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Updated: Aug 16, 2026
Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs
Published on: July 23, 2016
Safety of in vivo pharmacologic vitreolysis with recombinant microplasmin in rabbit eyes
Toshiro Sakuma1, Minoru Tanaka, Atsushi Mizota
1Department of Ophthalmology, Juntendo University, Urayasu Hospital, 2-1-1 Tomioka, Urayasu, Chiba 279-0021, Japan.
Purpose:
To investigate the safety of intravitreal microplasmin in rabbits and to confirm previous findings of posterior vitreous detachment (PVD).
Methods:
Different doses of microplasmin, from 12.5 microg to 250 microg, in 0.1 mL balanced salt solution (BSS) were injected into the vitreous cavity of rabbit eyes to induce PVD. Fellow eyes were injected with the same volume of BSS. Slit-lamp biomicroscopy, ophthalmoscopic fundus examinations, A- and B-mode ultrasonography, and electroretinography were performed to assess the retina. Electroretinograms (ERGs) were recorded up to 90 days after injection. Morphologic alterations were assessed by light microscopy, scanning electron microscopy (SEM), and transmission (TEM) electron microscopy.
Results:
A slight aqueous flare and cells were observed in the anterior chamber after microplasmin and BSS injection. A slight inflammatory reaction was also observed transiently in the vitreous cavity. In control eyes, B-mode ultrasonography and SEM examination demonstrated that PVD did not develop after BSS injection. Intravitreal injections of 125 microg or greater of microplasmin induced complete PVD with an internal limiting membrane (ILM) devoid of vitreous collagen fibrils. Eyes injected with 12.5 microg microplasmin had partial PVD, and SEM showed residual fibrils covering the ILM. In all eyes, there was a transient reduction in the a- and b-waves of the ERG on days 2 through 7. The ERGs showed less effect with < 250 microg microplasmin.
Conclusions:
Intravitreal injection of recombinant microplasmin in the rabbit induces no ERG or retinal ultrastructural abnormalities. Pharmacologic vitreolysis with this agent may be a useful adjunct to vitreous surgery and could be used to induce PVD without vitreous surgery.
Insights
Intravitreal microplasmin safely induces posterior vitreous detachment (PVD) in rabbits without causing retinal damage. This suggests its potential use in vitreous surgery for pharmacologic vitreolysis.
Area of Science:
- Ophthalmology
- Pharmacology
- Retinal Science
Background:
- Posterior vitreous detachment (PVD) is a common condition in the aging population.
- Current treatments for vitreous-related disorders often involve invasive surgical procedures.
Purpose of the Study:
- To evaluate the safety and efficacy of intravitreal microplasmin for inducing PVD in a rabbit model.
- To confirm previous findings regarding microplasmin's ability to cause PVD.
Main Methods:
- Rabbits received intravitreal injections of varying microplasmin doses (12.5–250 µg) or balanced salt solution (BSS).
- Ophthalmic examinations included slit-lamp biomicroscopy, funduscopy, ultrasonography, and electroretinography (ERG).
- Retinal morphology was assessed using light, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).
Main Results:
- Microplasmin injections (≥125 µg) successfully induced complete PVD, characterized by an internal limiting membrane (ILM) free of vitreous collagen fibrils.
- Lower doses (12.5 µg) resulted in partial PVD with residual fibrils.
- Transient, mild inflammatory reactions and temporary ERG reductions were observed, with less impact at higher doses (<250 µg).
Conclusions:
- Intravitreal microplasmin effectively induces PVD in rabbits without causing significant ERG or retinal ultrastructural abnormalities.
- Pharmacologic vitreolysis using microplasmin shows promise as an adjunct to vitreous surgery.
- Microplasmin may offer a non-surgical method for inducing PVD.
