J Korean Ophthalmol Soc.  2013 Jun;54(6):913-918. 10.3341/jkos.2013.54.6.913.

The Ability of Disc-to-Fovea Distance to Disc-Diameter Ratio to Estimate Optic Disc Size

• Yoo HG
• Ahn JH
• Lee MV

• KMID: 2217267
• DOI: http://doi.org/10.3341/jkos.2013.54.6.913

Abstract

PURPOSE
To investigate the usefulness of the measurement of disc-to-fovea distance to disc-diameter ratio (DF/DD ratio) in detecting large and small discs.
METHODS
A total of 300 randomly selected subjects were included in the present study. All patients underwent stereoscopic disc photography and DF/DD ratio, which is the shortest distance between disc margin and fovea divided by mean disc diameter was determined by planimetry. The diagnostic accuracy of DF/DD ratio was evaluated using areas under the receiver operating characteristics curves (AUCs), sensitivity, and specificity.
RESULTS
No significant differences in disc-to-fovea distance were observed among small and large disc groups. The DF/DD ratio was significantly lower in subjects with large discs (1.74 +/- 0.27) compared with subjects with small discs (2.70 +/- 0.15). AUCs of the DF/DD ratio were 0.942 and 0.947 in detecting large and small discs, respectively. In detecting disc size by a fixed DF/DD ratio of 2.0, sensitivity was 100% for both large and small discs, and specificity was 70.1% and 40.9% for the large and small discs, respectively.
CONCLUSIONS
The DF/DD ratio may be a simple and useful clinical aid in detecting large and small discs. The 2.0 fixed DF/DD ratio, showed 100% sensitivity in detecting both large and small discs, although medium discs may be misdiagnosed as small discs more often than as large discs.

Keyword

Disc diameter; Disc-to-fovea distance; Optic disc size; Stereoscopic disc photography

MeSH Terms

Area Under Curve
Humans
Photography
ROC Curve
Sensitivity and Specificity

Figure

• 

  Figure 1. Receiver operating characteristic (ROC) curve of the DF/DD ratio and R-DF/DD ratio for detection of small disc (A) and large disc (B). DF/DD ratio = disc-to-fovea distance to disc-diameter ratio; R-DF/DD ratio = round up scale of disc-to-fovea distance to disc-diameter ratio.

Reference

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