Virtual clinics for glaucoma care - Patients' and clinicians' experiences and perceptions: a qualitative evaluation.

BACKGROUND: The role of glaucoma virtual clinics has developed to help meet demand for capacity within busy glaucoma services. There is limited research of patient and clinician experiences and perceptions of these clinics and the aim of this study is to provide further information to help improve patient experience and guide service delivery. METHODS: A mixed methods research design was employed comprising of a patient satisfaction survey, and patient and clinician interviews. Consultant ophthalmologists were recruited from throughout the UK, and patients and data gathering clinical staff recruited from the Manchester Royal Eye Hospital and Bristol Eye Hospital. RESULTS: We received a total of 148 patient satisfaction questionnaires with an overall response rate of 55.4%. Most respondents were diagnosed with primary open angle glaucoma (33.9%) at Manchester and glaucoma suspect status at Bristol (50.6%). Patients had high levels of confidence in the person conducting the tests (94.8% Manchester, 98.8% Bristol), and most were likely to recommend the service to family or friends (94.8% Manchester, 92.6% Bristol). We interviewed 10 consultant ophthalmologists, 10 data gathering staff and 20 patients. A number of key themes emerged from the transcribed interviews including: patient experience, clinician perception of patient experience, service delivery, staffing and staff experience, and patient safety. CONCLUSIONS: Glaucoma virtual clinics can be acceptable to both clinicians and patients, including those with a varied complexity of glaucoma and glaucoma-related disease. Dissatisfaction seemed to relate to poor communication or processes and systems within the service rather than complexity of disease.

Defining stable glaucoma: a Delphi consensus survey of UK optometrists with a specialist interest in Glaucoma.

BACKGROUND: Increasing demand on hospital services has led to the development of alternative community-based services, often run by optometrists for monitoring 'stable' and low-risk glaucoma patients. METHODS: An online Delphi exercise was undertaken to derive a consensus definition of 'stable glaucoma' amongst optometrists with a special interest in glaucoma. Participants were asked to score their agreement for various clinical parameters. Results from each round were used to inform subsequent rounds. RESULTS: 31 optometrists participated in the study. 100%, 77%, and 68% completion rates were achieved over three rounds respectively. Consensus was reached for 7 parameters: Stability should be defined over a period of 36-48 months, summary measure Visual Field (VF), and/or Trend Analysis should be used to assess VF stability. Two or more decibel (dB) of change of VF mean deviation (MD) is considered unstable. Intraocular pressure (IOP) should be below a target defined by the patient's clinician or a fixed-percentage reduction compared to the presenting IOP. No treatment change during the stability assessment period is considered stable. Imaging with Ocular Coherence Topography Retinal Nerve Fibre Layer (OCT RNFL) assessment should be used to define glaucoma stability. Overview by a glaucoma consultant was considered important for glaucoma monitoring schemes. CONCLUSION: This Delphi exercise has generated a consensus definition for glaucoma stability by UK Optometrists with a specialist interest in glaucoma. This consensus definition can be used to inform the selection of suitable patients from hospital services for transfer to monitoring in community-based 'stable' optometry run glaucoma clinics.

Care pathways for glaucoma detection and monitoring in the UK.

Glaucoma presents considerable challenges in providing clinically and cost-effective care pathways. While UK population screening is not seen as justifiable, arrangements for case finding have historically been considered relatively ineffective. Detection challenges include an undetected disease burden, whether from populations failing to access services or difficulties in delivering effective case-finding strategies, and a high false positive rate from referrals via traditional case finding pathways. The enhanced General Ophthalmic Service (GOS) in Scotland and locally commissioned glaucoma referral filtering services (GRFS) elsewhere have undoubtedly reduced false positive referrals, and there is emerging evidence of effectiveness of these pathways. At the same time, it is recognised that implementing GRFS does not intrinsically reduce the burden of undetected glaucoma and late presentation, and obvious challenges remain. In terms of diagnosis and monitoring, considerable growth in capacity remains essential, and non-medical health care professional (HCP) co-management and virtual clinics continue to be important solutions in offering requisite capacity. National guidelines, commissioning recommendations, and the Common Clinical Competency Framework have clarified requirements for such services, including recommendations on training and accreditation of HCPs. At the same time, the nature of consultant-delivered care and expectations on the glaucoma specialist's role has evolved alongside these developments. Despite progress in recent decades, given projected capacity requirements, further care pathways innovations appear mandated. While the timeline for implementing potential artificial intelligence innovations in streamlining care pathways is far from established, the glaucoma burden presents an expectation that such developments will need to be at the vanguard of future developments.

