IOP-dependent retinal ganglion cell dysfunction in glaucomatous DBA/2J mice

Area of Science:

• Ophthalmology
• Neuroscience
• Genetics

Background:

• Glaucoma is a leading cause of irreversible blindness.
• The DBA/2J mouse is a genetic model exhibiting age-related glaucoma.
• Retinal ganglion cells (RGCs) are crucial for vision and are vulnerable in glaucoma.

Purpose of the Study:

• To investigate the impact of elevated and lowered intraocular pressure (IOP) on RGC function in DBA/2J mice.
• To assess age-related changes in RGC susceptibility to IOP fluctuations.
• To evaluate the utility of pattern electroretinogram (PERG) in monitoring RGC function under varying IOP conditions.

Main Methods:

• DBA/2J mice of different ages (3, 5, 10, 11 months) were used.
• Intraocular pressure (IOP) and PERG were measured under normal, head-down (IOP elevation), and mannitol-induced (IOP lowering) conditions.
• Light-adapted flash electroretinogram (ERG) was used as a control.

Main Results:

• Head-down position caused significant, reversible IOP increases (32-38%) across all ages.
• PERG amplitude reductions were age-dependent, worsening with age (-47% at 5 months, -65% at 10 months).
• Mannitol administration significantly lowered IOP (38%) and improved PERG amplitude (83%) in older mice, showing an inverse correlation between IOP and PERG changes.

Conclusions:

• RGCs in DBA/2J mice become more susceptible to IOP elevation with increasing age.
• Pharmacological IOP reduction can restore abnormal RGC function in older mice.
• PERG is a potent, non-invasive method for evaluating RGC susceptibility to IOP insult in glaucoma models.