The senescence of human vision Book

1	Theories
1.1	Introduction	1
1.1.1	Senescence - is it definable?	2
1.2	Ideas on senescence	3
1.2.1	Is senescence planned?	3
1.2.2	Organ-based concepts of senescence	4
1.2.3	Cellular senescence	22
1.2.4	From senescent cells to genes for ageing	30
1.3	Resume	44
2	The retinal image
2.1	Image homoeostasis	46
2.1.1	Introduction	46
2.2	A brief survey of the optics of the eye	46
2.2.1	Lenses	46
2.2.2	The role of the pupil	47
2.2.3	The depth of focus	49
2.3	Static refraction	52
2.3.1	Glancing backward at evolution	57
2.3.2	Chromatic aberration	57
2.4	Accommodation	59
2.4.1	The measurement of accommodation	59
2.4.2	The shape of the human crystalline lens	63
2.4.3	The power of the eye	68
2.4.4	The photography of the human accommodative process	70
2.4.5	An outline of the physiology of accommodation	73
2.4.6	Aspects of presbyopia	77
2.4.7	A possible evolutionary pressure	85
2.5	Image degradation	87
2.5.1	Introduction	87
2.6	Absorption and diffusion: tea versus egg-flip	87
2.7	Lenticular absorption of light	88
2.7.1	Basic notions	88
2.7.2	Methods of measurement	89
2.7.3	Absorption and environment	99
2.8	Lenticular fluorescence	102
2.9	Scattering of light	103
2.10	Cataract	108
2.11	Resume	111
3	Retinal senescence
3.1	Introduction	112
3.1.1	Repair processes during cerebral senescence	116
3.2	Losses in the brain	118
3.3	Further remarks on retinal vasculature	124
3.4	Age and the retinal photoreceptors	127
3.4.1	Receptor populations	127
3.4.2	The concentration of visual pigments	131
3.5	The macular pigment	137
3.6	Other retinal cells	138
3.6.1	The outer nuclear layer	138
3.6.2	Ganglion cells and optic nerve fibres	139
3.7	Bruch's membrane	140
3.8	The retinal pigment epithelium (RPE)	145
3.8.1	The pigments of the RPE	145
3.9	Non-visual effects of visible radiation	162
3.9.1	Blood-flow and light	162
3.9.2	Photic hazards	162
3.10	Age-related macular complications	164
3.11	Resume	168
4	Senescent vision
4.1	Introduction	169
4.2	Absolute visual thresholds	172
4.3	Incremental thresholds, with special reference to short-wavelength stimuli	177
4.4	Spectral sensitivity	180
4.5	The visual field	186
4.5.1	Some physical determinants of field size	186
4.5.2	Aspects of recent field measurements	188
4.6	Glare, light adaptation, and related effects	195
4.6.1	Transient light adaptation	196
4.6.2	Glare	199
4.6.3	Another digression on the role of the pupil	200
4.6.4	Glare and intensity	201
4.7	Contrast sensitivity: spatial and temporal parameters	204
4.7.1	A relation to incremental thresholds	204
4.7.2	Basic data	205
4.7.3	The role of physical factors	210
4.7.4	Nervous aspects	213
4.8	Colour vision	220
4.8.1	Normal changes	220
4.8.2	Some results on patients with age-related maculopathies	224
4.9	Resume	225
5	Coda
5.1	Correlation or coincidence?	226
5.2	Vital statistics	229
5.3	An anthropological aside	233
5.4	What limits life?	234
5.5	Limiting functions	236
5.6	The endpoint: is senescence programmed?	240
5.7	Resume	240
	References	242
	Index	267