Visual fields

Inner ret layers- arcuate damage + respect midlines

ret vasculature- arcuate or altitudinal ( Superior or Inferior)

Outer layer- does not respect horixontal or vertical midline + does not follow pattern of RNFL

Field loss

• unilateral in unilat pathology

• asymetric in bilateral pathology

VA

• affected if papillo-macular bundle is affected

• unaffected with macular sparing

• absolute scotoma - absence of photoreceptors

• R side of VF for R eye and vv (temporal)

1. Pre-chiasmal (retinl and optic nerve lesions) : affect VF on same side eg. RE lesion affect R VF.

   • Produce scotomas

2. Chiasmal: affect temporal field of each eye bx nasal ret fibres affected

   • bitemporal hemianopia

3. Post-chiasmal ( lesions in brain): VF of both eyes affected eg. R lesion affect L side of both VF.

   • produce hemianopas and quadrantanopias

   • respect vertical midline

Total:

• very poor VA in affected eye

• unaffected eye - direct and consensual response

• affected eye- NO direct OR consensual response

Relative:

• VA reduced in affected eye

• unaffected eye- direct and consensula response

• affected eye- delayed or partial direct and consensual response

• respect vertical mid line

• homonymous ( affect R of both or L of both)

• occur on opposite side of lesion ( if lesion on R, L VF of both affected)

• incongruous- not exact match on R or L - different appearance on R and L plots

• Optic atrophy or RAPD

• highly congruous hemianopias( same side of field is affected)

• macula can be split or spared ( if lesion is further back = mac sparing)

• lesions anterior produce optic atrophy and pupillary defects bx same gang cell axon from ONH to LGN= ONH pallor

• lesion posterior are more congruous and mac sparing = ONH not affected

1. Age- sensitivity reduces with age

2. Pupil size- central affected more than peripheral

3. Rx- low myopes ( less than -3.00) do not need correction. Hyperope correct if cant read

4. Artefact- not due to pathology eg. ptosis, trial lens rims ( use metal ones)

5. learning effects- px gets better at test

6. Fatigue effect- ensure px is positioned comfortably

7. Functional visual loss = reduced VF with no pathological cause. could be malingering ( disability- claim benefits, financial compensation, psychological )

Structure = diseases- Opthalmoscopy + OCT

Function= impact on px- VA ( macular func), CV (colour deficiency + optic nerve lesions), VF ( mac func)

• 60 superiorly

• 75 inferiorly

• 100 temporally

• 60 nasally

200 binoculary

Hemianopia- side to side defect.

1. Age: increased age = reduced sensitivity

2. Pupil size: small pupil = central affected more moe than peripheral fields

3. Rx: correct Rx for myopes above -3D and presbyopic when testing VF

4. Artefact: artificial defect on VF plot not due to pathology eg. trial lens frame

5. Learning effects: px tends to do better with repeated attempts

6. Fatigue effects: more detailed test= more accurate results but longe test = px fatigue

Malingering:

• disability- clain benefits

• financial compensation

• psychological

• claim insurance