Ovariectomy worsens visual function after mild optic nerve crush in rodents

Area of Science:

• Ophthalmology
• Neuroscience
• Endocrinology

Background:

• Glaucoma is a leading cause of irreversible blindness, disproportionately affecting women.
• Early menopause and estrogen deficiency are identified risk factors for glaucoma development.
• Previous research indicated surgical menopause worsens visual dysfunction in an ocular hypertension glaucoma model.

Purpose of the Study:

• To investigate the impact of surgical menopause on visual function following direct retinal ganglion cell (RGC) damage.
• To determine if ovariectomy exacerbates visual deficits in a rat model of optic nerve crush (ONC).

Main Methods:

• Female Long Evans rats underwent ovariectomy (OVX) or Sham surgery.
• Visual function was assessed using optomotor response before and after monocular ONC.
• Retinal function and retinal nerve fiber layer (RNFL) thickness were measured post-ONC.

Main Results:

• Optic nerve crush significantly reduced visual acuity in all operated rats.
• Surgically menopausal rats (OVX) exhibited a 31.7% greater reduction in visual acuity compared to Sham controls at 12 weeks post-ONC.
• Significant RNFL thinning and decreased RGC function were observed in ONC groups.

Conclusions:

• Surgical menopause exacerbates visual acuity loss after direct RGC injury induced by ONC.
• These findings suggest surgical menopause plays a significant role in visual impairment following optic nerve damage.
• Estrogen signaling may be crucial for maintaining visual function and protecting RGCs from injury.