Glaucoma, a collection of diseases that affect the optic nerve head and are associated with visual field loss, may be broadly classified as follows: primary open angle glaucoma (POAG), secondary open-angle glaucoma, primary angle-closure glaucoma (PACG), secondary angle-closure glaucoma, congenital glaucoma, and juvenile glaucoma. All of these diseases are associated with irreversible blindness. Thus, the public health importance of detecting undiagnosed and treatable glaucoma is important, as blindness has economic and societal consequences for the rest of an individual's life.<sup>97 Smith A.F., Smith J.G. The economic burden of global blindness: A price too high! Br J Ophthalmol 1996 ;  80 : 276  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> In this review the main focus is on POAG and PACG; some of the information on risk factor assessment and screening of POAG and PACG is relevant to the secondary glaucomas.

POAG is characterized by glaucomatous optic nerve damage and visual field loss in the presence of open and normal-appearing anterior chamber angles and the absence of other known causes of glaucoma. It has an adult onset, is usually bilateral, and has no symptoms until late in the disease when patients lose their central vision.<sup>79   Preferred Practice Pattern of Primary Angle-Closure Glaucoma San Francisco: American Academy of Ophthalmology (1996). 

Cliccare qui per andare alla sezione Riferimenti</sup> It is the third leading cause of blindness worldwide<sup>107 The International Bank for Reconstruction and Development/the World Bank. World Development Report 1993, Cary, N.C., Oxford University Press.

Cliccare qui per andare alla sezione Riferimenti</sup> and has an age-adjusted prevalence of 1.55%.<sup>112 Tielsch J.M., Sommer A., Katz J. , e al. Racial variations in the prevalence of primary open-angle glaucoma: The Baltimore Eye Survey JAMA 1991 ;  266 : 369

Cliccare qui per andare alla sezione Riferimenti</sup> Extrapolations to the year 2000, using estimates of glaucoma prevalence from earlier population-based survey data, place the worldwide population of people with POAG at approximately 68 million.<sup>81 Quigley H.A. Number of people with glaucoma worldwide Br J Ophthalmol 1996 ;  80 : 389  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> In Olmsted County, Minnesota, 9% of subjects with a mean age of 66 years at the time of glaucoma diagnosis<sup>40 Hattenhauer M.G., Johnson D.L.T., Ing H.H. , e al. The probability of blindness from open-angle glaucoma Ophthalmology 1998 ;  105 : 2099  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> were bilaterally blind at the 20 year follow-up, despite glaucoma treatment.

Patients with PACG may or may not have optic nerve damage. PACG is defined as the closure of the anterior chamber angle by relative pupillary block, which is the obstruction of the trabecular meshwork by the peripheral iris.<sup>79   Preferred Practice Pattern of Primary Angle-Closure Glaucoma San Francisco: American Academy of Ophthalmology (1996). 

Cliccare qui per andare alla sezione Riferimenti</sup> The iris is bowed forward because of the inability of the aqueous humor to pass easily into the anterior chamber from the posterior chamber. Patients with PACG may present acutely with elevated intraocular pressures, a mid-dilated pupil, and a red eye and with nausea and vomiting. Not infrequently they may have no complaints or complain only of a nonspecific headache, eye pain, or halos around lights.<sup>79   Preferred Practice Pattern of Primary Angle-Closure Glaucoma San Francisco: American Academy of Ophthalmology (1996). 

Cliccare qui per andare alla sezione Riferimenti</sup> PACG is more prevalent in Asia, whereas POAG has a more even distribution throughout the world.<sup>81 Quigley H.A. Number of people with glaucoma worldwide Br J Ophthalmol 1996 ;  80 : 389  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup>

Because most patients with glaucoma, except for those with PACG attacks, are asymptomatic, screening for glaucoma is considered to be a worthwhile societal goal if the cost is not too great.<sup>99 Sponsel W.E., Ritch R., Stamper R. , e al. Prevent Blindness America Visual Field Screening Study Am J Ophthalmol 1995 ;  120 : 699

Cliccare qui per andare alla sezione Riferimenti</sup> Because the prevalence of glaucoma is low in the general population, screening for glaucoma would be more cost effective in populations with risk factors for glaucoma as it would result in more cases of glaucoma being detected. Thus, prior to reviewing the issues of screening for glaucoma, the authors first define risk factors and then discuss the known risk factors for POAG and PACG.