Optical Coherence Topography (OCT) is a non-invasive imaging test. In this test, reflected light is used to see the structure inside the eye and create cross-section pictures of our retina (Turbert, 2025).

Surgery is not needed in this technique since there are no instruments that penetrate the tissue.

➤ Ophthalmologist and Optometrist can view the optic nerve fiber layer and all of the retina's distinctive layers with OCT. They also will be able to track and determine the retina thickness and changes as they develop.

➤ These measurements aid in the diagnosing process.

📌 Conditions That OCT can Help Diagnose

• Macular hole

• Macular pucker

• Macular edema

• Age-related Macular degeneration

• Geographic atrophy

• Glaucoma

• Central serous retinopathy

• Diabetic retinopathy

• Vitreous traction

• Abnormal blood vessels

• Blood vessel blockage

• Drusen

💡 Light waves are necessary for OCT. When there are factors that affect how light enters the eye, it cannot be used.

• Retina diagnostics: OCT is a good standard instrument for diagnosing and monitoring diseases like age-related macular degeneration (AMD), diabetic retinopathy, and macular holes.

• Glaucoma management: It helps in measuring retinal nerve fiber layer thickness, resulting in early detection and tracking progression.

• Non-invasive: produce cross-sectional imaging without dye injection or contact with the patient’s eye.

🛠️Benefit:

• Treatment Planning:

OCT provides detailed information about the eye's

structure, aiding in planning surgical interventions and

optimizing treatment strategies. 

• Can diagnose small changes in our eye’s structure effectively.

• Can produce high resolution image with great detail (each of the that help opthalmology and also optometrist to detect any abnormalities in our eye’s. the resolution of OCT is much higher than that of other medical imaging methods like ultrasound or magnetic resonance imaging (MRI).

• The procedure is non-invasive because OCT procedure not require to have eye contact and without touching patient’s eye.

1. Limited Field of View:

🎯 OCT produce images for small areas at one time. It's great for high-resolution, localized imaging but not for scanning large surfaces for a quick results.

2. Media opacities can interfere with optimal imaging.

🎯 This means that anything that block light wave from OCT can interfere how image was produced for example if the patient associated with disease like vitreous hemorrhage, dense cataracts, or corneal opacities. This disease produce thick liquid in the eye’s that may interfere the screening process.

3. AS-OCT (instrument to observe anterior segment of the eye).

🎯 Has a poor ability to show the details of ciliary body and the posterior surface of the iris ( since the posterior pigment epithelium of the iris and the ciliary epithelium block the passage of infrared light).

🧪 The drops enlarge the pupil, which facilitates retinal examination.

🧪 With the patient's head resting on a support to keep it still, patient will sit in front of the OCT machine.

🧪 Then, without making contact with their eye, the apparatus will scan it.

🧪 Five to ten minutes are needed for scanning.

🧪 After the examination, the patient's eyes can remain light-sensitive for a few hours if they were dilated.

A broadband light source splits light into two paths:

🔹 Reference arm (fixed mirror)

🔹 Sample arm (illuminates tissue)

📍 Reflected light from both arms is recombined to form interference patterns.

📍 Interference occurs only when the optical path lengths match within the coherence length.

📍 The interference data is used to reconstruct depth-resolved images of tissue structures.

Two main types:

🔹 Time-Domain OCT (TD-OCT): uses mechanical movement of reference mirror.

🔹 Fourier-Domain OCT (FD-OCT): uses spectral analysis; faster and more sensitive.

Link video:

https://youtu.be/jbuIfHmAwz4?si=OZXkEP8aK29ltD57

https://youtu.be/kpxpCy_FeZE?si=VhUiUgMyFFNADqsh

https://youtu.be/2lYEnA-OBZ0?si=v48VR8ajsFP9RRiD

• Recent advancement of the OCT technology focused on the improvement of resolution of the image along with the imaging speed.

• New high-speed OCT system provide real-time imaging and dynamic, in-depth visualization of the tissues structure.

• Assist the physician to detect even the most subtle tissues changes with precision.

  
  

2. Angiography and Blood Flow Imaging

• Advances in the OCT transformed the ability to visualize the blood vessels in the vivo.

• OCT angiography provides non-invasive, high-resolution and real times blood flow images whereas quite different with the traditional OCT angiography technique that involves procedures.

• This advancement especially valuable in ophthalmology, cardiology and other field where precise vascular monitoring to accurate diagnoses and treatments are essential.

  
  

3. Adaptive optics in optical coherence tomography

• Combining OCT systems with the adaptive optics has improved the images quality where the aberration in the optical systems are corrected.

