University of Edinburgh
 

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

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

graphic

Pattern of field defect

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 pupilKeyhole pupil

 

graphic

Coloboma – Right eye

right eye coloboma

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

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

effect of RP

No treatment?
Or is there?

nature magazine

journal paper

transplanted cells

transplanted cells

transplanted cells

journal paper

Macular Dystrophies

macular dystophy

macular dystrophy

Stargardt’s Disease

stargadt's

stargadt's

Optic Atrophy

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

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