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A comparison of cup‐to‐disc ratio evaluation in normal subjects using stereo biomicroscopy and digital imaging of the optic nerve head
Author(s) -
Hrynchak Patricia,
Hutchings Natalie,
Jones Deborah,
Simpson Trefford
Publication year - 2003
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1046/j.1475-1313.2003.00088.x
Subject(s) - stereoscopy , optic nerve , ophthalmology , medicine , digital image analysis , mathematics , nuclear medicine , optics , physics , computer vision , computer science
The cup‐to‐disc (CD) ratio evaluated using stereoscopic biomicroscopy was compared with that evaluated by viewing a non‐stereo digital image of the optic nerve head. Twenty normal subjects (mean age 26 ± 4 years) were evaluated by two observers. The average CD ratio was 0.29 with a range of 0–0.80. The intra‐class correlations between the observers ranged from 0.82 to 0.96, when comparing horizontal and vertical CD ratios for both evaluation techniques. The mean CD ratio was significantly smaller when viewing the digital image (0.25 ± 0.01) compared with stereoscopic observation (0.33 ± 0.03, p < 0.0001). Although the mean differences between the two techniques were small, the percentage of CD ratios that differed by ≥0.2 were between 5 and 25% of evaluations. Caution should be exercised when using stereoscopic and non‐stereo digital evaluations of CD ratio interchangeably to assess longitudinal progression in a multi‐clinician setting.