What is OCT (Optical Coherence Tomography)?

A Simple Guide to Retinal Imaging Technology

Overview

Optical Coherence Tomography (OCT) is a non-invasive imaging technology used to capture detailed cross-sectional images of the retina and optic nerve.

It allows clinicians to see the layers of the retina in high resolution, making it a critical tool for diagnosing and monitoring eye diseases.

How OCT Works

OCT uses light waves to create detailed images of the eye.

Similar to ultrasound (but with light instead of sound), OCT measures how light reflects off different layers of the retina to build a cross-sectional image.

Result: precise visualization of retinal structure in seconds

What OCT Is Used For

Retina

Age-related macular degeneration (AMD)
Diabetic retinopathy
Macular edema and holes

Glaucoma

Retinal nerve fiber layer (RNFL) analysis
Optic nerve evaluation
Progression tracking over time

General Eye Care

Baseline screening
Monitoring disease progression
Post-surgical evaluation

Types of OCT Technology

Spectral-Domain OCT (SD-OCT)

Widely used in clinical practice
Reliable and consistent imaging
Standard for glaucoma and general retina care

Example: ZEISS Cirrus OCT

Swept-Source OCT (SS-OCT)

Uses longer wavelength for deeper imaging
Better visualization of choroid and deeper structures
Often used in advanced retinal diagnostics

Example: Topcon Triton OCT

Automated OCT Systems

Designed for high-volume screening
Minimal operator involvement
Consistent, repeatable scans

Example: Topcon Maestro OCT

Who Uses OCT

Ophthalmologists
Optometrists
Retina specialists
Glaucoma specialists
Surgical centers

Why OCT Matters

OCT has become a standard of care because it allows:

Early detection of disease
Accurate diagnosis
Ongoing monitoring without invasive procedures

In most modern clinics, OCT is one of the most frequently used diagnostic tools

Real-World Insight

Most clinics today rely on OCT daily, not just for diagnosis but for tracking subtle changes over time.

As technology advances, systems are becoming faster, more automated, and capable of deeper imaging.

FAQ

What is OCT used for?
OCT is used to image the retina and optic nerve to diagnose and monitor eye diseases such as glaucoma and macular degeneration.

Is OCT safe?
Yes, OCT is non-invasive and does not involve radiation or injections.

What is the difference between OCT and OCTA?
OCT shows structural images of the retina, while OCT angiography (OCTA) shows blood flow.

Is OCT necessary for eye exams?
OCT is not required for all exams but is widely used for diagnosing and monitoring many eye conditions.