The Teherán-Morales color grading scale, an objective means of grading optic nerve coloring, appears to be a useful tool for assessing the health of the optic nerve, according to research published in Archivos de la Sociedad Española de Oftalmología. 

Investigators attempted to establish an objective means of analyzing the subjective, color grading methods currently used in the assessment of the optic nerve. They evaluated 150 optic nerve photographs from individuals with optic neuropathy, glaucoma patients, and healthy controls (n=51, n=49, and n=50, respectively). A software program assigned a numerical value to the color characteristics, describing them as vein red, normal, slight pallor, marked pallor, or waxy pallor (0, 1, 2, and 3, respectively) in the upper, nasal, lower, and temporal quadrants. Concurrently, 3 glaucoma optic nerve specialists, who were blind to the patient’s conditions, graded the same photographs using the same scale. 

An analysis revealed weak correlations and great interobserver variation in the glaucoma group, except for a statistically significant, slight interobserver agreement in the nasal sector (P <.05). However, it revealed moderate to strong correlations and very good interobserver agreement when analyzing groups of photographs from the optic neuropathy group (P <.0001). Correlations were weak and did not show much statistical significance in the control group. Cumulatively, researchers noted moderate to strong correlations in the nasal sector between the 3 observers, with all other correlations being weak and statistically significant (P <.0001).


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Researchers stress the importance of developing an objective means of optic nerve analysis. “[The current] grading is based solely on patterns learned during training and is operator dependent, which increases with practice. However, this evaluation will always be subjective and personal and although most frequently matches the criteria of other ophthalmologists, sometimes it does not.”

Study limitations include a small sample size, small number of observers, and failure to compare the Teherán-Morales with other objective tests. 

Reference

Morales Domínguez J, Teherán Forero ÓL, Ochoa-Díaz MM, Ramos Clason EC. Validation of the color graduation scale in the optical nerve photograph, an alternative for qualitative classification. Arch Soc Esp Oftalmol. Published online February 8, 2022. doi:10.1016/j.oftal.2021.10.004