Superior rectus/levator complex in acquired anophthalmic socket repaired with spheric implant—a computed tomography scan and topographic study

AIM:To determine whether the levator palpebrae superioris(LPS)/superior rectus(SR)muscle complex,can influence the position of the upper lid and fornix in acquired anophthalmic sockets.METHODS:This comparative non-randomized and non-interventional study included retrospective data of 21 patients with unilateral acquired anophthalmic sockets repaired with spheric implants.High-resolution computed tomography(CT)measurements of the LPM/SR muscle complex and clinical topographic position of the upper lid,superior and inferior fornix depth in primary gaze position were evaluated.Demographic data were presented as frequency and percentage proportions and quantitative variables comparing the socket measurements with the normal contralateral orbit was statistically analyzed using non-parametric tests considering P<0.05.RESULTS:The anophthalmic orbits had a significantly shorter LPS length(P=0.01)and significantly thicker SR(P=0.02)than the normal orbit.Lagophthalmos was present in anophthalmic sockets but not in normal orbits(P=0.002),while levator function was normal in both(P>0.05,all comparisons).The superior fornix depth was similar in the anophthalmic socket and the contralateral normal orbit(P=0.192)as well the inferior fornix depth(P=0.351).CONCLUSION:Acquired anophthalmic sockets repaired with spheric implants have shorter LPS,thicker SR,and more lagophthalmos than normal orbits.The relationship of the LPS and SR with other orbital structures,associated with passive or active forces acting in the final position of the lids and external ocular prosthesis should be further investigated.

Electromyography and Fos immunostaining study establish a possible functional link between trigeminal proprioception and the oculomotor system in rats

The objective of this study was to explore whether there was a functional link between trigeminal proprioception and the oculomotor system mediated through jaw muscle afferents.Electromyography（EMG） was undertaken of the levator palpebrae（LP） and superior rectus（SR）,and Fos expression was detected in the brainstem following consecutive down-stretching of the lower jaw at 2-4 Hz in rats.Retrograde tracing was undertaken of the interstitial nucleus of Cajal and Darkschewitsch nucleus（INC/DN） pre-oculomotor neurons.FMG-like responses were recorded from the LP/SR during down-stretching of the lower jaw at 2-4 Hz in 3 out of 11 rats.Fos expression was induced by consecutive down-stretching of the lower jaw at 2-4 Hz for 20-30 seconds.Interestingly,Fos expression was distributed mainly in the bilateral INC/DN area.We also examined Fos-like immunoreactivity in central mesencephalic and paramedian pontine reticular formation that harbors premotor neurons controlling horizontal eye movement,but no Fos-like staining was observed therein.By injection of retrograde tracers into the oculomotor nucleus combined with Fos immunostaining,double labeled pre-oculomotor neurons were visualized to distribute in the INC/DN.In conclusions,there may exist a trigeminal proprioceptive-oculomotor system neural circuit through jaw muscle afferents in rats.Judging from Fos distribution pattern,this pathway might be related to vertical and torsional eye movements.