Chapter 62 Telescreening for Retinopathy of Prematurity
Limitations of traditional care
Traditional screening for retinopathy of prematurity (ROP) involves indirect ophthalmoscopy at the bedside in the neonatal intensive care unit (NICU). Although this has been effective at identifying infants with severe treatment-requiring disease,1–3 there are important limitations. Ophthalmoscopic examinations are logistically difficult, require significant travel time and coordination, and are physiologically stressful for infants.4 Findings are documented using hand-drawn sketches, which are subjective and qualitative (Fig. 62.1). In addition, there may be variability in diagnosis of critical features such as zone I and plus disease, even among experts,5,6 and there is enormous medicolegal liability. Surveys have found that the number of retinal specialists and pediatric ophthalmologists willing to manage ROP is decreasing for these reasons.7 Meanwhile, more infants are at risk for disease because of increasing premature birth rates and improved neonatal survival throughout the world.
Telemedicine as an emerging approach
Telemedicine is an emerging approach with potential to improve the quality, delivery, and cost of care compared to traditional strategies. This may be particularly important in developing nations and other areas with limited accessibility to care. In this approach, clinical data and images are captured from the infant’s eyes by trained personnel in the NICU. Data are transmitted for review by a remote ophthalmologist, who sends management recommendations to the consulting physician. Examples of wide-angle images taken with a commercially available camera (RetCam; Clarity Medical Systems, Pleasanton, CA) are shown in Fig. 62.2. It has been shown that trained neonatal nurses can capture high-quality retinal images,8,9 and that imaging may cause less physiological stress to infants than ophthalmoscopy with scleral depression.10
In a telemedicine approach, the availability of archived retinal images would provide other advantages. Infant photographs could be directly compared to references such as the published standard photograph for plus disease,1 and may be transmitted securely to experts for second opinions. Images provide objective documentation of clinical findings, improve recognition of disease progression, enhance communication, and create infrastructure for education and research.11
Evaluation studies
Accuracy
Diagnostic accuracy of telemedicine for ROP has been evaluated since the late 1990s. Virtually all studies have used wide-angle digital images captured by a neonatal nurse, ophthalmologist, or ophthalmic photographer. Although these studies have varied in design and outcome measure, most have compared the diagnostic performance of telemedicine to a reference standard of dilated ophthalmoscopy. Schwartz et al. (19 eyes from 10 infants) examined the accuacy of telemedicine in a selected group of infants at 30–32 weeks postmenstrual age (PMA), all of whom had moderate or severe ROP. The sensitivity and specificity of telemedicine for detecting prethreshold or worse ROP were 89% and 100%, respectively.12
Since that time, research has involved larger and broader cohorts of consecutively enrolled infants. For diagnosis of any ROP regardless of severity, studies have demonstrated sensitivity of 46%–97% and specificity 49%–100% compared to a reference standard of indirect ophthalmoscopy8,13,14 (Table 62.1). Generally, lower accuracy has been found while examining infants at lower PMA, and when detecting presence of mild ROP (e.g. peripheral stage 1). This is presumably because younger infants have milder disease with more subtle diagnostic features, and because it may be technically more difficult to image smaller eyes with increased media opacities.15
Table 62.1 Diagnostic accuracy of telescreening for detection of any ROP using images captured by wide-angle camera.* Reference standard was standard indirect ophthalmoscopy
| Study | Outcome measures | Sensitivity/specificity |
|---|---|---|
| Roth et al., 200114 | Any ROP | 0.82/0.94 |
| Yen et al., 200215 | Any ROP at 32–34 wks PMA | 0.46/1.00 |
| Any ROP at 38–40 wks PMA | 0.76/1.00 | |
| Chiang et al., 200613 | Any ROP | 0.82–0.86/0.49–0.96 |
| Shah et al., 200616 | Any ROP | 0.86/0.92 |
| Chiang et al., 20078 | Any ROP at 31–33 wks PMA | 0.73–0.94/0.89–0.97 |
| Any ROP at 35–37 wks PMA | 0.91–0.97/0.98–1.00 | |
| Dhaliwal et al., 200917 | Any ROP at 34 wks PMA or 4–6 wks CA | 0.60/0.91 |
PMA, postmenstrual age; CA, chronological age.
* RetCam; Clarity Medical Systems, Pleasanton, CA.
Other studies have examined accuracy of telemedicine for detecting clinically significant ROP (Table 62.2). Ells et al. (371 exams from 36 infants) found sensitivity 100% and specificity 96% for diagnosis of “referral-warranted ROP”* during serial examinations throughout an infant’s hospital course.18 Wu et al. (serial exams from 43 infants) performed telemedicine screening for prethreshold or worse ROP, and found sensitivity 100% and specificity 98%.19 Chiang et al. (163 exams from 64 infants) reported sensitivity 72%–83% and specificity 90%–99% for detection of type 2 or worse ROP, and sensitivity 85%–90% and specificity 95%–97% for detection of treatment-requiring ROP.13 The multicenter prospective Photo-ROP Study (300 exams from 51 infants) found sensitivity 92% and specificity 37% for detection of “clinically significant ROP”† during weekly examinations throughout an infant’s hospital course.20
Table 62.2 Diagnostic accuracy of telescreening for detection of clinically significant ROP using images captured by wide-angle camera.* Reference standard was standard indirect ophthalmoscopy
| Study | Outcome measures | Sensitivity/specificity |
|---|---|---|
| Ells et al., 200318 | Any ROP zone I, presence of plus disease, or presence of any stage 3 ROP at any time during hospital course | 1.00/0.96 |
| Chiang et al., 200613 | Type 2 or worse ROP | 0.72–0.83/0.90–0.99 |
| Treatment-requiring ROP | 0.85–0.90/0.95–0.97 | |
| Wu et al., 200619 | Prethreshold or worse ROP | 1.00/0.98 |
| Chiang et al., 20078 | Type 2 or worse ROP at 31–33 wks PMA |
