Imaging
Expanding Indications of Imaging with Optovue Optical Coherence Tomography in Children
Matteo Sacchi, Massimiliano Serafino and Paolo Nucci Eye Clinic, San Giuseppe Hospital, University of Milan
Abstract
Although interest in optical coherence tomography (OCT) has increased markedly during the past decade in many fields of ophthalmology, there are only a few reports of the use of spectral domain (SD)-OCT in paediatric ophthalmology. In this article, the authors describe the use of SD-OCT in children as a new indication for OCT. Paediatric patients with aniridia were examined for the presence of keratopaty, cataract, glaucoma and foveal hypoplasia. Children with cataracts were followed for six months after surgery. The type of cataract, intraocular lens position, posterior capsule opacity and corneal incision healing were visualised by SD-OCT. In total, 24 eyes with aniridia and seven eyes with congenital cataract were enrolled. OCT was able successfully to detect ocular conditions associated with aniridia. After cataract extraction, OCT was also used to follow corneal incision healing and the development of posterior capsule opacity. In children with aniridia and congenital cataract, OCT can provide clinically relevant information. With the introduction of new generation, high-speed OCT, paediatric ophthalmology is likely to become a new and interesting target for OCT.
Keywords Aniridia, childhood, congenital cataract, paediatric ophthalmology, spectral domain optical coherence tomography
Disclosure: The authors have no conflicts of interest to declare. Received: 14 November 2011 Accepted: 8 December 2011 Citation: European Ophthalmic Review, 2012;6(1):7–11 Correspondence: Matteo Sacchi, University of Milan, San Giuseppe Hospital, Via San Vittore 12, 20123, Milano, Italy. E:
teosacchi@excite.it
Optical coherence tomography (OCT) is a noninvasive, objective optical modality providing cross-sectional images of in vivo tissue at a micrometer resolution scale.1
ophthalmology by Puliafito and Fujimoto in 1991,1
Since the first reports of its use in OCT has been
widely used and it is now one of the most useful devices in ophthalmic clinical practice.
The first OCT machine on the market was manufactured by Carl Zeiss Meditec in 1995; however, only in the past 10 years has OCT become largely available commercially. OCT technology was first applied to the retina, with clinical applications of OCT to retinal disease increasing over the past decade; OCT has overcome the adverse effects associated with fluorescein angiograms and, in many cases, is more informative.
OCT of the anterior segment is an evolution of the retinal OCT. It uses a longer wavelength (1,310 nm) than the retinal OCT (820 nm), which enables greater penetration through tissues that scatter light, such as sclera and limbus. Anterior OCT can visualise the corneal structure, the iridocorneal angle and the anterior lens. Imaging depth is limited to the pigment epithelium of the iris, which acts as a barrier to this optical method.
Briefly, in the OCT machine, an infrared beam is directed at a sample and the delay of the reflected light is measured. OCT measures the wave delay by comparing the sample reflection with a reference reflection in an interferometer. OCT has changed considerably in recent years, with the incorporation of spectral domain (SD) technology, which offers significant advantages over the traditional
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time domain (TD) OCT. Owing to their high frame transfer rate and fast Fourier transform algorithm, these recently introduced devices can perform up to 27,000 A-scans per second with a depth resolution of approximately 5 μm.2,3
Until the development of Fourier domain OCT techniques, including SD-OCT, OCT was a two-dimensional (2D) examination modality. The new generation SD-OCT offers a faster acquisition speed and an increased depth resolution compared with TD-OCT. In addition, it enables the three-dimensional (3D) in vivo examination of eyes.4,5
RTVue (Optovue Inc, Fremont, CA) is one of the commercially available instruments using SD-OCT technology to obtain cross-sectional and 3D images of both the posterior and anterior segments. It uses a scanning laser diode to emit a scan beam with a wavelength of 840 ± 10 nm. Unlike TD-OCT, RTVue uses a stationary reference mirror, and the OCT signal is acquired using a spectrometer as a detector. It offers a higher resolution than does TD-OCT, providing a significant reduction in motion artefacts and an increased signal:noise ratio compared with TD-OCT. RTVue can also perform up to 26,000 A-scans per second with a depth resolution of approximately 5 μm. For corneal and anterior segment imaging, an adaptor lens is mounted on the front objective lens.
The use of OCT is well established in adult patients for the management of retina and optic nerve head (ONH) disease. Recently, OCT has been widely used in graft assessment after corneal surgery.6–8
By contrast, the clinical application of OCT in paediatric patients is poorly studied. 7
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