Semiautomated analysis of retinal vessel diameter in retinopathy of prematurity patients with and without plus disease

Retinal imaging in infants

Digital retinal imaging is at the core of a revolution that is continually improving the screening, diagnosis, documentation, monitoring, and treatment of infant retinal diseases. Historically, imaging the retina of infants had been limited and difficult to obtain. Recent advances in photographic instrumentation have significantly improved the ability to obtain high quality multimodal images of the infant retina. These include color fundus photography with different camera angles, ultrasonography, fundus fluorescein angiography, optical coherence tomography, and optical coherence tomography angiography. We provide a summary of the current literature on retinal imaging in infants and highlight areas where further research is required.

Telemedicine for Retinopathy of Prematurity in 2020

Purpose:

Retinopathy of prematurity (ROP) is the leading cause of visual impairment in premature infants, and middle-income nations are currently experiencing the “third epidemic” of ROP. Screening programs are essential to prevent negative visual outcomes, but screening efforts require a great amount of resources from healthcare systems and are difficult to marshal, particularly in geographically isolated or resource-limited settings. Telemedical screening programs using remote digital fundus imaging (RDFI) systems hold the promise of alleviating many of the burdens that currently make screening for ROP logistically challenging.

Methods:

Literature review of the current evidence for RDFI telescreening for ROP, with editorial discussion and recommendations.

Results:

In this review, we summarize the robust body of literature regarding the efficacy of RDFI, the feasibility of telescreening programs, and experiences from current live telescreening programs. We discuss the strengths and limitations of the current evidence and of the screening programs and consider the best practices in developing de novo telemedical screening programs for ROP. The review concludes with a discussion of promising future areas of research and development.

Conclusions:

RDFI ROP screening programs can be accurate and reliable. They show promise in improving many current challenges in screening infants for ROP, may be able to improve some aspects of care, and have been demonstrated to be cost-effective.

Using an Image Fusion Methodology to Improve Efficiency and Traceability of Posterior Pole Vessel Analysis by ROPtool

Background:

The diagnosis of plus disease in retinopathy of prematurity (ROP) largely determines the need for treatment; however, this diagnosis is subjective. To make the diagnosis of plus disease more objective, semi-automated computer programs (e.g. ROPtool) have been created to quantify vascular dilation and tortuosity. ROPtool can accurately analyze blood vessels only in images with very good quality, but many still images captured by indirect ophthalmoscopy have insufficient image quality for ROPtool analysis.

Purpose:

To evaluate the ability of an image fusion methodology (robust mosaicing) to increase the efficiency and traceability of posterior pole vessel analysis by ROPtool.

Materials and Methodology:

We retrospectively reviewed video indirect ophthalmoscopy images acquired during routine ROP examinations and selected the best unenhanced still image from the video for each infant. Robust mosaicing was used to create an enhanced mosaic image from the same video for each eye. We evaluated the time required for ROPtool analysis as well as ROPtool’s ability to analyze vessels in enhanced vs. unenhanced images.

Results:

We included 39 eyes of 39 infants. ROPtool analysis was faster (125 vs. 152 seconds; p=0.02) in enhanced vs. unenhanced images, respectively. ROPtool was able to trace retinal vessels in more quadrants (143/156, 92% vs 115/156, 74%; p=0.16) in enhanced mosaic vs. unenhanced still images, respectively and in more overall (38/39, 97% vs. 34/39, 87%; p=0.07) enhanced mosaic vs. unenhanced still images, respectively.

Conclusion:

Retinal image enhancement using robust mosaicing advances efforts to automate grading of posterior pole disease in ROP.

Shifts in retinal vessel diameter and oxygen saturation in Chinese type 2 diabetes mellitus patients

BACKGROUND

The aim of this study was to analyze the shifts in retinal vessel diameter and oxygen saturation in diabetic patients with and without diabetic retinopathy (DR), as well as to assess the association between diabetes duration and either vessel diameter or oxygen saturation.

METHODS

In total, 99 Type 2 DM patients were recruited for the study and were divided into three groups: DM with non-obvious retinopathy (DM, n = 29), non-proliferative diabetic retinopathy (NPDR, n = 40), and proliferative diabetic retinopathy (PDR, n = 30). In addition, 78 age-matched healthy individuals were chosen as the control. The diameter and oxygen saturation of the retinal vessels were analyzed using a noninvasive retinal oximeter, and then compared between the three groups and the normal control. Association analysis was applied to analyze the possible influencing factors, including the diameter and oxygen saturation of retinal vessels, on best corrected visual acuity BCVA, as well as the relationship between diabetes duration and the oximetry values.

