EVALUATION OF CYTOLOGIC SPECIMENS OBTAINED DURING EXPERIMENTAL VITREOUS BIOPSY

Vitreous specimens can be useful for diagnosis of intraocular infectio n, inflammation, and neoplasms. Concern has been raised that obtaining vitreous specimens through a guillotine cutter might result in subopt imal cytologic changes. To determine if aspiration yields better cytol ogic information than vitrectomy, the authors performed experimental v itreous biopsies on rabbit eyes with vitritis to compare specimens tak en by aspiration or vitrectomy with cutting rates of 100, 300, 600 per minute. The specimens were processed by cytospin preparations and sta ined with Papanicolaou and May-Grunwald-Giemsa stain. There was no dif ference in the adequacy of the specimens. Cell loss or damage to cell morphologic features when obtaining specimens through aspiration or vi trectomy at different cutting rates could not be differentiated by a b linded cytologic evaluation. A theoretical model of shear stress on ce lls passing through a guillotine cutter was also developed. The experi mental and theoretical data show that vitrectomy with a cutting rate a s fast as 600 per minute yields an adequate specimen with a sufficient number of well preserved cells to make definite cytologic interpretat ions, and that vitreous aspiration is not necessary.