Let the Science Speak Series
How Comfortable is the RETeval for Patients?
Test Toleration Across Different Ages
RETeval® handheld ERG/VEP has been evaluated for its quality, and while waveform details may vary, the accuracy in results and their pathognomonic differences can be assessed with reasonable test-retest variability. This makes it clinically dependable and beneficial for diagnostics. However, a crucial question remains: How well is it tolerated by patients, and how seamlessly can users integrate it into their routine practice?
Testimonials from RETeval users highlight its ease of use and clinical benefits. For example, Melanie Schmitt from the University of Wisconsin noted, “It has changed the way that we practice and has allowed us to significantly decrease the amount of examinations under anesthetic (EUAs) with ERGs we perform.” But have these observations been systematically analyzed in peer-reviewed publications? Given the existence of over 200 RETeval-related publications, we aim to identify mentions of patient tolerance and failure rates.
What Do Publications Address?
Out of more than 200 publications, we identified 11 studies mentioning success rates, along with one additional PhD thesis. Seven of these studies included both pediatric and adult populations, with four focusing exclusively on pediatric subjects. The remaining four studies evaluated RETeval in adults, covering healthy individuals, glaucoma patients, and those with diabetic retinopathy. Pediatric studies primarily examined inherited diseases.
Toleration in Adults
The four adult-focused publications generally examined RETeval in a screening context, where the testing personnel were not necessarily trained ophthalmologists. Reported success rates without pupil dilation ranged from 85% (Weerasingh et al.10) to 100% (Kato et al.8), which is a strong performance for non-mydriatic testing. For comparison, non-mydriatic fundus imaging in Weerasinghe et al.’s study10 had a success rate of just 43.3%. Other studies report even lower reliability, such as Chen et al.12, who observed a success rate below 12% in a real-world dataset, while some handheld non-mydriatic fundus cameras reported up to 80% success rates.13
Test Toleration in Children
Testing children presents unique challenges. While infants can be physically restrained for testing, toddlers often resist due to discomfort or fear, particularly in visual electrophysiology exams, where electrodes are placed on the eye and bright flashes are used.
The PhD thesis by Albuhayzah (2021)14 acknowledged these difficulties: “One limitation of the present study is that younger children (4-6 years) were not included in the analysis. This was because most children within this age range could not tolerate the Espion visual electrophysiology system and the DTL electrodes.” In this study, “subsequently, ERG data for younger children were collected using a hand-held ERG system with skin electrodes.” In some clinical settings, this leads to the assumption that all children below a certain age require sedation for ERG testing. While sedation options exist, they add cost and risk to the procedure. Thus, having an ERG system that allows testing without sedation would be highly beneficial. Among the identified RETeval studies reporting success rates, testing was successfully conducted in children as young as four months old. Excluding Ji et al.2, test success rates reached 90% (Carter et al).1, including both scotopic and photopic tests. Zhang et al.5 reported a 93% success rate, though 6.9% of children required oral sedation using a troland-based (non-dilated) protocol. In contrast, Carter et al.1 achieved a 90% success rate with dilation but without sedation. The use of a Troland-based protocol may explain the higher failure rate in Ji et al.’s study2. Ultimately, a dilation-based protocol can eliminate the need for sedation in at least 90% of pediatric cases.
What Does This Mean for Clinical Practice?
The practical implications for RETeval depend on the intended use. In pediatric settings, or traditional ERG applications for inherited retinal diseases, RETeval “may result in savings for clinical services in terms of time, cost, staffing, and training” (Carter et al.)1.
For retinal specialists, RETeval provides a valuable tool when image quality is low and further information is still needed. It can also assist in screening cases where non-mydriatic digital retinal imaging results in non-gradable images. As Maa et al.11 noted, “Sensitivity and specificity compare favorably to non-mydriatic digital retinal imaging when subjects with ungradable images are referred and included in the performance analysis.”
