Optical coherence tomography (OCT) is a technology that has the potential to dramatically change the way physicians, researchers and scientists see and understand the human body in order to better diagnose and treat disease, Dr Idrees Adhi, consultant ophthalmologist at the Civil Hospital Karachi, said at a pre-conference workshop organised by the Ophthalmologists Society of Pakistan on Wednesday.
Other speakers at the pre-KAROPATH Conference 2012 workshop included Dr Usman, Dr Muhammad Hanif and Dr Qazi Wasif.
Adhi termed the technology a promising new class of diagnostic medical imaging technology that utilises advanced photonics and fibre optics to obtain images and tissue characterisation on a scale that was never possible before, within the human body.
“OCT imaging can be performed over approximately the same distance of a biopsy at high resolution and in real time making the most attractive applications for OCT those where conventional biopsies cannot be performed or are ineffective,” he noted.
“Standard electronic techniques are adequate for processing ultrasonic echoes that travel at the speed of sound, interferometric techniques are required to extract the reflected optical signals from the infrared light used in OCT,” he added.
Dr Muhammad Hanif discussed the importance of OCT in progression scan in patient management and said the technology provides images of tissues at near histological resolution without the need for excision or processing of the specimen.
“In addition to providing high-level resolutions for the evaluation of micro-anatomic structures, OCT is inherently able to provide information regarding tissue composition,” he pointed out.
“The professionals using spectroscopy can evaluate the spectral absorption characteristics of tissue while simultaneously determining the orderliness of the tissue through the use of polarisation imaging,” he added.
OCT is a noninvasive, non-contact and transpupillary imaging technology that can image retinal structures in vivo with a resolution of 10 to 17 microns. Cross-sectional images of the retina are produced using the optical backscattering of light in a fashion analogous to B- scan ultrasonography. The anatomic layers within the retina can be differentiated and retinal thickness can be measured.
The appearance of a variety of posterior segment pathologies using OCT has been described. These include diabetic retinopathy, macular holes, epiretinal membranes, cystoid macular edema, central serous choroidopathy and optic disc pits.
Since the early 1990s, OCT has revolutionised the way retinal and glaucoma surgeons approach diagnostics in their practices, and it continues to show promise for additional applications.
When the technology for OCT was first developed in 1991, surgeons were impressed by the precise imaging created by this modality but questioned if it would become clinically indispensable. Now, many cannot imagine their practices without it.
Since its introduction to the commercial market in 1996, OCT has become a common tool in thousands of retina and glaucoma practices, but it took a lot of work and time to convince the community that the technology was not only useful but vital to the treatment of many patients.
