Effect of intermittent versus continuous patient monitoring on reliability indices during automated perimetry

Remote Video Monitoring of Simultaneous Visual Field Testing

PRCIS

In this prospective interventional case series that included 474 patients, there were no significant differences in visual field (VF) parameters between fields from patients tested one-at-a-time and simultaneously, except for fixation losses.

PURPOSE

To test for differences in reliability and performance parameters of patients taking VF tests while using a remote patient monitoring system to supervise 1 or 2 test sessions simultaneously.

METHODS

In a prospective interventional case series, 861 eyes of 474 consecutive patients undergoing automated perimetry during a 6-month period were monitored during the test using an audio/video-enabled remote monitoring system. Two patients were simultaneously tested (simultaneous test) by a single technician if they were ready for testing at the same time. Patients were otherwise tested individually (single test). Performance and reliability parameters including false negatives, false positives, fixation losses, mean deviation, pattern standard deviation, VF index, and test duration were compared between patients undergoing simultaneous tests and single tests. Patients undergoing remotely monitored testing, for whom a prior VF could be found, had performance and reliability parameters compared with those prior tests. VFs were analyzed separately for 2 test strategies: SITA Standard 24-2 and SITA Faster 24-2C.

RESULTS

No significant parameter differences were observed among SITA Standard 24-2 VFs between single and simultaneous tests, except for fixation losses (single: 16.8±19.7%, simultaneous: 22.5±25.0%, P=0.01). Similarly, there were no significant differences observed among SITA Faster 24-2C tests. Paired analyses comparing remotely monitored VFs with prior traditionally monitored VFs showed no significant differences for any parameters, except for fewer fixation losses with remote monitoring (traditional: 23.6±27.5%, remote 17.7±20.8%, P=0.003).

CONCLUSIONS

Remote patient monitoring of VF testing enabled technicians to supervise testing of 2 patients simultaneously with preserved performance and reliability.

Factors Predicting a Greater Likelihood of Poor Visual Field Reliability in Glaucoma Patients and Suspects

Purpose

Identify factors predicting worse or better than expected visual field (VF) performance.

Methods

A total of 10,262 VFs from 1538 eyes of 909 subjects with manifest or suspected glaucoma were analyzed. Linear mixed-effects models predicted mean deviation (MD) at each timepoint. Differences between observed and predicted MD (ΔMD) were calculated and logistic regression identified factors predicting lower than expected (ΔMD <-1 dB) or higher than expected (ΔMD >1 dB) sensitivity.

Results

Both higher and lower than expected sensitivity were more likely in VFs with severe compared with mild damage (relative risk [RR] >1.3, P < 0.05). Higher than expected sensitivity was more likely in VFs with moderate damage (RR = 2.57, P < 0.001). False-positive (FP) errors increased the likelihood of higher than expected sensitivity at all disease stages (RR >2.1 per 10% increase, P < 0.001), whereas false-negative (FN) errors increased the likelihood of lower than expected sensitivity in mild and moderate disease (RR >1.19 per 10% increase, P < 0.05). Fixation loss errors slightly increased the likelihood of higher than expected VF sensitivity in moderate and severe disease (RR >1.1 per 10% increase, P < 0.01). Longer test duration increased likelihood of lower than expected sensitivity at all disease stages (RR >1.36 per minute increase, P < 0.001). Lower than expected sensitivity was more likely in late afternoon tests (RR = 1.27, P < 0.01). A total of 26.6% of VFs had higher or lower than expected sensitivity in the absence of FPs, FNs, or fixation losses.

Conclusions

FPs, test duration, and FNs are the primary measures predicting if a VF is likely to be reliable, although tests with normal reliability measures may still be unreliable. Our results help clinicians judge VF reliability and highlight the need to integrate reliability measures with other clinical data when making treatment decisions.

Translational Relevance

This likelihood model derived from a large dataset helps clinicians identify VFs that may either falsely suggest disease progression or mask true worsening, thereby improving the utility of VFs in clinical practice.

