CHAPTER 1
Methods in Ocular Cytology
In this chapter, methods for processing ocular cytology specimens are described. Most of the routine eye cytology specimens can be prepared by simple fixation and staining methods; although, occasionally more elaborate techniques, such as electron microscopy and immunocytochemistry, are helpful.
FIXATION AND STAINING METHODS
Each fixative and stain has advantages and disadvantages. In general, slides are either rapidly air dried or rapidly fixed in 95% ethanol. Air drying artificially expands the cells while ethanol artificially shrinks the cells. If air dried, a modified Wright or Giemsa stain should be used. (1) May-Grünwald Giemsa demonstrates excellent cytologic differentiation and is especially good for cells of hematopoietic origin. The Papanicolaou stain is excellent for squamous lesions. Hematoxylin and eosin recapitulates standard histopathology and is often preferred by those adept at surgical pathology, while Papanicolaou is preferred by those expert in exfoliative cytology. A combination of stains is helpful. The method of fixation and staining is determined by the clinical question to be answered. If allergic conjunctivitis is to be differentiated from infectious conjunctivitis, then air-dried, Giemsa-stained preparations are appropriate to differentiate eosinophils and neutrophils. If squamous dysplasia or carcinoma is suspected, then ethanol-fixed material reacted with direct fluorescent antibody is very sensitive. (
2) Giemsa-stained, air-dried smears can be done as an adjunctive procedure. Example protocols for staining by May-Grünwald Giemsa, Papanicolaou, and hematoxylin and eosin are shown in Tables 1-1, 1-2, and 1-3.
References:
1. Reich C. Modified Wright stain. Am J Clin Pathol 1954:24:881.
2.
Bell TA et al. Pediatrics 1984;74:224-228.
