David Crabb

City, University of London · Division of Optometry and Visual Science

Background/aims To elicit the preferences and calculate the willingness to pay (WTP) of patients with ocular hypertension (OHT) for eye monitoring services in the UK. Methods Patients with OHT aged at least 18 years recruited from four NHS ophthalmology departments were included in the study. Patients’ preferences and WTP for an OHT monitoring ser...

Background Charles Bonnet syndrome (CBS) is a condition characterised by the occurrence of vivid and complex visual hallucinations in individuals with visual impairment. Objective To explore the relationship between emotional distress and the perceived impact of CBS symptoms on participants’ lives. We tested the hypothesis that heightened negative...

Background/Aims To assess the cost-effectiveness of making treatment decisions for patients with ocular hypertension (OHT) based on a risk prediction (RP) tool in the United Kingdom. Methods A discrete event simulation model was constructed to compare the cost-effectiveness of an alternative care pathway in which the treatment decision was guided...

Background The use of patient-reported outcome measures (PROMs) in clinical research increases and use of heterogeneous instruments reflects how well diverse traits are captured by a medical specialty. In order to reflect the heterogeneity of current PROM use in ophthalmology, we reviewed the available literature. Methods The medical literature da...

Objective To investigate the views, hopes and concerns of patients living with glaucoma and age-related macular degeneration (AMD) regarding vision home-monitoring. Design Qualitative study using focus groups and questionnaires. Participants were given three disease-relevant home-monitoring tests to try. The tests consisted of three visual field t...

Purpose We sought to develop and evaluate a practical framework that supports structurally enhanced perimetric examinations. Methods Two perimetric strategies were compared: standard Zippy Estimation through Sequential Testing (ZEST) procedure, a traditional visual field test with population-based prior distributions, and structural-ZEST (S-ZEST),...

Background Cataract waiting lists are growing globally. Pragmatic, cost-effective methods are required to prioritise the most urgent cases. Here we investigate the feasibility of using a third-party pen-and-paper contrast sensitivity, CS, test (SpotChecks TM ), delivered by mail, and performed by patients at home unsupervised, to flag eyes requirin...

Purpose: The purpose of this study was to estimate the distribution of the true rates of progression (RoP) of visual field (VF) loss. Methods: We analyzed the progression of mean deviation over time in series of ≥ 10 tests from 3352 eyes (one per patient) from 5 glaucoma clinics, using a novel Bayesian hierarchical Linear Mixed Model (LMM); this...

Purpose: To investigate whether intraocular pressure (IOP) fluctuation is independently associated with the rate of visual field (VF) progression in the United Kingdom Glaucoma Treatment Study. Design: Randomized, double-masked, placebo-controlled multicenter trial. Participants: Participants with ≥5 VFs (213 placebo, 217 treatment). Methods: As...

Aims/Purpose: To assess the use of structural data to guide perimetric examination. Methods: Two perimetric strategies were tested on ten healthy participants: standard ZEST with population‐based prior distributions and Structural‐ZEST (S‐ZEST), enhanced with OCT data to determine the starting parameters. Both strategies were tested twice, in rando...

Purpose: We aim to confirm the association between multiple deprivation and late diagnosis of glaucoma in England and to determine whether multiple deprivation is associated with rapid VF progression. Methods: A total of 602 439 records were obtained by retrospectively extracting Humphrey VFs from electronic medical records (EMRs) from five hospita...

Introduction Geographic atrophy (GA) is the advanced form of the non-neovascular (‘dry’) type of age-related macular degeneration (AMD). Previously untreatable, complement inhibitors delivered by regular intravitreal injections have recently been demonstrated to slow down the progression of GA lesions in phase 3 trials. One such treatment, Syfovre...

Background: The glymphatic system removes neurodegenerative debris. The ocular glymphatic outflow is from the eye to the proximal optic nerve. In multiple sclerosis (MS), atrophy of the optic nerve increases the glymphatic outflow space. Here, we tested whether vitreous haze (VH) can provide novel insights into the relationship between neurodegener...

Purpose (1) To assess the feasibility of conducting tablet‐based vision tests in hospital clinic waiting areas; (2) To test the hypothesis that increasing severity of diabetic macular oedema (DME) is associated with the performance of tablet‐based surrogates of everyday tasks and self‐reported visual function. Methods Sixty‐one people with mild (...

Purpose The purpose of this study was to test whether functional loss in the glaucomatous macula is characterized by an enlargement of Ricco's area (RA) through the application of a computational model linking retinal ganglion cell (RGC) damage to perimetric sensitivity. Methods One eye from each of 29 visually healthy subjects <40 years old, 30 p...