RESULTS

All of the diabetic patients showed thinner arterioles, wider venules, and a smaller arteriolar-to-venular ratio (AVR) than the healthy individuals. The AVR results from the controls through to the PDR group were 0.81 ± 0.07, 0.78 ± 0.07, 0.76 ± 0.07 and 0.67 ± 0.07, respectively. Both the NPDR and PDR groups showed significantly smaller AVR than the control. All of the diabetic patients exhibited higher retinal vessel oxygen saturation than the healthy individuals. Among all of the oximetry values, AVR exhibited the most significant correlation with best corrected visual acuity (BCVA) (β = 1.533, P < 0.0001). An increased diabetes duration was associated with decreased arteriolar diameter (slope = -0.082 pixels/year, r (2) = 0.085, P = 0.004) and AVR (slope = -0.009/year, r (2) = 0.349, P < 0.001), and with increased venular diameter (slope = 0.104 pixels/year, r (2) = -0.109, P = 0.001).

CONCLUSIONS

In this Chinese population with type 2 DM, the thinner arterioles and wider venules point to microvascular dysfunction in DR. The increased oxygen saturation of the retinal vessels suggests that retinal oxygen metabolism is affected in diabetic retinopathy.

Plus disease in retinopathy of prematurity: qualitative analysis of diagnostic process by experts

IMPORTANCE

Plus disease is the most important parameter that characterizes severe treatment-requiring retinopathy of prematurity, yet diagnostic agreement among experts is imperfect and the precise factors involved in clinical diagnosis are unclear. This study is designed to address these gaps in knowledge by analyzing cognitive aspects of the plus disease diagnostic process by experts.

OBJECTIVE

To examine the diagnostic reasoning process of experts for plus disease in retinopathy of prematurity using qualitative research techniques.

DESIGN

Cognitive walk-through, with qualitative analysis of videotaped expert responses and quantitative analysis of expert diagnoses.

SETTING

Experimental setting in which experts were videotaped while reviewing study data.

PARTICIPANTS

A panel of international retinopathy of prematurity experts who had the experience of using qualitative retinal features as their primary basis for clinical diagnosis.

INTERVENTION

Six experts were video recorded while independently reviewing 7 wide-angle retinal images from infants with retinopathy of prematurity. Experts were asked to explain their diagnostic process in detail (think-aloud protocol), mark findings relevant to their reasoning, and diagnose each image (plus vs pre-plus vs neither). Subsequently, each expert viewed the images again while being asked to examine arteries and veins in isolation and answer specific questions. Video recordings were transcribed and reviewed. Diagnostic process of experts was analyzed using a published cognitive model.

MAIN OUTCOME AND MEASURES

Interexpert and intraexpert agreement.

RESULTS

Based on the think-aloud protocol, 5 of 6 experts agreed on the same diagnosis in 3 study images and 3 of 6 experts agreed in 3 images. When experts were asked to rank images in order of severity, the mean correlation coefficient between pairs of experts was 0.33 (range, -0.04 to 0.75). All experts considered arterial tortuosity and venous dilation while reviewing each image. Some considered venous tortuosity, arterial dilation, peripheral retinal features, and other factors. When experts were asked to rereview images to diagnose plus disease based strictly on definitions of sufficient arterial tortuosity and venous dilation, all but 1 expert changed their diagnosis compared with the think-aloud protocol.

CONCLUSIONS AND RELEVANCE

Diagnostic consistency in plus disease is imperfect. Experts differ in their reasoning process, retinal features that they focus on, and interpretations of the same features. Understanding these factors may improve diagnosis and education. Future research defining more precise diagnostic criteria may be warranted.

Validating retinal fundus image analysis algorithms: issues and a proposal

This paper concerns the validation of automatic retinal image analysis (ARIA) algorithms. For reasons of space and consistency, we concentrate on the validation of algorithms processing color fundus camera images, currently the largest section of the ARIA literature. We sketch the context (imaging instruments and target tasks) of ARIA validation, summarizing the main image analysis and validation techniques. We then present a list of recommendations focusing on the creation of large repositories of test data created by international consortia, easily accessible via moderated Web sites, including multicenter annotations by multiple experts, specific to clinical tasks, and capable of running submitted software automatically on the data stored, with clear and widely agreed-on performance criteria, to provide a fair comparison.

