Temporary morphological changes in plus disease induced during contact digital imaging

Retinopathy of prematurity: from oxygen management to molecular manipulation

INTRODUCTION

Retinopathy of prematurity (ROP) is a vasoproliferative disorder of the premature retina with the potential to progress to extraretinal neovascularisation. This review serves as an introduction to retinopathy of prematurity (ROP), outlining key parts of ROP pathophysiology, diagnosis and treatment. ROP is traditionally diagnosed by indirect ophthalmoscopy and classified using anatomical zones, stages of disease, and the presence or absence of "plus disease" (dilation and tortuosity of the major retinal arterioles and venules). ROP has a bi-phasic pathophysiology: initial hyperoxia causes reduced retinal vascularisation, followed by pathological vaso-proliferation resulting from subsequent hypoxia and driven by vascular endothelial growth factor (VEGF).

ADVANCEMENTS IN MANAGEMENT

This review summarises previous trials to establish optimum oxygen exposure levels in newborns and more recently the development of anti-VEGF agents locally delivered to block pathological neovascularisation, which is technically easier to administer and less destructive than laser treatment.

FUTURE DIRECTIONS

There remains an ongoing concern regarding the potential unwanted systemic effects of intravitreally administered anti-VEGF on the overall development of the premature baby. Ongoing dosing studies may lessen these fears by identifying the minimally effective dose required to block extraretinal neovascularisation.

Assessment of Retinal Vessel Tortuosity Index in Patients with Fabry Disease Using Optical Coherence Tomography Angiography (OCTA)

Vessel tortuosity (VT) is a parameter used to assess retinal involvement in patients affected by systemic diseases such as Fabry disease (FD). In this study, we assessed a retinal VT index (VTI) using optical coherence tomography angiography (OCTA) in a group of patients with FD (FD cohort) compared to a healthy control group (HC cohort). This is a single-center, retrospective study analysis of all consecutive patients with genetically tested and confirmed FD who underwent regular ophthalmological visits from December 2017 to January 2020 at the Department of Ophthalmology at the University Hospital of Zurich, Switzerland. VTI was calculated for each OCTA image and the results were compared between FD and HC cohort. A total of 56 participants, 32 (male:female ratio 12:20) in the FD cohort and 24 (male:female ratio 13:11) in the HC cohort. Classic onset was determined in 18 patients. Overall, mean VTI (±SD) was 0.21 (±0.07). Male patients with classic-onset FD had a significantly higher mean VTI (0.33, SD ± 0.35) compared to all other subgroups (p-value < 0.05). Further investigations of retinal VTI in patients with FD could be helpful to use OCTA as a noninvasive screening and follow-up modality to assess disease progression in affected patients.

Ocular Pigmentation Impact on Retinal Versus Choroidal Optical Coherence Tomography Imaging in Preterm Infants

Purpose

To evaluate the association of fundus pigmentation with the visibility of retinal versus choroidal layers on optical coherence tomography (OCT) in preterm infants.

Methods

For infants enrolled in BabySTEPS, ophthalmologists recorded fundus pigmentation (blond, medium, or dark) at the first retinopathy of prematurity (ROP) examination. Bedside OCT imaging was performed at each examination, and a masked grader evaluated all OCT scans from both eyes of each infant for visibility (yes/no) of all retinal layers and of the chorio-scleral junction (CSJ). Multivariable logistic regression was used to assess associations between fundus pigmentation and visibility of all retinal layers and CSJ, controlling for potential confounders (i.e., birth weight, gestational age, sex, OCT system, pupil size, and postmenstrual age at imaging).

Results

Among 114 infants (mean birth weight, 943 grams; mean gestational age, 27.6 weeks), 43 infants (38%) had blond, 56 infants (49%) had medium, and 15 infants (13%) had dark fundus pigmentation. Of 1042 scans, all retinal layers were visible in 977 (94%) and CSJ in 895 (86%). Pigmentation was not associated with retinal layer visibility (P = 0.49), but medium and dark pigmentation were associated with decreased CSJ visibility (medium: odds ratio [OR] = 0.34, P = 0.001; dark: OR = 0.24, P = 0.009). For infants with dark pigmentation, retinal layer visibility increased (OR = 1.87 per week; P ≤ 0.001) and CSJ visibility decreased (OR = 0.78 per week; P = 0.01) with increasing age.

Conclusions

Although fundus pigmentation was not associated with the visibility of all retinal layers on OCT, darker pigmentation decreased CSJ visibility, and this effect increased with age.

