A Novel Application of Heidelberg Retina Tomograph II (HRTII)/ Rostock Cornea Module Confocal Microscope as a Tool of Conjunctival in vivo Cytology versus Conjunctival Impression Cytology

Abstract

Purpose: : To demonstrate applicability of the Heidelberg Retina Tomograph II (HRTII)/ Rostock Cornea Module confocal microscope as a tool of in-vivo cytology in the evaluation of conjunctival epithelium in comparison to impression cytology in a prospective controlled study.

Methods: : Twenty right eyes of 20 SS patients (20 females; mean age: 54.1 ± 14.5 years) and 15 right eyes of 15 age and sex matched controls were studied. All subjects underwent Schirmer test, tear film break-up time (BUT), fluorescein, Rose Bengal staining of the ocular surface, conjunctival impression cytology (IC) and confocal microscopy of the nasal inferior bulbar conjunctiva. IC specimens underwent PAS staining. The longest conjunctival epithelial cell diameter, nuclear diameter, nucleocytoplasmic ratios and conjunctival inflammatory cell density were devised as new confocal microscopy parameters, and their correlation with measurements from IC as well as Nelson’s squamous metaplasia gradings were calculated and a new grading system was proposed. IRB approval and informed consents were obtained for this study.

Results: : The tear quantity, tear stability and vital staining scores were significantly worse in patients with SS compared to control subjects (p<0.01). Eyes of SS patients had a significantly lower goblet cell density and higher squamous metaplasia grades compared to eyes of healthy control subjects (p<0.01). The mean longest conjunctival epithelial cell size was longer ,the nuclear diameter was shorter and the N:C ratios were smaller in SS patients compared to controls both in confocal microscopy and impression cytology (p<0.01). These confocal microscopy parameters showed a strong positive linear correlation with the same parameters measured from the IC specimens of the same patients (r=0.74 for N:C ratio stats). The confocal microscopy in-vivo cytology parameters showed a very strong correlation with tear stability and tear quantity and with the vital staining scores(r=0.76~0.88).

Conclusions: : Confocal scanning laser microscopy was useful in the assessment of the conjunctival epithelial morphological alterations and inflammatory cell infiltrates in dry eye disease and proved applicable as a promising non-invasive tool of conjunctival in-vivo cytology with its new quantitative grading of squamous metaplasia expected to find applications in various ocular surface diseases.

Keywords: cornea: tears/tear film/dry eye • cytology • imaging/image analysis: clinical