• The improvement of the technology counteracts the distortion that is caused by the eyes and the tissues to completely get hold of the images that are sharper and accurate.

  
  

4. Swept-Source OCT (SS-OCT)

• A swept laser used as a light source, provided some of the advantages in terms of imaging speed and deeper penetration.

• These improvements are beneficial for the imaging structures such as choroid.

  
  

5. Advancements in Light Sources

• The development of the light sources, for an example, supercontinuum lasers are improved in terms of imaging capabilities and spectral diversity.

  
  

6. Functional Optical Coherence Tomography

• The functional OCT technique have evolved to not only provide the structural but also the functional information regarding the tissues.

• Doppler OCT allow the measurements and the rate of the blood flow and support the valuation and diagnosis of vascular condition accurately.

• Another function OCT is elastography, which is functioned to assess the stiffness of the tissues and diagnosed the liver fibrosis.

  
  

7. Multimodal Imaging

• The integration between the OCT and the photoacoustic or fluorescence imaging has opened new challenges in characterization of tissues properties.

• The combination gives the complementary information and more detailed images of the structure of the tissues and its functions.

  
  

8. Artificial Intelligence Integration

• By using the artificial intelligence with the OCT, it is easier to interpret the images.

• Machine learning algorithm can automatically help to highlight the area of concern, detect the diseases and might even possible to predict the progress of the condition.

• The integration of these helps doctors to diagnose quickly and accurately.

  
  

9. Miniaturization and Portable Optical Coherence Tomography Devices

• The advancement in the miniaturization open the new path to the development of the portable OCT devices.

• The combination of the system gives point-of-care imaging.

• These helps bring the OCT technique into various range of clinical settings, that allows faster and efficient diagnoses.

📍 Link to the full article:

https://www.octcases.com/retina-case-50

📍 Link to the full article:

https://www.octcases.com/glaucoma-case-2

📍 Link to the full article:

https://f1000research.com/articles/11-968

• The modern CT systems provide superior resolutions (considerably down to 2-3 microns) as well as faster scanning speeds, which enables detailed visualization of microstructures and bigger scan regions with the minimal motion artifacts.

• These advancements improve the ability to detect and monitor recurrent eye disorders earlier.

• SS-OCT use longer wavelengths, adjustable lasers (usually 1050-1060nm) to penetrate deeper tissues, specifically the choroid and sclera and offer sharper images of deeper organ structures.

• Wide-field imaging allows clinicians to record wider portions of the retina and the optic nerve in simply one time scan, facilitating thorough retinal examinations.

• Integrating OCT with surgical microscopes allows for real-time, high-resolution imaging during eye surgery.

• This function assists surgeons in monitoring changes and improving precision during procedures like membrane peeling and corneal transplantation, resulting in better surgical outcomes.

• AI and deep learning algorithms are being utilized to carry out the segmentation of retinal layers, detect patterns and measure illness progression.

• Automated diagnosis improves accuracy, lessens clinician workload and enables earlier intervention for diseases such as diabetes and macular degeneration.

• New technologies such as 3D Point Optical Coherence Refraction Tomography (3D OCRT) offers superior contrast and resolution over a larger 3D field of view, revealing details that traditional OCT may overlook.

• Advancements in technology allow for more accurate and thorough assessments, leading to new diagnostic possibilities in both research and clinical practice.

1) ZEISS

2) Topcon Healthcare

3) Santec

🌟 ZEISS

-        Is the pioneer which introduces first commercial OCT instrument during 1996. ZEISS Cirrus 6000 and ZEISS Cirrus 5000 model

🌟 Topcon Healthcare

-        Manufacturing spectral domain & swept-source technology

-        Maestro2 and Triton is the OCT model

🌟 Santec

-        Manufacturing SS-OCT (swept-source) model after overcoming time-domain, fourier domain and spectral domain OCT shortcoming.

-        ARGOS SS-OCT equipment is one of the models manufactures by “MOVU” one of Santec medical equipment division.

📎 ZEISS and Topcon Healthcare are the main manufacturer for OCT equipment in the healthcare industry regarding eye.

1.      Heidelberg Engineering GmbH

2.     Agfa-Gevaert Group

3.     Imalux Corp

4.     Michelson Diagnostics

5.     Carl Zeiss Meditec AG

✨ G&H

One of the famous company to manufacturer 3rd parties components for Optical Coherence Tomography (OCT) such as custom product to improve the OCT equipment result.

➤ There are few range of related products manufacturer by G&H such as:

• Polarization diverse receivers

• Optical delay line

• Fused fiber couplers