Glaucoma is a chronic, slowly progressing, and asymptomatic optic neuropathic disorder with a great variety of causes that involve gradual retinal ganglion cell axon loss. The disease is the second most common cause of blindness in the industrialized world. Once vision loss develops it is irreversible-although in many cases further loss can be slowed if adequate treatment is provided. If not treated, glaucoma can lead to complete vision loss in the affected eye. Primary open-angle glaucoma (POAG) is the most prevalent form of the disease in the industrialized countries, representing 94% of all glaucomas. In a Spanish study of 569 individuals, the prevalence of POAG was 2.1% (99% confidence interval 1.9%-2.3%) in the age range between 40 and 79 years. Assessing glaucomatous damage progression remains one of the most important and challenging aspects in glaucoma management. In addition, a better understanding of clinical risk factors for glaucoma worsening may help us to develop new strategies to improve glaucoma care. Over the past 2 decades, many studies have addressed the issue of risk factors associated with or predicting for glaucoma progression. Although many studies have attempted to identify the prognostic factors capable of predicting the course of POAG, the results have been varied and in some cases contradictory, and are thus of scant practical utility. This study was designed to evaluate the methodologic quality of the studies published in the literature on the prognostic factors for POAG progression measured by visual field deterioration.