Proliferative Vitreoretinopathie – Pathogenese und Therapie

[Laser flare photometry for identification of high-risk patients for proliferative vitreoretinopathy]

Proliferative vitreoretinopathy (PVR) is a complication of rhegmatogenous retinal detachment and trauma, which occurs in approximately 10% following vitreoretinal surgery. The visual prognosis for established PVR is poor and so far there is no established conservative treatment for PVR. In the currently recruiting PRIVENT trial the aim is to find a prophylactic treatment possibility for PVR. The PRIVENT study examines the influence of intraoperative adjuvant pharmacotherapy on reducing the incidence of PVR; however, this requires the identification of eyes with increased risk for PVR. Laser flare photometry is a simple method to predict the individual risk for PVR. It is a non-invasive technique that objectifies the Tyndall effect. Various laser flare meter devices are available on the market. In previous studies it could be shown that laser flare photometry can predict the development of PVR in eyes with primary rhegmatogenous retinal detachment with a sensitivity of 80%. The identification of these high-risk eyes for PVR could be the first step towards solving the problem of PVR.

Retinal shortening: Ultrasonic evaluation of proliferative vitreoretinopathy

Purpose:

To evaluate the effect of extraretinal proliferative vitreoretinopathy (PVR) on retinal shortening in eyes with rhegmatogenous retinal detachment (RD) using ultrasound (USG) and objectively prove the presence of intraretinal PVR (iPVR).

Methods:

This is a double-masked pilot prospective controlled case series. Patients with total RD planned for vitreoretinal surgery were included in the study. USG was used to determine retinal-to-choroidal length ratios (RCRs) in all the quadrants. Group 1 included 10 patients with preoperative PVR more than Grade B while Group 2 had 14 with PVR of Grades A or B. Severe retinal shortening was defined as RCR < 0.8. Primary outcome measures were severe retinal shortening and an early unexplained recurrence of RD within 15 days of surgery.

Results:

Mean RCRs were significantly low in all the four quadrants of Group 1 upon comparison with Group 2. The mean RCR had a good negative correlation with number of quadrants of PVR (R = −0.66, P ≤ 0.001). Overall, severe quadrantic retinal shortening was detected in nine patients. In these 9 patients, 11 of the 36 retinal quadrants had severe retinal shortening in the absence of extraretinal PVR (ePVR). Six patients developed early unexplained RD, and all of these belonged to Group 1. Severe quadrantic retinal shortening had the highest odds ratio of developing early unexplained RD (odds ratio = 58, P = 0.01).

Conclusion:

Retinal shortening occurs both due to ePVR and iPVR, and iPVR occurs independently at least in some cases. Severe quadrantic retinal shortening indicates poor primary anatomical prognoses.

[The role of the vitreous body in diseases of neighboring structures]

BACKGROUND

The vitreoretinal interface is not merely the space between the vitreous body and the retina but it is also a site for highly complex pathologies with the vitreous body exerting an influence on all the neighbouring structures.

METHODS

A literature search was performed in Pubmed and current book articles

RESULTS

This review article highlights the role of the vitreous body in vitreomacular adhesion and traction, in the development of macular holes and epiretinal membranes as well as its role in age-related macular degeneration. In the retinal periphery the vitreous structures play a pivotal role in retinal tears and detachment as well as in diabetic and other proliferative vitreoretinopathies. The role of the vitreous bodyin the emergence of various forms of cataract is often underestimated.

DISCUSSION

Vitreo-etinal surgeons should thoroughly understand the pathophysiological relationship between the vitreous body and the neighboring structures, especially in the era of medical vitreolysis.

Pathophysiology of proliferative vitreoretinopathy in retinal detachment

Because proliferative vitreoretinopathy cannot be effectively treated, its prevention is indispensable for the success of surgery for retinal detachment. The elaboration of preventive and therapeutic strategies depends upon the identification of patients who are genetically predisposed to develop the disease, as well as upon an understanding of the biological process involved and the role of local factors, such as the status of the uveovascular barrier. Detachment of the retina or vitreous activates glia to release cytokines and ATP, which not only protect the neuroretina but also promote inflammation, retinal ischemia, cell proliferation, and tissue remodeling. The vitreal microenvironment favors cellular de-differentiation and proliferation of cells with nonspecific nutritional requirements. This may render a pharmacological inhibition of their growth difficult without causing damage to the pharmacologically vulnerable neuroretina. Moreover, reattachment of the retina relies upon the local induction of a controlled wound-healing response involving macrophages and proliferating glia. Hence, the functional outcome of proliferative vitreoretinopathy will be determined by the equilibrium established between protective and destructive repair mechanisms, which will be influenced by the location and the degree of damage to the photoreceptor cells that is induced by peri-retinal gliosis.