Structure and mechanics of the vitreoretinal interface

Role of the Vitreous in Retinal Pathology: A Narrative Review

The vitreous body is an anatomically and biochemically complex structure. Because of its proximity and firm adherence to the retina, researchers have examined the link between these two structures and how their individual pathologies might be connected. Several experimental and clinical studies have already demonstrated the important role of vitreous in the pathogenesis of retinal disorders. This narrative review highlights the role of the vitreous in retinal diseases and the improvements that have been made since the introduction of optical coherence tomography. This leads to a better understanding of vitreoretinal diseases and demonstrates its determinant role in other retinal pathologies, such as diabetic retinopathy or age-related macular degeneration. As we deepen our knowledge of the vitreous's structure, function, and abnormal conditions, we can better link the changes in diseases and identify effective treatments.

The adhesion behavior of the retina

Ocular diseases and treatment related to rhegmatogenous retinal detachment (RRD) are highly correlated with retinal adhesion behavior. Therefore, this paper proposes to study the adhesion behavior of the intact retina. This can provide theoretical guidance for the treatment and research of retinal detachment (RD) related diseases. To systematically analyze this aspect, two experiments were performed on the porcine retina. The pull-off test combined with the modified JKR theory was used to study the adhesion behavior of the vitreoretinal interface, while the peeling test was used to study the adhesion behavior of the chorioretinal interface. In addition, the adhesion phase involved in the pull-off test was simulated and analyzed by building the corresponding finite element method (FEM). The experimental results of adhesion force on the vitreoretinal interface were obtained by pull-off test with five sizes of rigid punch. The experimental value of the pull-off force F_PO tends to increase gradually with increasing punch radius in the range of 0.5-4 mm. A comparison of the experimental results with the simulation results shows that they are in a well agreement. And there is no statistical difference between the experimental and theoretical values of the pull-off force F_PO. In addition, the values of retinal adhesion work were also obtained by pull-off test. Interestingly, there is a significant scale effect of the retinal work of adhesion. Finally, the peeling test gave a maximum peeling strength T_Max of about 13 mN/mm and a stable peeling strength T_D of about 11 mN/mm between the retina and the choroid. The pull-off test well shows the process of retinal traction by the diseased vitreous at the beginning of RRD. A comparison of the experimental results with the finite element results verifies the accuracy of the simulation. The peeling test well investigated the adhesion behavior between the retina and the choroid and obtained key biomechanical data (peeling strength, etc.). The combination of the two experiments allows a more systematic study of the whole retina. This research can provide more complete material parameters for finite element modeling of retina-related diseases, and it also can provide the theoretical guidance for individualized design of retinal repair surgery.

The effect of vitreomacular interface in neovascular age-related macular degeneration treated with intravitreal injection of anti-VEGF

BACKGROUND

The purpose of this study is to study the effect of repeated intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) drugs on vitreomacular interface.

METHODS

Neovascular age-related macular degeneration patients who received intravitreal injections of anti-VEGF drugs were included. Eyes with severe vitreous opacity, uveitis, complicated cataract surgery and previous vitrectomy were excluded. Vitreomacular interface, best corrected visual acuity (BCVA) and central retinal thickness (CRT) assessment were performed once a month for at least 3 months. The nature and time of the change event are recorded. Groups were divided according to whether vitreomacular interface change events occurred. To analyse the risk factors of vitreomacular interface changes and their influence on treatment effect.

RESULTS

A total of 87 eyes were evaluated. Vitreomacular interface change event occurred in 9 eyes. Pre-existing vitreomacular interface abnormality (VMIA) was a risk factor for the VMI change (P = 0.033, OR = 16.518, 95% CI: 1.258 to 216.939). 60% of interface events occurred in the first 3 months of treatment. The final BCVA of eyes with vitreomacular interface unchanged was significantly higher than that at baseline (P = 0.001), and the final CRT was also significantly lower than that at baseline (P < 0.001). The final CRT of eyes vitreomacular interface changed was significantly lower than that at baseline (P = 0.015), however, there was no statistical significance in BCVA (P = 0.468).

CONCLUSION

Intravitreal injection of anti-VEGF drugs has a certain probability to cause changes in the vitreomacular interface, and the risk is higher in eyes with pre-existing vitreomacular interface abnormality. The effect of intravitreal injections on the vitreomacular interface was concentrated in the first three injections, and subsequent increases in the number of injections did not significantly increase the risk of vitreomacular interface abnormality. Ophthalmologists should increase attention to the vitreomacular interface in the early stages of anti-VEGF therapy and counsel patients accordingly.