Translational Relevance

The ability of bedside OCT to capture retinal layer microanatomy in preterm infants, regardless of fundus pigmentation, may represent an advantage over fundus photography for ROP telemedicine.

Quantitative comparison of blood vessel changes after treatment of retinopathy of prematurity with laser versus bevacizumab

Current therapies for treatment-indicated (type 1) retinopathy of prematurity mainly consist of laser photocoagulation and intravitreal anti-vascular endothelial growth factor (eg, bevacizumab) injection. The first visible signs of acute-phase regression are typically vascular, including decreased plus disease. Using a semiautomated computer program, we quantitatively compared posterior pole vascular changes following treatment with laser versus bevacizumab and found that in the first month following treatment, vascular dilation and tortuosity significantly decreased following either treatment modality, but tortuosity decreased earlier and faster after bevacizumab.

Progression from preplus to plus disease in the Telemedicine Approaches to Evaluating Acute-Phase Retinopathy of Prematurity (e-ROP) Study: incidence, timing, and predictors

PURPOSE

To determine the incidence of and timing and predictors for progression from pre-plus to plus disease, based on evaluation of images.

METHODS

Two trained readers independently evaluated posterior pole images of infants from 13 North American centers for pre-plus/plus disease, stage, and zone of retinopathy of prematurity (ROP). Discrepancies between readers were adjudicated. To be eligible for analysis, eyes had to have at least two imaging sessions, the earlier one with pre-plus disease.

RESULTS

Of 681 eyes of 444 infants with pre-plus first detected at mean postmenstrual age (PMA) of 35.5 ± 2.1 weeks, 54 (7.9%) progressed to plus disease at a mean PMA of 37.6 ± 2.4 weeks with the mean interval for progression of 2.7 weeks (range, 0.4-8.9 weeks). Progression rate was higher for eyes with larger number of quadrants of pre-plus (44% for eyes with four quadrants vs 4% with one quadrant [P < 0.0001]), earlier PMA with pre-plus (18% for 32 weeks' PMA vs 3% for PMA of >37 weeks [P = 0.02]), higher ROP stage (12% for stage 3, 2.5% for no ROP [P < 0.0001]), lower ROP zone (24% for zone I, 6% for zone II or no ROP [P < 0.0001]) at the time of first pre-plus detection.

CONCLUSIONS

Based on image evaluation, 8% of eyes progressed from pre-plus to plus disease at a mean interval of 3 weeks. Pre-plus in multiple quadrants, higher stages of ROP, and lower zones of ROP were associated with higher risk of progression. Image evaluation for pre-plus may help in the identification of high-risk eyes for developing plus disease.

Resolution patterns and duration of retinal haemorrhages measured by two-dimensional retinal area pixel counts from sequential retinal imaging in childhood encephalopathies: a morphometric study

Objective

To determine the time to resolution of different-layered retinal haemorrhages (RHs), and to describe the main patterns of their resolution in a group of children with encephalopathies.

Methods and analysis

From a prospective study of 114 children with traumatic and non-traumatic encephalopathies, 429 selected individual RHs (iRHs) from 18 children were serially imaged from admission using a RetCam. Photoshop and Scion Imaging software allowed calculation of RH area in pixels.

Results

Two patterns of the resolution were recognised on the basis of area measurements: a progressive decrease (pattern A, 60% of iRHs), and a form of asymmetrical decay in which iRHs first increased in size before then progressively decreasing (pattern B, 35% of iRHs). Within the pattern A group, the Kaplan-Meier median survival time (MST) (95% CI) was 10 (9.3 to 10.7) days for intra-RHs (IRHs) and 38 (10.8 to 65.2) days for pre-RHs (PRHs), log rank (Mantel-Cox) p=0.001. The mean percentage reduction in area per day was 12.5% for all iRHs, 14.5% for IRHs and 6.3% for PRHs.

Conclusion

Serial area measurements of iRHs revealed that 35% haemorrhages became temporarily larger before decreasing to resolution. Serially imaged selected RHs showed a longer MST for PRHs than for IRHs.

Computer-assisted quantification of pre-plus and plus disease in images obtained using Pictor versus video indirect ophthalmoscopy: a pilot study

Subjectivity in the diagnosis of plus disease in retinopathy of prematurity has prompted the creation of computer programs to objectively measure vascular characteristics. ROPtool is a semiautomated computer program that analyzes retinal vascular dilation and tortuosity. To explore its ability to trace images taken with a FDA-approved, portable, handheld noncontact digital fundus camera (Pictor), we compared ROPtool analysis of Pictor still images acquired by nonophthalmologists to video indirect ophthalmoscopy (VIO) still images acquired by ophthalmologists. ROPtool could trace more Pictor versus VIO images. In addition, receiver operating characteristic curves showed that accuracy for diagnosing pre-plus or plus disease was higher using Pictor versus VIO images.