Robot Assistants for Perimetry: A Study of Patient Experience and Performance

Purpose

People enjoy supervision during visual field assessment, although resource demands often make this difficult. We evaluated outcomes and subjective experience of methods of receiving feedback during perimetry, with specific goals to compare a humanoid robot to a computerized voice in participants with minimal prior perimetric experience. Human feedback and no feedback also were compared.

Methods

Twenty-two younger (aged 21-31 years) and 18 older (aged 52-76 years) adults participated. Visual field tests were conducted using an Octopus 900, controlled with the Open Perimetry Interface. Participants underwent four tests with the following feedback conditions: (1) human, (2) humanoid robot, (3) computer speaker, and (4) no feedback, in random order. Feedback rules for the speaker and robot were identical, with the difference being a social interaction with the robot before the test. Quantitative perimetric performance compared mean sensitivity (dB), fixation losses, and false-positives. Subjective experience was collected via survey.

Results

There was no significant effect of feedback type on the quantitative measures. For younger adults, the human and robot were preferred to the computer speaker (P < 0.01). For older adults, the experience rating was similar for the speaker and robot. No feedback was the least preferred option of 77% younger and 50% older adults.

Conclusions

During perimetry, a social robot was preferred to a computer speaker providing the same feedback, despite the robot not being visible during the test. Making visual field testing more enjoyable for patients and operators may improve compliance and attitude to perimetry, leading to improved clinical outcomes.

Translational Relevance

Our data suggest that humanoid robots can replace some aspects of human interaction during perimetry and are preferable to receiving no human feedback.

Impact of Different Visual Field Instruction Strategies on Reliability Indices

PURPOSE

To investigate and compare the visual field performance following three different types of visual field instruction strategies.

METHOD

Ninety consecutive visual field-naïve glaucoma patients who can perform the test and understand instructions were imparted three forms of instructions prior to the visual field test. Patients with visual acuity <20/200, central corneal opacities, or anterior segment pathology and patients unable to understand general instructions/uncooperative were excluded. All forms of instructions were given by a trained optometrist in the patients' own language as an instruction leaflet read out in 5 min for a verbal group (group1) and by a 5 min video created in house (group 2). Group 3 patients were shown the video first, followed by verbal instructions. We evaluated the reliability parameters in each group after visual field testing by an independent optometrist blinded to the form of instruction given.

RESULTS

Among the three groups, group 3 patients had the least number of repeat tests. Eyes with MD<-12Db had better reliability than that of the other groups. Mixed-model linear regression analysis shows that the duration of the test was significantly influenced by the severity of glaucoma in group 1, which is further predisposed by false negatives (FN; β = 0.06, p < 0.0001, R² 61.7%).

CONCLUSION

The video with verbal instruction can minimize the number of repeated tests compared with only verbal or only video instruction medium. The video as well as the combined video/verbal instructions have a practical influence of obtaining more reliable fields compared with only verbal instruction.

Evidence-based Criteria for Assessment of Visual Field Reliability

PURPOSE

Assess the impact of false-positives (FP), false-negatives (FN), fixation losses (FL), and test duration (TD) on visual field (VF) reliability at different stages of glaucoma severity.

DESIGN

Retrospective.

PARTICIPANTS

A total of 10 262 VFs from 1538 eyes of 909 subjects with suspect or manifest glaucoma and ≥5 VF examinations.

METHODS

Predicted mean deviation (MD) was calculated with multilevel modeling of longitudinal data. Differences between predicted and observed MD (ΔMD) were calculated as a reliability measure. The impact of FP, FN, FL, and TD on ΔMD was assessed using multilevel modeling.

MAIN OUTCOME MEASURES

ΔMD associated with a 10% increment in FP, FN, and FL, or a 1-minute increase in TD.