Acceptability and use of glaucoma virtual clinics in the UK: a national survey of clinical leads.

OBJECTIVE: The purpose of this paper is to describe the findings of a national survey that aimed to estimate the proportion of Hospital Eye Service (HES) units using glaucoma virtual clinics, to determine how these services differ and to gauge clinicians' views and opinions on the safety and acceptability of this model of care compared with usual care. METHODS AND ANALYSIS: This 12-question survey was disseminated nationally to 92 clinical lead consultant ophthalmologists using SurveyMonkey. RESULTS: The response rate was 45.7%. There were 21 out of the total 42 respondents (50.0%) who were based at an NHS Trust where glaucoma virtual clinics were already being used and a further 9 (21.4%) were planning to establish one. Clinical leads largely rated efficiency and patient safety to be at least equivalent to usual care (92.9%) and 81.0% perceived glaucoma virtual clinics to be acceptable to patients. The main reasons for not running glaucoma virtual clinics were insufficient staff (71.4%) and inadequate space (47.6%). The majority of those running virtual clinics used this model of care for 'lower risk' patients such as ocular hypertensives (90.5%) and glaucoma suspects. CONCLUSION: Glaucoma virtual clinics are employed by a large proportion of HES units, with many seeking to develop such services. Clinical leads largely rate efficiency, patient safety and the perception of patient acceptability to be at least equivalent to usual care.

Analysis of the diurnal intraocular pressure profile pre and post trabeculectomy using 24-hour monitoring of intraocular pressure.

PURPOSE: To compare the diurnal intraocular pressure (IOP) profile pre and post trabeculectomy with a control group of medically controlled patients. We compared the change in mean, peak, and diurnal IOP fluctuation. METHODS: This was an observational study of patients at the Bristol Eye Hospital, United Kingdom. All patients underwent initial and subsequent phasing, with surgery between for cases. The unpaired Student t test compared the changes (initial-subsequent) in mean, peak, and fluctuation between cases and controls. RESULTS: Fifteen eyes underwent trabeculectomy surgery while the control group contained 17 eyes controlled on topical medical treatment. There was a statistically significant reduction in both mean IOP of 3.7 mmHg (p=0.002) and peak IOP of 4.4 mmHg (p=0.025) in the surgical group compared to the medical group. There was no statistically significant change in the IOP fluctuation between the 2 study groups (p=0.296). CONCLUSIONS: There is a significant reduction in mean IOP and peak IOP following trabeculectomy. We showed no statistically significant change in the diurnal fluctuation of IOP following trabeculectomy.

Technical Note: grading the vertical cup:disc ratio and the effect of scaling.

PURPOSE: To evaluate the effect of scaling on sensitivity to change for grading the vertical cup:disc ratio (CDR). METHODS: Vertical CDR was assessed by six observers (three ophthalmologists and three optometrists) on 43 stereo disc photographs. Repeated observations were made for both 0.1 and 0.05 interval scales. Paired differences were calculated for all observers and each observer separately. Mean and standard deviation of differences and agreement statistics were used to compare scales. RESULTS: Five observers demonstrated a reduction in the spread of differences (mean difference 0.19 to 0.15) and all observers demonstrated a reduction in concordance using the finer scale (mean concordance 54% to 39%). CONCLUSION: The use of a finer scale reduces test-retest variability and increases sensitivity to change when estimating the vertical CDR. Use of this scale does not require any additional resource and it may be easily implemented in routine clinical practice.

Normal age-related sensitivity loss for a variety of visual functions throughout the visual field.

PURPOSE: The purpose of this study is to compare the rate of age-related decline, the magnitude of practice effects, and test-retest variability among normal subjects using six different tests of visual function. METHODS: One hundred normal subjects aged between 20 and 85 were enrolled in the study. Six visual field test procedures were used consisting of standard automated perimetry (SAP), short wavelength automated perimetry (SWAP), temporal modulation perimetry (TMP), frequency-doubling technology perimetry (FDT), detection acuity perimetry (DAP),and resolution acuity perimetry (RAP). To facilitate direct comparison, the results for each test were divided by that test's estimated dynamic range. RESULTS: Of the three tests used clinically most commonly, SWAP exhibited the greatest aging and practice effects and test-retest variability followed by FDT with SAP exhibiting the least. RAP was the most variable test followed by TMP. CONCLUSIONS: These results should be taken into account when evaluating glaucomatous loss using different functional tests and when comparing the performance, predictive power, and speed of detection of the different tests.

