Abstract
Purpose: :
To test the hypothesis whether the presence of hyaluronic acid is the main inducer of photoreceptor cell apoptosis in retinal detachment.
Methods: :
Retinal detachments were created in adult C57BL/6Jmice (n=8) by injecting 1% sodium hyaluronate (Healon®, Abbott, IL) into the subretinal space through a 42-G cannula. In control animals retinal detachment was induced by injecting equiosmolar solution of 2.5% hydroxypropyl methylcellulose (GonakTM, Akorn, Inc, IL).Animals were sacrificed 24 hours later and photoreceptor apoptosis rate was determined with fluorescence activated cell sorting (FACS) after staining for terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). Results were also confirmed with immunohistochemisty of the retinal flat mounts. Undetached retina and DNase I treated-retina samples were used as negative and positive controls, respectively.
Results: :
Only 0.8% of the retinal cells in the control eyes were stained positive for TUNEL. Detachment of the sensory retina with hydroxypropyl methylcellulose increased TUNEL (+) cell population to 1.2% at 24 hours; however, presence of sodium hyaluronate in the subretinal space resulted in a significantly higher rate of apoptosis (17.8%). Retinal flat mounts showed a similar increase in TUNEL staining in eyes that the retina was detached with sodium hyaluronate.
Conclusions: :
Injection of subretinal hyaluronic acid induces photoreceptor cell apoptosis in experimentally induced retinal detachment. This finding may explain why vision is better preserved in serous and tractional retinal detachments, compared to rhegmatogenous retinal detachment where photoreceptors come in contact with vitreal hyaluronic acid that gains an access to the subretinal space.
Keywords: retinal detachment • apoptosis/cell death • retina