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INI-CET 2014 — Ophthalmology

Q: Which cells are affected in glaucomatous optic neuropathy?

Ganglion cells. **Explanation:** **Glaucomatous Optic Neuropathy (GON)** is characterized by progressive damage to the optic nerve, primarily involving the **Retinal Ganglion Cells (RGCs)** and their axons. 1. **Why Ganglion Cells are correct:** The pathophysiology of glaucoma involves mechanical compression (due to elevated Intraocular Pressure) and vascular ischemia at the lamina cribrosa. This leads to the **apoptosis (programmed cell death)** of Retinal Ganglion Cells. Since the axons of these RGCs converge to form the optic nerve, their loss results in the characteristic "cupping" of the optic disc and corresponding visual field defects. 2. **Why other options are incorrect:** * **Amacrine and Bipolar cells:** These are interneurons located in the inner nuclear layer of the retina. While some secondary degeneration may occur in advanced stages, they are not the primary site of injury in glaucoma. * **Rods and Cones:** These are photoreceptors located in the outermost layer of the retina. They are responsible for converting light into electrical signals. Glaucoma is a disease of the "inner retina" (output neurons), whereas diseases like Retinitis Pigmentosa primarily affect the photoreceptors. **Clinical Pearls for NEET-PG:** * **Earliest Change:** The earliest structural change in glaucoma is often the thinning of the **Retinal Nerve Fiber Layer (RNFL)**, which consists of RGC axons. * **Mechanism of Death:** RGC death in glaucoma occurs via **Apoptosis**, triggered by neurotrophin deprivation and glutamate excitotoxicity. * **Diagnostic Tool:** **Optical Coherence Tomography (OCT)** is used to quantify the loss of the Ganglion Cell Complex (GCC) and RNFL thickness for early diagnosis. [Practice more Ophthalmology PYQs on OnCourse]

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Which cells are affected in glaucomatous optic neuropathy?