The role of standard automated perimetry in age-related macular degeneration [thesis]

Yiu Jeung Choi
2019
Standard automated perimetry (SAP) is a well-established test of visual function, Goldmann size III (GIII) being the standard stimulus size used. Studies have shown that using GIII across the visual field (VF) may however result in lower separability between normals and those with optic nerve disease, as loss of visual function is greater within complete spatial summation. In contrast, GII operates largely within complete spatial summation for most of the conventional VF test grid thus may
more » ... rm better than GIII in detecting visual function loss, particularly in optic nerve disease. It is not known if a similar issue is present when SAP is used to assess age-related macular degeneration (AMD), which exhibits abnormal sensitivity measurements in the central VF. Reports on the use of SAP in AMD however are limited. Understanding of the normal spatial summation characteristics of the central VF is also unclear. This thesis measured contrast sensitivity in the central 20° VF using GIII and other Goldmann stimulus sizes in normal and AMD cohorts. From this, it was found that GIII did not operate within complete spatial summation in the central 20° VF whereas GI and GII did. Thus they may be more suitable for testing this region. An additional surprising finding was that the AMD cohort showed increased sensitivity with GV relative to normals, also suggesting large stimulus sizes may be useful in assessing early to intermediate AMD. This thesis also explored the use of contrast sensitivity isocontours (CSIs) in reducing test variability. CSIs are groups of test locations with statistically similar sensitivities identified by pattern recognition. This thesis established normal CSIs within the central 20° VF and showed that CSI guided analysis returned a greater defect depth than standard clinical pointwise analysis in assessing the AMD cohort, suggesting that CSIs may be useful in minimising test variability in SAP. The outcomes of this thesis may provide guidance in devising an optimum test paradigm and analysis techn [...]
doi:10.26190/unsworks/24165 fatcat:pfhhy44cz5g45ig4fqikbvdh44