If the particles are more difficult to trap than standard dielectric spheres, the scattering force provided by the optical shield is greater, and the shield should prove more effective. If the scattering force on a particle is less than the particle’s weight, the particle will not be cleared from the region. This can be overcome with increased laser power or, if possible, reducing the size of particles used. Focusing the shield and trap 5 μm above the coverslip helped prevent particles entering the trap from below, and is far enough from the coverslip that hydrodynamic influences are small. Using 532 nm laser light helps reduce the effect of laser heating on the sample [10]. Reference [13] outlines some difficulties of using LG beams to clear paths through turbid media. The experimental requirements differ in this work as only a small volume around the trap is required to be kept clear, rather than a continuous path. We also have no requirement to clear the area inside the annulus, which is arranged to be clear at the start of the experiment. In conclusion, we have shown that introducing an LG beam centred around an optical trap reduces the probability that freely diffusing material will enter that trap. We have devised a procedure for detecting such an event and find nearly an order of magnitude increase in arrival time of contaminates compared to standard procedures. We use the approach to measure viscosity in a turbid sample and obtain the expected value. With the simplicity of generating the LG beam with holographic OT, we foresee that this approach may assist measurements in samples which involve a plethora of diffusing material.