Plus disease in retinopathy of prematurity: diagnostic impact of field of view

PURPOSE

To examine the impact of retinal field of view and magnification on interexpert reliability of plus disease diagnosis in retinopathy of prematurity.

METHODS

Fifteen wide-angle images from infants with retinopathy of prematurity were cropped and adjusted in magnification to create 2 additional image categories: medium angle (40°-50°) and narrow angle (20°-30°). These 45 images were uploaded to a Web-based system and interpreted independently by 13 experts of retinopathy of prematurity using a 3-level (plus, preplus, neither) and 2-level (plus, not plus) classification. Absolute agreement and kappa statistics were calculated to compare interexpert reliability.

RESULTS

In the 3-level classification, ≥ 70% experts agreed on the same diagnosis in 8 of the 15 wide-angle images (53%), but only in 3 of the 15 medium-angle (20%) and 3 of the 15 narrow-angle (20%) images. In the 2-level classification, ≥ 80% experts agreed on the same diagnosis in 11 of the 15 wide-angle images (73%), but only in 9 of the 15 medium-angle (60%) and 3 of the 15 narrow-angle (20%) images. Mean kappa of each expert compared with all other experts was 0.40 to 0.59 in 8 of 13 experts (62%) using wide-angle images, was 0 to 0.19 in 7 of 13 experts (54%) using medium-angle images, and was 0.20 to 0.39 in 9 of 13 experts (69%) using narrow-angle images.

CONCLUSION

Interexpert agreement in plus disease diagnosis in wide-angle images is higher than from medium-angle and narrow-angle images. Plus disease is defined using a narrow-angle standard published photograph, yet this study suggests that peripheral findings also contribute to diagnosis.

Digital image analysis in retinopathy of prematurity: a comparison of vessel selection methods

PURPOSE

To evaluate vessel selection methods to distinguish between eyes with and without retinopathy of prematurity (ROP) and between different stages of ROP when quantifying the associated vessel changes in width and tortuosity semiautomatically from digital retinal images.

METHODS

Color digital images from 75 infants screened for ROP were cropped to a standardized diameter of 240 pixels and evaluated by semiautomated vessel analysis software, Computer-Aided Image Analysis of the Retina (CAIAR), to measure retinal vessel width and tortuosity. Two methods of vessel selection were used: (1) clinical observer selecting the most prominent arteriole or venule in each retinal quadrant (4-vessel analysis) and then separately the 4 most prominent arterioles and venules from each quadrant (8-vessel analysis); (2) CAIAR selecting, regardless of retinal quadrant, the 4 widest or most tortuous arterioles or venules. Selected vessels were measured by CAIAR for tortuosity and width.

RESULTS

When comparing ROP stages, whether observer or CAIAR selected and whether 4 or 8 vessels were analyzed, we found that arteriolar tortuosity was significantly greater with advancing ROP stage for stage 0 versus stage 2; stage 0 or 1 versus stage 3; stages 1+2 combined versus stage 3; and stage 0 versus 1+2+3 combined (P < 0.01). Venular tortuosity was significantly greater with advancing ROP stage for stage 0 versus stage 3 and stage 0 versus stages 1 and 2+3 combined (P < 0.01). Width parameters did not help us to distinguish between stages.

CONCLUSIONS

Distinguishing between arterioles and venules is not necessary to differentiate stage 0 ROP from stage 2 or 3 ROP when one is using CAIAR. Tortuosity shows more promise than width at providing a reliable vessel parameter for distinguishing between eyes without and with ROP.

Computer-based image analysis for plus disease diagnosis in retinopathy of prematurity

Presence of plus disease in retinopathy of prematurity (ROP) is an important criterion for identifying ROP requiring treatment. Plus disease is defined by a standard published photograph selected more than 20 years ago by expert consensus. However, diagnosis of plus disease has been shown to be subjective and qualitative. Computer-based image analysis using quantitative methods has potential to improve the objectivity of plus disease diagnosis. The objective was to review the published literature involving computer-based image analysis for ROP diagnosis. The PubMed and Cochrane library databases were searched for the keywords "retinopathy of prematurity" AND "image analysis" AND/OR "plus disease." Reference lists of retrieved articles were searched to identify additional relevant studies. All relevant English-language studies were reviewed. There are four main computer-based systems-ROPtool (area under the receiver operating characteristic curve [AUROC], plus tortuosity 0.95, plus dilation 0.87), RISA (AUROC, arteriolar TI 0.71, venular diameter 0.82), Vessel Map (AUROC, arteriolar dilation 0.75, venular dilation 0.96), and CAIAR (AUROC, arteriole tortuosity 0.92, venular dilation 0.91)-attempting to objectively analyze vessel tortuosity and dilation in plus disease in ROP. Some show promise for identification of plus disease using quantitative methods. This has potential to improve the diagnosis of plus disease and may contribute to the management of ROP using both traditional binocular indirect ophthalmoscopy and image-based telemedicine approaches.

