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physiology of Aging2


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physiology of Aging2

  1. 1. Physiological Impact of Ageing Part II Ocular Changes
  2. 2. Eyelids
  3. 3. • progressive loss of tone and bulk. • Loss of tonus, reduced movement, reduced palpebral aperture (ptosis), decreased lid tension. • Changes in astigmatism with age. • More difficulty in lid evertion, greater CL comfort?, more difficulty getting CLs out? • Xanthelasma (xanthoma) raised yellowish plaques found on the upper and lower lids. common in elderly women can be associated with diabetes and  blood LDLs Eyelids
  4. 5. • Corneal shape changes - from with to against-the- rule astigmatism. • Corneal fragility increases with age. • Corneal sensitivity halves by 80 (esp. 40+) - easier CL wear, but possible greater problems (more regular after-care)- greater with arcus senilus? • Endothelial changes (cell density dec., increased polymegathism & pleomorphism) Cornea
  5. 6. Arcus Senilis • lipid infiltration of the peripheral cornea that is commonly seen in the elderly • characterised by being separated from the limbus by a narrow line of comparatively clear cornea. • asymptomatic and has little consequences for vision • if seen in Pxs < 40 can indicate  blood LDL level
  6. 8. Conjunctival ageing changes • Reduced arterial oxygen concentration to conjunctiva - less available to cornea? And increased overnight swelling with CLs? • Pingueculae more common with age. Can lift the lids away from the underlying conjunctiva - local area of drying and vascularisation.
  7. 9. Pingueculae
  8. 10. Pingueculae • age related change of the conjunctiva • associated with prolonged exposure to sunlight, wind, dust etc. • due to hyaline infiltration and degeneration of the elastic sub-mucous tissue. • occurs near the limbus in the palpebral aperture its apex points away from the cornea.
  9. 11. Pterygium
  10. 12. Concretions • Minute hard, yellow spots in the palpebral conjunctiva. • due to the accumulation of epithelial cells and mucous • can lead to abrasion of the cornea and persistent foreign body sensation in the eye.
  11. 13. Tear film changes • Decreased tear film stability (NIBUT). • ? No real change in tear volume. • Several drugs tend to reduce tear production & many are increasingly used with age. • Sxs of ‘dry eye’ may not always be elicited from older Pxs - reduced corneal sensitivity, and acceptance of this as ‘normal’ for age etc.
  12. 16. Pupil size changes with age Dark adapted eye Light adapted eye
  13. 17. Pupil size changes with age • Pupil gets smaller with age. • Increases depth of focus, range of near vision,  retinal illuminance. • ? Due to atrophy of dilator muscle fibres and inc. rigidity of iris blood vessels. • No change with gender, Rx and iris colour. • Greatest age changes at lowest luminances (mesopic 7 to 4mm, photopic 5 to 3mm)
  14. 19. Anterior Chamber changes • The anterior chamber depth dec. with age due to the increase in size of the lens. • (This can reverse in some patients with cataract, where lens size can decrease). • Leads to increases in IOP with age. • Leads to closed-angle glaucoma and need to check angles prior to pupillary dilation.
  15. 20. Ageing lens changes • Increased thickness with age (28%, 20-70). • Inc. hardening of nucleus & loss of elasticity of lens and capsule - loss of accommodation (zero at 55-60 years). • No need to binocular balance over 60 years, no point in measuring amplitude of accommodation for 60+.
  16. 24. Ageing lens changes • Increased light scatter: inc. cortical layers and inc. large aggregates in nucleus. Greater problems with glare. • Increased lens yellowing , i.e., increased absorption of blue light. Colour vision goes tritanopic with age (+ ? neural component). • Fluorophors increase with age. UV radiation leads to light scatter; UV tints?
  17. 26. Vitreous changes with age • Vitreous undergoes liquefaction and shrinkage (syneresis) with age. • Leads to increases in vitreous floaters, increase in PVDs (~60% over 65) and increases in the prevalence of retinal detachments.
  18. 27. Posterior Vitreous Detachment
  19. 28. Macular changes with age • No loss of cones, loss of central rods. • Disorganisation of rods and cones and lipofuscin accumulation. • Leads to inc. photostress recovery time. • No change in macular pigment with age. Macular pigment is very variable.
  20. 29. Macular drusen • Hyaline deposits between the RPE and Bruch’s membrane. • ? Due to small areas of hypoxia due to choriocapillaris age changes - leads to RPE malfunction and “spitting out” of collagen and basement membrane material = drusen. • Distinction between hard and soft drusen.
  21. 32. Peripheral retina ageing changes • Peripheral pigmentary degeneration seen in ~20% of 40+ - hypo and hyperpigmentation. • Peripheral drusen. • Inc. paving-stone degeneration (chorioretinal atrophy) - white areas of sclera with overlying choroidal vessels - closure of small area of choriocapillaris.
  22. 35. Visual pathway changes with age • No cell loss in LGN. • No loss of striate cortex neurons with age. • VEP changes with age suggest there are functional cell changes with age, perhaps linked to vascular changes.