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Primary angle-closure glaucoma (PACG) is a common cause of blindness. Angle closure is a fundamental pathologic process in PAGC. With the development of imaging devices for the anterior segment of the eye, a better understanding of the pathogenesis of angle closure has been reached. Aside from pupillary block and plateau iris, multiple-mechanisms are more common contributors for closure of the angle such as choroidal thickness and uveal expansion, which may be responsible for the presenting features of PACG. Recent Genome Wide Association Studies identified several new PACG loci and genes, which may shed light on the molecular mechanisms of PACG. The current classification systems of PACG remain controversial. Focusing the anterior chamber angle is a principal management strategy for PACG. Treatments to open the angle or halt the angle closure process such as laser peripheral iridotomy and/or iridoplasty, as well as cataract extraction, are proving their effectiveness. PACG may be preventable in the early stages if future research can identify which kind of angles and/or persons are more likely to benefit from prophylactic treatment. New treatment strategies like adjusting the psychological status and balancing the sympathetic-parasympathetic nerve activity, and innovative medicines are needed to improve the prognosis of PACG. In this review, we intend to describe current understanding and unknown aspects of PACG, and to share the clinical experience and viewpoints of the authors.

Capillary networks in the human perifovea are morphometrically heterogeneous. Morphometric features of regional capillary networks in the layered retina may serve a critical role in supporting neuronal homeostasis. Improved knowledge of these features may be important for understanding pathogenic mechanisms underlying retinal vascular diseases.

PURPOSE. We investigated quantitatively the distribution of blood vessels in different neural layers of the human retina. METHODS.A total of 16 human donor eyes was perfusion-fixed and labeled for endothelial f-actin. Retinal eccentricity located 3 mm superior to the optic disk was studied using confocal scanning laser microscopy. Immunohistochemical methods applied to whole-mount and transverse sections were used to colocalize capillary networks with neuronal elements. Capillary morphometry, diameter, and density measurements were compared among networks.RESULTS. Four different capillary networks were identified and quantified in the following regions: Nerve fiber layer (NFL), retinal ganglion cell (RGC) layer, border of the inner plexiform layer (IPL) and superficial boundary of the inner nuclear layer (INL), and boundary of the deep INL and outer plexiform layer. The innermost and outermost capillary networks demonstrated a laminar configuration, while IPL and deep INL networks displayed a complex three-dimensional configuration. Capillary diameter in RGC and IPL networks were significantly less than in other networks. Capillary density was greatest in the RGC network (26.74%), and was significantly greater than in the NFL (13.69%), IPL (11.28%), and deep INL (16.12%) networks. CONCLUSIONS.The unique metabolic demands of neuronal subcompartments may influence the morphometric features of regional capillary networks. Differences in capillary diameter and density between networks may have important correlations with neuronal function in the human retina. These findings may be important for understanding pathogenic mechanisms in retinal vascular disease. (Invest Ophthalmol Vis Sci. 2012;53:5728-5736)

In the outer retina of the monkey the P(O2) minimum is lower, and the oxygen consumption rate is higher in the parafoveal region. During systemic hyperoxia, outer retinal oxygen consumption is unaffected, but in the foveal area, total oxygen consumption increases. This regulation of oxygen consumption in the monkey retina is comparable to that reported in lower mammals and may represent an important mechanism in retinal homeostasis.

Excess photoreceptor degeneration in the P23H-3 retina begins just after eye opening, peaks in early postnatal life, and then slows, but persists into adulthood. In the adult retina, surviving photoreceptors operate in an environment that is chronically hyperoxic (and therefore toxic) and in which protective factors (CNTF, FGF-2) are chronically upregulated. The net result, slow degeneration and degraded function in an environment that is both toxic and protective, may be representative of adult photoreceptor status in a number of human retinal degenerations. Hyperoxia-induced photoreceptor death may be a self-reinforcing factor that increases oxidative stress in surviving photoreceptors.

FFA provides incomplete morphologic information about the superficial capillary network and even less information about the deep capillary network. Caution should, therefore, be exercised when using FFA data to extrapolate information about microvascular histopathologic processes. The usefulness of newer technology for studying retinal capillary detail should be investigated.