We would like to thank Young Hoon Hwang
1 for the interest in our recent papers.
2–4 Optical coherence tomography is a new technology that allows quantitative assessment of the retinal nerve fiber layer (RNFL), optic nerve head (ONH), and ganglion cell inner plexiform layer (GCIPL). Prior to using new technology in clinical practice, it is important to compare it with established diagnostic techniques. Our recent studies quantitatively evaluated macular GCIPL and assessed its diagnostic performance at various stages of glaucoma and in a specific ocular condition including high myopia.
Hwang demonstrated irregular patterns of macular GCIPL thickness in eyes with epiretinal membrane (ERM) and suggested that GCIPL thickness in eyes with ERM and glaucoma should be interpreted carefully. Lee and Yu
5 recently reported decreased macular GCIPL thickness, 6 months after vitrectomy, in eyes with idiopathic ERM when compared with fellow unaffected eyes. Their study reminds us of the importance of a vitrectomy history of patients before evaluating the macular GCIPL thickness in eyes with idiopathic ERM.
Our group recently showed that 40% of idiopathic ERM eyes had vitreopapillary traction (VPT).
6 Vitreopapillary traction was associated with altered ONH parameters and increased peripapillary RNFL thickness, primarily in the temporal quadrant; VPT affected the visual field of the patients. Thus, the presence of VPT should be considered while interpreting macular GCIPL or RNFL thickness profiles in eyes with idiopathic ERM. Since VPT increased temporal peripapillary RNFL thickness, GCIPL thickness in the nasal sector may be affected in eyes with idiopathic ERM and VPT. In addition, various conditions, such as diabetic retinopathy, macular edema, macular degeneration, and other optic neuropathies, can affect macular thickness measurements, thereby limiting their clinical applicability for evaluation of glaucoma.
Since the main pathologic process of glaucoma is characterized by loss of retinal ganglion cells (RGCs) and their axons, macular GCIPL thickness can be used as a good diagnostic indicator of RGC loss. Our recent studies suggest that the diagnostic performance of macular GCIPL assessment is comparable with ONH parameters and peripapillary RNFL measurements for the detection of glaucomatous changes. However, certain conditions such as macular diseases and optic neuropathy may affect GCIPL thickness measurements. Therefore, in a clinical setting, this should be taken into consideration when using a macular GCIPL map for glaucoma diagnosis.