Computerized analysis of narrow-field ROP images for the assessment of vessel caliber and tortuosity

Retinopathy of prematurity (ROP) is a disease involving abnormal development of retinal vasculature in premature infants, which might eventually lead to retinal detachment and visual loss. The quantitative assessment of vessel morphological features, such as width and tortuosity, can improve the clinical diagnosis and evaluation of ROP. We propose here a computerized system for the vascular analysis of narrow-field premature infant images. It is based on the manual drafting of the vessel axis, followed by automatic Canny filter edge extraction and automatic caliber and tortuosity estimation. We implemented this method as a web-based tool, ROPnet, which allows the quantitative assessment of vessel width and tortuosity simply using a web browser. To test the accuracy of the estimated parameters, fifteen narrow-field (30°) retinal images were acquired in infants with a non-contact fundus camera and analyzed with ROPnet. We compared the results with the corresponding ground-truth values derived from manual analysis. Average widths and tortuosities estimated with ROPnet vs. manual ones showed a correlation coefficient of 0.96 and 0.90, respectively.

A pilot study using ROPtool to measure retinal vascular dilation

BACKGROUND

Plus disease is abnormal retinal vascular dilation and tortuosity, and it is now the primary indication for laser treatment in retinopathy of prematurity (ROP). ROPtool is a computer program that measures retinal arteriolar tortuosity. Our aim was to assess the accuracy of ROPtool's newly developed measurement of retinal vascular width (dilation).

METHODS

ROPtool was used to measure the width of 154 blood vessels in 20 high-quality RetCam images from 20 premature infants. ROPtool's accuracy was determined by comparing results with the mean grades of 2 authors who scored retinal vascular dilation using a 10-point scale.

RESULTS

There was very good correlation (r = 0.80) between ROPtool's measurement of retinal vascular dilation and author judgment. Areas under receiver operating characteristics curves for identification of dilation sufficient for plus disease and for pre-plus disease were 0.93 and 0.90, respectively. At an optimal point on the receiver operating characteristics curve, ROPtool's sensitivity for diagnosing dilation sufficient for plus disease was 89% (24/27), and its specificity was 83% (106/127).

CONCLUSION

In addition to measuring retinal vascular tortuosity, ROPtool now accurately measures retinal vascular width in high-quality RetCam images. Application of this technology has the potential to remove subjectivity from the assessment of plus disease.

Semiautomated digital image analysis of posterior pole vessels in retinopathy of prematurity

Plus disease is a major indicator for treatment in retinopathy of prematurity (ROP), and computer-assisted image analysis of vessel caliber and tortuosity in the posterior pole may indicate disease progression and severity. We sought to determine whether semiautomated digital analysis of posterior pole vessels using narrow field images with varying severity of ROP correlated with vessel width and tortuosity.

Retinopathy of prematurity

This article briefly reviews the history of ROP followed by a discussion of the pathogenesis of this complex disorder. We describe the International Classification System for ROP and identify risk factors and screening recommendations. Finally, we discuss some of the measures that have been used in an attempt to both prevent and treat ROP.

Telemedicine for retinopathy of prematurity diagnosis: evaluation and challenges

Retinopathy of prematurity (ROP) is a vasoproliferative disorder affecting low birth weight infants. Although timely diagnosis and treatment can significantly reduce the risk of severe complications, ROP remains a leading cause of childhood blindness worldwide. Limitations of current disease management strategies include extensive travel and logistical coordination requirements for ophthalmologists and neonatologists, decreasing availability of adequately trained ophthalmologists at the point of care, variability in how retinal findings are diagnosed and documented, and a growing need for ROP care worldwide. Store-and-forward telemedicine is an emerging technology by which medical data are captured for subsequent interpretation by a remote expert. This has potential to improve accessibility, quality, and cost of ROP management. In this article, we summarize the current evaluation data on applications of telemedicine for ROP, particularly involving the diagnostic accuracy and reliability of remote image interpretation by experts. We also address challenges such as the cost-effectiveness of telemedicine, and highlight potential barriers to implementation of these systems. Understanding these principles is essential to determine future directions in research and development of telemedicine systems for ROP, as well as for other ophthalmic diseases.

