Minireview: Fibronectin in retinal disease

Retinal fibrosis, characterized by dysregulation of extracellular matrix (ECM) protein deposition by retinal endothelial cells, pigment epithelial cells, and other resident cell-types, is a unifying feature of several common retinal diseases. Fibronectin is an early constituent of newly deposited ECM and serves as a template for assembly of other ECM proteins, including collagens. Under physiologic conditions, fibronectin is found in all layers of Bruch's membrane. Proliferative vitreoretinopathy (PVR), a complication of retinal surgery, is characterized by ECM accumulation. Among the earliest histologic manifestations of diabetic retinopathy (DR) is capillary basement membrane thickening, which occurs due to perturbations in ECM homeostasis. Neovascularization, the hallmark of late stage DR as well as exudative age-related macular degeneration (AMD), involves ECM assembly as a scaffold for the aberrant new vessel architecture. Rodent models of retinal injury demonstrate a key role for fibronectin in complications characteristic of PVR, including retinal detachment. In mouse models of DR, reducing fibronectin gene expression has been shown to arrest the accumulation of ECM in the capillary basement membrane. Alterations in matrix metalloproteinase activity thought to be important in the pathogenesis of AMD impact the turnover of fibronectin matrix as well as collagens. Growth factors involved in PVR, AMD, and DR, such as PDGF and TGFβ, are known to stimulate fibronectin matrix assembly. A deeper understanding of how pathologic ECM deposition contributes to disease progression may help to identify novel targets for therapeutic intervention.

External validation of existing formulas to predict the risk of developing proliferative vitreoretinopathy: the Retina 1 Project; report 5

PURPOSE

To externally validate the accuracy of previously published formulas for predicting proliferative vitreoretinopathy development after retinal detachment surgery.

METHODS

Clinical variables from consecutive retinal detachment patients (n = 1,047) were collected from the Retina 1 Project conducted in 17 Spanish and Portuguese centers. These data were used for external validation of four previously published formulas, F1 to F4. Receiver-operating characteristic curves were used to validate the quality of formulas, and measures of discrimination, precision, and calibration were calculated for each. Concordance among the formulas was determined by Cohen kappa index.

RESULTS

The areas under the receiver-operating characteristic curves were as follows: F1, 0.5809; F2, 0.5398; F3, 0.5964; and F4, 0.4617. F1 had the highest accuracy, 74.21%. Almost 19% of proliferative vitreoretinopathy cases were correctly classified by F1 compared with 13%, 15%, and 10% for F2, F3, and F4, respectively. There was moderate concordance between F2 and F3 but little between the other formulas.

CONCLUSION

After external validation, none of the formulas were accurate enough for routine clinical use. To increase its usefulness, other factors besides the clinical ones considered here should be incorporated into future formulas for predicting risk of developing proliferative vitreoretinopathy.