The efficient use of perimetry for neuro-ophthalmic diagnosis

Validating tablet perimetry against standard Humphrey Visual Field Analyzer for glaucoma screening in Indian population

Purpose:

The aim of this study was to determine the correlation between the perimetric outcomes using a free application program of the iPad, 'Visual Fields Easy' (VFE), and Humphrey Visual Field Analyzer (HVFA), in normal as well as eyes with glaucomatous damage of varying severity.

Methods:

In this prospective, cross-sectional, observational pilot investigation, visual field testing was carried out in 210 eyes of 210 patients (60 Normal, 150 Glaucoma), using suprathreshold VFE application (Version 8) on the iPad and Standard White-on-White using HVFA. Severity of glaucoma was categorized using Hodapp-Anderson-Parrish criteria for visual field defects. The results of the VFE program were compared to the 24-2 SITA FAST HVFA.

Results:

Data of 210 patients, 100 (47.6%) females, and 110 (52.4%) males, age ranging from 42 to 78 years, Mean 56.64 ± 10.67 years, was analyzed. The Spearman correlation coefficient showed a significant inverse relationship between missed points on the VFE app with MD (S = –0.783) and a parabolic relationship with PSD (S = 0.646) values obtained with the HVFA. As regards missed points, for mild glaucoma, missed points were 37.5, sensitivity was 77.8% and specificity was 52.6%; for moderate glaucoma, missed points were 33.5, sensitivity was 90% and specificity was 48% while for severe glaucoma, missed points were 23, sensitivity was 97% and specificity was 70%. AROC for eyes with mild glaucoma versus normal was 0.419 (95% CI: 0.343-0.495), moderate glaucoma versus normal was 0.705 (95% CI: 0.630-0.780) and severe glaucoma versus normal was 0.857 (95% CI: 0.806-0.908).

Conclusion:

Suprathreshold perimetry using VFE is not suitable as a rapid screening tool for mass screening of glaucoma. VFE cannot be used as a substitute for HVFA in clinic because of its inability to detect early or moderate glaucoma.

Comparative Study Between the SORS and Dynamic Strategy Visual Field Testing Methods on Glaucomatous and Healthy Subjects

Purpose

To clinically validate the noninferiority of the sequentially optimized reconstruction strategy (SORS) when compared to the dynamic strategy (DS).

Methods

SORS is a novel perimetry testing strategy that evaluates a subset of test locations of a visual field (VF) test pattern and estimates the untested locations by linear approximation. When testing fewer locations, SORS has been shown in computer simulations to bring improvements in speed over conventional perimetry tests, while maintaining acquisition at high-quality acquisition. To validate SORS, a prospective clinical study was conducted at the Department of Ophthalmology of Bern University Hospital, over 12 months. Eighty-three subjects (32 healthy and 51 glaucoma patients with early to moderate visual field loss) of 114 participants were included in the study. The subjects underwent perimetry tests on an Octopus 900 (Haag-Streit, Köniz, Switzerland) using the G pattern with both DS and SORS. The acquired sensitivity thresholds (ST) by both tests were analyzed and compared.

Results

DS-acquired VFs were used as a reference. High correlations between individual STs (r ≥ 0.74), as well as between mean defect values (r ≥ 0.88) given by DS and SORS were obtained. The mean absolute error of SORS was under 3 dB with a 70% reduction in acquisition time. SORS overestimated healthy VFs while slightly underestimating glaucomatous VFs. Qualitatively, SORS acquisition yielded VF with detectable defect patterns, albeit some isolated and small defects were occasionally missed.

Conclusions

This clinical study showed that for healthy and glaucomatous patients, SORS-acquired VFs sufficiently correlated with the DS-acquired VFs with up to 70% reduction in acquisition time.

Translational Relevance

This clinical study suggests that the novel perimetry strategy SORS could be used in routine clinical practice with comparable utility to the current standard DS, whereby providing a shorter and more comfortable perimetry experience.

Visual field findings after a ruptured intracranial aneurysm

BACKGROUND

Visual field defects (VFDs) negatively affect activities of daily living and rehabilitation following aneurysmal subarachnoid haemorrhage (aSAH). The aim here was to assess VFDs in patients with aSAH and their associations with age, gender, aSAH severity, and clinical outcome.

METHODS

Patients admitted to Helsinki University Central Hospital and treated during 2011 were participants in this prospective study. Findings obtained with the Octopus 900 perimeter (Haag-Streit Inc, Koenic, Switzerland), the Goldmann perimeter (Haag-Streit Inc, Bern, Switzerland), or the confrontation visual field test on admission and 3 days, 14 days, 2 to 4 months, and 6 months postoperatively were assigned to 16 classes. Associations between post-chiasmal VFDs and relevant clinical, radiological, and demographic data were analysed with uni- and multivariate logistic regression.

