Scottish Sensory Centre

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 tooptic 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

Where next

• Understanding visual fields
• Neurological causes