Anatomic and physiological ocular changes with age final
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This document discusses various age-related changes that occur in the eye and visual system. It notes decreased visual field and corneal sensitivity with age. The eyelids show signs of atrophy, wrinkling, and misalignment. The conjunctiva thins and produces fewer tears. The lens thickens and becomes less transparent, increasing nearsightedness. The vitreous shrinks and detaches from the retina more easily. The retina has poorer response to light and contrast sensitivity. Overall, aging reduces visual acuity, especially for moving targets, and increases the need for brighter lighting.
Anatomic and physiological ocular changes with age final
- 1. AGE RELATED CHANGES IN THE EYE? “ARE WE AWARE ABOUT IT” Hira Nath Dahal
- 3. • Decreased visual field • corneal hypoxia dermatochalasisptosis Periorbit and eyelid
- 4. skin & soft tissue atrophy glabellar rhytids poliosis orbital septal dehiscene ⇒ herniation of orbital fat lacrimal gland dysfunction, ↓ed tear production, meibomian gland disease & goblet cell dysfunction ⇒ dry eye
- 5. LID LAXITY ⇒ ENTROPION, ECTROPION • associated with ageing, • both can be successfully treated with surgery if they produce discomfort or a threat to vision.
- 7. CONJUNCTIVA: • atrophy & degeneration • ↓ in no. & height of epithelial cells • shortening of inferior fornix • the number of mucous cells decreases leading to dry eye.
- 8. CORNEA: • ↓ed corneal sensitivity • ↑ against-the-rule astigmatism • no. of the people having with-the-rule astigmatism ↓es with age • Arcus senilis • corneal endothelial cell population decreases along with polymegathism and pleomorphism
- 9. fig: Typical age-related changes including sagging of the upper lid, loss of the normal upper lid crease, eyelid wrinkling and arcus senilis.
- 10. ANTERIOR CHAMBER: • depth ↓es with age, causing • the increment in the refractive power of the eye (↑ myopia) • More interference with aqueous outflow
- 11. PUPIL AND UVEA: • senile miosis • due to • atrophy of the dilator muscle fibres, or • an increased rigidity of the iris blood vessels, or • both • ↓ retinal blur circles and retinal illuminance
- 12. less difference in the diameter of the pupil in the light- and dark-adapted state less reactive to light slight ↑ in the latency of pupillary responses hypertrophy of ciliary muscle
- 13. LENS: • Morphological Changes: • ↑ in both the mass & dimension of the lens • axial thickness of the lens ↑es by about 28% by age 70 over that which existed at age 15 to 20 yrs
- 14. • the nuclear thickness remains constant while the cortical thicknesses increase • the anterior cortex increases by 0.6mm & the posterior, by 0.4mm • flattening of the anterior lens surface & conical bulging of the posterior lens surface
- 15. LENS:… Morphological Changes: epithelial cells- becomes flatter & density ↓es lens fibers- total loss or partial degradation of a no. of plasma membrane & cytoskeletal proteins cholesterol:phospholipid ratio ↑es lens capsule- thickens throughout life (collagen type IV vs. I, III, IV)
- 16. LENS:… Physiological Changes: Changes to the cellular junctions and alteration on cation permeability membrane potential- from –50mV (at age of 20 yrs) to –20mV (at the age of 80 yrs)
- 17. • sodium concentration - ↑es • Na+ :K+ permeability ratio ↑es by six fold • free calcium level ↑es Ca ATPase inhibited
- 18. LENS:… • Biophysical Changes: • UV & visible light absorption ↑es • ↑ 3-hydroxykynurenine glucoside (3-HKG) • ↑ yellow-pigmented proteins • ↑ fluorophores
- 19. • thus transmission of visible light & lens transparency ↓es • the amount of light reaching the retina in a normal 60- year-old is only about 1/3rd that reaching the retina of a 20- year old • amplitude of accommodation ↓es
- 20. LENS:… • Biochemical Changes: • overall metabolic activity of the lens ↓es • ↓ glycolytic activity • ↓ level / activity of antioxidants
- 21. • Changes in Crystallins: • accumulation of high molecular weight aggregates • some act as scatter points for light • ↑ed insolubility
- 22. • Exaggeration of normal nuclear ageing change • Causes increasing myopia • Increasing nuclear opacification • Initially yellow then brown
- 23. VITREOUS: index of refraction of the vitreous increases ( hypermetropia)↑ syneresis of the vitreous Increased vitreous floaters Decreased support to the posterior lens surface
- 24. RETINA AND NEURAL CONNECTIONS: in the absence of pathology, only little decline in static visual acuity with age that can not be accounted for by miosis and increased density of the lens pathologies that are the major cause of decline in static visual acuity are cataract, macular degeneration and glaucoma
- 25. • mesopia occurs at higher levels of ambient illuminace in older people • The arteries and veins of the retina become narrower with age, reducing the flow of blood.
- 26. The ageing retina is duller and exhibits a less responsive light reflex. The optic disk may be paler also. This creates a need for more light in order to read or accomplish other tasks.
- 27. SENILE MACULAR DEGERATION • Warning signs may include: • gradual, spotty loss of detail vision (dry macular degeneration); • sudden and severe loss of central vision (wet macular degeneration); • a need for more light.
- 28. RETINA AND NEURAL CONNECTIONS:… • ↓ contrast sensitivity due to increased lens fluorescence and light scatter • with shift of peak sensitivity to lower frequencies • ↓ in the ability to discriminate colours
- 29. • ↓ visual field size and sensitivity • absolute level of dark adaptation reached by the elderly is less than that reached by younger individuals
- 30. REFRACTIVE STATUS: • static power of the eye: hypermetropic shift • cornea: ↑ against-the-rule astigmatism • anterior chamber: ↑ myopia • lens: hypermetropia or myopia • vitreous: ↑ hypermetropia
- 31. OCULAR MOTOR SYSTEM: under scotopic conditions, aging people have difficulty with fixation ↑ exotropia with age the range of voluntary eye movements becomes limited supraduction ↓es with age ↑ tonic vergence with distance heterophoria (esophoria)
- 32. ↓ positive fusional vergence but same negative fusional vergence ↓ accommodation with ↑ AC/A ratio & ↓ CA/C ↓ stereopsis
- 33. OTHER CHANGES WITH AGING: • ↓ aqueous secretion • ↓ resistance to distraction • ↓ ability to selectively attend to one source of information in the presence of competing messages
- 34. ↓ ability to separate visual events that happen serially declines with age ↓ dynamic visual acuity (VA for moving targets) related to ↓ in the rate of smooth following eye movements ↑ variability in visual performance between individuals