Ocular pulse amplitude before and after cataract surgery

To investigate the impact of cataract surgery on the association of the ocular pulse amplitude (OPA) and intraocular pressure (IOP) with respect to the interpretation of OPA as an estimate of ocular blood flow.

Twenty-four patients with cataract were included in a clinical study. OPA was measured using dynamic contour tonometry (DCT, Pascal(®), SMT Swiss Microtechnology AG, Switzerland). IOP was measured by means of Goldmann applanation tonometry (IOP GAT) and DCT (IOP DCT). All measurements were performed before and one day after cataract surgery.

At baseline, OPA was correlated to IOP GAT (r = 0.67, P = 0.0002) and IOP DCT (r = 0.82, P < 0.0001), but not to age or axial length. Postoperative OPA was correlated to IOP GAT (r = 0.67, P = 0.0002) and IOP DCT (r = 0.65, P = 0.0004). In 17 patients, IOP GAT decreased after surgery (IOP DCT n = 14), whereas an increase was apparent in seven patients (IOP DCT n = 10). The mean absolute deviation of IOP GAT pre- to post-surgery was 4.54 mmHg ± 2.47 (range 1-10 mmHg) and 5.4 mmHg ± 3.2 (range 1.1-13.1 mmHg) for IOP DCT. The changes of OPA were significantly correlated to changes in IOP GAT (r = 0.48, P = 0.017) and IOP DCT (r = 0.60, P = 0.001). IOP GAT and IOP DCT changes were not correlated to changes in corneal thickness.

The OPA measured with the Pascal(®) device seems to be dependent on IOP changes. Particular caution should be taken in the interpretation of OPA in estimating pulsatile ocular blood flow.