Quantitative comparison of disc rim color in optic nerve atrophy of compressive optic neuropathy and glaucomatous optic neuropathy.
OBJECTIVE
The purpose was to investigate an objective and quantitative method to estimate the redness of the optic disc neuroretinal rim, and to determine the usefulness of this method to differentiate compressive optic neuropathy (CON) from glaucomatous optic neuropathy (GON).


METHODS
In our study there were 126 eyes: 40 with CON, 40 with normal tension glaucoma (NTG), and 46 normal eyes (NOR). Digital color fundus photographs were assessed for the redness of disc rim color using ImageJ software. We separately measured the intensity of red, green, and blue pixels from RGB images. Three disc color indices (DCIs), which indicate the redness intensity, were calculated through existing formulas.


RESULTS
All three DCIs of CON were significantly smaller than those of NOR (P < 0.001). In addition, when compared with NTG, DCIs were also significantly smaller in CON (P < 0.05). A comparison of mild CON and mild NTG (mean deviation (MD) > -6 dB), in which the extent of retinal nerve fiber layer thinning is comparable, the DCIs of mild CON were significantly smaller than those of mild NTG (P < 0.05). In contrast, DCIs did not differ between moderate-to-severe stages of CON and NTG (MD ≤ -6 dB), though the retinal nerve fibers of CON were more severely damaged than those of NTG. To differentiate between mild CON and mild NTG, all AUROCs for the three DCIs were above 0.700.


CONCLUSIONS
A quantitative and objective assessment of optic disc color was useful in differentiating early-stage CON from GON and NOR.
Department of Ophthalmology and Visual Sciences, Kyoto University, 54 Shougoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
Eri
E
Nakano
Department of Ophthalmology and Visual Sciences, Kyoto University, 54 Shougoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan. trj74h6@kuhp.kyoto-u.ac.jp.
Masayuki
M
Hata
Department of Ophthalmology and Visual Sciences, Kyoto University, 54 Shougoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
Akio
A
Oishi
Department of Ophthalmology and Visual Sciences, Kyoto University, 54 Shougoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
Kazuaki
K
Miyamoto
Department of Ophthalmology and Visual Sciences, Kyoto University, 54 Shougoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
Akihito
A
Uji
Department of Ophthalmology and Visual Sciences, Kyoto University, 54 Shougoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
Masahiro
M
Fujimoto
Department of Ophthalmology and Visual Sciences, Kyoto University, 54 Shougoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
Manabu
M
Miyata
Department of Ophthalmology and Visual Sciences, Kyoto University, 54 Shougoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
Nagahisa
N
Yoshimura
D005260:Female; D005500:Follow-Up Studies; D005654:Fundus Oculi; D005901:Glaucoma / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009896:Optic Atrophy / Q000175:diagnosis* / Q000209:etiology; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000209:etiology; D012165:Retinal Ganglion Cells / Q000473:pathology; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence
Compressive optic neuropathy; Glaucomatous optic neuropathy; Optic nerve atrophy