Summary Tears for diagnostic testing of brain disease

Tears for diagnostic testing of brain disease
(Prof. Gijs)
1. Anatomy of the eye
 In front of the iris is the cornea
 Cornea is transparent because light needs to go through
 Anterior chamber is between the lens and cornea which is filled with fluid
 Posterior part of the eye  lined with retina
 In retina is a complete inner lining which contain neuron cells  travel to
optic disc  transmit visual signals into neural signals
o The retina is composed of 10 layers
o Rods and cones catch visual signals and transform them into
neuronal signals
 A lot of muscles surrounding the eye because you can move the eye in
different directions
 Blood vessels in the eye




2. Three most common eye diseases
2.1. Cataract
= disease of the lens  lens is refracting visual signals  with cataract you
have no sharpening of your vision

2.1.1.Definition and causes
 = clouding of the lens
 Slow progression and painless
 Pictures
o Left




1

,  Healthy individual: lens is refracting the eye to the center 
centering then you get a sharp vision
o Right = cataract
 Not centralized in the retina = blurry vision
 Causes
o Age
o Metabolic disease (eg diabetes)
o Ocular diseases (eg uveitis)
o Ocular surgery
o Trauma
o Congenital
o Medication (eg steroids)
 Treatment = lens which is replacing your original lens?

2.1.2.Symptoms
 Decreased vision
 Halo’s = light sources  very large glow around it
 Monocular diplopia = double vision in one eye




2.2. Glaucoma
= disease of the papil
 Progressive neuropathy
 (A) Excavation optic disc, thinning of nerve fibers
o All nerves and axons come together and go to the brain
o Healthy: small entry side with a lot of nerves and blood vesels
o Glaucoma has a larger entry side
 (B) Visual field loss
o They will still have a sharp image but in the periphery they will lose
vision
o Sharp central vision but not complete because loss of visual field
o They don’t see black spots because the brain is filling it in
A B




2

,  Neuroretinal rim
 Cup/disc ratio = diameter of cup expressed as fraction of diameter of disc
 Picture
o Blue: optic cup
o Green: optic disc
o Inbetween is a rim
 Rim is decreasing and cup is altered
o Upper donut is healthy example




 Visual field loss
 Very slowly progressive, brain fills in missing spots
o Damage is irreversible and difficult to treat  tunnel vision in late
stages




2.2.1.Glaucoma main risk factor = increase intraocular pressure (IOP)
 Misbalance between aqueous humor production and outflow
 Not directly the cause
 Normal IOP because the eye is a closed ball
o Pressure increases  press against tissues of the eye  especially
the retina
o Signals cannot travel to the brain
 IOP is caused by misbalance between production and outflow

3

, o Production is normal but outflow is blocked

2.2.2.Treatment
 Medication, topical eye drops
o Reduce aqueous humor production (eg beta blokkers)
o Increase aqueous humor outflow (eg prostaglandins)
 Laser: shoot wholes to increase drainage
 Surgery: fluid is given an alternative outflow
o Trabeculectomy (bleb)
o Implants (drainage)
o Shunts

2.3. Age-related macula degeneration (AMD)
= disease of the retina
= degeneration of the macula
 Types of AMD
o Dry AMD (90%)
 No exucative
 No neovascularisation
o Wet AMD (10%)
 Exucative
 Neovascularization
 Fast progression, fast loss of vision
 Observations in the retina
o Drusen = extracellular waste products between RPE and Bruch
membrane




o Hyper- and hypopigmentation on the RPE
o Atrophy RPE (degeneration)




2.3.1.AMD symptoms (dry AMD)
 Gradual vision loss over months/years
 (A) Metamorphopsia = deformation of the squares
 (B) (Para)central scotoma = black spot in the center of your vision
B




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