Characteristics of the normative database for the Humphrey matrix perimeter.

PURPOSE: The Humphrey Matrix (Carl Zeiss Meditec, Dublin CA; Welch-Allyn, Skaneateles, NY) is a high-spatial-resolution perimeter that uses frequency-doubling stimuli. It incorporates an efficient test strategy that assumes that age, eccentricity, and test procedure type have only small effects on sensitivity. The results used to create the normative database for the perimeter were examined, to see whether these assumptions were met and to examine the form of the normative data. METHOD: Visual fields were measured (Matrix 30-2, 24-2, 10-2 and Macula patterns) in >275 subjects judged to be normal by a battery of clinical procedures. The right eye was always tested first. RESULTS: Sensitivity decreased by approximately 0.7 dB per age decade across all eccentricities; sensitivity decreased with eccentricity, typically by <5 dB at the most peripheral points tested. Although there was no systematic difference in sensitivity between the 30-2 and 24-2 tests, the Macula test sensitivities were typically 1 dB higher than for the 10-2 test. Sensitivity in the left eye was slightly lower than in the right, with the difference being significantly greater in the temporal visual field. In most test locations, the 95% confidence interval of normal sensitivity was approximately 6 dB below the median sensitivity. CONCLUSIONS: The performance of the test strategy in the Matrix perimeter is appropriately matched to the response characteristics of the normal population. The finding of a spatially nonuniform difference in sensitivity between left and right eyes is attributable to light-adaptation differences between the eyes. This effect is accounted for in the perimeter's normative database.

Psychophysical investigation of ganglion cell loss in early glaucoma.

PURPOSE: To evaluate ganglion cell loss in early glaucoma using a variety of psychophysical tests and to identify optimal perimetric technique(s) for detection of early glaucomatous visual function loss. METHODS: Five perimetric tests, short wavelength automated perimetry (SWAP), temporal modulation perimetry (TMP), frequency doubling technology perimetry (FDT), detection acuity perimetry (DAP), and resolution acuity perimetry (RAP) were compared in their ability to discriminate between normal individuals and patients with early glaucoma or glaucoma suspects. Comparisons were also made by their ability to produce repeatable defects. The tests examined different visual functions that are likely to be mediated by different retinal ganglion cell subpopulations, thereby permitting examination of hypotheses of ganglion cell death in early glaucoma. RESULTS: All visual field tests demonstrated high performance in separating glaucoma patients from normal individuals. SWAP, TMP, FDT, and DAP provided the greatest discrimination between normal individuals and high- and low-risk glaucoma suspects. However, SWAP, TMP, and FDT obtained better consistency across the various analysis approaches (global indices and pointwise) than DAP and RAP. Of all the test types, FDT exhibited the highest proportion of repeatable abnormal test locations, with poor confirmation rates achieved by DAP and RAP. CONCLUSION: The performance of SWAP, FDT, and TMP suggests that these test types may all be suitable for detection of early loss of visual function in glaucoma. Ganglion cell subpopulations with lower levels of redundancy and/or those with larger cell sizes offer the most parsimonious explanation for earliest ganglion cell losses occurring in glaucoma.

Polymorphisms in OPA1 are associated with normal tension glaucoma.

PURPOSE: [corrected] To confirm whether specific polymorphisms in intron 8 (IVS8) of the OPA1 gene are found more commonly in patients with normal tension glaucoma (NTG) compared to normal controls. METHODS: This is a cohort study of 61 patients with NTG, 49 known healthy controls and 119 individuals from the general population. The DNA sequence was determined at the +4 and +32 positions of IVS8 of the OPA1 gene. Hardy-Weinberg equilibrium was confirmed in our population by comparing the allele frequencies in two additional genes, TP53 and TYRP1. Genotypes for the NTG and control groups were compared for statistically significant differences. RESULTS: There were no differences in the OPA1 genotypes of the NTG and control groups at the +4 location, as had been suggested in a previous study, but a significant difference was observed at the +32 location of IVS8. The CC genotype was found in 28% of NTG patients compared to 13% of controls (p=0.006). The TC genotype was more prevalent in the control population (p=0.02) but this difference did not reach statistical significance when the Bonferroni adjustment was made for multiple analyses. CONCLUSIONS: We have refined the previously reported association between OPA1 sequence changes and NTG by identifying a specific CC genotype at position +32 in IVS8 of the OPA1 gene that acts as a marker for NTG. At the current time, NTG is frequently diagnosed late when loss of neurons has already caused significant and irreversible peripheral field loss. If a test could be designed to identify those people at risk of developing NTG, then careful screening might detect earlier signs of disease allowing commencement of treatment before significant field loss has occurred.

