Abstract
Purpose :
Involutional blepharoptosis (ptosis) is currently thought to be due to dehiscence of the levator palpebrae superioris (LPS), however, supporting data is limited. Recent studies show decreased levator function is correlated with eyelid height, suggesting an LPS abnormality. Sarcopenia, or age-related muscle degeneration, is characterized by fatty infiltration of muscles. We hypothesize that sarcopenia may contribute to the underlying pathophysiology of involutional ptosis. In this study, we assess sarcopenia using the change in signal intensity of the extraocular muscles with age on orbital magnetic resonance imaging (MRI).
Methods :
Charts of patients with T1 coronal, non-fat saturated orbital MRIs between 11/2014 – 11/2023 were reviewed. Patients < 18 years old and eyes with extraocular muscle abnormalities, such as trauma, thyroid eye disease, infection or malignancy were excluded. If both eyes met eligible criteria, one eye was randomly chosen for analysis. The average intensity was obtained for medial (MR), lateral (LR), superior (SR) and inferior (IR) rectus muscles and the intraconal orbital fat. The ratio of muscle to fat intensity accounts for differences in MRI protocols. A regression analysis was performed between the intensity of each muscle and age, as well as the ratio of muscle to fat intensity and age.
Results :
30 eyes were included in this study. The intensity of each muscle individually and the average of all four muscles significantly increased with age. On average the intensity increased by 10.33±3.09, P=0.002; 11.94±3.79, P=0.004; 10.51±3.10, P=0.002; 10.30±3.08, P=0.002, and 10.77±3.12, P=0.002 per year for MR, LR, SR, IR, and average of all muscles, respectively. The ratios of LR and IR muscle to fat intensity were also statistically increased with age (LR/Fat: 0.0025±0.0009, P= 0.008, IR/Fat: 0.0021±0.0009, P = 0.025). Additionally, the ratio of average of all muscles to fat intensity exhibited a significant increase with age (0.0020±0.0006, P=0.003).
Conclusions :
There is a positive association between age and signal intensity of extraocular muscles on T1 MRI, indicative of sarcopenia. MRI may be useful to assess for sarcopenia of the extraocular muscles and is consistent with the hypothesis that blepharoptosis is at least in part due to sarcopenia.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.