFS group.

The AFS procedure appears to protect macular and optic disc microcirculation during phacoemulsification, and it may represent a more prudent approach, particularly in cases that require specific care to preserve residual peripapillary and macular vasculature (e.g., diabetic or glaucomatous eyes).

The active-fluidics system reduces intraoperative intraocular pressure fluctuations, that can affect retinal and optic nerve vasculature

The active-fluidics system reduces intraoperative intraocular pressure fluctuations, that can affect retinal and optic nerve vasculature

In both AFS and GFS groups, macular thickness showed a transient increase in the immediate postoperative period, accompanied by a decrease in DCP VD in both groups. It remained persistently higher in GFS-group, in parallel with a rebound increase in DCP VD with values at 7 days that were higher that baseline values.Seven days after surgery eyes from GFS group showed a significantly higher RNFLT in the nasal and inferior quadrant, and a significantly lower RCP VD in the inferior quadrant compared to eyes in AFS group.We postulated a mechanism of ischemia and reperfusion accompanied by intraretinal oedema involving both the papillary region and the macular region in GFS group.

In both AFS and GFS groups, macular thickness showed a transient increase in the immediate postoperative period, accompanied by a decrease in DCP VD in both groups. It remained persistently higher in GFS-group, in parallel with a rebound increase in DCP VD with values at 7 days that were higher that baseline values.

Seven days after surgery eyes from GFS group showed a significantly higher RNFLT in the nasal and inferior quadrant, and a significantly lower RCP VD in the inferior quadrant compared to eyes in AFS group.

We postulated a mechanism of ischemia and reperfusion accompanied by intraretinal oedema involving both the papillary region and the macular region in GFS group.