Within-test variability of frequency-doubling perimetry using a 24-2 test pattern.

PURPOSE: To evaluate patient-response (within-test) variability for targets of the smaller frequency-doubling technology perimetry test that employs a 24-2 stimulus-presentation pattern. METHODS: Patient-response variability was examined using the method of constant stimuli for standard (10 degrees ) and small (4 degrees ) customized frequency-doubling technology perimetry stimuli presented on a CRT screen. Small stimuli were designed for use in a 24-2 test pattern. Matched test locations were examined in 24 subjects (8 normal, 8 in whom glaucoma was suspected, and 8 glaucoma patients). Threshold sensitivity (in decibels for the 50% detection level) and variability (interquartile range in decibels) were obtained from frequency-of-seeing curves derived from data fitting with cumulative Gaussian functions. Groups were compared using a two-way ANOVA. RESULTS: Thresholds obtained using standard and small stimuli were highly correlated (R = 0.94, P < 0.001, Pearson correlation), although smaller targets systematically estimated sensitivity to be 2.0 dB (95% CI, 1.7-2.4 dB) lower than standard targets. No significant difference in patient-response variability was observed between standard and small targets (P = 0.067), although both target sizes demonstrated small but significant increases in variability with reduced sensitivity. Mean (SD) patient-response variability for the normal, suspect, and glaucoma groups was 1.0 (0.6), 0.9 (0.4), and 1.8 (1.4) dB for standard-sized stimuli and 1.1 (0.8), 1.5 (1.2), and 2.0 (0.9) dB for small stimuli. CONCLUSIONS: Small (4 degrees ) frequency-doubling technology perimetry targets have variability characteristics that are not statistically significantly different from those observed for standard-sized (10 degrees ) stimuli. Reduction in frequency-doubling technology perimetry stimulus size necessary to produce 24-2 test resolution is unlikely to affect test repeatability. Smaller, more numerous stimuli may offer clinical advantages both in terms of detecting small defects and identifying progressive loss.

Identification of progressive glaucomatous visual field loss.

In normal individuals, visual field measures are not perfectly repeatable and individual test locations exhibit both short- and long-term sensitivity variations. This physiologic variability is greatly increased in glaucoma and confounds detection of real progressive loss in visual function. Distinguishing progressive glaucomatous visual field loss from test variability therefore represents a complex task. Procedures used for detection of glaucomatous visual field progression may be broadly grouped into four categories: 1) clinical judgment, which consists of simple subjective observation of sequential visual field test results; 2) defect classification systems, whereby specific criteria are used to stratify field loss by discrete score and define progression as score change over time, such as the Advanced Glaucoma Intervention Study scoring system; 3) trend analyses, which follow test parameters sequentially over time to determine the magnitude and significance of patterns within the data, for example linear regression; and 4) event analyses, which identify single events of significant change relative to a reference examination. All of these methods demonstrate distinct benefits and drawbacks, making each useful in specific circumstances, although no single method appears universally ideal. At the present time the best method of detection of progression may be to rely upon confirmation of change at successive examinations and also by correlation of visual field changes with other clinical observations. Alternative analysis methods may become available in the near future to help identify cases of progressive loss.

The effect of ocular dominance on visual field testing.

PURPOSE: During standard automated perimetry (SAP), some patients experience visual disturbances in the tested eye while the other eye is covered with an opaque occluder. It is possible that a binocular interaction producing an inhibitory response in the nonoccluded eye, such as rivalry or Ganzfeld blankout, may be the causative factor, particularly when the dominant eye is occluded. The objective of this experiment was to determine whether subjective visual disturbances occurring during conventional perimetric test conditions were related to ocular dominance and to investigate the effect of these disturbances on measurements made during threshold visual field analysis. METHOD: Ocular dominance was determined by questioning and objective testing on 55 normal subjects. Each subject underwent program 24-2 Full Threshold SAP on a Humphrey Field Analyzer, and an opaque black patch was used to occlude the nontested eye. After testing, patients were asked to report symptoms of visual disturbance characteristic of rivalry or blankout, and the relationship between ocular dominance and visual disturbances was investigated. To determine whether symptoms of rivalry or blankout had affected visual field quantification, comparisons of short-term fluctuation, mean deviation, and false-negative errors were performed between eyes with and without visual disturbances. RESULTS: A total of 24 of 55 subjects reported visual disturbances consistent with rivalry or blankout (44%). Sixteen subjects complained of the phenomenon in one eye, and eight complained of the phenomenon in both eyes. Of the 16 experiencing disturbances in one eye only, nine cases occurred during occlusion of the dominant eye. The association between ocular dominance and visual disturbances was not found to be significant (p > 0.10). No significant differences in short-term fluctuation (p = 0.78), mean deviation (p = 0.64), or false-negative errors (p = 0.10) were found between eyes with and without visual disturbances. CONCLUSIONS: Patients undergoing standard automated perimetry with opaque patch occlusion of the nontested eye often experience visual disturbances consistent with rivalry or blankout, although these disturbances do not cause increased within-test variability or reduced sensitivity as quantified by visual field global indices. In terms of summary visual field indices, ocular dominance does not appear to affect visual field test results.

