Download The Ageing Eye Dr Kelly Caruso

The Ageing Eye
Dr Kelly Caruso-Whittaker – Veterinary Ophthalmologist
Ageing affects the following:
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Orbit
Adnexa
Cornea
Iris
Lens
Vitreous
Retina
Disposition
Ageing and the orbit
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Important Concepts
- Bony encasement
- Surrounded by oral cavity, nasal cavity, tooth roots, paranasal sinuses
Orbital Anatomy
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Intraorbital contents
- 7 extraocular muscles
- Retrobullar fat
- Zygomatic salivary gland
So what happens in old age in the orbit?
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Retrobullar tissue atrophy
Loss of retrobullar fat stores
All contributes to a sunken eye
- Enophtalmous
- Entropion
- Chronic ocular discharge
What can we do for a sunken eye?
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Not much really
Try to correct secondary effects
Entropion – surgery
Ocular discharge – good ocular hygiene
Effects of age on the adnexa
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Lids
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Loss of muscle tone
Forehead skin droop. Esp Spaniel breeds
Leads to dorsal entropion
Effects of age on the adnexa
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Lower lid sagging – leads to gap between eyelid and globe
So what can we do?
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Usually some type of entropion surgery is needed
- Simple like Hotz Celsus
- More complicated such as Arrowhead
Effect of age on the cornea
To understand the effects of age on the cornea, we need to understand some basic anatomy
and physiology
The Cornea
Normal Anatomy and Healing
 Epithelium = heals by cells sliding – hydrophobic
 Stroma = heals by mitosis – hydrophilic
Endothelical Cells
 Basement membrane is Descemet’s membrane
 NA+/ K+ ATPase water pumps
 Poor regeneration
Why is the cornea clear?
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Collagen lamellae are perfectly aligned
Relatively dehydrated
Disease = water accumulation in the stroma
Effects of age on the cornea
Endothelial cell number:
 Maintains corneal deturgescene
 Born with -2500 -3000 cells/ mm2
 At -1300 -1500 cells/ mm2 start to get diffuse corneal oedema
Corneal endothelial cell degeneration
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Can start in focal spots
Slowly progresses over time
Effects of age on the cornea
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Diffuse oedema causes:
- Keratoconus
- Epithelial bullae
- Ulceration
Treatment on endothelial cell degeneration
What works best?
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Conjunctival graft
Thermokeratoplasty
Topical hyperosmotics
Gunderson Flap
Effect of age on the cornea
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Corneal degeneration
- Mineralisation of cornea
Treatment
- None if not painful
- Keratectomy if it is
Effect of age on the Uveal Tract
What is the uveal tract?
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Uvea = iris, ciliary body, choroid
Anteriour uvea = iris + ciliary body
Posterior uvea = choroid
Degeneration of the iris stroma
Iris atrophy – no cataract
Iris atrophy – mature cataract
Iris atrophy
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Iris holes may make the eye light sensitive (photophobic)
This causes blepharospasm
Treatment – doggles? Coloured contact lenses? Behavioural modification
The Lens
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Anatomy
- Held by zonules
- Surrounded by lens capsule which thickens with age
The Lens
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Physiology
- Grows from cortex into nucleus
- Nucleus becomes compacted
- “nuclear sclerosis”
- Presnyopia – far sightedness due to loss of elasticity
Ageing changes the vitreous
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Asteroid hyalosis
- Cholesterol deposits in the cornea
- Probably decreases vision
- Light scatter – startles animal
(image on next page)
Ageing changes in the vitreous
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Vitreous syneresis
- Liquefaction of the stable jelly-like vitreous
- Predisposes to a retinal detachment
Posterior segment changes with ageing
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Pheripheral cystoid degeneration
- Predisposes to retinal detachments
Retinal changes with ageing
Cats and to a lesser extent dogs, may get excessive optic nerve myelination