Ex vivo metabolic analysis of eye bank corneas using phosphorus nuclear magnetic resonance

Application of nondestructive and noninvasive nuclear magnetic resonance (NMR) techniques to the evaluation of corneal donor tissue metabolism may provide information that would allow improved selection of donor material for keratoplasty. A phosphorus 31 NMR spectrum was generated from a single intact human cornea, evaluating phosphatic metabolites qualitatively and quantitatively. The NMR analyses were conducted on four corneas (from patients aged from 73 to 75 years). Intracorneal pH (7.2) was monitored from the resonance shift position of inorganic orthophosphate (Pi). A numerical index (1.15) of tissue energy status was determined by comparing the relative tissue content of high-field, high-energy phosphate signals (adenosine triphosphate, adenosine diphosphate, nicotinamide-adenine dinucleotide, and the uridine diphospho-hexoses) to that of the low-field, low-energy phosphate signals (Pi, sugar phosphates, and phosphodiesters). This is the first demonstration of the feasibility of using nondestructive 31P NMR to monitor the metabolic status of a single intact eye bank cornea as would be required in the evaluation of eye bank tissue before keratoplastic procedures.