Purpose The purpose of this study was to evaluate the power of trend-based visual field (VF) progression end points against long-term development of event-based end points accepted by the US Food and Drug Administration (FDA). Methods One eye from 3352 patients with ≥10 24-2 VFs (median = 11 years) follow-up were analyzed. Two FDA-compatible crite...

Purpose To assess the performance of a perimetric strategy using structure–function predictions from a deep learning (DL) model. Methods Visual field test–retest data from 146 eyes (75 patients) with glaucoma with (median [5th–95th percentile]) 10 [7, 10] tests per eye were used. Structure–function predictions were generated with a previously desc...

Objective Geographic Atrophy (GA) is the advanced form of the non-neovascular (‘dry’) type of age-related macular degeneration (AMD) and responsible for one-quarter of legal blindness in the UK. New therapies delivered by intravitreal injection are in late-stage development, and two such therapies (pegcetacoplan (Syfovre) and avacincaptad pegol (Iz...

Purpose: The purpose of this study was to assess test-retest variability and discriminatory power of measures from macular integrity assessment (S-MAIA) and AdaptDx. Methods: This is a cross-sectional study of 167 people with intermediate age-related macular degeneration (iAMD), no AMD (controls; n = 54), early AMD (n = 28), and late AMD (n = 41...

BACKGROUND/OBJECTIVES: The acceptability of emerging intravitreal therapies for patients with Geographic Atrophy (GA) is currently unknown. This study therefore aimed to investigate the extent to which regular intravitreal injections may be acceptable to GA patients. SUBJECTS/METHODS: Thirty UK-based individuals with GA secondary to age-related ma...

Background/Objectives To examine the association between multiple deprivation with late diagnosis and rapid worsening of glaucoma in patients in English hospital eye services (HES). Methods 602,439 visual fields (VFs) were extracted from five regionally different glaucoma clinics in England. Mean Deviation (MD) worse than −12 dB was used as a surr...

Purpose: This study was designed to determine if point analysis of the Humphrey visual field (HVF) is an effective outcome measure for people with idiopathic intracranial hypertension (IIH) compared with mean deviation (MD). Methods: Using the IIH Weight Trial data, we performed a pointwise analysis of the numerical retinal sensitivity. We then...

This paper describes data from Asfaw at al. [1], which examined the eye movements of glaucoma patients (n=15) with pronounced asymmetrical vision loss (visual field loss worse in one eye). This allows for within-subject comparisons between the better and worse eye, thereby controlling for the effects of individual differences between patients. All...

Spatial summation of perimetric stimuli has been used to derive conclusions about the spatial extent of retinal-cortical convergence, mostly from the size of the critical area of summation (Ricco's area, RA) and critical number of retinal ganglion cells (RGCs). However, spatial summation is known to change dynamically with stimulus duration. Conver...

BACKGROUND/OBJECTIVES: To examine the association between multiple deprivation with late diagnosis and rapid worsening of glaucoma in patients in English hospital eye services (HES). METHODS: 602 439 visual fields (VFs) were extracted from five regionally different glaucoma clinics in England. Mean Deviation (MD) worse than −12 dB was used as a sur...

Purpose Geographic atrophy (GA) is the advanced form of the non-neovascular (dry) type of age-related macular degeneration. Presently, GA cannot be treated. However, new therapies administered by intravitreal injection are in late-stage development. These can slow down, but do not stop or reverse, GA progression. The acceptability of these emerging...

Purpose: to compare visual field (VF) progression between glaucoma patients receiving cataract surgery alone (CS) or with a Hydrus microstent (CS-HMS) DESIGN: post-hoc analysis of VF data from the HORIZON multicenter randomized controlled trial METHODS: 556 patients with glaucoma and cataract were randomized 2:1 to either CS-HMS (369) or CS (187)...

Objective: Geographic Atrophy (GA) is the advanced form of the non-neovascular (‘dry’) type of age-related macular degeneration (AMD) and responsible for one-quarter of legal blindness in the UK. While no approved treatment for GA currently exists, new therapies delivered by intravitreal injection are in late-stage development. These therapies slow...

Purpose: to compare visual field (VF) progression between the two arms of the Treatment of Advanced Glaucoma Study (TAGS) DESIGN: post-hoc analysis of VF data from a two-arm multicenter randomized controlled clinical trial METHODS: 453 patients with newly diagnosed advanced open-angle glaucoma in at least one eye from 27 centers in the United King...

Objective To assess the accuracy of probabilistic deep learning models to discriminate normal eyes and eyes with glaucoma from fundus photographs and visual fields. Design Algorithm development for discriminating normal and glaucoma eyes using data from multicenter, cross-sectional, case-control study. Subjects and participants Fundus photograph...

