a 17-year - old male , a nonsmoker , presented with the sensation of left malar heaviness of 1 month 's duration . there was no history of trauma , chronic rhinosinusitis , or sinonasal surgery . on examination radiograph of the paranasal sinuses showed a small left maxillary antrum with depression of the orbital floor . nasal endoscopy revealed a roomy left middle meatus with lateral retraction of the middle turbinate . a subsequent computerized tomography ( ct ) there was inward retraction of the anterior , lateral , and superior antral walls ; their thickness was normal . the middle turbinate was lateralized , and the uncinate process was apposed to the inferomedial orbital wall . there was also increase in the left retroantral fat [ figs . 3 and 4 ] . as the cosmetic deficit was minimal , no orbital reconstruction was undertaken . at follow - up after 6 months the left malar eminence also has a flattened contour radiograph of the paranasal sinuses ( water 's view ) reveals a small left maxillary antrum with depression of the anteroinferior orbital floor . a septal spur toward the right side is also noted ( a and b ) a panel of axial computerised tomography images ( caudocranial ) in bone window of the maxillary antra reveals atelectatic left maxillary sinus ( * ) , retracted anterior wall of the antrum ( white arrow ) , widened middle meatus ( # ) , and increased retroantral fat ( + ) ( a and b ) a panel of coronal computerized tomography images ( anterior - posterior ) in bone window of the orbits and maxillary antra shows the atelectatic left maxillary sinus ( * ) . there is lateralization of the middle turbinate , and the uncinate process is apposed to the inferomedial orbital wall ( white arrow ) a syndrome of facial asymmetry due to spontaneous painless enophthalmos and hypoglobus , due to asymptomatic chronic maxillary sinus atelectasis was first described by montgomery . alluding to the silent  antral disease , this syndrome was named the sss by soparkar et al . to better describe the antral atelectasis , rose et al . named it the  imploding antrum  syndrome . there is no laterality bias ; however , some have reported right - sided predisposition . there is no history of acute or chronic sinus mucosal disease and prior facial trauma . the negative association with smoking is attributable to the fact that smokers with predisposing abnormal sinonasal anatomy present with diffuse mucosal disease early and undergo treatment before developing the syndrome . physical examination findings may include upper lid retraction , lid lag , deepened upper lid sulcus , malar depression , facial asymmetry , and diplopia . the degree of enophthalmos and hypoglobus ranges between 26 mm ( mean : 3.4 ) and 16 mm ( mean : 3.2 mm ) , respectively . ocular dysmotility ( inferior rectus and inferior oblique ) is noted only with significant hypoglobus . ct scan is the best diagnostic method because it best delineates the osseous and anatomic changes needed for its diagnosis and differentiation from other conditions . the opacified antrum is atelectatic with inward bowing of the walls , and consequent increased orbital volume and enlargement of the middle meatus . generally , all four antral walls are involved . the maxillary roof ( orbital floor ) the maxillary infundibulum is occluded , and the uncinate process is apposed to the inferomedial aspect of the orbital wall . there is a lateral retraction of the middle turbinate and the middle meatus is widened . the nasal septum is deviated toward the affected side in the majority of the patients . the ipsilateral retroantral fat is also increased . a hypoplastic antrum with chronic obstructive mucosal disease was initially believed to be the cause of the syndrome . it is now believed that ostiomeatal occlusion with the loss of aeration and gradual resorption of secretions and residual air , and chronic mucosal inflammation with osseous demineralization leads to implosion of the weakened antral walls , a phenomenon akin to middle ear atelectasis due to eustachian tube dysfunction . an abnormally narrowed nasal cavity due to septal deviation and/or laterally deviated middle turbinate may also predispose to maxillary hypoventilation . in the later stages of the disease , mucosal inflammation might lead to hyperostosis and thickened antral walls . although plausible , this theory does not explain the rarity of this entity amid the commonality of sinus mucosal disease nor the selective involvement of the maxillary sinus . it is possible that anatomic variations such as type 2 ( hypoplastic or absent uncinate process with an opacified affected sinus ) maxillary sinus hypoplasia and hitherto other undefined anomalies may be predisposing factors . local iatrogenic trauma may also be a predisposing factor in this condition . the diagnosis of ia can be made clinically , but it should be differentiated from other causes of spontaneous enophthalmos such as parry  romberg syndrome ( progressive hemifacial atrophy ) and linear scleroderma . the treatment has two objectives - to reestablish maxillary antral ventilation and restore orbital architecture . careful identification of structures during surgery is essential to avoid orbital injury in view of altered anatomy and osseous rarefaction . as orbital remodeling after antrostomy with improvement in enophthalmos and hypoglobus has been observed , it might be prudent to delay orbital reconstruction for 26 months . orbital floor repair depends on the degree of enophthalmos and hypoglobus and the consequent cosmetic defect . some prefer to combine both procedures in view of rarity of complications and to avoid a second hospitalization and surgery . the absence of thin antral walls indicates chronicity and implies commencement of the disease process at an even younger age . the  imploding antrum  is a rare and unusual entity characterized by spontaneous painless enophthalmos and hypoglobus caused by chronic obstructive maxillary sinus atelectasis . the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s ) has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal . the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed . the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s ) has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal . the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed .
the imploding antrum or silent sinus syndrome is a rare phenomenon that presents with spontaneous painless enophthalmos and hypoglobus . 
 it occurs due to ipsilateral maxillary antral atelectasis secondary to asymptomatic obstructive chronic sinus mucosal disease . 
 ophthalmologists , otorhinolaryngologists , and radiologists must be aware of this entity . 
 this article illustrates the typical presentation in a 17-year - old male with unilateral ptosis and a deep superior sulcus , and characteristic imaging findings of ipsilateral increased orbital volume and depression of the orbital floor , maxillary sinus opacification and atelectasis with retraction of the posterolateral and medial walls , lateralization of the uncinate process , and obstruction of the ostiomeatal unit . 
 this is probably the first time that the syndrome is being reported in such a young person . 
 the pathogenesis , differential diagnosis , and treatment modalities of this entity are also reviewed .