Evaluation of lighted catheter phototherapy in endoscopic treatment of urethral strictures: a rabbit pilot study

To improve the success of minimally invasive urethral stricture treatments with red and near-infrared (NIR) light emitted via catheters after direct vision internal urethrotomy (DVIU). We hypothesized that catheter-emitted light therapy would improve success rate and histologic wound characteristics.

Twenty-four male New Zealand rabbits underwent stricture induction by electroresection and then were randomized into three groups: red light catheter (650 nm wavelength), NIR light (810 nm wavelength), or control (no light). After DVIU, a catheter was inserted for 7 days providing 5.4 J/cm²/day. The primary endpoint was radiographic success (as defined by > 10% improvement in urethral lumen diameter). Secondary endpoints were improvement in histologic parameters. Cystoscopy and retrograde urethrogram were performed post-operatively. Hematoxylin and eosin and Masson-Trichrome stains were used for histology evaluation.

One control rabbit had worsening stricture after DVIU, while no stricture in either treatment arm got worse. The red light group had 28% absolute improvement in stenosis, followed by NIR with 20%, and controls with 8% (p = 0.17). On pair-wise testing, NIR had significantly lower chronic inflammation compared to red (p = 0.024) and control (p = 0.033) groups, while red light had significantly higher vascularity compared to controls (p = 0.009).

Catheters emitting red and NIR phototherapy after DVIU demonstrated improved reductions in stenosis, though these findings were not statistically significant. There were significant improvements in chronic inflammation with the NIR lighted catheter and in vascularity with the red light catheter. Cumulatively, these results suggest a promising adjunct to minimally invasive treatment in urethral stricture disease that warrants further investigation.