we selected patients who were diagnosed with impending central retinal vein occlusion from january 2003 to march 2007 in wonju christian hospital , and we retrospectively studied their medical records . by gass ' definition
, impending central retinal vein occlusion has mild or no loss of vision with venodilation and retinal dot hemorrhages under fundus examination . in all patients , slitlamp examination , intraocular pressure ,
gonioscopy , refraction , visual field , funduscopy , and fluorescein angiography were performed as part of a physical examination . to determine any underlying systemic disease , blood test , neurologic examination including brain computed tomography scan , carotid artery ultrasonography
in ten patients with impending central retinal vein occlusion , eight were male ( 80% ) and two were female ( 20% ) .
the age distribution was between 18 and 48 years , with impending central retinal vein occlusion usually affecting a relatively young age group averaging 31.09.1 years of age .
the ocular pressures in all subjects were found to be normal . on fundus examination , mild venous dilation and retinal hemorrhage were observed .
the initial vision for the affected eyes was logmar 0.30 , and the final vision was logmar 0.04 .
one case had progressed to central retinal vein occlusion , and after treatment with vitrectomy , radial optic neurotomy and intravitreal injection of triamcinolone , the patient 's vision improved .
the other six patients had no specific systemic disease and no abnormalities on neurologic examination .
an 18-year - old male patient with no specific history was admitted due to complaints of amaurosis fugax in his left eye .
on fundus examination , venous tortuosity and dilation in the central retinal vein were found .
the logmar vision after one month was improved to 0.0 , and venous tortuosity and congestion in the central retinal vein disappeared completely ( fig 1 ) .
a 31-year - old male patient with complaints of mild vision loss in his left eye visited the hospital .
the initial vision was logmar 0.2 , and on fundus examination , venous tortuosity , venous dilation , dot hemorrhages , and cotton - wool spots were observed .
the patient was followed for two months without treatment , after which his vision improved to 0.0 and the previously observed central vein and retinal lesions improved ( fig 2 ) .
a 39-year - old male patient without any specific history visited the hospital with the chief complaint of vision loss in his right eye .
under fundus examination , venous tortuisity , dilation , and retinal h emorrhages were observed .
after two weeks of admission , the retinal hemorrhage was aggravated , and the vision was down to logmar 1.0 .
the patient was treated with vitrectomy , radial optic neurotomy and intravitreal injection of triamcinolone .
the retinal venous tortuisity and dilation in the central retinal vein improved , and the logmar vision also improved to 0.2 .
a 38-year - old male patient with a history of bronchiolitis visited the hospital due to vision loss in the right eye .
on fundus examination , papilledema was discovered together with retinal venous tortuisity , dilation , and retinal dot hemorrhages in central retinal vein occlusion .
two weeks after the visit , the vision was aggravated to 0.2 , with macular edema and papilledema ( fig 4 ) .
an 18-year - old male patient with no specific history was admitted due to complaints of amaurosis fugax in his left eye .
on fundus examination , venous tortuosity and dilation in the central retinal vein were found .
the logmar vision after one month was improved to 0.0 , and venous tortuosity and congestion in the central retinal vein disappeared completely ( fig 1 ) .
a 31-year - old male patient with complaints of mild vision loss in his left eye visited the hospital .
the initial vision was logmar 0.2 , and on fundus examination , venous tortuosity , venous dilation , dot hemorrhages , and cotton - wool spots were observed .
the patient was followed for two months without treatment , after which his vision improved to 0.0 and the previously observed central vein and retinal lesions improved ( fig 2 ) .
a 39-year - old male patient without any specific history visited the hospital with the chief complaint of vision loss in his right eye .
under fundus examination , venous tortuisity , dilation , and retinal h emorrhages were observed .
after two weeks of admission , the retinal hemorrhage was aggravated , and the vision was down to logmar 1.0 .
the patient was treated with vitrectomy , radial optic neurotomy and intravitreal injection of triamcinolone .
the retinal venous tortuisity and dilation in the central retinal vein improved , and the logmar vision also improved to 0.2 .
a 38-year - old male patient with a history of bronchiolitis visited the hospital due to vision loss in the right eye .
on fundus examination , papilledema was discovered together with retinal venous tortuisity , dilation , and retinal dot hemorrhages in central retinal vein occlusion .
