Effects of probe geometry on transscleral diffuse optical spectroscopy

Area of Science:

• Ophthalmology
• Biomedical Optics
• Medical Instrumentation

Background:

• Accurate optical diagnostics of the eye require optimized instrumentation.
• Fiber optic probes are crucial for in vivo spectroscopy.
• Understanding probe geometry's impact on light interaction with the sclera is vital for diagnostic accuracy.

Purpose of the Study:

• To investigate how fiber optic probe geometry affects light transmission and reflection through the scleral eye wall.
• To optimize fiber optic probe design for transscleral spectroscopy.
• To assess the safety and impact of transscleral spectroscopy on the human eye.

Main Methods:

• Investigated source-detector distance and fiber protrusion parameters.
• Used diffuse reflectance and laser-induced fluorescence spectroscopy on ex vivo porcine eyes with tumor phantoms.
• Monitored intraocular pressure (IOP) and temperature; analyzed scleral surface with scanning electron microscopy.

Main Results:

• Optimal spectroscopic contrast achieved with 5 mm source-detector distance and zero fiber protrusion.
• A slight fiber protrusion (0.5 mm) may offer clinical advantages.
• Transscleral spectroscopy demonstrated no unacceptable IOP elevation, significant temperature rise, or visible scleral damage.

Conclusions:

• Fiber optic probe geometry significantly influences transscleral light interaction.
• Transscleral spectroscopy is a safe and viable diagnostic technique for in vivo human eyes.
• Optimized probes can improve diagnostic accuracy for intraocular conditions.