Consider a concomitant neurological disease in a glaucoma patient when there is only partial topographic agreement between structure and function.

The Science behind the Tip

One of the key elements in the diagnosis and monitoring of glaucoma is the assessment of the topographic agreement between structure and function.1 The clinician needs to be familiar with the topographic map which relates different sectors of the optic nerve head to different regions of the visual field test.2 The corresponding topographic map for the glaucomatous damage of the macula has also been described.3 With this knowledge, the clinician knows where to expect the visual field damage, given the anatomical findings, and vice versa. It is possible for patients with glaucoma to also have a previously undiagnosed neurological disease (e.g a space occupying lesion of the brain) and be completely asymptomatic. This suspicion should be raised in the case of reproducible visual field defects which correspond only partially to glaucomatous structural damage. Clinicians should remain alert, particularly if the non-congruous part of the visual field defect is bitemporal or homonymous in location, even without a typical ‘neurological’ configuration (e.g the defects may only be partial and not extend all the way to the vertical axis).

References

1. European Glaucoma Society. Terminology and Guidelines for Glaucoma. 5th Edition. PubliComm, Savona, Italy; 2020.
2. Garway-Heath DF, Poinoosawmy D, Fitzke FW, Hitchings RA. Mapping the visual field to the optic disc in normal tension glaucoma eyes. Ophthalmology. 2000;107(10):1809-1815.
3. Hood DC, Raza AS, de Moraes CG, Liebmann JM, Ritch R. Glaucomatous damage of the macula. Prog Retin Eye Res. 2013;32:1-21.

Contributor: Panayiota Founti, MD, PhD, Moorfields Eye Hospital, London, UK

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