Two new tests assist in the diagnosis of a small calibre vein occlusion

Abstract

A 37-year-old white male was diagnosed with a small calibre retinal branch vein occlusion. Two new psychophysical tests were employed to assist in the patient evaluation and diagnosis – the Gordon Macula Profiler and the Vascular Entoptoscope. Under computer control, the Gordon Macula Profiler projects a six by six grid of letters onto a standard ophthalmic projection screen. Each letter can be independently changed. The display can be customised to show any one letter of the grid individually or in any arrangement of choice. The size of letter can be optically zoomed up or down allowing the determination of between-standard-line acuity, for example, 6/5.1 (20/17) as opposed to 6/6+ (20/20+) or 6/4.5- (20/15-). Testing with the Gordon Macula Profiler revealed the patient’s visual acuity was slightly depressed and there was a local loss in the visual field one-third to one-half of a degree nasal to fixation. The Vascular Entoptoscope enables a patient to see his/her own foveal and parafoveal retinal vasculature and pre-receptor retinal defects. Testing with the Vascular Entoptoscope revealed a small but easily visible, localise, parafoveal pre-receptor retinal defect that appeared as a ‘bunch of grapes’ between 33 and 41 minutes of arc nasal and inferior to fixation in the visual field. Together, the results of these two new tests focused the retinal specialist’s attention to the specific retinal area of interest and led to the diagnosis of a small branch vein occlusion.