How (and when) to Safely Get a Corneal Cytology Sample

I know touching the cornea can be scary, especially if it looks like ice cream on a hot day melting off the critter’s face. You can confidently and safely obtain your own corneal cytology samples if you know when and how to do it, so I’ve made a simple guide to help you! Check out the video at the end to watch me obtain a sample in a step-by-step tutorial.

• • First, determine if you need a sample. Examples of good candidates for corneal cytology are melting stromal ulcers or plaque like lesions on the corneal surface. If you have an ulcer that isn’t healing or if there is more opacity (edema or cellular infiltrate) then you may want to sample to be sure there is no infection present. *If the eye looks like it may rupture or is ruptured, do not attempt to get a cytology! *
  • Once you have decided you want to get a sample you’ll need:
    • Topical anesthetic such as Proparacaine or Tetracaine
    • Glass Microscope Slide
    • Adequate restraint, however, you should not need sedation
    • Your preference of cytology sampling tool
      • I recommend the blunt (non-cutting) end of any stainless-steel blade (#10, #15, #11)
      • I use a 6400 Beaver Blade *You probably don’t have those but they’re super cute and work great*
      • Cytology brush
      • Kimura spatula
    • Topical antibiotic to apply after you acquire your sample
• I do not recommend using cotton swabs because they do not release the cells back on to the slide well after sample acquisition.
• If you are submitting to a clinical pathologist, please follow their suggestions on whether you should stain before submission or send unstained.
• If you are looking at it yourself, stain with diff quick and see what you can find! I start on the 10X and then focus in at 100X to look for cells and to identify organisms.

Watch this short video on how to obtain a sample!

What should you see on a slide?
You should see epithelial cells with or without pigment, but there will probably be some pigment if it’s a brachycephalic dog!

If you see organisms (rods, cocci or fungal hyphae) or loads of neutrophils and macrophages then you’ve got an infection and now you can treat accordingly!

If it’s a proliferative lesion in a cat and you see eosinophils…what is your diagnosis? Eosinophilic keratitis!

Figure 3

Figure 2:
Cornel cytology with cocci bacteria

Figure 3:
Corneal cytology with branching fungal hyphae