Episode 48 – Electrophysiology

Welcome back to Basic Sciences in Ophthalmology.

Hi, I am your host Dr Thomas Whitelaw and in this episode, we explore the fascinating field of ocular electrophysiology. While clinical examination allows us to assess the structure of the eye, electrophysiology allows us to measure its function objectively. By recording electrical responses generated by the retina and visual pathways, electrophysiological tests provide valuable information about retinal, optic nerve, and cortical function.

These techniques are particularly important when clinical findings are subtle, when patients are unable to cooperate fully with visual testing, or when inherited retinal diseases are suspected.

Today’s episode is divided into three sections:

1. ERG types and components

2. Visual Evoked Potentials (VEP)

3. Clinical utility in diagnosis

Episode 47 – Phototransduction Cascade

Welcome back to Basic Sciences in Ophthalmology.

Hi my name is Dr Thomas Whitelaw and I am your host. In this episode, we explore one of the most elegant and important biochemical processes in vision: the phototransduction cascade.

Phototransduction is the mechanism by which light energy is converted into an electrical neural signal within the retina. This process occurs within the photoreceptors — rods and cones — and forms the foundation of visual perception.

The cascade involves highly coordinated molecular events including:

• Activation of visual pigments

• Intracellular signalling pathways

• Ion channel regulation

• Signal amplification

• Recovery and adaptation mechanisms

Understanding phototransduction is fundamental to retinal physiology and helps explain many inherited retinal disorders and degenerative diseases.

Today’s episode is divided into three sections:

1. Rhodopsin activation

2. The G-protein cascade

3. Signal amplification and recovery

Episode 46 – Physiology of the Macula and Fovea.

Welcome back to Basic Sciences in Ophthalmology.

Hi I am Dr Thomas Whitelaw and in this episode, we explore one of the most specialised regions of the human retina: the macula and fovea.These structures are responsible for the highest levels of visual acuity, colour discrimination, and fine central vision.

The remarkable physiology of the macula depends upon highly specialised anatomy, precise photoreceptor organisation, and complex metabolic support systems. Understanding macular physiology is essential not only forappreciating normal vision, but also for understanding major retinal diseases such as age-related macular degeneration and macular oedema.

Today’s episode is divided into three sections:

1. Anatomy of the fovea

2. Macular pigment and function

3. Diseases of the macula