Comparison of strategies for grading retinal images of premature infants for referral warranted retinopathy of prematurity

PURPOSE

To determine the accuracy of identifying referral-warranted retinopathy of prematurity (RW-ROP, defined as any zone I ROP, stage 3 or worse, or plus disease) from retinal image sets using three grading protocols: a single optic disk-centered image, a set of 3 horizontal images, and a 5-image set.

METHODS

In this secondary analysis of images from the e-ROP study, a weighted sample of 250 image sets from 250 infants (125 with RW-ROP and 125 without RW-ROP) was randomly selected. The sensitivities and specificities for detecting RW-ROP and its components from a single disk center image, along with nasal and temporal retinal images, were calculated and compared with the e-ROP grading of RW-ROP of all 5 retinal images (disk center and nasal, temporal, superior, and inferior retinal images).

RESULTS

RW-ROP was identified with a sensitivity of 11.2% (95% CI, 6.79%-17.9%) using a single disk center image, with a sensitivity of 70.4% (95% CI, 61.9%-77.9%) using 3 horizontal images, and a statistically higher sensitivity of 82.4% (95% CI, 75.0%-89.0%) using all 5 images (P = 0.002). The specificities were 100%, 86.4%, and 90.4%, respectively. For grading using 3 horizontal images, sensitivity was 14.3% for plus disease, 25% for zone I ROP, and 71.2% for stage 3 or worse compared to 40.8%, 50%, and 79.8% for grading using 5-image sets, respectively.

CONCLUSIONS

Both a single, disk-centered, posterior pole image and 3 horizontal images were less effective than a 5-image set in determining the presence of RW-ROP on qualitative grading by trained readers.

ULTRA-WIDEFIELD FUNDUS IMAGING: A Review of Clinical Applications and Future Trends

PURPOSE

To review the basic principles of ultra-widefield fundus imaging and discuss its clinical utility for a variety of retinal and choroidal disorders.

METHODS

A systematic review of the PubMed database was performed using the search terms Optos, optomap, panoramic, ultra-widefield, wide-angle, and ellipsoid mirror. This yielded 158 publications of which 128 were selected based on content and relevance.

RESULTS

A total of 128 articles pertaining to ultra-widefield imaging were cited in this review.

CONCLUSION

Optos ultra-widefield imaging has become an essential tool for the identification of peripheral retinal and vascular pathology. The high resolution and multimodal capabilities of this device are also providing new insights into a variety of disorders, even those that primarily involve the posterior pole. Although the presence of artifact and the need for clinical validation are significant hurdles to more widespread use, ultra-widefield is evolving to become the standard-of-care imaging modality for many diseases and is finding new clinical and research applications such as for screening and telemedicine.

Three-dimensional assessment of vascular and perivascular characteristics in subjects with retinopathy of prematurity

PURPOSE

To study vascular features detected with spectral domain optical coherence tomography (SD-OCT) in subjects undergoing retinopathy of prematurity (ROP) screening.

DESIGN

Cross-sectional study.

PARTICIPANTS AND CONTROLS

Fifty-seven premature neonates, 10 with plus disease in at least 1 eye and 47 without plus disease.

METHODS

Bedside noncontact SD-OCT imaging was performed after obtaining parental consent on 97 consecutive infants between January 2009 and September 2012. Fifty-seven subjects (31-49 weeks' post-menstrual age) who had an SD-OCT scan in at least 1 eye showing the edge of the optic nerve and at least 1 major retinal vascular arcade were included. One eye per subject was randomly selected for analysis. Two masked graders evaluated scans for (1) retinal vessel elevation, (2) scalloped retinal layers, (3) hyporeflective vessels, and (4) retinal spaces. To coalesce the weight of these features, a Vascular Abnormality Score by OCT (VASO) was created. For quantitative assessment of vessel elevation, retinal surface maps were created.

MAIN OUTCOME MEASURES

Prevalence of SD-OCT vascular abnormalities, the VASO, intergrader agreement, and presence of elevation on surface maps.

RESULTS

From among 67 SD-OCT characteristics that were recorded, the most common characteristics found were vessel elevation (44%), hyporeflective vessels (40%), scalloped layers (22%), and retinal spaces (11%). Features significantly associated with plus disease were vessel elevation (P = 0.01), hyporeflective vessels (P = 0.04), and scalloped retinal layers (P = 0.006). Intragrader agreement was between 74% and 90% for all features. The VASO was significantly higher in subjects with plus disease (P = 0.0013). On 3-dimensional SD-OCT volumes, eyes with plus disease had greater retinal surface elevation that more often matched en face retinal vascular patterns.