RESULTS

FL had little impact on ΔMD (<0.2 decibels [dB] per 10% abnormal catch trials), and no level of FL produced ≥1 dB of ΔMD at any disease stage. FP yielded greater than expected MD, with a 10% increment in abnormal catch trials associated with a ΔMD = 0.42, 0.73, and 0.66 dB in mild (MD >-6 dB), moderate (-6 ≤MD <-12 dB), and severe (-12 ≤MD ≤-20 dB) disease, respectively, up to 20% abnormal catch trials, and a ΔMD = 1.57, 2.06, and 3.53 dB beyond 20% abnormal catch trials. FNs generally produced observed MDs below expected MDs. FN were minimally impactful up to 20% abnormal catch trials (ΔMD per 10% increment >-0.14 dB at all levels of severity). Beyond 20% abnormal catch trials, each 10% increment in abnormal catch trials was associated with a ΔMD = -1.27, -0.53, and -0.51 dB in mild, moderate, and severe disease, respectively. |ΔMD| ≥1 dB occurred with 22% FP and 26% FN in early, 14% FP and 34% FN in moderate, and 16% FP and 51% FN in severe disease. A 1-minute increment in TD produced ΔMDs between -0.35 and -0.40 dB.

CONCLUSIONS

FL have little impact on reliability in patients with established glaucoma. FP, and to a lesser extent FNs and TD, significantly affect reliability. The impact of FP and FN varies with disease severity and over the range of abnormal catch trials. On the basis of our findings, we present evidence-based, severity-specific standards for classifying VF reliability for clinical or research applications.

Levodopa as a possible treatment of visual loss in nonarteritic anterior ischemic optic neuropathy

PURPOSE

To determine the clinical effectiveness and potential neuroprotection of levodopa in improving visual acuity, visual field, and retinal nerve fiber layer (RNFL) thickness in eyes affected by NAION.

METHOD

Retrospective cohort study involving 59 eyes of 59 participants with NAION who were evaluated within 15 days of NAION onset. Participants received 25 mg carbidopa/100 mg levodopa three times daily with meals for 12 weeks (levodopa group) or were untreated (control group). Best-corrected visual acuity converted to logMAR, mean deviation (MD) threshold sensitivity on automated perimetry, and mean RNFL thickness on optical coherence tomography (OCT) were assessed. The primary outcome was the categorization of eyes into improved visual acuity (by 0.3 logMAR difference), worsened visual acuity (by 0.3 logMAR difference), or no change in visual acuity. The proportions in each category were compared between the levodopa and control groups.

RESULTS

Among participants with 20/60 or worse initial visual acuity, levodopa-treated participants had significant improvement (P < 0.0001) in the mean change from initial to final logMAR visual acuity of -0.74 ± 0.56 (95 % CI, -0.98 to -0.50), while the mean change for the control group at -0.37 ± 1.09 (95 % confidence interval estimate, -1.00 to +0.26) was not significant (P = 0.23). A significant difference between groups was observed (P = 0.0086) such that 19/23 (83 %) in the levodopa group improved and none got worse, as compared with 6/14 (43 %) in the control group improving while four (29 %) worsened. The change in visual field MD and RNFL thickness on OCT showed no significant difference at P = 0.23 and P = 0.75 respectively. No levodopa-treated participant had any adverse event from the levodopa.

CONCLUSIONS

Treatment within 15 days of onset of NAION with levodopa improved central visual acuity by an average of 6 lines on Snellen acuity chart. Levodopa may promote neuroprotection of the maculopapular retinal ganglion cell fibers in NAION.

Measuring visual function in age-related macular degeneration with frequency-doubling (matrix) perimetry

PURPOSE

To determine the agreement between the Humphrey Matrix perimeter 10-2 test and the 10-2 Humphrey Field Analyzer (HFA) test when assessing visual function in patients with age-related macular degeneration (AMD).

