1. (a) Identification. A diagnostic neurosurgical microscope filter is a device intended for use during neurosurgery to visualize fluorescence and enhance visualization of tissue associated with a specific disease or condition.

2. (b) Classification. Class II (special controls). The special controls for this device are:

   1. (1) Non-clinical performance testing must demonstrate that the device performs as intended under anticipated conditions of use, and verify and validate filter specifications and functional characteristics, including the following:

      1. (i) Spectrum and intensity of the illumination source;
      2. (ii) Spectrum of the excitation and emission filter modules when integrated in the surgical operating microscope;
      3. (iii) Excitation power and power density;
      4. (iv) Optical path loss from illumination source to objective lens or microscope camera;
      5. (v) Homogeneity of the excitation light at the focal plane;
      6. (vi) Fluorescence detection sensitivity;
      7. (vii) Verification of calibration or preoperative procedures; and
      8. (viii) If camera-based, spectral sensitivity of the camera.

   2. (2) Labeling must include:

      1. (i) Identification of the filter characteristics in conjunction with a compatible surgical operating microscope, to include the following:

         1. (A) Illumination spectrum and power density; and
         2. (B) Excitation and emission filter spectra.
      2. (ii) Instructions for calibration or preoperative checks to ensure device functionality prior to each use;
      3. (iii) Instructions for use with compatible surgical operating microscopes, external light sources, and cameras;
      4. (iv) A warning that the device should only be used with fluorophores approved for use within the specified spectral ranges; and
      5. (v) A warning that the device is not a standalone diagnostic.

[86 FR 73973, Dec. 29, 2021]