Can Radiolabeled PPD Provide Quantitative Assay of Optic Nerve Damage?

Abstract

Abstract: : Purpose: To develop a quantitative assay of optic nerve damage using radiolabeled PPD. The use of PPD stain provides only qualitative assay of optic nerve damage in glaucoma. Methods: Radiolabeled ¹⁴C–PPD was synthesized. Rats were injected intravitreally with ET–1 (500 µM) to induce optic nerve damage. Optic nerve was surgically removed and sectioned into 1 mm sections and incubated with ¹⁴C–PPD for 60 min followed by 4 washes then counting in scintillation counter. Results: Control optic nerve sections had more counts that endothelin–treated optic nerve sections. The ratio of counts in control to treated optic nerve sections was almost 162%. Conclusions: The use of radiolabeled PPD may provide a quantitative assay of optic nerve damage. Further testing is needed to develop such novel assay that can provide quantitative measurement of optic nerve degeneration and comparison to current PPD qualitative stain.

Keywords: degenerations/dystrophies • ganglion cells • neuro-ophthalmology: optic nerve