OCT and paediatrics

OCT images of: A) A normal macula; B) Foveal hypoplasia (presence of the inner retinal layers posterior to the foveola, shallower or absent foveal pit, diminished outer nuclear layer widening, decreased photoreceptor outer segment lengthening, and overall thickening of the retina); C) Macular retinosquisis (separation of layers, mainly affecting inner nuclear layers); and D) Combined Hamartoma (a hyperreflective mass showing thickened and disorganised retinal tissue). Courtesy of Araceli Trueba Lawand MD, PhD Optical coherence tomography (OCT) is quickly becoming an increasingly valuable tool in paediatric ophthalmology, thanks to its noninvasive characteristics and the enhancement of image resolution and acquisition speeds, according to Araceli Trueba Lawand MD, PhD. “Fourier domain OCT technology, eye tracking and handheld devices have all aided in the clinical implementation of OCT in paediatric ophthalmology. Large amounts of research are being done in this field but not all have conclusive clinical implications as yet,” Dr Trueba Lawand told delegates attending the European Society of Ophthalmology (SOE) Congress in Barcelona. While OCT has the potential to play an important role in the monitoring of various ocular diseases in children, its scope is currently limited by the lack of normative OCT data needed to identify deviations from the normal range in younger populations, noted Dr Trueba Lawand. “We must know normality in order to detect abnormality in these patients.” “The lack of normative data limits longitudinal studies. One application where OCT may prove particularly useful in the future is in measuring macular ganglion cell layer-inner plexiform layer (GCL-IPL) thickness as an early marker of structural damage in children with optic pathway gliomas (OPGs), and a possible future surrogate of visual acuity and visual fields in young children.” Some progress has already been made in obtaining normative values of retinal nerve fibre layer (RNFL) and macular parameters in children using spectral domain OCT, said Dr Trueba Lawand. She cited a recent study of Al-Haddad et al. in which RNFL and macular thickness measurements were performed in 108 children using the Cirrus OCT machine. The authors give extensive comparative data of previous studies in the literature, and their results were comparable to other studies using the same Cirrus OCT machine. There is, however, great variability among results between the different OCT machines. This must be considered when evaluating and comparing OCT measurements in children, as suggested by Dr Trueba Lawand. OCT has also proven useful in characterising the time course of normal foveal development in vivo in term infants and young children, said Dr Trueba Lawand. Studies by Lee et al. have successfully modelled the complex, non-linear developmental trajectories for each retinal layer in infants and young children and demonstrated that development continues until adolescence (Figure A). In another OCT-based study, Thomas et al. developed a structural grading system for foveal hypoplasia based on the stage at which foveal development was arrested. This helps to provide a prognostic indicator for visual acuity and is applicable in a range of disorders associated with foveal hypoplasia, she said (Figure B). More controversial is the possible role of the retina in amblyopia, noted Dr Trueba Lawand. While a study by Al-Haddad et al. found no changes in the RNFL between amblyopic and normal eyes, qualitative and quantitative macular changes suggestive of foveal immaturity seem to persist into adulthood. OCT is also being used to characterise and monitor retinal dystrophies and dysplasias that present in early childhood, said Dr Trueba Lawand, and has also proven helpful in identifying the aetiology of infantile nystagmus syndrome, a heterogeneous group of disorders for which there are multiple causes with different prognoses (Figure C). In the field of oncology, OCT is useful in differentiating between various paediatric intraocular tumours through a systematic evaluation of tumour reflectivity, the degree of involvement of individual retinal layers, associated vitreoretinal interface abnormalities and the transition pattern between abnormal and normal retina, she said (Figure D). Another area where OCT may play a valuable role in the future is in evaluating risk factors for vision loss in paediatric idiopathic intracranial hypertension (IIH). A study by Gospe et al. showed that clinical observation of high papilloedema grade on presentation is predictive of poor visual outcomes, and that vision loss is associated not only with optic atrophy but also with photoreceptor damage. Initial OCT findings may permit better risk stratification and aid in determining how aggressively to treat idiopathic intracranial hypertension in these young patients, she concluded. Araceli Trueba Lawand: aratru@gmail.com

Tags: optical coherence tomography