METHODS

Forty-two eyes of 42 subjects with AMD (average 75.0 years, SD=6.2: median visual acuity in logarithm of the minimum angle of resolution of 0.26, range, -0.12 to 1.04) were evaluated with the Matrix and HFA 10-2 visual field tests. Mean deviation (MD), pattern standard deviation, and test time were recorded. We calculated spatial concordance of individual test locations, being the proportion of spatially agreeing locations with identical classification (normal vs. abnormal, p < 5%) on the pattern deviation plot. As multiple HFA stimuli overlapped with some Matrix locations, several criteria for grouping HFA data into locations were investigated.

RESULTS

Both MD and pattern standard deviation were significantly correlated for the two devices (r(2)=0.79 and r(2)=0.80, respectively, p<0.0001). Using our standard criterion for abnormal HFA locations (≥50% stimuli abnormal), the median spatial concordance was 0.76, with 95% of tests giving a concordance of ≥0.59. A small, but significant, increase in concordance occurred when a stricter criterion (all stimuli abnormal at a location) was applied. Median fixation loss percentages were 7 and 0% for the HFA and Matrix, respectively. Visual acuity in logarithm of the minimum angle of resolution showed modest correlations with both defect depth (HFA MD: r(2)=0.39, p<0.0001) and size of defect (number of abnormal points on the HFA: r(2)=0.24, p<0.0001).

CONCLUSIONS

Using a simple metric to calculate spatial concordance, the Matrix 10-2 test quantifies the spatial extent of significant depression of the central visual fields in AMD in a manner similar to the HFA 10-2. The spatial extent and depth of central visual field loss in AMD are only modestly predicted by visual acuity measurements.

Comparison of the ASA, MOBS, and ZEST threshold methods

The modified binary search, or MOBS, technique is an adaptive, non-parametric procedure for estimating thresholds [Tyrrell, R. A, & Owens, D. A. (1988). A rapid technique to assess the resting states of eyes and other threshold phenomena: the modified binary search (MOBS). Behavior Research Methods, Instruments, and Computers, 20, 137-141.], which has recently been incorporated into a commercially available perimeter. Information regarding the performance of this technique is limited, however. We performed Monte Carlos simulations on the MOBS procedure, as well as on a Zippy Estimation by Sequential Testing, or ZEST, procedure (King-Smith, Grigsby, Vingrys, Benes & Supowit, 1994) and an Accelerated Stochastic Approximation, or ASA, procedure (Kesten, 1958) for comparison. The efficiency, convergence probability, and robustness to false positive and false negative responses were determined. Differences between the three procedures typically were small, the most prominent being the number of presentations required to estimate threshold.

Effect of a patient training video on visual field test reliability

AIMS

To evaluate the effect of a visual field test educational video on the reliability of the first automated visual field test of new patients.

METHODS

A prospective, randomised, controlled trial of an educational video on visual field test reliability of patients referred to the hospital eye service for suspected glaucoma was undertaken. Patients were randomised to either watch an educational video or a control group with no video. The video group was shown a 4.5 minute audiovisual presentation to familiarize them with the various aspects of visual field examination with particular emphasis on sources of unreliability. Reliability was determined using standard criteria of fixation loss rate less than 20%, false positive responses less than 33%, and false negative responses less than 33%.

RESULTS

244 patients were recruited; 112 in the video group and 132 in the control group with no significant between group difference in age, sex, and density of field defects. A significant improvement in reliability (p=0.015) was observed in the group exposed to the video with 85 (75.9%) patients having reliable results compared to 81 (61.4%) in the control group. The difference was not significant for the right (first tested) eye with 93 (83.0%) of the visual fields reliable in the video group compared to 106 (80.0%) in the control group (p = 0.583), but was significant for the left (second tested) eye with 97 (86.6 %) of the video group reliable versus 97 (73.5%) of the control group (p = 0.011).

CONCLUSIONS

The use of a brief, audiovisual patient information guide on taking the visual field test produced an improvement in patient reliability for individuals tested for the first time. In this trial the use of the video had most of its impact by reducing the number of unreliable fields from the second tested eye.