Digital image analysis of plus disease in retinopathy of prematurity

An accurate assessment of retinopathy of prematurity (ROP) is essential in ensuring correct and timely treatment of this potentially blinding condition. Current modes of assessment are based upon clinical grading by expert examination of retinal changes. However, this may be subjective, unreliable and difficult and there has been significant interest in alternative means of measurement. These have been made possible through technological advancements in image capture and analysis as well as progress in clinical research, highlighting the specific importance of plus disease in ROP. Progress in these two fields has highlighted the potential for digital image analysis of plus disease to be used as an objective, reliable and valid measurement of ROP. The potential for clinical and scientific advancement through this method is argued and demonstrated in this article. Along with the potential benefits, there are significant challenges such as in image capture, segmentation, measurement of vessel width and tortuosity; these are also addressed. After discussing and explaining the challenges involved, the research articles addressing digital image analysis of ROP are critically reviewed. Benefits and limitations of the currently published techniques for digital ROP assessment are discussed with particular reference to the validity and reliability of outcome measures. Finally, the general limitations of current methods of analysis are discussed and more diverse potential areas of development are discussed.

Tortuosity of arterioles and venules in quantifying plus disease

BACKGROUND

Plus disease is the major criterion for laser treatment of retinopathy of prematurity. ROPtool is a computer program that traces retinal blood vessels and measures their tortuosity. Our objectives were to determine (1) whether examiners could accurately discriminate between arterioles and venules and (2) whether tortuosity sufficient for plus disease and pre-plus disease was assessed most accurately by considering arterioles, venules, or both.

METHODS

One hundred retinal vessels were identified in 25 images randomly selected from 184 total images. Three pediatric ophthalmologists independently designated vessels as arteriole or venule. Seventy-seven images that had at least 1 traceable arteriole and venule in each quadrant were analyzed by ROPtool, and the results were compared with the consensus of 3 expert examiners. Receiver operating characteristics (ROC) curves were generated and areas under the curves calculated to quantify the diagnostic utility of ROPtool's assessment of tortuosity of arterioles, venules, and both.

RESULTS

Three pediatric ophthalmologists agreed on the designation of arteriole or venule for 83 of 100 blood vessels. With the use of expert consensus as the reference standard, areas under the ROC curves for identification of tortuosity sufficient for plus disease were 0.91, 0.70, and 0.93 for arterioles, venules, and both, respectively. Areas under the ROC curves for identification of tortuosity sufficient for pre-plus disease were 0.91, 0.63, and 0.90 for arterioles, venules, and both, respectively.

CONCLUSIONS

When considering whether tortuosity is sufficient for plus or pre-plus disease, the assessment of either arterioles alone or of arterioles and venules together resulted in high diagnostic accuracy.

Surgical management of retinopathy of prematurity

PURPOSE OF REVIEW

The surgical management of retinopathy of prematurity continues to employ a paradigm of peripheral laser followed by vitrectomy for patients who develop retinal detachment. This review addresses significant advances that have been made in our understanding of the indications, timing, techniques, and outcomes of these interventions.

RECENT FINDINGS

The indications for laser are highly dependent on the diagnosis of plus disease. Recognition of plus disease is variable and subjective. Efforts are underway to develop more objective measures of plus using image analysis software. Intravitreal injection of bevacizumab is emerging as an adjunct to laser for aggressive posterior retinopathy of prematurity. Although vitrectomy for retinal detachment is effective in eyes without plus, management of eyes with retinal detachment and persistent plus continues to be a major challenge. Older children with regressed retinopathy of prematurity may suffer from vitreous hemorrhage in the absence of retinal tears, detachments, or active neovascularization.

SUMMARY

Our understanding of the best indications, timing, and techniques for the surgical management of retinopathy of prematurity continues to evolve and outcomes have improved in recent years. Areas that generate significant ongoing interest and investigation include the assessment of plus disease and the use of adjuncts for aggressive posterior retinopathy of prematurity.

Systematic review of digital imaging screening strategies for retinopathy of prematurity

BACKGROUND

Retinal imaging with remote interpretation could decrease the number of diagnostic eye examinations that premature infants need for the detection of retinopathy of prematurity and thus decrease the time demand on the relatively small pool of ophthalmologists who perform retinopathy of prematurity examinations.

