Early detection of glaucoma is important for slowing disease progression; however, common glaucoma measures, such as retinal nerve fiber layer thickness, are affected by axial length, making diagnosis challenging in myopic eyes. Now, researchers suggest certain OCT parameters and retinal ganglion cells counts are reliable diagnostic tools.
The cross-sectional observational study included 154 eyes (36 controls, 64 perimetric and 54 primary open-angle glaucoma eyes). To analyze the effect of myopia, the eyes in each group were subdivided into three more groups based on axial length: emmetropic, myopic with axial length <25mm and myopic with axial length >25mm. The researchers used a model to determine retinal ganglion cell count.
They found that ganglion cell complex thickness was weakest and less significantly correlated with axial length in all groups. The researchers also noted that inferior ganglion cell complex and global loss volume were the most sensitive for change in the myopic groups and had the best diagnostic ability for distinguishing between controls and glaucotamous eyes. Retinal ganglion cells count demonstrated 83% sensitivity in myopic eyes and more than 91% specificity in all groups.
The researchers concluded that ganglion cell complex is less influenced by axial length and that inferior ganglion cell complex and global loss volume have the best diagnostic performance. They noted that retinal ganglion cell count can be used as a complementary test in glaucoma diagnosis for myopic preperimetric eyes due to its good sensitivity and specificity.
Rolle T, Bonetti B, Mazzuco A and Dallorto L. Diagnostic ability of OCT parameters and retinal ganglion cells count in identification of glaucoma in myopic preperimetric eyes. BMC Ophthalmology. September 22, 2020. [Epub ahead of print].