Quantitative Analysis of Ganglion Cell-Inner Plexiform Layer Thickness, Inner Plexiform Layer Integrity, and Macular Vascular Density in High Myopia Using Optical Coherence Tomography Angiography

Abstract

Background A thinner ganglion cell-inner plexiform layer (GC-IPL) and inner plexiform layer (IPL) are indicative of several ophthalmic and central nervous system diseases. We aim to To investigate alterations in the thickness of the GC-IPL and IPL, as well as their relation to changes in macular microvasculature, in patients with high myopia. Methods Optical coherence tomography (OCT) and OCT-angiography (OCT-A) were performed on patients with high myopia (HM) and non-HM individuals. Comparative analysis was conducted to assess the thickness of the choroid, macula, GC-IPL, IPL, and macular superficial and deep vascular density (VD). Additionally, correlations between GC-IPL and IPL thickness with axial length or macular vascular density were examined. Results The results showed that HM eyes exhibited a significantly thinner subfoveal choroid and macular thickness (MT) in the 6 mm area than non-high myopia eyes (p < 0.05). In the 3 mm area, HM eyes had a lower average thickness of GC-IPL and IPL with some partial areas also showing reduced thickness (p < 0.05). Within the 6 mm area, HM eyes had significantly thinner GC-IPL and IPL overall. The ratios of GCIPL/MT and IPL/MT were smaller in HM eyes in both total and partial areas within the 6 mm area (all p < 0.05), but no difference was observed in the 3 mm area. The macular vascular density, both in the superficial and deep retinal layers, was lower in HM eyes (p < 0.05). Correlations were found between the macular vascular density and the GC-IPL and IPL within 6 mm (p < 0.005), but no linear relationship was observed between the thickness of the GC-IPL, IPL, and axial length. Conclusion High myopia eyes exhibited significant thinning of both the GC-IPL and IPL, possibly due to reduced vascular density in the retina. This thinning of the GC-IPL and IPL may indicate that neurodegenerative processes may commence prior to the development of maculopathy associated with high myopia.