Asteroid hyalosis in a 33-year-old female aircrew member mimicking synchysis scintillans: a case report

Abstract Background Asteroid hyalosis (AH) is a primary vitreous degeneration typically seen in individuals over 50 years of age. Early-onset AH is extremely rare and prone to misdiagnosis, as it shares overlapping onset ages with synchysis scintillans (SS) and exhibits comparable static slit-lamp findings. In clinical practice, careful differentiation of the features of these two vitreous crystalline degenerative diseases is essential to avoid misdiagnosis. Case presentation A 33-year-old female aircrew member was found to have vitreous opacities in the left eye during an annual physical examination and had been previously diagnosed with SS based solely on clinical slit-lamp assessment. The patient was asymptomatic, with best-corrected visual acuity (BCVA) of 20/16 in the right eye and 20/20 in the left eye. Slit-lamp examination revealed numerous yellowish-white, highly reflective punctate crystalline particles in the left vitreous, which exhibited limited mobility upon eye movement and promptly returned to their original position after motion ceased. B-scan ultrasonography revealed scattered punctate hyperechoic foci with low mobility, without significant vitreous liquefaction, and a distinct anechoic clear zone between the opacities and the retina. These findings were consistent with AH rather than SS, as vitreous opacities in SS are gravity-dependent. The misdiagnosis was attributed to two main factors: the similar ophthalmoscopic appearance of crystalline opacities and the age-related bias, as the patient’s age of 33 years is typical for SS but extremely rare for AH. Conclusions Early-onset AH is rare in young adults and can easily be misdiagnosed as SS when relying merely on age and static slit-lamp findings. Accurate differentiation in young patients with vitreous crystalline opacities necessitates integrating clinical history, dynamic sedimentation assessment, and multimodal imaging. Moreover, we innovatively hypothesize a potential association between high-altitude occupational exposure and early-onset AH, though this requires further study.