Purpose: The acceptability of emerging intravitreal therapies for GA (that can slow down, but not stop or reverse, GA progression) is currently unknown. This study therefore aimed to: investigate whether regular intravitreal injections will be acceptable as treatment for GA patients; identify which attributes of current treatments in late stage dev...

Quantification of the relative ellipsoid zone reflectivity (rEZR) might be a structural surrogate parameter for an early disease progression in the context of age-related macular degeneration (AMD). Within the European multicenter, cross-sectional MACUSTAR study, we have devised an automatic approach to determine the mean rEZR [arbitrary units, AU]...

Purpose To evaluate the relationship between intraocular straylight perception and: (i) contrast sensitivity (CS), (ii) halo size, and (iii) hazard recognition distance, in the presence and absence of glare. Subjects and methods Participants were 15 (5 female) ophthalmologically healthy adults, aged 54.6–80.6 (median: 67.2) years. Intraocular stra...

Spatial summation of perimetric stimuli have been used to derive conclusions about the spatial extent of retinal-cortical convergence, mostly from the size of the critical area of summation (Ricco's area, RA) and critical number of Retinal Ganglion Cells (RGCs). However, spatial summation is known to change dynamically with stimulus duration. Conve...

Purpose To assess differences in rod-mediated dark adaptation (RMDA) between different grades of age-related macular degeneration (AMD) severity using an Optical Coherence Tomography (OCT)-based criterion compared to the Beckman Colour Fundus Photography-based (CFP) classification. To assess association between subretinal drusenoid deposit (SDD) pr...

Purpose To evaluate if an artificial intelligence (AI) model can better select candidates that would demonstrate visual field (VF) progression in order to shorten the duration or the number of patients needed for a clinical trial Design Retrospective cohort study Methods 7,428 eyes of 3,871 patients from the University of Washington Department of...

Purpose (i) To assess how well contrast sensitivity (CS) predicts night-time hazard detection distance (a key component of night driving ability), in normally sighted older drivers, relative to a conventional measure of high contrast visual acuity (VA); (ii) To evaluate whether CS can be accurately quantified within a night driving simulator. Mate...

Importance: There is a need for validated clinical end points that are reliably able to quantify potential therapeutic effects of future treatments targeting age-related macular degeneration (AMD) before the onset of serious visual impairment. Objective: To assess the reliability and discriminatory power of 5 simple chart-based visual function (...

Importance: There is a need for validated clinical end points that are reliably able to quantify potential therapeutic effects of future treatments targeting age-related macular degeneration (AMD) before the onset of serious visual impairment. Objective: To assess the reliability and discriminatory power of 5 simple chart-based visual function (VF)...

p>Purpose: Serum lipids are modifiable, routinely collected blood test features associated with cardiovascular health. We examined the association of commonly collected serum lipid measures (total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C], and triglycerides) with intraocular pressure...

Purpose To develop and validate a deep learning (DL) system for predicting each point on visual fields (VF) from disc and optical coherence tomography (OCT) imaging and derive a structure-function mapping. Design Retrospective, cross-sectional database study Participants 6437 patients undergoing routine care for glaucoma in three clinical sites i...

Purpose: Vitreous haze (VH) is a key marker of inflammation in uveitis but limited by its subjectivity. Optical coherence tomography (OCT) has potential as an objective, noninvasive method for quantifying VH. We test the hypotheses that OCT can reliably quantify VH and the measurement is associated with slit-lamp based grading of VH. Methods: In...

Background Recruiting asymptomatic participants with early disease stages into studies is challenging and only little is known about facilitators and barriers to screening and recruitment of study participants. Thus we assessed factors associated with screening rates in the MACUSTAR study, a multi-centre, low-interventional cohort study of early st...

Purpose: To develop a Bayesian model (BM) for visual field (VF) progression accounting for the hierarchical, censored and heteroskedastic nature of the data. Methods: Three versions of a hierarchical BM were developed: a simple linear (Hi-linear); censored at 0 dB (Hi-censored); heteroskedastic censored (Hi-HSK). For the latter, we modeled the t...

Glaucoma is a progressive optic neuropathy with characteristic changes to the optic nerve head and the visual field (VF). Detecting progression of VF damage with Standard Automated Perimetry (SAP) is of paramount importance for clinical care. One common approach to detecting progression is to compare each new VF test to a baseline SAP test (event a...

Most uveitis entities are rare diseases but, taken together, are responsible for 5–10% of worldwide visual impairment which largely affects persons of working age. As with many rare diseases, there is a lack of high-level evidence regarding its clinical management, partly due to a dearth of reliable and objective quantitative endpoints for clinical...