Spatial and temporal processing of threshold data for detection of progressive glaucomatous visual field loss.

OBJECTIVE: To evaluate the effect of spatial and temporal filtering of threshold visual field data on the ability of pointwise linear regression (PLR) to detect progressive glaucomatous visual field loss. METHODS: Longitudinal visual field data (Full-Threshold Program 30-2 test point pattern) were simulated using a computer model of glaucomatous visual field progression. This approach permitted construction of a "gold standard" because matching visual field data without variability could be generated and analyzed. Four clustered progressive defects were produced, consisting of 2, 3, 9, and 18 locations, respectively, each with progression rates of -1 and -2.5 dB/y. Pointwise linear regression was used to identify progressive test locations (criterion for progression of statistically significant slope of < or =-1 dB/y, P<.05). Each visual field series was analyzed after the following 3 procedures: (1) no filtering (unprocessed data), (2) Gaussian spatial possessing (3 x 3 grid), and (3) temporal processing (2 field moving average). The effect of spatial and temporal processing on PLR discriminatory power for progression detection was quantified by comparison with the gold standard. RESULTS: Spatial processing reduced PLR sensitivity to levels below that achieved for analysis of unprocessed data for small progressive defects (< or =9 locations) or at the low true progression rate (-1 dB/y). Under these conditions, spatial processing caused small PLR specificity improvement. Spatial processing only improved PLR sensitivity above unprocessed levels when progressive defects were large and changing rapidly (progression rate of -2.5 dB/y). Temporal processing gave consistent PLR improvement in sensitivity for all defect sizes and true progression rates. Pointwise linear regression sensitivity gain provided by temporal processing allowed progression to be detected 2 to 3 visual fields earlier than for analysis of raw data. Specificity dropped slightly as a result of temporal processing but remained at 89% or above for all conditions studied. CONCLUSIONS: Gaussian spatial processing reduces PLR discriminatory power with low true progression rates or small progressive defect sizes and, therefore, is of limited use for detection of progressive visual field loss. Temporal processing improves the sensitivity of PLR and reduces the number of tests required to detect progressive loss with minimal loss of specificity. CLINICAL RELEVANCE: Image processing techniques can be applied to threshold visual field data to enhance sensitivity or specificity of PLR for the determination of progressive change. This investigation demonstrates that temporal processing may assist with the detection of significant progressive visual field loss with fewer test results than unprocessed data.

Sensitivity differences between real-patient and computer-stimulated visual fields.

PURPOSE: The authors sought to verify computer simulation of visual fields by comparing thresholds of real and corresponding simulated visual fields. METHODS: Four patients with stable glaucomatous visual fields and three patients with progressing glaucomatous visual fields were chosen for the study. Visual fields had been recorded at 6-month intervals for 5 to 7.5 years. A previously described computer simulation program was used to generate a corresponding simulated visual field for each of the real fields. Twenty different levels of response variability and long-term variability were used in the simulations. Pointwise sensitivity differences between real and simulated fields were calculated. The average difference and 95% interval of the differences were analyzed for the different simulation conditions, for the pointwise sensitivities in the real patient fields, and to determine whether the field was stable or progressing. RESULTS: In almost all simulation conditions, the average pointwise sensitivity differences ranged from -1 to 1 dB and were not significantly different among different simulation conditions. The 95% interval of the average difference increased significantly with response variability, whereas long-term variability failed to show any apparent effect. Average pointwise differences and the 95% intervals were greatest in locations where the real-patient field had reduced sensitivity of 14 dB or worse. CONCLUSION: The simulation program provided good estimates of visual field sensitivities. Increasing amounts of response, but not long-term variability, produced a linear increase in the variability of threshold sensitivities. This finding implies that short-term rather than long-term fluctuation is the most important factor determining the variability of thresholds.