Purpose:
Technologies presently used in clinical practice to detect ocular foreign bodies (FB), include X-ray, CT, MRI, and ultrasonography, but each has significant limitations, particularly in the combat casualty care setting.The potential advantage of Ultrawideband (UWB) detection technology is that it offers greater sensitivity compared to existing detection methods, and may be accomplished using a small, portable device. Past research showed that this novel UWB detection system could successfully identify the presence of both metallic and nonmetallic FBs in an explanted porcine eye. Further investigation was performed to determine if more specific ocular FB characteristics, including size and location, can be detected for both metallic and nonmetallic FBs.
Methods:
An R2a nanoscale radar coupled to Vivaldi directional antennas, was used to acquire radar signatures. An explanted porcine eye was placed 40 cm from the radar antennas.Various size metallic (stainless steel 1.26 and 12.6 mm3) and nonmetallic (wood 5.064 and 50.64 mm3)FBs were surgically implanted at four test locations(cornea, anterior chamber, mid vitreous, and posterior sclera).Using strobed sampling to capture data, the radar recorded multiple trial runs including 900 samples of data which were then averaged. The changes in the reflected UWB energy for each of the trials was compared with the radar signature for the eye alone to detect the characteristics of each FB.
Results:
FB radar signatures reflecting different materials and sizes at various locations on the explanted eye resulted in reproducible characteristic alterations in both the position and amplitude of reflected radar energy peaks. The signatures of extraocular FB on the cornea and posterior sclera were indistinguishable regardless of the size and material of FB. However, intraocular FB within the AC and vitreous, repeatedly reflected more distinct signatures.This suggests the radar's senstivity to FB located inside the eye as well as its abilty to characterize size and type of material (Figure 1).
Conclusions:
UWB radar technology poorly distinguishes between size and material when detecting extraocular FB on the cornea and posterior sclera. The UWB radar is more sensitive to detecting intraocular FBs inside the AC and vitreous.
Keywords: detection • trauma • imaging/image analysis: clinical