Objective Patient-reported outcome measures (PROMs) are commonly used in clinical trials and research. Yet, in order to be effective, a PROM needs to be understandable to respondents. The aim of this cross-sectional analysis was to assess reading level of PROMs validated for use in common eye conditions. Methods and analysis Readability measures d...

Purpose to evaluate the ability of additional central testing locations to improve detection of macular visual field (VF) defects in glaucoma. Design prospective cross-sectional study. Participants 440 healthy people and 499 patients with Glaucomatous Optic Neuropathy (GON) were tested with a fundus tracked perimeter (CMP, CenterVue, Italy) using...

Background Perimetry is important in the management of children with glaucoma, but there is limited evidence-based guidance on its use. We report an expert consensus-based study to update guidance and identify areas requiring further research. Methods Experts were invited to participate in a modified Delphi consensus process. Panel selection was b...

Prcis: Multiple questionnaires exist to measure glaucoma's impact on quality of life. Selecting the right questionnaire for the research question is essential, as is patients' acceptability of the questionnaire to enable collection of relevant patient-reported outcomes. Purpose: Quality of life (QoL) relating to a disease and its treatment is an...

Introduction Age-related macular degeneration (AMD) is a common cause of visual impairment, affecting central vision. Geographic atrophy (GA) is an advanced form of the non-neovascular (dry) type of AMD. Late-stage clinical trials suggest that intravitreal injections of novel therapeutics may slow down the rate of GA progression by up to 30% in 1 y...

Purpose: Selecting reliable visual field (VF) test takers could improve the power of randomised clinical trials in glaucoma. We test this hypothesis via simulations using a large real world dataset. Design: Methodology analysis: assessment of how improving reliability affects sample size estimates. Methods: A variability index (VI) estimating...

Glaucoma is a progressive optic neuropathy determining characteristic changes to the optic nerve head and the visual field (VF). Detecting progression of VF damage with Standard Automated Perimetry (SAP) is of paramount importance for clinical care. One common approach to detecting progression is to compare each new VF test to a baseline SAP test (...

In age-related macular degeneration (AMD) research, dark adaptation has been found to be a promising functional measurement. In more severe cases of AMD, dark adaptation cannot always be recorded within a maximum allowed time for the test (~ 20–30 min). These data are recorded either as censored data-points (data capped at the maximum test time) or...

Objectives To explore the acceptability of home visual field (VF) testing using Eyecatcher among people with glaucoma participating in a 6-month home monitoring pilot study. Design Qualitative study using face-to-face semistructured interviews. Transcripts were analysed using thematic analysis. Setting Participants were recruited in the UK throug...

Purpose: To provide structural and functional evidence of inner retinal loss in diabetes prior to vascular changes and interpret the structure-function relationship in the context of an established neural model. Methods: Data from one eye of 505 participants (134 with diabetes and no clinically evident vascular alterations of the retina) were in...

Purpose To introduce a novel method to quantitively analyse in three dimensions traction forces in a vast area of the ocular posterior pole. Methods Retrospective analysis of 14 eyes who underwent peeling surgery for idiopathic, symptomatic and progressive epiretinal membrane. The technique measures the shift in position of vascular crossings afte...

p>Background: associations between microvascular variation and chronic kidney disease (CKD) have been reported previously. Non-invasive retinal fundus imaging enables evaluation of the microvascular network and may offer insight to systemic risk associated with CKD. Methods: retinal microvascular parameters (fractal dimension [FD] – a measure of t...

Purpose: Quantify the spatial error in mapping perimetric stimuli for structure-function analysis resulting from the choice of mapping scheme and eye movements. Methods: We analyzed data from 17 healthy and 30 glaucomatous participants. Structural data of the macula were collected with a spectral-domain optical coherence tomography. We extracted...

Introduction: Dark adaptation (DA) has been proposed as a possible functional biomarker for age-related macular degeneration (AMD). In this systematic review we aim to evaluate current methodology used to assess DA in people with AMD, the evidence of precision in detecting the onset and progression of AMD, and the relationship between DA and other...

Quantifying intraocular inflammation is crucial in managing uveitis patients. We assessed the minimum B-scan density for reliable automated vitreous intensity (VI) assessment, using a novel approach based on optical coherence tomography (OCT). OCT volume scans centered on the macula were retrospectively collected in patients with uveitis. Nine B-sc...

Clinical visual field testing is performed with commercial perimetric devices and employs psychophysical techniques to obtain thresholds of the differential light sensitivity (DLS) at multiple retinal locations. Current thresholding algorithms are relatively inefficient and tough to get satisfied test accuracy, stability concurrently. Thus, we prop...