Disappearance of concentrated hyaluronan from the anterior chamber of monkey eyes

Abstract

The removal of hyaluronan (HYA) from the primate eye has received attention due to the use of the polymer in ophthalmic surgery. The turnover of concentrated HYA injected into the anterior chamber of 12 cynomolgus monkeys was therefore studied using a technique earlier described for rabbits. The technique is based on the observation that when HYA labelled with tritium in the acetyl group leaves the eye and enters the circulation it is rapidly taken up by the liver and degraded to tritiated water. A mixture of tritium-labelled HYA and high concentration, high molecular weight HYA (Healon R) was injected in amounts of 50 μl (or 75 μl, for three monkeys) into the anterior chamber. The concentration of tritiated water in blood plasma was followed for up to 3 weeks. An initial rise of radioactivity in blood was followed by an exponential decrease, representing the turnover of water in the body. The initial rise of tritium could be corrected for water losses and thereafter corresponded to the disappearance of HYA from the eye, plus a 45-min time lag due to the catabolism in the liver. Using this technique it was found that half of the material had left the anterior chamber after 20 hr when 50 μl (or 75 μl) were injected. Four animals were treated with pilocarpine topically during the first day and the corresponding time was then 8·5 hr. Maximal IOP occurred about 6 and 3 hr after the injection for non-treated and pilocarpine treated animals, respectively.