Changes in retinal and choroidal morphology after cerebrospinal fluid pressure reduction: a Beijing iCOP study

The association of cerebrospinal fluid pressure with optic nerve head and macular vessel density

The present study aims to investigate the effect of temporary cerebrospinal fluid pressure (CSFP) reduction on optic nerve head (ONH) and macular vessel density (VD) using optical coherence tomography angiography. Forty-four eyes of 44 adults with diagnostic lumbar puncture and CSFP reduction were recruited. Thirty-two eyes of 32 healthy volunteers were controls. ONH and macular VD images were evaluated differences between baseline and after CSFP reduction. The results showed that the mean CSFP decreased from (11.6±2.1) mmHg to (8.2±3.4) mmHg (P<0.001). VD in the macular regions decreased significantly after CSFP reduction in the study group (all P<0.05). The control group showed no significant changes in macular VD (all P>0.05). In the study group, decreased VD in the macular parainferior region was associated with CSFP reduction (R²=0.192, P=0.003), the reduction of macular VD in parafoveal (R²=0.098, P=0.018), parainferior (R²=0.104, P=0.021), parasuperior (R²=0.059, P=0.058), paranasal (R²=0.057, P=0.042), paratemporal (R²=0.079, P=0.026) was associated with mean ocular perfusion pressure decrease following CSFP reduction. ONH vessel density did not differ after CSFP reduction (all P>0.05). In conclusion, macular vessel density decreased in association with CSFP reduction. Retinal vessel density in the macular region is more sensitive than that in peripapillary region after CSFP reduction.

The Association of Acute Cerebrospinal Fluid Pressure Reduction with Choroidal Thickness

PURPOSE

To investigate the changes in choroidal thickness (CT) after acute cerebrospinal fluid pressure (CSFP) reduction in human subjects.

METHODS

Before and 15 minutes after diagnostic lumbar puncture (LP), 44 patients underwent measurement of CT by swept-source optical coherence tomography. Thirty-two healthy volunteers imitated the body posture of LP procedure and underwent the same measurement before and 15 minutes after body posture change.

RESULTS

After CSFP reduction from 10.9 ± 2.1 mmHg at baseline to 8.1 ± 1.5 mmHg (p < 0.001), CT decreased in subfoveal region (p = 0.005), small to medium vessel layer (SMVL, p < 0.001), peripapillary regions in temporal (p = 0.001), nasal (p < 0.001), superior (p < 0.001) and inferior (p < 0.001), respectively. However, no significant change in CT in the control group after body posture change (all p > 0.05). A significant association between CSFP and the ratio of small to medium vessel layer to total choroidal thickness was found (p = 0.009). The CSFP reduction rate was associated with the change rate of SMVL to total CT portion, for each percent decrease in CSFP was associated with a decrease by 0.22% in the rate of SMVL to total CT portion (R² = 0.125, p = 0.018).

CONCLUSIONS

A significant decrease in subfoveal CT, small to medium vessel layer and peripapillary region were observed following acute CSFP reduction. The CSFP reduction rate was associated with the change rate of small to medium vessel layer to total CT portion.

BDNF improves axon transportation and rescues visual function in a rodent model of acute elevation of intraocular pressure

Optic neuropathies lead to blindness; the common pathology is the degeneration of axons of the retinal ganglion cells. In this study, we used a rat model of retinal ischemia-reperfusion and a one-time intravitreal brain-derived neurotrophic factor (BDNF) injection; then we examined axon transportation function, continuity, physical presence of axons in different part of the optic nerve, and the expression level of proteins involved in axon transportation. We found that in the disease model, axon transportation was the most severely affected, followed by axon continuity, then the number of axons in the distal and proximal optic nerve. BDNF treatment relieved all reductions and significantly restored function. The molecular changes were more minor, probably due to massive gliosis of the optic nerve, so interpretation of protein expression data should be done with some caution. The process in this acute model resembles a fast-forward of changes in the chronic model of glaucoma. Therefore, impairment in axon transportation appears to be a common early process underlying different optic neuropathies. This research on effective intervention can be used to develop interventions for all optic neuropathies targeting axon transportation.

Decreasing intraocular pressure significantly improves retinal vessel density, cytoarchitecture and visual function in rodent oxygen induced retinopathy

We attempted to explore a noninvasive, easily applicable and economically affordable therapy for retinopathy of prematurity (ROP). Rat pups were raised in 80% oxygen from postnatal day 7 to P12, and returned to room air. Travoprost eye drops were administered twice a day for 7 days, to reduce intraocular pressure (IOP) by about 20%. Immunohistochemical staining was performed to visualize vessel endothelial cells, to analyze retinal neurons and cytoarchitecture. Behavioral experiments were carried out to test visual acuity and contrast sensitivity. At the end of the 7-day treatment, the number of vessels extending to the vitreous body was significantly reduced and retinal vessel density increased. This improvement was maintained to the end of the 12th week. In the central retina of the model group, the horizontal cells were completely wiped out, the outer plexiform layer was undetectable, and the rod bipolar cell dendrites sprouted into the outer nuclear layer. The treatment partially reverted these architectural changes. Most importantly, behavioral experiments revealed significantly improved visual acuity and contrast sensitivity in the treated group. Therefore, reducing IOP could potentially serve as a safe and economical measure to treat ROP.