| Reference | # of patients | Age group | Disease | Test Type | Success rate | Usability comments |
|---|---|---|---|---|---|---|
| Carter, 2020¹ | 81 | 4m – adult | Various | RETeval, scotopic & photopic | 90% | |
| Ji, 2019² | 9 | 6–27 months | Vigabatrin toxicity | RETeval Td protocols | 31% | |
| Soekamto, 2021³ | 20 | 4-17 | Healthy | ISCEV 5 step tests RETeval | 97.5% | All patients tolerated the examinations with no complications. |
| Liu, 2018⁴ | 35 | 11m-69y | Various | ISCEV 5 step, RETeval + conventional | 97% | 1 child refused sedation – no conventional ERG done |
| Zhang, 2021⁵ | 204 | 4m-18y | Healthy | RETeval – ISCEV TD | 86% | (without oral sedation) & 93% with oral sedation) |
| Grace, 2017⁶ | 71 | 1-12 | Nystagmus | RETeval, cd tests | 92% | |
| Inooka 2023⁷ | 497 | 40-89 | Various and healthy | RETeval | 89.4% | |
| Kato, 2020⁸ | 156 | 20-29 | Healthy | RETeval | 95% |
Ulrike Rahn
Director of Clinical Marketing at LKC Technologies
References
1 Carter P, Gordon-Reid A, Shawkat F, Self JE. Comparison of the handheld RETeval ERG system with a routine ERG system in healthy adults and in paediatric patients. Eye. Published online October 19, 2020. doi:10.1038/s41433-020-01221-2
2 Ji X, McFarlane M, Liu H, Dupuis A, Westall CA. Hand-held, dilation-free, electroretinography in children under 3 years of age treated with vigabatrin. Doc Ophthalmol. 2019;138(3):195-203. doi:10.1007/s10633-019-09684-9
3 Soekamto CD, Gupta R, Keck KM. Using the RETeval Device in Healthy Children to Establish Normative Electroretinogram Values. J Pediatr Ophthalmol Strabismus. 2021;58(1):17-22.
doi:10.3928/01913913-20200910-03
4 Liu H, Ji X, Dhaliwal S, et al. Evaluation of light- and dark-adapted ERGs using a mydriasis-free, portable system: clinical classifications and normative data. Doc Ophthalmol. 2018;137(3):169-181. doi:10.1007/s10633-018-9660-z
5 Zhang T, Lu J, Sun L, et al. Mydriasis-Free Flicker Electroretinograms in 204 Healthy Children Aged 0–18 Years: Reference Data From Two Cohorts. Trans Vis Sci Tech. 2021;10(13):7.
doi:10.1167/tvst.10.13.7
6 Grace SF, Lam BL, Feuer WJ, Osigian CJ, Cavuoto KM, Capo H. Nonsedated handheld electroretinogram as a screening test of retinal dysfunction in pediatric patients with nystagmus. Journal of American Association for Pediatric Ophthalmology and Strabismus. 2017;21(5):384-388. doi:10.1016/j.jaapos.2017.06.022
7 Inooka T, Kominami T, Yasuda S, et al. Assessment of factors affecting flicker ERGs recorded with RETeval from data obtained from health checkup screening. PLoS One. 2023;18(4):e0284686. doi:10.1371/journal.pone.0284686
8 Kato K, Sugawara A, Nagashima R, Ikesugi K, Sugimoto M, Kondo M. Factors Affecting Photopic Negative Response Recorded with RETeval System: Study of Young Healthy Subjects. Trans Vis Sci Tech. 2020;9(9):19-19. doi:10.1167/tvst.9.9.19
9 Nakamura N, Fujinami K, Mizuno Y, Noda T, Tsunoda K. Evaluation of cone function by a handheld non-mydriatic flicker electroretinogram device. Clin Ophthalmol. 2016;10:1175-1185. doi:10.2147/OPTH.S104721
10 Weerasinghe LS, Dunn HP, Fung AT, et al. Diabetic Retinopathy Screening at the Point of Care (DR SPOC): detecting undiagnosed and vision-threatening retinopathy by integrating portable technologies within existing services. BMJ Open Diabetes Res Care. 2023;11(4):e003376.
doi:10.1136/bmjdrc-2023-003376
11 Maa AY, Feuer WJ, Davis CQ, et al. A novel device for accurate and efficient testing for vision-threatening diabetic retinopathy. J Diabetes Complicat. 2016;30(3):524-532. doi:10.1016/j.jdiacomp.2015.12.005
12 Qi Chen, Mengtian Zhou, Yang Cao, Xuanli Zheng, Huiyan Mao, Changrong Lei, Wanglong Lin, Junhong Jiang, Yize Chen, Di Song, Xiang Xu, Cong Ye, Yuanbo Liang - Quality assessment of non-mydriatic fundus photographs for glaucoma screening in primary healthcare centres: a real-world study: BMJ Open Ophthalmology 2023;8:e001493.
13 Lin TC, Chiang YH, Hsu CL, Liao LS, Chen YY, Chen SJ. Image quality and diagnostic accuracy of a handheld nonmydriatic fundus camera: Feasibility of a telemedical approach in screening retinal diseases. J Chin Med Assoc. 2020 Oct;83(10):962-966. doi: 10.1097/JCMA.0000000000000382. PMID: 32649414; PMCID: PMC7526587.
14 Albuhayzah H. Retinal Structure and Function in Typical Children and Young Adults. University of Waterloo; 2021.