Proprioceptive Phenomenon With Involutional Ptosis: Evidential Findings in Anophthalmic Ptosis.

PURPOSE: To determine the effect of ptosis on compensatory frontalis contraction in patients without visual input and to identify if a sensory stimulus contributes to brow elevation. METHODS: A prospective study. Clinical photographs were measured by 2 masked oculoplastic surgeons to determine brow height in 8 patients with unilateral ocular prosthesis in 3 conditions: at baseline, after a gold weight was applied to the upper eyelid inducing acute ptosis, and with the gold weight plus topical anesthetic. The measured brow height was then compared between the 3 scenarios. RESULTS: Mean brow height increased after application of the gold weight when compared with baseline, and this difference reached significance (p = 0.012). After topical anesthetic was applied, the mean brow height decreased but not back to baseline. When mean brow height during the gold weight with topical anesthesia was compared with baseline and with the gold weight only scenarios, the difference was not significant (p > 0.05). CONCLUSIONS: Frontalis contraction is observed when acute ptosis is simulated in anophthalmic patients, confirming that a contracted visual field cannot be the only stimulus for compensatory brow elevation. A sensory or proprioceptive mechanism is suggested but not confirmed by the trend of reduction in brow elevation with topical anesthesia.

Invasive annual grasses indirectly increase virus incidence in California native perennial bunchgrasses.

In California valley grasslands, Avena fatua L. and other exotic annual grasses have largely displaced native perennial bunchgrasses such as Elymus glaucus Buckley and Nassella pulchra (A. Hitchc.) Barkworth. The invasion success and continued dominance of the exotics has been generally attributed to changes in disturbance regimes and the outcome of direct competition between species. Here, we report that exotic grasses can also indirectly increase disease incidence in nearby native grasses. We found that the presence of A. fatua more than doubled incidence of infection by barley and cereal yellow dwarf viruses (B/CYDVs) in E. glaucus. Because B/CYDV infection can stunt E. glaucus and other native bunchgrasses, the indirect effects of A. fatua on virus incidence in natives suggests that apparent competition may be an additional mechanism influencing interactions among exotic and native grasses in California. A. fatua's influence on virus incidence is likely mediated by its effects on populations of aphids that vector B/CYDVs. In our study, aphids consistently preferred exotic annuals as hosts and experienced higher fecundity on them, suggesting that the exotics can attract and amplify vector populations. To the best of our knowledge, these findings are the first demonstration that exotic plants can indirectly influence virus incidence in natives. We suggest that invasion success may be influenced by the capacity of exotic plant species to increase the pathogen loads of native species with which they compete.