Levodopa may improve vision loss in recent-onset, nonarteritic anterior ischemic optic neuropathy

OBJECTIVE

To study the effect of levodopa in improving visual function in patients treated within 45 days of onset of nonarteritic anterior ischemic optic neuropathy (NAION).

DESIGN

Nonrandomized, retrospective, comparative trial.

PARTICIPANTS

The study involved 37 patients with NAION of less than 45 days duration.

METHODS

Eighteen patients who had been treated with levodopa were assigned to the case group, and 19 untreated patients were assigned to the control group. Snellen visual acuity converted to logMAR and mean deviation on Humphrey automated perimetry (Program 24-2, Humphrey Instruments, San Leardro, CA) were evaluated at the initial and 6-month visits.

INTERVENTION

The 18 patients in the case group were administered a capsule of 100 mg levodopa/25 mg carbidopa (Sinemet 25-100) three times daily for 3 weeks.

MAIN OUTCOME MEASURES

The primary outcome measures were changes in visual acuity and visual field at 6 months from baseline. Improvement in visual acuity was defined as a difference of -0.3 logMAR or less between the 6-month and initial visual acuities, whereas worsened visual acuity was a difference of +0.3 logMAR or more. Each 0.3 LogMar represented a doubling of the visual angle, i.e., a change by three lines on the eye chart. Improvement in visual field was defined as a difference in mean deviation of +3.0 dB or more between the 6-month and initial visual field tests, whereas worsened visual field was a difference in mean deviation of -3.0 dB or less.

RESULTS

The proportions of patients with worsened, unchanged, and improved visual acuity at 6 months were compared for the levodopa and control groups. There was a significant difference (P = 0.012) between the groups. Examination of the proportions showed that a higher proportion of patients who received levodopa had improved visual acuity with a corresponding lower proportion having worsened visual acuity as compared with the control patients. Ten of 13 patients (76.9%) in the levodopa group with 20/40 visual acuity or worse at baseline had improved visual acuity at 6 months, and none of the 18 patients had worsened visual acuity. In contrast, 3 of 10 control patients (30%) with 20/40 visual acuity or worse at baseline had improved visual acuity at 6 months, and 3 of 19 control patients (16.3%) had worsened visual acuity. The proportions of patients with worsened, unchanged, and improved visual fields at 6 months were compared for the levodopa and control groups. There was no significant difference between the groups (P = 0.25).

CONCLUSIONS

Patients treated with levodopa within 45 days of onset of NAION were more likely to experience improvement and less likely to have worsened visual acuity than untreated patients. Levodopa appears to be beneficial in the treatment of recent-onset NAION.

Analysis of reliability indices from Humphrey visual field tests in an urban glaucoma population

PURPOSE

Visual field assessment is extremely important in glaucoma management, but interpretation is affected by the quality of the patient's performance. The authors have investigated the reliability of visual field performance by a randomly selected sample of the chronic glaucoma population at an urban tertiary care practice.

METHODS

Patient reliability in Humphrey automated visual field testing was studied in 106 randomly selected chronic open-angle glaucoma patient charts, which provided 768 tests (mean, 7.2 +/- 4.8 fields; range, 2-18 fields). Reliability criteria were established as less than 20% fixation losses, less than 33% false-negative error, and less than 33% false-positive error, as recommended by Humphrey Instruments, Inc (San Leandro, CA).

RESULTS

Patients performed reliably in 61% of right eye fields, 58% of left eye fields, and 59.5% overall. Of the 106 patients, only 35 (33%) were always reliable in both eyes, whereas 8 (7.5%) were always unreliable in both eyes. The most common cause of unreliability was fixation loss (39%), whereas false-positive error (5%) and false-negative error (9%) were less frequent. A more severely depressed mean deviation correlated significantly with poorer performance on the three reliability indices, with false-negative error having the greatest correlation, followed by fixation loss and false-positive error. Corrected pattern standard deviation correlated closely only with false-negative error. Prolonged test time also correlated with all three reliability indices. Age was a significant factor for fixation loss but not for false-negative or false-positive error.

