Sensor-integrated dual-clad fiber probe for OCT-guided retinal endolaser photocoagulation.

Abstract

Significance: Retinal endolaser photocoagulation is a widely performed vitreoretinal procedure but currently lacks real-time intraoperative feedback on treatment outcomes. Integrating optical coherence tomography (OCT) directly into the endolaser probe enables co-localized, intraoperative sensing of tissue response during laser delivery, offering the potential to significantly enhance surgical safety and efficacy.

Aim: The aim of the study is to design, fabricate, and demonstrate a fiber-optic smart instrument with a 3D nano-printed microlens and instrument-integrated OCT sensing that enables co-localized, concurrent surgical laser delivery and tomographic sensing of tissue alterations during REPC.

Approach: A dual-clad fiber was used to co-axially deliver surgical and OCT beams through the outer multi-mode and inner single-mode cores. A 3D nano-printed aspherical microlens ( $300\mu m$ diameter) at the fiber tip optimized beam shaping for both lasers in the intravitreal cavity. The optical performance of the 23G instrument-integrated OCT (iiOCT) probe was characterized, and ex vivo validation experiments were conducted on porcine eyes.

Results: Optical performance assessments demonstrated close alignment between measured and simulated beam profiles, with an OCT spot size of $37.9\mu m$ at best focus and a surgical laser beam divergence half-angle of 6.0 deg. The probe demonstrated stable power transmission with a mean deviation of 0.35% across repeated pulses. Ex vivo experiments confirmed co-localized, concurrent surgical laser delivery and OCT sensing of retinal tissue alterations.

Conclusions: The miniaturized iiOCT endolaser probe combines surgical laser delivery with OCT sensing, achieving adequate performance for the targeted clinical application. This sensor-integrated instrument has the potential to enable intraocular, intraoperative, and quantitative assessment of treatment outcomes. It could support feedback-driven, robotic endolaser photocoagulation, enhancing the safety and efficacy of retinal endolaser surgery.