RESULTS

Of 105 survivors at 6 months, 20 (19 %) had VFDs occurring for aneurysm- or operation-related reasons; homonymous hemianopias or quadrantanopias were the most common finding, occurring in 16 patients (15 %). Posterior ischaemic optic neuropathy presented in two patients (2 %). Ten survivors (10 %) no longer fulfilled visual field requirements for driving licences. Significant associations emerged between VFDs at 6 months and the Hunt and Hess (H&H), World Federation of Neurosurgical Societies (WFNS), and Fisher grades on admission, presence of intracerebral haemorrhage (ICH), hydrocephalus, or postoperative infarction, and higher modified Rankin Scale scores at 6 months. Multivariate logistic regression showed the H&H grade and presence of ICH to independently predict VFDs.

CONCLUSIONS

Assessing VFDs is advisable, especially among patients with poor-grade aSAH (H&H grade IV or V) and ICH.

Rarebit perimetry for bedside testing: comparison with standard automated perimetry

BACKGROUND

Rarebit perimetry (RBP), a technique developed for the detection of early damage to the afferent visual system, has not been extensively tested at the bedside. This study was designed to test the feasibility of bedside testing with RBP in comparison with standard automated perimetry (SAP) performed in the clinic.

METHODS

We tested 29 eyes of 15 subjects admitted with neurologic or neurosurgical diseases affecting the afferent visual system. RBP was performed on a laptop computer at the bedside. SAP (Humphrey field analyzer) testing was performed later in the clinic. Results were evaluated by a masked neuro-ophthalmologist.

RESULTS

Visual fields corresponded between RBP and SAP in 21(72%) of the 29 tested eyes. RBP detected defects in 5 subjects who had normal visual field results on SAP. All subjects preferred RBP for convenience.

CONCLUSION

RBP is a convenient method of bedside visual field testing and is no less sensitive to visual field defects in this role than SAP.

Hypercholesterolemia is associated with visual field alterations detectable with computerized perimetry

Computerized perimetry analysis of the visual field enables the capacity of the visual cortex to process the electric impulse received from the eyeball to be detected. Considering that hypercholesterolemia can cause cognitive worsening by altering the functioning of the cerebral cortex, we attempted to determine whether it can affect the cortical processing of the visual stimuli, as detected by computerized perimetry. We undertook computerized perimetry analysis of 208 male and female patients (mean age, 48.5 years) with plasma low density lipoprotein (LDL) cholesterol concentrations above 3.36 mmol/L and compared the results with the same number of matched controls with LDL cholesterol concentrations below 3.36 mmol/L. No subject had any neuro-ophthalmological disease that could have affected the results. A Humphrey 745 computerized perimetry device was used to measure the mean deviation, the pattern standard deviation, the corrected pattern standard deviation, short-term fluctuations and the foveal threshold. Compared with the control subjects, the patients with hypercholesterolemia showed worsening in all the perimetry variables analyzed. Moreover, we also found a direct association between plasma LDL cholesterol concentrations and the perimetry alterations, and an inverse association between these alterations and the figures for HDL cholesterol. Our data show that computerized perimetry can detect alterations in the visual field of persons with hypercholesterolemia, suggesting that increased plasma concentrations of cholesterol may have a negative influence on the visual neuron cells.

Use of a portable head mounted perimetry system to assess bedside visual fields

AIM

This study was designed to test the ability of a portable computer driven, head mounted visual field testing system to perform automated perimetry on patients at their bedside and to compare these results with the "gold standard" for bedside examinations, confrontation visual fields.

METHODS

The Kasha visual field system is a portable automated perimeter which utilises a virtual reality headset. 37 neurosurgery patients were examined at their bedside with a central 24 degree suprathreshold testing strategy after confrontation visual field testing. The patterns of visual field defects were categorised and compared with the results of confrontation testing.

RESULTS

A total of 42 field examinations were completed on 37 patients, and the average testing time for both eyes was 4.8 minutes with the perimetry system. Each of the 11 fields (100%) classified with defects on confrontation testing was similarly categorised on head mounted perimetry. 26 out of 31 (84%) visual fields were normal on both confrontation and perimetry testing, while five out of the 31 fields (16%) which were full on confrontation had visual field defects identified by head mounted perimetry.

CONCLUSION

The head mounted, automated perimetry system proved easily portable and convenient for examining neurosurgical patients at their bedside in the perioperative period. The device demonstrated equal sensitivity to confrontation visual field testing methods in detecting field defects and offers the advantage of standardised, quantifiable testing with graphic results for follow up examinations.