David B Henson Medical School University of Manchester MSc Investigative Ophthalmology & Vision Sciences Visual field defects in glaucoma David B Henson Medical School University of Manchester

Classification of glaucoma Primary 95% Secondary 5% Closed angle 33% Open angle 66% Congenital 1%

Definition of POAG Progressive optic neuropathy with characteristic changes at the optic nerve head and to the visual field. Associated with a raised IOP

Detecting glaucoma Based on 3 measures IOP ONH evaluation Visual fields

Types of visual field loss Nerve fibre bundle defects Paracentreal Arcuate Nasal step Site of lesion Overall depression Enlargement of the blind spot

Paracentral/Arcuate defects Follow nerve fibre distribution More common in superior hemifield Abrupt discontinuity at horiz midline

Involvement of the macular OCT of macular from case with early glaucoma Thickness of nerve fibre layer complex. Note how inferior region is thinner Probability plot- highlights regions outside normal Comparison to normal Hood D et al IOVS 2014;55:633-

Involvement of macular: OCT plus VF 10-2 visual field. Position of stimuli adjusted to match RGC displacement OCT of macular Defect in superior VF and inferior macular

Involvement of macular: OCT and VF Probability plot Early glaucomatous defect. Very few 24-2 points involved

Nasal Step Due to sensitivity difference above and below the horizontal midline Small steps are not uncommon in ‘normals’ (>5 degrees significant) Highly specific Predominantly found with kinetic strategy

Overall depression Due to diffuse loss of nerve fibres Common 38% About 1-2dB Not specific to glaucoma Could be due to cataract Contributes little to diagnosis

Enlargement of the Blind spot Not specific to glaucoma Large range of ‘normal’ sizes Cannot detect small increases in size with current static techniques Linked to peripapillary atrophy (PPA)

Henson DB et al. Invest Ophthal Vis Sci 2000;41:417-421.

Variability Difficult to diagnose Normal Suspect Defect intermittent 3.5 years (1-6 years) Normal Suspect Defect 3 consecutive normal fields 3 consecutive abnormal fields Also add: Variability is first sign of glaucoma Heijl A, Bengtsson B (1996) Glaucoma: Decision Making in Therapy. Ed. Bulli, Springer

When did this patient develop a VF defect in the RE? How does this relate to the definition of glaucoma?

Factors that affect Variability Stimulus size, decreases with larger stimuli Increases towards periphery Related to lower sensitivity in periphery Increases when you test sparse populations of retinal ganglion cells, e.g. blue on yellow Not only found in glaucoma, same with other pathologies Test algorithm, extended test algorithms tend to give more accurate threshold estimates but take longer (SITA Std vs SITA fast) Patient vigilance

William Burley, Global grad PD –1.473 Patient WB

Patient TS

Evolution of glaucoma defects Earliest sign is an increase in the scatter of results Defects might be intermittent Early sign is an asymmetry between the two eyes Develops into a permanent defect, paracentral. Develops into an arcuate Develops into a hemifield loss

Asymmetry

Asymmetry

Is this glaucoma?

Conclusions Defects Follow distribution of nerve fibres Asymmetric between eyes and between hemispheres Variable Patient dependent Intermittent