Cone Integrity in Glaucoma: An Adaptive-Optics Scanning Laser Ophthalmoscopy Study

Area of Science:

• Ophthalmology
• Neuroscience
• Vision Science

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Damage to the retinal nerve fiber layer and optic nerve is characteristic of glaucoma.
• The impact of glaucoma on photoreceptor integrity, particularly cones, remains an area of active investigation.

Purpose of the Study:

• To investigate changes in cone photoreceptors in patients with primary open-angle glaucoma.
• To compare cone density and spatial organization between glaucomatous and normal eyes.
• To assess the integrity of photoreceptor layers using advanced imaging techniques.

Main Methods:

• A cross-sectional study involving 35 eyes of glaucoma patients and 21 eyes of normal subjects.
• Exclusion criteria included axial length ≥26.0 mm.
• Ophthalmologic examination with spectral-domain optical coherence tomography (SDOCT) and adaptive-optics scanning laser ophthalmoscopy (AO-SLO).

Main Results:

• No significant differences in cone density or spatial organization were found between glaucoma and normal eyes (P > .75).
• SDOCT revealed no significant differences in photoreceptor layer thickness, with a continuous ellipsoid zone in all eyes.
• Microcystic lesions were observed in some glaucoma eyes, potentially affecting AO-SLO imaging of the cone mosaic.

Conclusions:

• Cone photoreceptors maintain their integrity in eyes with glaucoma, even in regions with prior visual field and nerve fiber loss.
• Advanced imaging techniques (AO-SLO and SDOCT) demonstrate preserved cone structure.
• Observed imaging artifacts in AO-SLO may be related to microcystic changes in the inner nuclear layer.