CONCLUSIONS

We present a novel 3-dimensional analysis of vascular and perivascular abnormalities identified in SD-OCT images of eyes with ROP. The SD-OCT characteristics that are more common in eyes with plus disease provide the first in vivo demonstration of the effects of vascular dilation and tortuosity on perivascular tissue. The VASO and surface maps also delineate the severity of vascular pathology in plus disease. Further studies evaluating these findings in eyes with pre-plus versus normal posterior pole vessels may determine the usefulness of SD-OCT in the early detection of vascular abnormalities in ROP.

Retinopathy of prematurity

The immature retinas of preterm neonates are susceptible to insults that disrupt neurovascular growth, leading to retinopathy of prematurity. Suppression of growth factors due to hyperoxia and loss of the maternal-fetal interaction result in an arrest of retinal vascularisation (phase 1). Subsequently, the increasingly metabolically active, yet poorly vascularised, retina becomes hypoxic, stimulating growth factor-induced vasoproliferation (phase 2), which can cause retinal detachment. In very premature infants, controlled oxygen administration reduces but does not eliminate retinopathy of prematurity. Identification and control of factors that contribute to development of retinopathy of prematurity is essential to prevent progression to severe sight-threatening disease and to limit comorbidities with which the disease shares modifiable risk factors. Strategies to prevent retinopathy of prematurity will depend on optimisation of oxygen saturation, nutrition, and normalisation of concentrations of essential factors such as insulin-like growth factor 1 and ω-3 polyunsaturated fatty acids, as well as curbing of the effects of infection and inflammation to promote normal growth and limit suppression of neurovascular development.

Telemedicine for retinopathy of prematurity

PURPOSE OF REVIEW

To examine and review digital retinal imaging via telemedicine as an important screening and diagnostic tool in the management of retinopathy of prematurity (ROP).

RECENT FINDINGS

The use of wide-angle digital retinal photography to detect clinically significant ROP has been described in numerous reports since 2000. Comparisons with the gold standard of binocular indirect ophthalmoscopy have been favorable. Digital image capture can provide more objective information for disease detection, thereby facilitating internet consultation and retrospective analysis as part of the electronic medical record. As the presence of plus disease in ROP is now the most important criteria for determining the need for laser treatment, computer-based image analysis can potentially provide additional benefit to digital retinal imaging. Telemedicine screening also allows for the extension of diagnostic expertise to underserved areas in both the developed and third world. The role of telemedicine in ROP education will impact both screening efforts and traditional fellowship training in future years.

SUMMARY

As the worldwide incidence of ROP continues to rise, the use of telemedicine for screening, diagnostic and educational purposes will assume increasing importance in the delivery of healthcare for premature infants.

Non-contact ultra-widefield imaging of retinopathy of prematurity using the Optos dual wavelength scanning laser ophthalmoscope

AIMS

The purpose of this report is to demonstrate that a non-contact ultra-widefield dual wavelength laser camera (Optos) is able to capture high-quality images in retinopathy of prematurity (ROP).

MATERIALS AND METHODS

We conducted a retrospective review of patients attending the Oxford Eye Hospital with ROP between 1 August 2012 and 16 November 2012 that underwent standard clinical assessment. Anterior segment imaging, where relevant, was performed with Retcam. Retinal imaging was then performed with Optos, using a modified 'flying baby position'.

RESULTS

The Optos scanning laser ophthalmoscope was able to acquire ultra-widefield fundal images in nine ROP subjects. The images obtained show clear views of the different stages of ROP features at the posterior pole and peripheral retina. Regression of ROP features were identified, following laser and intravitreal bevacizumab treatment. Additionally, 'skip areas' missed by initial laser treatment could be identified in the peripheral retina.

CONCLUSION

The Optos ultra-widefield scanning laser ophthalmoscope is capable of acquiring clinically useful high-quality images of the fundus in ROP subjects. The imaging technique could potentially be used in monitoring ROP progression and documenting ROP regression following treatment.

Retinal vessel tortuosity measures and their applications

Structural retinal vascular characteristics, such as vessel calibers, tortuosity and bifurcation angles are increasingly quantified in an objective manner, slowly replacing subjective qualitative disease classification schemes. This paper provides an overview of the current methodologies and calculations used to compute retinal vessel tortuosity. We set out the different parameter calculations and provide an insight into the clinical applications, while critically reviewing its pitfalls and shortcomings.