CONCLUSIONS

The authors conclude that fewer than two thirds of the Humphrey visual fields were reliable with the authors' urban tertiary care population of patients with glaucoma. Relaxing the fixation loss criterion to less than 33% improved the rate of reliability to approximately 75%. The severity of glaucomatous visual field defects, test time, and age were identified as factors influencing the reliability of the Humphrey visual fields.

Effect of levodopa and carbidopa on recovery of visual function in patients with nonarteritic anterior ischemic optic neuropathy of longer than six months' duration

PURPOSE

We conducted a pilot clinical trial to determine the efficacy of levodopa in promoting visual recovery in eyes with nonarteritic anterior ischemic optic neuropathy of greater than six months' duration.

METHODS

This prospective, randomized, double-masked, placebo-controlled clinical trial involved 20 subjects with nonarteritic anterior ischemic optic neuropathy of 30 months' mean duration. Subjects were randomly assigned to receive either low-dose levodopa and carbidopa or a placebo for three weeks. At 12 weeks after the baseline visit, the levodopa group then was provided a higher, conventional dose of levodopa and carbidopa for three more weeks. Change in visual function was monitored at four, 12, 16, and 24 weeks after the baseline visit.

RESULTS

At 12 weeks after the baseline visit, the levodopa group experienced a significant (P = .016) mean difference in improvement of visual acuity of 5.9 letters from the placebo group. At 24 weeks after the baseline visit, a significant treatment effect (P = .036) for visual acuity was still evident; the levodopa group had a mean gain in improvement of 7.5 letters difference from baseline from the placebo group. Three subjects in the levodopa group experienced a doubling of the visual angle as denoted by a gain of at least 15 letters. Significant improvement was not observed for color vision (P = .82) or mean deviation of visual field loss (P = .82).

CONCLUSION

The study found significant improvement of visual acuity among subjects receiving levodopa and carbidopa despite long-standing visual loss from nonarteritic anterior ischemic neuropathy. Confirmation of our results is awaited from larger population studies and with a longer follow-up time interval regarding the efficacy of levodopa in reversing visual loss in this disease.

Confrontation visual field loss as a function of decibel sensitivity loss on automated static perimetry. Implications on the accuracy of confrontation visual field testing

PURPOSE

To evaluate the accuracy of confrontation visual field testing with regard to the density of the visual field defect and its location in the peripheral visual field.

METHODS

A prospective comparison of confrontation visual field testing with full-threshold Humphrey automated static perimetry C24-2 or C30-2 was conducted at a university eye center over a 3-month period. Seventy-two patients with a variety of neurologic and ophthalmologic conditions underwent confrontation visual field testing and automated perimetry as a part of their evaluation. One visual field from each patient was analyzed for this study.

RESULTS

Confrontation visual field testing yielded an overall sensitivity for detecting an abnormal visual field (full-field analysis) of 63%, when sensitivity of confrontation testing rested on the detection of just one abnormal quadrant. The sensitivity of confrontation testing varied depending on the type of visual field loss present: 51% for arcuate scotomas, 67% for visual field constriction, 78% for altitudinal scotomas, and 90% for hemianopias. The sensitivity of detecting abnormal visual field quadrants, rather than the full-field analysis, was, however, poor at 38%. The sensitivity of confrontation testing was lower for superior quadrant defects and higher for inferior quadrant defects. The estimated probability of detecting an abnormal visual field quadrant occurring at a -26-decibel sensitivity loss from age-matched healthy patients for superior quadrant defects and a -19-decibel sensitivity loss for inferior quadrant defects was 50%. The increased sensitivity noted for visual field defects and for inferior quadrant defects appears to be related, in part, to the density of the visual field loss present.

CONCLUSION

Confrontation visual field testing is relatively insensitive unless a moderate to dense defect is present, and as such is a poor screening test. However, when visual field defects are identified with confrontation visual field testing, the defects often are real as per the high specificity (97%) and high positive predictive value (96%).