Understanding Visual Fields
Presented on Friday 2 November 2007
Ocular Causes of Field Loss: Coloboma, Glaucoma, Epilepsy medication, Optic atrophy, Cone dystrophies, Retinitis pigmentosa.
Dr Andrew Blaikie, Consultant Ophthalmologist, Fife
Whole Globe
Glaucoma
- Raised intraocular pressure (IOP)
- Bupthalmous – enlarged corneas
- Increased pressure damages optic nerve fibres at back of the eye
- Field loss then visual acuity loss
Raised IOP can lead to optic nerve damage
Pattern of field defect
Coloboma & Microphthalmia
Coloboma
- Incomplete closure of optic fissure during uterine development
- Children are born with defect rare (0.5 to 0.7 per 10,000 births)
- Can affect one or both eyes
- Can affect iris, lens, retina, choroid and optic disc
- Occur in isolation or other body parts can be affected (example CHARGE syndrome)
Keyhole pupil
Coloboma – Right eye
Retinitis Pigmentosa
Inherited condition
- Umbrella term for a number of disorders affecting the rods and/or cones in the retina, that is, Rod-cone Dystrophy, Leber’s Amaurosis
- Can be coexist with other conditions, that is, deafness + RP = Ushers syndrome
- Autosomal Recessive condition with vision signs in teen years – although if visual problems present sooner (type US1) blindness is more likely to occur.
- Progressive degeneration of Photoreceptors
- First signs – night blindness (Due to rod disorder)
- Followed by Peripheral visual loss
- Then Central vision loss
RP – mottled appearance
- Mottling of Retinal pigment epithelium and bone spicule appearance gives diagnostic appearance
- attenuated retinal vessels
- waxy pallor of the optic nerve head
- Maculopathy affecting central vision - that is, cystic macular oedema
- A cataract may also develop in later stages
Visual Field Plot for RP
No treatment?
Or is there?
transplanted cells
Macular Dystrophies
Stargardt’s Disease
Optic Atrophy
Optic Atrophy
- Loss of retinal ganglion cells
- Different forms of the condition
- Inherited (genetic)
- Acquired (secondary to glaucoma, brain injury, maternal drug use)
Inherited types
Autosomal Dominant inheritance - gradual decrease in vision through childhood
Autosomal Recessive inheritance - more severe within first 2 years of life - often exists with nystagmus
Signs – Autosomal Dominant
- Better visual prognosis that AR
- More common, onset typically 4-6 years
- No associated neurological defect
- Mostly affects both eyes to a similar degree
- Reduced vision
- Reduced colour vision
- Central field defect
- Vision can vary between 6/6 to 6/60
- Pale disc
- Cupped disc
- Field loss – dependent on the extent of the damage and which fibres are involved generally – central or paracentral scotomas
Central + Para-central Loss
Optic Atrophy: Autosomal Recessive
- More severe but very rare
- Present in 1st year of life
- Sensory Nystagmus almost always present
- Very pale disc
- Cupped disc