Quality of nonmydriatic digital fundus photography obtained by nurse practitioners in the emergency department: the FOTO-ED study

Abstract

Objective: Nonmydriatic fundus photography by non-ophthalmic-trained personnel has recently been shown to be a potential alternative to direct ophthalmoscopy in the emergency department (ED). We evaluated the reliability of a novel quality rating scale and applied this scale to nonmydriatic fundus photographs taken during routine ED patient encounters to determine factors associated with diminished photograph quality.

Design: Prospective, cross-sectional study.

Participants: We included 350 patients enrolled in the Fundus photography versus Ophthalmoscopy Trials Outcomes in the Emergency Department study who were photographed by nurse practitioners after <30 minutes of training followed by supervision.

Methods: Photographs of both eyes were graded for quality on 2 occasions by 2 neuro-ophthalmologists. Four regions were independently evaluated for quality: Optic disc, macula, and superior and inferior vascular arcades. Quality as a function of the number of photographs taken was evaluated by Kaplan-Meier analysis. Mixed effects ordinal logistic regression was used to evaluate for predictors of image quality while accounting for the repeated measures design.

Main outcome measures: Overall photographic quality (1-5 scale; 5 best).

Results: We evaluated 1734 photographs. Inter- and intraobserver agreements between neuro-ophthalmologists were very good (weighted kappa, 0.84-0.87). Quality of the optic disc area was better than those of other retinal areas (P<0.002). Kaplan-Meier analysis showed that if a high-quality photograph of an eye was not obtained by the third attempt, it was unlikely that one would be obtained at all. A 10-second increase in the interphotograph interval before a total of 40 seconds increased the odds of a 1-unit higher quality rating by 1.81 times (95% confidence interval [CI], 1.68-1.98), and a 10-year increase in age decreased the odds by 0.76 times (95% CI, 0.69-0.85). Black patients had 0.42 times (95% CI, 0.28-0.63) the odds of a 1-unit higher quality rating compared with whites.

Conclusions: Our 5-point scale is a reliable measure of nonmydriatic photograph quality. The region of interest, interphotograph interval, and patient age and race are significant predictors of image quality for nonmydriatic photographs taken by nurse practitioners in the ED. Addressing these factors may have a direct impact on the successful implementation of nonmydriatic fundus photography into the ED.

Conflict of interest statement

No conflicting relationship exists for any author.

Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Example images for each level of the five-point scale used for general quality assessment: 1) The quality is inadequate for any diagnostic purpose. 2) Graders are unable to exclude all emergent findings. 3) Graders are only able to exclude emergent findings. 4) The quality is not ideal, but graders are able to exclude subtle findings. 5) Ideal quality. Grade 4 and 5 were considered high-quality photographs.

Figure 2

Regional quality assessment. Upper half: The four regions that were analyzed for quality independently: (1) the optic disc region, (2) the macular region, (3) the superior vascular arcade region, and (4) the inferior vascular arcade region. Lower half: The method by which each region of each photograph was assigned a grade.

Figure 3

Frequency of each quality grade for the four different regions of the best photograph of the right eye (results similar for the left eye, not shown) for each patient.

Figure 4

Mean quality of images vs. the midpoint of the interphotograph intervals (circles) within twenty groups of essentially equal sample size (i.e., 20-quantiles or vigintiles with breaks chosen by the interphotograph interval). The best fit piecewise linear regression (dashed line, knot at 40 seconds) is superimposed. This shows a non-linear relationship between how long it took to obtain a photograph and its quality with an apparent inflection point at 40 seconds.

Figure 5

Kaplan-Meier curve showing the proportion of patients who have not yet had a photograph of quality 4 or 5 (i.e., high-quality) in the right eye as a function of number of photographs taken. This figure shows that the chances of obtaining a high-quality photograph rapidly decreased with additional attempts.