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Design and validation of a method to determine the position of the fovea by using the nerve-head to fovea distance of the fellow eye.

van de Put MA, Nayebi F, Croonen D, Nolte IM, Japing WJ, Hooymans JM, Los LI - PLoS ONE (2013)

Bottom Line: The effect of age, gender, and refractive error on NFD was analysed.We found a significant effect of age (center of the nerve-head (P = 0.006) and rim of the nerve head (P = 0.003)) and refractive error (center of nerve-head (P<0.001) and rim of nerve head (P<0.001)) on NFD.Age and refractive error have an effect on NFD.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. m.a.j.van.de.put@umcg.nl

ABSTRACT

Purpose: To measure the nerve-head to fovea distance (NFD) on fundus photographs in fellow eyes, and to compare the NFD between fellow eyes.

Methods: Diabetic patients without retinopathy, (n = 183) who were screened by fundus photography at the University Medical Center Groningen, the Netherlands from January 1(st) 2005 until January 1(st) 2006 were included. The NFD was measured in left and right eyes both from the center and from the rim of the nerve-head. To determine inter- and intra-observer agreement, repeated measurements by one observer (n = 3) were performed on all photographs and by two observers on 60 photographs (30 paired eyes). The effect of age, gender, and refractive error on NFD was analysed.

Results: The correlation of NFDs between the left and the right eye was 0.958 when measured from the center of the nerve head (mean difference 0.0078 mm. ±SD 0.079 (95% limits of agreement -0.147-0.163)) and 0.963 when measured from the rim (mean difference 0.0056±SD 0.073 (95% limits of agreement -0.137-0.149)). Using the NFD between fellow eyes interchangeably, resulted in a standard error of 0.153 mm. Intra- and inter-observer variability was small. We found a significant effect of age (center of the nerve-head (P = 0.006) and rim of the nerve head (P = 0.003)) and refractive error (center of nerve-head (P<0.001) and rim of nerve head (P<0.001)) on NFD.

Conclusions: The NFD in one eye provides a confident, reproducible, and valid method to address the position of the fovea in the fellow eye. We recommend using the NFD measured from the center of the nerve-head since the standard error by this method was smallest. Age and refractive error have an effect on NFD.

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A. NFD made by observer 1 plotted against this measurement made by observer 2 together with the line of equation.B. the distribution of differences of the NFDs between the two observers. C. The difference between NFDs against NFD averaged over both observers. The solid line indicates the mean and the dotted lines the 95% limits of agreement.
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pone-0062518-g006: A. NFD made by observer 1 plotted against this measurement made by observer 2 together with the line of equation.B. the distribution of differences of the NFDs between the two observers. C. The difference between NFDs against NFD averaged over both observers. The solid line indicates the mean and the dotted lines the 95% limits of agreement.

Mentions: No intra-observer difference between the three measurements was observed for both observers (Table 3). Inter-observer differences were significant for NFD measured from the rim of the nerve-head for both the left eye (P = 0.0072) and the right eye (P = 9.3 10−7), but not for NFD measured from the center of the nerve-head. Observer 2 measured the distance from the rim of the nerve-head to the fovea 0.164 mm. shorter in the right eye (95% limits of agreement: −0.141–0.468 for a single measurement; −0.120–0.447 for triple measurements) and 0.076 mm. in the left eye (−0.222–0.374 single; −0.206–0.358; triple) (Table 4; Figure 6). The upper limits of agreement were large for all four measurements ranging from 0.141–0.222, with three of them being larger than the lateral resolution of 0.2 mm implying that these measurement errors are unacceptable.


Design and validation of a method to determine the position of the fovea by using the nerve-head to fovea distance of the fellow eye.

van de Put MA, Nayebi F, Croonen D, Nolte IM, Japing WJ, Hooymans JM, Los LI - PLoS ONE (2013)

A. NFD made by observer 1 plotted against this measurement made by observer 2 together with the line of equation.B. the distribution of differences of the NFDs between the two observers. C. The difference between NFDs against NFD averaged over both observers. The solid line indicates the mean and the dotted lines the 95% limits of agreement.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646827&req=5

pone-0062518-g006: A. NFD made by observer 1 plotted against this measurement made by observer 2 together with the line of equation.B. the distribution of differences of the NFDs between the two observers. C. The difference between NFDs against NFD averaged over both observers. The solid line indicates the mean and the dotted lines the 95% limits of agreement.
Mentions: No intra-observer difference between the three measurements was observed for both observers (Table 3). Inter-observer differences were significant for NFD measured from the rim of the nerve-head for both the left eye (P = 0.0072) and the right eye (P = 9.3 10−7), but not for NFD measured from the center of the nerve-head. Observer 2 measured the distance from the rim of the nerve-head to the fovea 0.164 mm. shorter in the right eye (95% limits of agreement: −0.141–0.468 for a single measurement; −0.120–0.447 for triple measurements) and 0.076 mm. in the left eye (−0.222–0.374 single; −0.206–0.358; triple) (Table 4; Figure 6). The upper limits of agreement were large for all four measurements ranging from 0.141–0.222, with three of them being larger than the lateral resolution of 0.2 mm implying that these measurement errors are unacceptable.

Bottom Line: The effect of age, gender, and refractive error on NFD was analysed.We found a significant effect of age (center of the nerve-head (P = 0.006) and rim of the nerve head (P = 0.003)) and refractive error (center of nerve-head (P<0.001) and rim of nerve head (P<0.001)) on NFD.Age and refractive error have an effect on NFD.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. m.a.j.van.de.put@umcg.nl

ABSTRACT

Purpose: To measure the nerve-head to fovea distance (NFD) on fundus photographs in fellow eyes, and to compare the NFD between fellow eyes.

Methods: Diabetic patients without retinopathy, (n = 183) who were screened by fundus photography at the University Medical Center Groningen, the Netherlands from January 1(st) 2005 until January 1(st) 2006 were included. The NFD was measured in left and right eyes both from the center and from the rim of the nerve-head. To determine inter- and intra-observer agreement, repeated measurements by one observer (n = 3) were performed on all photographs and by two observers on 60 photographs (30 paired eyes). The effect of age, gender, and refractive error on NFD was analysed.

Results: The correlation of NFDs between the left and the right eye was 0.958 when measured from the center of the nerve head (mean difference 0.0078 mm. ±SD 0.079 (95% limits of agreement -0.147-0.163)) and 0.963 when measured from the rim (mean difference 0.0056±SD 0.073 (95% limits of agreement -0.137-0.149)). Using the NFD between fellow eyes interchangeably, resulted in a standard error of 0.153 mm. Intra- and inter-observer variability was small. We found a significant effect of age (center of the nerve-head (P = 0.006) and rim of the nerve head (P = 0.003)) and refractive error (center of nerve-head (P<0.001) and rim of nerve head (P<0.001)) on NFD.

Conclusions: The NFD in one eye provides a confident, reproducible, and valid method to address the position of the fovea in the fellow eye. We recommend using the NFD measured from the center of the nerve-head since the standard error by this method was smallest. Age and refractive error have an effect on NFD.

Show MeSH
Related in: MedlinePlus