Retinal Examination in Babies and Young Children

With retinal disorders becoming a major cause of childhood blindness worldwide (1), thoroughly and regularly examining the retina in children has become more important than ever. While indirect ophthalmoscopy (IDO) is the traditional standard for retinal examination, accurate visualization of the peripheral retina tends to be operator-dependent, and the procedure can often be distressing for children (2). By contrast, digital retinal imaging provides objective and extensive information in a much faster and convenient manner. It serves as a valuable complement to clinical examinations, particularly in eyes with media opacities or inadequate pupil dilation.

Changing diagnostic paradigms: digital retinal imaging

Traditional retinal examination using an indirect ophthalmoscope headset or a condensing lens on a slit lamp presents several practical challenges, especially when examining children. For instance, neonates can be kept still through swaddling, but uncooperative older children may require anaesthesia, carrying potential neurotoxic risks (3). The need for skilled examiners, long examination times, and subjective documentation with fundus drawings are some other drawbacks. Conventional fundus photography, which captures 30°-50° of the fundus (or up to 100° with montaging) (4), has been used for decades, but clinicians have realized that this field-of-view (FOV) can be inadequate in pediatric vitreoretinal pathologies, such as retinopathy of prematurity (ROP), familial exudative vitreoretinopathy (FEVR), and Coats’ disease, which can have significant peripheral manifestations (5).

Widefield (WF) imaging is defined by the International Widefield Imaging Study Group as capturing retinal anatomy beyond the posterior pole but posterior to the vortex vein ampullae in all four quadrants. Ultra widefield (UWF) imaging, by contrast, extends further to capture details anterior to the vortex vein ampullae in all quadrants (6). These imaging systems provide fovea-centred images covering 60°-100° (WF) and 110°-220° (UWF) of the retina in a single capture, thereby combining the advantages of digital imaging, such as accurate documentation and reproducibility, with the ability to visualize peripheral retina that is inaccessible with traditional fundus photography (4).

Among the WF systems that are used in pediatric ophthalmology, the RetCam 3 (Clarity Medical Systems, Inc., Pleasanton, CA, US) is probably the most well-known device (4), although there are now newer machines, including an updated version of the RetCam known as the Envision (Natus Medical Inc., Pleasanton, CA, US) (7). Other 100°-140° examples include the Phoenix ICON (Phoenix Technology Group, Pleasanton, CA, US) (7), the 3nethra neo (Forus Health, Bangalore, India) (8), the PANOCam (Visunex Medical Systems, Inc., Fremont, CA, US) (8) and the SUOER SW-8000 (Tianjin Suowei Electronic Technology Co., Ltd., Tianjin, China) (9). Figure 1 compares images obtained by various WF retinal imaging devices.

These WF systems are contact-based (requiring a topical anaesthetic, a coupling gel between the tip of the camera and the cornea, and frequently, a speculum), which limit their use to neonates, smaller babies, or older children under anaesthesia. These cameras need multiple captures in various directions to visualize retina beyond the vortex veins, that is, the far peripheral retina. All of them are mydriatic-based systems, so the image quality is very sensitive to poor pupillary dilation.

A newly described prototype of a contact-based optical system I find particularly creative is the PedCam, which utilises trans-planar illumination to achieve whole retinal illumination. In theory, this affordable smartphone-based non-mydriatic handheld camera can achieve up to 240° of effective retinal visualisation with two photographs, which would be very advantageous for ROP screening (10).

UWF imaging systems on the other hand depict the retina till the far periphery (anterior to the vortex vein ampulla in all four quadrants (6)) in a single capture. An example is the Clarus fundus camera (Carl Zeiss AG, Jena, Germany), which covers 133° in a single true-colour image, and requires a stitch or montage of two images to achieve a 200°-wide image (11).

In our practice, we rely on a commonly utilized UWF device (Silverstone, Optos PLC, Dunfermline, UK), which employs scanning laser ophthalmoscopy to capture 200° of the retina in a single image, with montaging extending the FOV to 220° (4). It is a non-contact procedure that does not require dilatation or sedation in children (5, 12). Interestingly, the origin of this company has a close connection with pediatric ophthalmology – Optos was founded by Douglas Anderson after his young son was blinded when a peripheral retinal detachment was missed during a routine examination. The Optos imaging systems are traditionally equipped with the red-green imaging modality, and have recently added the true colour modality of red-green-blue imaging (13, 11).

One thing to note is that these table-top UWF imaging systems require patients to be upright, which can present unique challenges in the pediatric population. Achieving optimal image quality can involve some trial-and-error to determine the best alignment and patient-device distance (12). Previous studies have shown that infants can be successfully imaged with the “flying baby” technique (12, 14), in which the chest and chin is supported on one arm and the head is stabilized with the other hand.

In our high-volume pediatric clinic, UWF imaging has become an essential tool, especially for retinal screening. Obtaining a baseline UWF image during any patient’s first visit, where feasible, is a practice I strongly advocate, as it often uncovers unexpected retinal pathologies that might otherwise go unnoticed. UWF also allows for rapid screening of genetic conditions – such as retinal dystrophies, Coats’ disease, and FEVR or retinoblastoma – in patients as well as their relatives. With further technological advancements, digital imaging is likely to become more indispensable in pediatric eyecare. In particular, the upcoming integration of artificial intelligence in retinal imaging holds promise for reducing the burden of retinal blindness (8).

Multimodal imaging for a comprehensive retinal evaluation

Advanced imaging modalities, such as optical coherence tomography (OCT), OCT angiography (OCTA), fluorescein angiography (FA), and fundus autofluorescence (FAF), provide crucial additional diagnostic insights and can reveal subclinical changes not apparent on IDO or standard colour photography.

OCT and OCTA are particularly valuable in documenting microstructural changes in various pediatric retinal disorders, especially vascular conditions like ROP (8). Among table-top systems, the Silverstone (Optos) device combines UWF imaging with swept-source OCT (Figure 2). Recently, WF handheld OCT and OCTA prototypes have also emerged, with their applications expected to be increasingly explored in future research (15, 16). This is a very exciting development, as the portability of such devices will enhance the clinical characterization of pediatric retinovascular disease, particularly ROP, to a whole new level.

FA remains critical for the detection, staging, and monitoring of retinal nonperfusion, neovascularization, and exudation in retinal vascular disorders (8). UWF imaging has significantly facilitated the use of FA in children due to its large area of capture in a single shot and a quick acquisition time. The use of oral fluorescein – a less invasive alternative to intravenous FA – has demonstrated comparable image quality and clinical utility (17), providing another alternative to further reduce distress during the procedure for children (and their parents or guardians as well).

Conclusion

While there are a variety of retinal imaging technologies to choose from, most are optimized for adult patients, leaving significant challenges when applied to pediatric populations. Successfully imaging children requires innovative examination techniques and solutions tailored to their unique needs. Future advancements in retinal imaging should prioritize manoeuvrability, ease of use, and comfort while expanding imaging modalities to maximize diagnostic potential. By addressing these gaps, the next generation of imaging systems can better support early detection, accurate diagnosis, and improved outcomes for pediatric patients.