Aging retina

Moreover, efficient rhodopsin regeneration may precede enzymatic reduction of all-fran.v-retinal to all-trans-retinol in the aged retina (Figure 15.2c) (Schadel et al., 2003). Upon rhodopsin regeneration, all-trans-retinal is released from the exit site of the protein into the lipid membrane (Figure 15.2c) (Schadel et al., 2003). From here the removal of all-tnms-retinal to the outer leaflet of the disc membrane is dependent on activity of ATP-binding cassette trasporter A4 (ABCA4) present in the rim of photoreceptor disc, known also as ABCR protein. 

Liu, J., Itagaki, Y., Ben-Shabat, S., Nakanishi, K., Sparrow, J.R., 2000. The biosynthesis of A2E, a fluorophore of aging retina, involves the formation of the precursor, A2-PE, in the photoreceptor outer segment membrane. J Biol Chem. 275, 29354-29360. 

Cell loss in the aging retina. Relationship to lipofuscin... 

Louie JL, Kapphahn RJ, Ferrington DA. 2002. Proteasome function and protein oxidation in the aged retina. Exp Eye Res 75 271-284. 

A disease process characterized by deterioration of the macula of the retina that results in a loss of shaip central vision. AMD is the leading cause of central vision loss in the developed countries today for those over the age of fifty years. 

Ferrara N, Damico L, Shams N, et al (2006) Developmemt of Ranibizumab, an anti-vascular endothelial growth factor antigen binding fragment, as therapy for neovascular age-related macular degeneration. Retina 26 859-870... 

The incidence and severity of ROP both rise with decreasing birthweight and gestational age. Fielder et al. (1992) have shown that the incidence of ROP in infents of < 1700 g birthweight is about 50%, although only 5% had severe disease. Severe ROP results in vitreous haemorrhage from new vessel formation on the immature retina, retinal traction and eventually retinal detachment (Fig. 9.6). In the most severe cases, retinal detachment is complete, resulting in total blindness. Treatment with cryotherapy or laser has halved the incidence of retinal detachment. 

Early macular changes are often called age-related macu-lopathy and are characterized by large drusen and pigmentary abnormalities in the macula.20 Age-related maculopathy accounts for 85% to 90% of all age-related macular changes. Ten to fifteen percent of these patients will develop advanced atrophy and/or develop abnormal blood vessels in and under the retina called choroidal neovascular membranes. Patients are then classified as having AMD.23... 

Gellermann W, Ermakov IV, Ermakova MR, McClane RW, Zhao DY, and Bernstein PS (2002a), In vivo resonant Raman measurement of macular carotenoid pigments in the young and the aging human retina, J. Opt. Soc. Am. A 19 1172-1186. 

Dillon, J., L. Zheng et al. (2004). Transmission of light to the aging human retina possible implications for age related macular degeneration. Exp. Eye Res. 79(6) 753-759. 

Leung, I. Y., M. M. Sandstrom et al. (2004). Nutritional manipulation of primate retinas, II Effects of age, n-3 fatty acids, lutein, and zeaxanthin on retinal pigment epithelium. Invest. Ophthalmol. Vis. Sci. 45(9) 3244-3256. 

Mares, J. A., T. L. LaRowe et al. (2006). Predictors of optical density of lutein and zeaxanthin in retinas of older women in the carotenoids in age-related eye disease study, an ancillary study of the women s health initiative. Am. J. Clin. Nutr. 84(5) 1107-1122. 

The retina does not contain high concentrations of hydrocarbon carotenoids but Mares-Perlman et al. (1995) have shown a correlation between age-related macular degeneration and low levels of serum LYC and this apparent contradiction is discussed in Section 14.5. 

Increased age and smoking are associated with an increased oxidative stress and depletion of low-molecular weight antioxidants in many tissues including the retina (Beatty et al., 2000). Epidemiological studies indicate that on average, smokers develop late stage AMD 10 years earlier than nonsmokers (Kelly et al., 2004 Klein et al., 1998 Mitchell et al., 2002 Thornton et al., 2005 Tomany et al., 2004). 

Chowers, I, Wong, R, Dentchev, T, Farkas, RH, Iacovelli, J, Gunatilaka, TL, Medeiros, NE, Presley, JB, Campochiaro, PA, Curcio, CA, Dunaief, JL, and Zack, DJ, 2006. The iron carrier transferrin is upregulated in retinas from patients with age-related macular degeneration. Invest Ophthalmol Vis Sci 47, 2135-2140. 

Dasch, B, Fuhs, A, Behrens, T, Meister, A, Wellmann, J, Fobker, M, Pauleikhoff, D, and Hense, HW, 2005. Inflammatory markers in age-related maculopathy—Cross-sectional analysis from the Muenster Aging and Retina Study. Arch Ophthalmol 123, 1501-1506. 

Li, CM, Presley, B, Zhang, XM, Dashti, N, Chung, BH, Medeiros, NE, Guidry, C, and Curcio, CA, 2005. Retina expresses microsomal triglyceride transfer protein Implications for age-related maculopathy. J Lipid Res 46, 628-640. 

Moshfeghi, DM and Blumenkranz, MS, 2007. Role of genetic factors and inflammation in age-related macular degeneration. Retina 27, 269-275. 

Rozanowski, B, Burke, J, Sarna, T, and Rozanowska, M, 2008a. The pro-oxidant effects of interactions of ascorbate with photoexcited melanin fade away with aging of the retina. Photochem Photobiol 84, 658-670. 

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