To investigate whether the occasional increase in intraocular pressure
that may arise following injection of sodium hyaluronan into the ante
rior segment during intraocular surgery is related to the polymer size
of hyaluronan, controlled fragmentation of hyaluronan chains in vitro
was obtained using progressive incubation with testicular hyaluronida
se. The profile of molecular sizes of the hyaluronan polymers in vario
us preparations was determined using molecular sieve column chromatogr
aphy. Individual preparations were injected into six rabbit eyes and i
ntraocular pressures were measured every one-half hour for 12 hours. L
onger incubations of hyaluronan with hyaluronidase resulted in more ex
tensive degradation with accumulation of shorter chain lengths. In the
rabbit, mean intraocular pressure for 12 hours following intracameral
injection of hyaluronic acid (HA) is proportional to the polymer size
of HA. The occasional elevation of intraocular pressure that occurs f
ollowing injection of hyaluronan during ophthalmic surgery can be avoi
ded in part by assuring the rapid fragmentation of the large molecular
size hyaluronan polymer.