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Which pathogenic mechanisms underlie age-related macular degeneration (AMD)? Are they different for dry and wet variants, or do they stem from common metabolic alterations? Where shall we look for altered metabolism? Is it the inner choroid, or is it rather the choroid–retinal border? Again, since cell-clearing pathways are crucial to degrade altered proteins, which metabolic system is likely to be the most implicated, and in which cell type? Here we describe the unique clearing activity of the retinal pigment epithelium (RPE) and the relevant role of its autophagy machinery in removing altered debris, thus centering the RPE in the pathogenesis of AMD. The cell-clearing systems within the RPE may act as a kernel to regulate the redox homeostasis and the traffic of multiple proteins and organelles toward either the choroid border or the outer segments of photoreceptors. This is expected to cope with the polarity of various domains within RPE cells, with each one owning a specific metabolic activity. A defective clearance machinery may trigger unconventional solutions to avoid intracellular substrates’ accumulation through unconventional secretions. These components may be deposited between the RPE and Bruch’s membrane, thus generating the drusen, which remains the classic hallmark of AMD. These deposits may rather represent a witness of an abnormal RPE metabolism than a real pathogenic component. The empowerment of cell clearance, antioxidant, anti-inflammatory, and anti-angiogenic activity of the RPE by specific phytochemicals is here discussed.

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PURPOSE: To evaluate the safety, efficacy, and stability of LASIK, using positive cylinder and negative sphere nomograms in sequence (sequential ablation) to correct mixed astigmatism. METHODS: This prospective study included 40 eyes of 20 patients with mixed astigmatism. Patients underwent bilateral sequential ablation LASIK using the Technolas 217 excimer laser (Bausch & Lomb Surgical, Rochester, NY). The main outcome measures, uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), were evaluated 3 and 12 months after surgery. RESULTS: Preoperative astigmatism ranged from + 1.75 to +6.00 diopters (D) and negative sphere from -0.50 to -3.00 D. The postoperative refraction at 3 months remained unchanged at 1 year postoperative in all patients. A total of 32 (80%) eyes showed no significant residual astigmatism (<0.50 D); the remaining 8 (20%) eyes had 0.50 to 1.00 D of residual astigmatism. Residual negative sphere was present in 2 eyes of 2 patients with a planned monovision target. In the remaining 38 (95%) eyes, no significant residual negative sphere was present. Sixteen (40%) eyes had one line of improvement in BSCVA. No eye lost lines of visual acuity. The efficacy index shows that uncorrected vision after surgery is equal or better than corrected vision before surgery. Less corneal tissue is removed and fewer laser spots are required compared to other techniques for the correction of mixed astigmatism. CONCLUSIONS: The sequential ablation approach to the correction of mixed astigmatism was efficacious, safe, and stable 1 year after surgery. [J Refract Surg. 2006;22:787-794.]

The present article discusses the role of light in altering autophagy, both within the outer retina (retinal pigment epithelium, RPE, and the outer segment of photoreceptors) and the inner choroid (Bruch’s membrane, BM, endothelial cells and the pericytes of choriocapillaris, CC). Here autophagy is needed to maintain the high metabolic requirements and to provide the specific physiological activity sub-serving the process of vision. Activation or inhibition of autophagy within RPE strongly depends on light exposure and it is concomitant with activation or inhibition of the outer segment of the photoreceptors. This also recruits CC, which provides blood flow and metabolic substrates. Thus, the inner choroid and outer retina are mutually dependent and their activity is orchestrated by light exposure in order to cope with metabolic demand. This is tuned by the autophagy status, which works as a sort of pivot in the cross-talk within the inner choroid/outer retina neurovascular unit. In degenerative conditions, and mostly during age-related macular degeneration (AMD), autophagy dysfunction occurs in this area to induce cell loss and extracellular aggregates. Therefore, a detailed analysis of the autophagy status encompassing CC, RPE and interposed BM is key to understanding the fine anatomy and altered biochemistry which underlie the onset and progression of AMD.