Assessment of consumer VR-headsets’ objective and subjective field of view (FoV) and its feasibility for visual field testing

Virtual reality as a research environment has seen a boost in its popularity during the last decades. Not only the usage fields for this technology have broadened, but also a research niche has appeared as the hardware improved and became more affordable. Experiments in vision research are constructed upon the basis of accurately displaying stimuli with a specific position and size. For classical screen setups, viewing distance and pixel position on the screen define the perceived position for subjects in a relatively precise fashion. However, projection fidelity in HMDs strongly depends on eye and face physiological parameters. This study introduces an inexpensive method to measure the perceived field of view and its dependence upon the eye position and the interpupillary distance, using a super wide angle camera. Measurements of multiple consumer VR headsets show that manufacturers’ claims regarding field of view of their HMDs are mostly unrealistic. Additionally, we performed a “Goldmann” perimetry test in VR to obtain subjective results as a validation of the objective camera measurements. Based on this novel data, the applicability of these devices to test humans’ field of view was evaluated.

Investigations and their interpretation

‘Investigations and their interpretation’ introduces the reader to both standard and emerging technologies that enable assessment of the structure or function of the eye and visual system. Starting with visual field testing, the chapter covers automated and Goldmann perimetry, novel protocols and progression analysis. Anterior segment imaging covers keratometry, topography and OCT. Posterior segment imaging includes angiographic techniques, novel blood flow quantification methods, OCT, and adaptive optics. Electrodiagnostic tests are introduced including multifocal techniques. Finally ophthalmic ultrasonography and radiology are supported by clinical strategies and examples to support the practice and interpretation of these techniques.

Impact of internal carotid endarterectomy on visual fields: a non-randomised prospective cohort study in Austria

PurposeThe goal of this study was to determine whether internal carotid endarterectomy is associated with visual field changes.MethodsBetween March 2007 and December 2010, a cohort study involved 29 patients with stenosis of the carotid artery. All patients underwent ophthalmoscopy and kinetic visual field examination (Goldmann perimetry) preoperatively and postoperatively. Furthermore, a detailed area calculation was performed. On both the operated and the contralateral side, the areas surrounded by the different isopters (isopter areas) were determined and preoperative and postoperative values compared. The three isopters were classified from the centre to the periphery (I, II and III). Isopter area values are given as ratio compared with total perimetric circle. p Values <0.05 were considered to be statistically significant.Results1) The ophthalmologists assessmentEight of eleven patients with precarotid endarterectomy impairments experienced focal or concentric improvement. Six cases with preoperative concentric narrowing of the isopters returned to normal or improved substantially. Three out of 18 patients with normal preoperative visual field presented with deteriorations after surgery, two cases with ipsilateral and one with contralateral focal impairment. In 15 cases, there was no preoperative or postoperative abnormality.2) Area calculation (preoperative area, postoperative area, P)Ipsilateral: isopter area I (0.015, 0.018, 0.131), isopter area II (0.107, 0.120, 0.087), isopter area III (0.392, 0.425, 0.015)Contralateral: isopter area I (0.017, 0.021, 0.222), isopter area II (0.119, 0.125, 0.333), isopter area III (0.416, 0.434, 0.171)ConclusionsWe found a statistically significant extension of the ipsilateral peripheral isopter area (III). Further studies will focus on the question which subgroup is most likely to profit from internal carotid endarterectomy with respect to visual field changes.

OPTIC NEUROPATHY INDUCED BY LOW DOSE OF ETHAMBUTOL: A RARE PRESENTATION

Ethambutol is a bacteriostatic antimicrobial agent used in the treatment of tuberculosis. Optic neuropathy is a potentially severe side effect of ethambutol, which is dose related. Ethambutol-induced optic neuropathy (EON) incidence is 15%, 5% & 1% when taken at 50 mg/kg/day , 25 mg/kg/day & 15 mg/kg/day respectively for 3 months. We report a case of bilateral EON in 20-year-old female after 1 month of exposure to 15 mg/kg/day of ethambutol for tubercular meningitis. Ophthalmologic examination revealed bilateral ill sustained pupillary reactions and optic disc pallor. Deranged color vision test and scotomas on Goldmann perimetry in both eyes, aided in diagnosis.Keywords: Low dose ethambutol, Optic neuropathy, Tuberculosis.

Investigations and their interpretation

‘Investigations and their interpretation’ introduces the reader to both standard and emerging technologies that enable assessment of the structure or function of the eye and visual system. Starting with visual field testing, the chapter covers automated and Goldmann perimetry, novel protocols and progression analysis. Anterior segment imaging covers keratometry, topography and OCT. Posterior segment imaging includes angiographic techniques, novel blood flow quantification methods, OCT, and adaptive optics. Electrodiagnostic tests are introduced including multifocal techniques. Finally ophthalmic ultrasonography and radiology are supported by clinical strategies and examples to support the practice and interpretation of these techniques.