This clinical syndrome of PSH with or without IPH was described in 1975.[1] It has been observed in people with European ethnicity,[5] but is most common in people with Asian ethnicities.[3,4,6,7] In our study, the syndrome comprised a benign condition with acute onset, which spontaneously resolved over a period of several months without sequelae or recurrence. Notably, this syndrome is more common in myopic eyes and in younger people. The characteristics of our case series are similar to those of other published reports.[1-7]
There had no effect on visual acuity if PSH was present alone, because the BCVAs in Group 1 had no difference between the baseline and final visit. There was symptomatic when retina exhibited IPH brought out thickening of retina. There had mild to moderate decline of visual acuity depending on the amount of hemorrhages, especially the vitreous hemorrhages occurred. With the absorption of bleeding, vision improved. It also confirmed that there was no neurological insult to the nerve, otherwise the vision would not be recovered fully due to absorption of bleeding. The patients in Group 1 had normal vision but symptoms. This might be due to the presence of IPH at the onset of PSH. When they came to the clinic, IPH had absorbed already. In other words, patients in different groups might be in different clinical stages not different classifications.
In prior studies, IPH has been considered more influential with respect to the outcome, relative to PSH and vitreous hemorrhage.[1-4,7] Accordingly, the most commonly proposed cause has been acute vitreopapillary traction,[1,3-5,8] which induced superficial bleeding of the optic disc. In our study, PSH was present in 38 eyes (100%), however IPH was present in 89.5% (34 eyes). According to FFA and FP results, PSH alone (without IPH, Group 1) was found in 4 eyes (10.5%). In contrast, IPH without PSH was not found. All clinical characteristics suggested that PSH was the more basic aspect of bleeding in our case series. Thus, we consider PSH to be the fundamental manifestation.
The vascular anatomy of the optic nerve head has a unique structure, and its vascular supply varies with the region.[9-12] The superficial nerve fiber layer (NFL) is principally supplied by arterioles in the adjacent retina. Most of these vessels are capillaries that originate from peripapillary branches of the retinal arteries. The prelaminar portion receives its arterial supply via direct branches of the short posterior ciliary arteries, as well as vessels originating from the circle of Zinn-Haller. Branches of the short posterior ciliary arteries may pass through the choroid. The circle of Zinn-Haller communicates with the peripapillary retinal arterioles. The venous system almost exclusively drains to the central retinal vein, with minor contributions to peripapillary choroidal veins. Based on the morphological features of bleeding, PSH may originate from capillaries of choroidal origin, whereas IPH may originate from capillaries of retinal origin in the NFL. Because PSH is the primary manifestation of this syndrome, the deep part of the retina or choroid might be the original site of bleeding. Depending on the extent of involvement, triggering events cause choroidal vascular bleeding, and develop into retinal vascular bleeding, which has a tendency from deep to superficial. There is no sign of vitreopapillary traction in B-ultrasound and OCT.[2,3,5] This observation confirms that bleeding does not originate superficially, primarily from deep part of the optic disc.
The cause of acute onset of hemorrhage is not certain.[3-5] Existing theories suggest the involvement of acute vitreopapillary traction [1,4,5,8] and acute disc edema.[3] Some studies have reported evidence of vitreopapillary traction based on B-scan ultrasonography and OCT.[1,4] However, vitreoretinal relationships were not confirmed in other series.[3,5] In our study, there was no evidence for vitreous traction based on B-scan ultrasonography and OCT. In addition, vitreous traction induces superficial IPH, which is incompatible with the observation of eyes with PSH alone. Based on FFA results, Kokame et al.[3] postulated that acute disc edema may be the cause of PSH. In prior studies, FFA has shown hyperfluorescence of disc staining.[2,3,5] Kokame et al. suggested that acute disc edema was due to inflammation.[3] However, in our study, there was no apparent fluorescence leakage of the papillary vascular network, nor was there was direct evidence of inflammation. Furthermore, 4 patients in the current series were found no specific signs in the brain and orbit (3 underwent head CT and 1 underwent MRI). These results suggest that there may be other acute triggers of hemorrhage.
The Valsalva maneuver was considered as another possible cause in previous studies. [3,7] Sneezing [3,13] was observed as a cause of bleeding in a prior study. The authors postulated that the Valsalva maneuver places a shearing force on the vulnerable capillaries of choroidal origin on the nasal edge of the disc.[3,13] Moreover, the Valsalva maneuver may increase the pressure of the venous system.[14,15] Because of the sudden increase in venous pressure, retinal capillaries spontaneously rupture.[14-19] Notably, retinal capillaries supply the NFL layer;[11] thus, this rupture manifests as IPH. In addition, the classical pattern of Valsalva retinopathy often presents as preretinal hemorrhage or sub-internal limiting membrane hemorrhage.[16-19] It demonstrates that the original bleeding site in cases caused by the Valsalva maneuver is of superficial retinal origin. In our study, only 10 eyes (10/38) showed evidence of the Valsalva maneuver. Thus, we consider the Valsalva maneuver to be a possible cause for intrapapillary bleeding in our series, but not a cause of PSH.
Tilted optic discs have generally been regarded as a risk factor for bleeding in prior studies [2-5,7,9], similar to the findings in our study. These discs appear small, crowded, and elevated in the nasal regions. The insertion angle of the nerve fiber in the nasal region is sharp, and the cup of affected optic discs is narrow and deep. These unique morphological features might draw the retinal and choroidal tissues over and around the elevated region. The vascular network of affected optic discs is tightened and exhibits high tension, which makes it vulnerable to bleeding. We speculate that capillaries of choroidal origin in the nasal region are most susceptible to bleeding with sufficient irritation.
Based on our findings, we suspect that a sudden fast movement may be the trigger to initiate bleeding in patients with PSH. First, when rapid eye movement occurs, the retinal and choroidal tissue with high tension in the elevated region might be strongly pulled in 1 particular direction. In this situation, susceptible deep retinal and choroid tissues are more likely to bleed. Second, depending on the extent of bleeding and the distribution of triggered vessels, blood may drain into the vitreous cavity. When the vascular supply for NFL is affected, IPH appears. Finally, this movement occurs abruptly, where 1 eye moves in 1 particular direction and causes the susceptible retinal tissue to bleed; however, the other eye, which may exhibit the same unique morphologic structure, moves in the opposite manner (with respect to orientation within the socket and the muscles that cause movement) and may even relax. This might explain why the bleeding is typically observed unilaterally.
Our study has several limitations. First, the study designed without intervention is drawback. Second, although we performed study procedures on the first day of clinical visit, subjects in the study required extra time in or an extra trip to the clinic, not the initial time of onset, which may present bias on the clinical manifestation of inclusion subjects. Another potential limitation is that there were no control subjects. Considering the fact that anatomical peculiarity of optic discs is the basis, quantification from OCT and comparison with that of normal discs warranted further study.