Longer Axial Length Poses Myopia Complication Risks in Adults

Longer axial length in adults (>26.6 mm) may result in a greater neural tissue loss and worsening blood supply in eyes with myopia, according to research published in Clinical Ophthalmology.

Researchers included 381 patients (mean age, 31 years) in a retrospective study conducted between 2016 and 2022 and stratified participants according to refractive error (emmetropia, n=93; hyperopia, n=102; myopia, n=186). Participants with myopia were further stratified according to myopia progression (progressive myopia, n=48; non progressive myopia, n=138). The team determined ganglion cell complex (GCC) mean thickness, focal loss of volume (FLV), global loss of volume (GLV), foveal avascular zone (FAZ) area, FAZ perimeter, and foveal vascular zone density measurements using optical coherence tomography-angiography (OCT-A) and sought markers for neural tissue loss in eyes with myopia. 

Stratified by refractive error, FAZ area, FAZ perimeter, GLV, and FLV were highest among participants with myopia, and individuals with progressive myopia demonstrated the highest values within this cohort (0.52 mm²; 3.8 mm; 4.01%; 2.24%, respectively). GCC values were thinnest among these participants, and thickest in individuals with hyperopia (81.76 vs 98.01 μm). Overall, differences in FAZ (P =.0001), FAZ perimeter (P =.0008), FLV (P =.0023), GLV (P =.0020), and GCC (P =.0423) were significantly different between the cohorts. 

In all participants, FLV was significantly correlated with FAZ perimeter (r, 0.28) and foveal vascular density (r, -0.34; P <.05 for both). GLV demonstrated a correlation with FAZ perimeter (r, 0.32) and FD (r, -0.39; P <.05 both), and superior GCC thickness correlated with FD (r, 0.34; P <.05). Among the myopia and progressive myopia subgroups, all pairwise comparisons of the mean, superior, and inferior GCC, FLV, and GLV with FAZ, perimeter, and FD were significantly correlated (all P <.05). 

Among all participants, axial length was positively associated with FAZ (r, 0.54), FLV (r, 0.24), and GLV (r, 0.41) and negatively correlated with GCC (r, -0.12; P <.05). Stratified by refractive error, no correlations were observed among participants with hyperopia and emmetropia. 

In individuals with myopia, an axial length of 26.6 mm or longer resulted in a FAZ that negatively correlated with mean GCC thickness. This results in greater vascular and neovascular complications resulting from myopia, according to the report.  

“The findings of this study underline the importance of reducing myopia progression even in adult population[s],” according to the researchers. “Patients with [axial length] of 26.6 mm and greater length are at particular risk for future myopia complications. They should receive special ophthalmological care, and methods to inhibit eyeball growth should be considered.”

Study limitations include an overrepresentation of women in the study sample and failure to recalculate OCT-A measurements to account for magnification effect.