Dr Robert Harper and Sonali Patel describe a less well known field defect caused by glaucoma
Damage to nerve fibers on the nasal side of the optic disc may result in temporal wedge-shaped VF defects. Occasionally, these defects are seen as the sole defect. Sometimes, as is the case here, there may be companion losses in sensitivity else where in the VF. Temporal wedge defects may not necessarily respect the horizontal meridian, probably because the retinal nerve fibers ‘kink up’ at the retinal horizontal raphe (a seamlike union between two parts or halves of an organ).
Posted by Mike Hale
While it is recognized that glaucoma can cause diffuse, non-specific losses in sensitivity in the visual field (VF), specific localized losses in VF sensitivity are considered most useful diagnostically. Nasal step, arcuate and para-central ‘nerve fiber bundle’ VF defects represent the characteristic pattern defects that occur in glaucoma 1, 2 and typically reflect the course of retinal nerve fibers respecting the nasal horizontal meridian. Commonly, glaucomatous VF loss occurs in the upper hemi-field and affects para-central regions.3-5 In contrast, glaucomatous pattern VF defects that are temporal wedge in nature are much less common 6 and are arguably less well recognized as a result. In this short article we present the case of a patient with a temporal wedge VF defect due to glaucoma.
A 66-year-old Caucasian woman initially presented to Manchester Royal Eye Hospital (MREH) in 2003, having been found during a routine sight test to have elevated intraocular pressures (IOPs) of 25mmHg in both eyes along with a suspiciously cupped optic disc. At the initial ophthalmology assessment, the patient was noted to be asymptomatic and had recently been diagnosed with diabetes mellitus. It had been when she attended for diabetic retinopathy screening that her community optometrist referred her for suspect glaucoma. There was no previous history of ocular disease and no family history of glaucoma.
On examination, the patient was noted to have normal visual acuities, modestly raised IOPs of 22mmHg in the right eye and 24mmHg in the left eye, modestly thicker than average central corneal thicknesses (~580 microns in each eye), a normal anterior segment with gonioscopically wide open angles, and a cup to disc ratio documented as ~0.7 in each eye, with inferior neuroretinal rim thinning, particularly in the right eye. Subsequent maximum IOPs were noted to be 27mmHg in the right eye and 28mmHg in the left eye. Full threshold 24-2 VF testing on the HFA revealed an abnormal glaucoma hemi-field test (GHT) in the right eye and a borderline GHT in the left eye. The patient was diagnosed with primary open-angle glaucoma and initially commenced on guttae latanoprost od nocte right and left. At first follow-up the patient was noted to have had a satisfactory response at 15mmHg in both eyes, and thereafter she continued to be monitored in the consultant led glaucoma service, with treatment subsequently being modified to dual therapy with guttae travaprost od nocte right and left and guttae dorzolamide bd right and left.
In 2010 the patient was transferred to the hospital’s Optometry Led Glaucoma Assessment (OLGA) clinic for monitoring while continuing the same treatment. On assessment, both optic discs showed large cup to disc ratios (RE ~0.85 LE ~0.80) with the right eye in particular showing both inferior and, significantly, nasal rim excavation……….
Read more: http://www.opticianonline.net/temporal-wedge-visual-field-defect-glaucoma/
Source: Optician Online