Preoperative aqueous humour flare values do not predict proliferative vitreoretinopathy in patients with rhegmatogenous retinal detachment

Abstract

Background/aims Patients with rhegmatogenous retinal detachment (RRD) who develop postoperative proliferative vitreoretinopathy (PVR) have been found to have higher preoperative laser flare values than patients with RRD who do not develop this complication. Measurement of laser flare has therefore been proposed as an objective, rapid and non-invasive method for identifying high-risk patients. The purpose of our study was to validate the use of preoperative flare values as a predictor of PVR risk in two additional patient cohorts, and to confirm the sensitivity and specificity of this method for identifying high-risk patients. Methods We combined data from two independent prospective studies: centre 1 (120 patients) and centre 2 (194 patients). Preoperative aqueous humour flare was measured with a Kowa FM-500 Laser Flare Meter. PVR was defined as redetachment due to the formation of traction membranes that required reoperation within 6 months of initial surgery. Logistic regression and receiver operating characteristic analysis determined whether higher preoperative flare values were associated with an increased risk of postoperative PVR. Results PVR redetachment developed in 21/314 patients (6.7%). Median flare values differed significantly between centres, therefore analyses were done separately. Logistic regression showed a small but statistically significant increase in odds with increasing flare only for centre 2 (OR 1.014; p=0.005). Areas under the receiver operating characteristic showed low sensitivity and specificity: centre 1, 0.634 (95% CI 0.440 to 0.829) and centre 2, 0.731 (95% CI 0.598 to 0.865). Conclusions Preoperative laser flare measurements are inaccurate in discriminating between those patients with RRD at high and low risk of developing PVR.

Postoperative aqueous humour flare as a surrogate marker for proliferative vitreoretinopathy development

“…In contrast to previous reports, we recently reported that the preoperative aqueous flare value is not a strong predictor for the development of PVR postoperatively (Mulder et al. ).…”

“…Anterior chamber aqueous flarea surrogate marker for inflammation -has been proposed as a predictor for PVR in patients with a RRD (Schroder et al 2012;Hoerster et al 2013;Conart et al 2017). In contrast to previous reports, we recently reported that the preoperative aqueous flare value is not a strong predictor for the development of PVR postoperatively (Mulder et al 2017).…”

“…While the logistic regression analysis showed a statistically significant value (p = 0.005), the accompanying OR was low (1.014) and at a cut‐off value of 15 pc/ms, the low sensitivity (50%), specificity (76%) led to a positive predictive value of only 12% (Mulder et al. ). The choice of using a test with a relatively low positive predictive value and thus a high false discovery rate depends on the consequences and risks for the patient associated with a positive test, such as possible side‐effects of the treatment initiated.…”

“…). For the purpose of the sample size calculation of the original study (Mulder et al ), it was assumed that the standard deviation (SD) would be slightly higher (SD = 0.4). The incidence of PVR was estimated at 10%, the two‐sided significance level was set at α = 0.05, power at p = 0.80 and a factor two increase in flare value was thought to be clinically relevant.…”

“…All patients gave written informed consent. This patient cohort has been part of a previously published report with a different research question exclusively on preoperative measurements (Mulder et al 2017).…”