two weeks after the visit , the vision was aggravated to 0.2 , with macular edema and papilledema ( fig 4 ) .
central retinal vein occlusion has a wide range of manifestations , from mild and sporadic retinal hemorrhage to vitreous hemorrhage .
since leber   first described the clinical manifestation of central retinal vein occlusion as retinal apoplexy in 1854 , scholars have suggested multiple classifications of the disease .
classified central retinal vein obstruction into two categories , venous stasis retinopathy and hemorrhagic retinopathy .
venous stasis retinopathy is a mild form without central retinal vein occlusion , and hemorrhagic retinopathy is a severe form with central retinal vein occlusion .
magargal et al .   added an intermediate category into the original classification of hayreh et al . and at the same time classified it into three types based on ischemic and hyperpermeable conditions .
gass et al .   reported impending or incipient central retinal vein occlusion . by gass ' definition
, impending central retinal vein occlusion has no or mild loss of vision with venodilation and retinal dot hemorrhage under fundus examination .
considered impending central retinal vein occlusion as a risk factor for the development of central retinal vein occlusion .
however , no confirmed theory has been published regarding the natural progress of impending central retinal vein occlusion .
mancall   suggested that in the case of central retinal vein occlusion , the left eye is more frequently involved in males .
however , raitta   reported no discrepancies between left and right involvement or in male and female prevalence . in this study , we found that impending central retinal vein occlusion is more prevalent in males .
factors known to cause central retinal vein occlusion include hypertension , diabetes mellitus , atherosclerosis , hyperlipidemia and primary open angle glaucoma .
reported that hypertension , atherosclerosis and diabetes mellitus accompany central retinal vein occlusion in 57% , 34% , and 34% of cases , respectively .
other studies have discovered that hematologic disease , paraproteinemia , vasculitis , and autoimmune disease accompanying changes in coagulation mechanism and viscosity of blood are often associated with central retinal vein occlusion [ 10 - 13 ] . in our study , four patients had systemic disease including hypertension , hypotenstion , bronchiolitis and pulmonary tuberculosis .
hypertension , diabetes mellitus , hyperlipidemia , and other factors are relatively less associated with the occurrence of central retinal vein occlusion than they are with increased age .
most of our patients were rather young , so they did not have general systemic risk factors of central retinal vein occlusion , except for hypertension .
central retinal vein occlusion in young individuals usually has a good prognosis and a decreased risk for serious vision loss . in this study
, we found that most patients recovered without any specific treatment , with only two patients developing aggravated disease . in the case of one patient , treatment with vitrectomy , radial optic neurotomy , and intravitreal injection of triamcinolone improved the condition .
we conclude that most cases of impending central retinal vein occlusion have a good prognosis . on the other hand
, we found that the disease can advance to the prodromal phase of central retinal vein occlusion with intensifying obstruction and hemorrhages .
 purposeimpending central retinal vein occlusion is associated with mild or no loss of vision ; however , its progress and vision prognosis have not been clearly defined until now . 
 therefore , we studied the progress and prognoses in patients with impending central retinal vein occlusion.methodsfor this study , we selected ten subjects who had been diagnosed with impending central retinal vein occlusion , and we retrospectively reviewed their progress and prognoses.resultsthe average age of the subjects was 31.0 years ( 18 to 48 years ) . 
 eight patients were male and two were female . 
 the average observational period was 5.5 months . 
 six out of ten subjects were found to have no underlying systemic disease , four subjects had underlying disease . 
 all ten patients were affected unilaterally . 
 when initially tested , the affected eyes showed an average vision of logmar 0.30 . 
 the final vision test revealed an average of logmar 0.04 , which indicates good progress and prognosis . in one patient , 
 retinal hemorrhage and macular edema progressively worsened after the diagnosis , and the patient was treated with radial optic neurotomy.conclusionsthe cases of impending central retinal vein occlusion that we observed seemed to primarily affect young patients with generally good prognoses . 
 however , in some cases , the degrees of obstruction and hemorrhage increased as time progressed . 
 this suggests that impending central retinal vein occlusion could develop into the prodromal phase of an acute attack . 
Materials and Methods
Results
Case 3
Case 6
Case 8
Case 9
Discussion