OBJECTIVE

Our goal was to review systematically the evidence regarding the reliability, validity, safety, costs, and benefits of retinal imaging to screen infants who are at risk for retinopathy of prematurity.

METHODS

We searched Medline, the Cochrane library, CINAHL, and the bibliographies of all relevant articles. All English-language studies regardless of design with primary data about our study questions were included. We excluded (1) studies that only included subjects with retinopathy of prematurity, (2) hypothetical models other than cost-effectiveness studies, and (3) validity studies without sufficient data to determine prevalence, sensitivity, and specificity or that only evaluated subjects for 1 component of retinopathy of prematurity (eg, plus disease only).

RESULTS

Studies of only 1 retinal imaging device (RetCam [Clarity Medical Systems, Inc, Pleasanton, CA]) met the inclusion criteria. There was a wide range in reported sensitivity, but specificity was high. There were several important limitations noted, including the eye as the unit of analysis instead of the individual or variations in the criteria for determining a true-positive or true-negative screening result. The risk of retinal hemorrhage resulting from imaging is low, and systemic effects (eg, bradycardia, hypertension, decreased oxygen saturation) are mild. No generalizable cost-effectiveness data were found.

CONCLUSIONS

The evidence base is not sufficient to recommend that retinal imaging be routinely adopted by NICUs to identify infants who have serious retinopathy of prematurity.

Agreement among pediatric ophthalmologists in diagnosing plus and pre-plus disease in retinopathy of prematurity

PURPOSE

Plus disease has become the major criterion for laser treatment in infants with retinopathy of prematurity (ROP), but its assessment is subjective. Our purpose was to compare quadrant-level and eye-level assessment of plus disease and pre-plus disease among 3 experienced ROP examiners and to report their rate of agreement.

METHODS

One hundred eighty-one high-quality RetCam images from premature infants were graded by 3 of the authors. Dilation and tortuosity were judged separately using a scale of normal or sufficiently abnormal to meet criteria for pre-plus or plus disease.

RESULTS

There was disagreement on the presence of plus disease for 18 images (10%), on tortuosity sufficient for plus disease (plus tortuosity) for 26 images (14%), and on dilation sufficient for plus disease (plus dilation) for 26 images (14%). Of 67 images judged to have pre-plus disease or worse, there was disagreement on the presence of plus disease for 18 images (27%), on plus tortuosity for 25 images (37%), and on plus dilation for 21 images (31%). For distinguishing plus or pre-plus disease from normal, there was disagreement on pre-plus tortuosity for 38 of 181 images (21%) and on pre-plus dilation for 58 of 181 images (32%).

CONCLUSIONS

Three experienced ROP examiners disagreed frequently on the diagnosis of plus or pre-plus disease when evaluating cropped clinical photographs of infants, many of which had borderline plus disease. Further study is required to determine the implications of these observations on clinical decision making.

Plus disease in retinopathy of prematurity: development of composite images by quantification of expert opinion

PURPOSE

To demonstrate a methodology for generating composite wide-angle images of plus disease in retinopathy of prematurity (ROP), using quantitative analysis of expert opinions.

METHODS

Thirty-four wide-angle retinal images were independently interpreted by 22 ROP experts as "plus" or "not plus." All images were processed by the computer-based Retinal Image multiScale Analysis (RISA) system to calculate two parameters: arterial integrated curvature (AIC) and venous diameter (VD). Using a reference standard defined by expert consensus, sensitivity and specificity curves were calculated by varying the diagnostic cutoffs for AIC and VD. From these curves, individual vessels from multiple images were identified with particular diagnostic cutoffs, and were combined into composite wide-angle images using graphics-editing software.

RESULTS

The values associated with 75% underdiagnosis of true plus disease (i.e., 25% sensitivity cutoff) were AIC 0.061 and VD 4.272, the values associated with 50% underdiagnosis of true plus disease (i.e., a 50% sensitivity cutoff) were AIC 0.049 and VD 4.088, and the values associated with 25% underdiagnosis of true plus disease (i.e., 75% sensitivity cutoff) were AIC 0.042 and VD 3.795. Composite wide-angle images were generated by identifying and combining individual vessels with these characteristics.

CONCLUSIONS

Computer-based image analysis permits quantification of retinal vascular features, and a spectrum of abnormalities is seen in ROP. Selection of appropriate vessels from multiple images can produce composite plus disease images corresponding to expert opinions. This method may be useful for educational purposes, and for development of future disease definitions based on objective, quantitative principles.