The Association between Foveal Morphology and Macular Pigment Spatial Distribution: An Ethnicity Study

Purpose Macular pigment (MP) spatial distribution varies considerably among individuals. We investigated ethnic variations in MP spatial distribution in relation to foveal architecture. Methods We measured MP optical density (MPOD) using heterochromatic flicker photometry (MAP test, City, University of London) in 76 white, 80 South Asian and 70 black volunteers (18 to 39 years). MPOD spatial profiles were classified objectively as exponential, ring-like or central dip, based on deviations away from an exponential fit. Measurements including total retinal thickness (RT), inner retinal layer (IRL), inner and outer plexiform layer (IPL and OPL) thickness, foveal width and foveal pit slope were taken from Spectralis SD-OCT (Heidelberg, Germany) scans. Results Integrated MPOD up to 1.8° (MPODint) was higher in South Asian (0.84±0.26) and black (0.84±0.31) than whites (0.63±0.24, P0.05). Conclusion We report a significant difference in the amount and distribution of MP between ethnicities that is not explained by variations in foveal morphology

Development and validation of a new glaucoma screening test using temporally modulated flicker

Purpose Describing the psychometric characteristics and diagnostic accuracy of the Accelerator 4‐Alternative Forced‐Choice Flicker Test prototype (A4FTp) for detecting chronic open angle glaucoma (COAG). Methods A4FTp measures temporally‐modulated flicker thresholds in regions of the visual field with high susceptibility to glaucomatous loss. We initially evaluated its psychometric properties on 20 normals (aged 33.8 ± 8.5 years) who were tested multiple times over a period of 3 months. All subjects underwent four repetitions for shorter (T8) and longer (T12) staircase termination criteria, to determine the most suitable threshold criterion. Four randomly selected subjects underwent a total of 10 repetitions to study test‐retest repeatability and learning effects. To determine its diagnostic accuracy, one eye of 40 participants with COAG and 38 normal controls were tested with the A4FTp in comparison with the Frequency Doubling Technology (FDT; C20‐5 programme) and iVue Spectral Domain Optical Coherence Tomography (SD‐OCT). Tests were conducted in a random order with results masked to the clinician conducting the reference ophthalmic examination. The accuracy of each test was determined by analysis of the area under the receiver operator characteristic curve (AUROC). Results A4FTp flicker thresholds were stable, with standard deviations of only 0.52 decilog (dL) for T8, increasing to 1.32 dL for T12, and no significant flicker sensitivity threshold improvement over the 10 repeat runs. T8 was superior to T12 on several other measures, so it was used for the remaining comparisons. In terms of diagnostic accuracy, the mean AUROC for the three tests were A4FTp [T8 criterion; 0.82, 95% confidence interval (0.73–0.92)]; SD‐OCT [any RNFL parameter p < 1% level; 0.90 (0.83–0.97)]; and FDT [one or more locations missed at p < 5% level; 0.91 (0.82–0.96)]. There was no statistical difference in AUROC between A4FTp and SD‐OCT (p = 0.18) or FDT (p = 0.12). The A4FTp test duration averaged just over 2 min per eye, taking approximately one‐third of the time for completion of the HFA SITA 24‐2 algorithm (conducted as part of the reference examination) and twice the time for the suprathreshold FDT. Conclusion Test accuracy for the A4FTp was comparable to those of the FDT and SD‐OCT for the detection of COAG. Time taken to complete the A4FTp was relatively short and initial results are promising. With further refinement, the A4FTp could have a future role in glaucoma detection

Associations between adult attachment and vision-related quality of life in visually impaired individuals

PURPOSE An attachment theory framework approach may allow insight into how social and psychosocial factors interact to impact vision-related quality of life (QoL). In this pilot study, we investigated potential associations between adult attachment style and visual function QoL of visually impaired individuals. METHODS We recruited 38 visually impaired individuals (15 females, 23 males; 51.8 ± 16.0 years). Visual function measures included distance and near visual acuity (VA) and contrast sensitivity. All participants completed: the 25-item National Eye Institute Visual Functioning Questionnaire-25 (NEI-VFQ 25) and the Experiences in Close Relationships–Relationships Structures questionnaire. RESULTS Presenting conditions included inherited retinal dystrophy (n = 10), nystagmus (n = 9), glaucoma (n = 7) and other eye conditions (n = 12). There was a statistically significant negative correlation between the NEI-VFQ-25 composite score (45.5 ± 14.7) and attachment-related anxiety (r = −0.352, p = 0.033). The latter correlation still held when controlling for participants’ level of vision (r = −0.352, p = 0.035). Despite the range of conditions and wide age range, these were not significantly correlated with any variable of interest in the current study. CONCLUSION Attachment-related anxiety ought to be taken into account when managing a visually impaired individual. Attachment-based approaches could be used to improve access to support services for visually impaired individuals, as well as self-management of their condition

Variations in normative foveal morphology SD-OCT data: A study of White, South Asian and Black ethnicities

Purpose Foveal morphology shows significant inter‐individual variation and ethnicity may play a role. We investigated variations in specific retinal layer thickness and foveal pit shape in three ethnic groups. Methods We recruited 226 healthy volunteers age 18–39 years (76 white, 80 South Asian and 70 black; male to female ratio 1:2 per ethnic group). Foveal thickness including inner retinal layer (IRL), outer nuclear layer (ONL), photoreceptor layer (PRL), retinal pigment epithelium (RPE), foveal width and foveal pit depth (FPD) were taken from Spectralis (Heidelberg, Germany) SD‐OCT scans. Retinal layer thickness measurements were taken from 0° to 3.8° eccentricity from the fovea. Two‐way ANCOVA evaluated the impact of ethnicity and gender confounders on foveal morphology parameters, while controlling for refractive error. Results White subjects had thicker central IRL (130 ± 21 μm) than South Asian (123 ± 16 μm) and blacks (116 ± 14 μm; F (2) = 12.4, p 0.05). The depth of the foveal pit was significantly shallower in white (120 ± 25 μm) and South Asian (121 ± 18 μm) than blacks (129 ± 17 μm, F (2) = 4.8, p < 0.009), with no significant effect of gender (p = 0.39). Conclusions The overall foveal pit profile significantly varies with ethnicity. Our results indicate that ethnicity explains more of the variation in foveal morphology than gender, and should be taken into account when interpreting OCT scans

Ethnic differences in the spatial distribution of macular pigment and its association with foveal anatomy

Macular pigment (MP) at the centre of the retina is thought to serve a protective function shielding the photoreceptors from damaging effects of blue light. The amount of MP and its spatial density distribution across the macula i.e. its spatial profile varies among individuals. Lower levels of MP and certain MP spatial profile phenotypes are believed to be associated with increased risk of age-related macular degeneration (AMD). There is suggestion that MP spatial profiles differ between ethnicities, with non-exponential profiles occurring more frequently in non-whites. This may explain some of the ethnic variations seen in AMD prevalence. However, previous investigations have used several methodologies to measure MP. In addition, inconsistent MP spatial profile definitions have been used; thus comparing data between studies is difficult. Nevertheless, it has been hypothesised that variations in MP spatial distribution could be due to differences in foveal architecture, in particular at the foveal centre where MP levels peak. A study was designed to investigate the effect of ethnicity on MP spatial density distribution and its relation to foveal architecture. The influence of known risk factors for AMD was also considered. Young (18 to 39 years), healthy volunteers of white (n = 76), South Asian (n = 80) and black (n = 70) ethnic origin were recruited to take part. MP measurements were obtained using a method based on heterochromatic flicker photometry (HFP) and foveal morphology measurements were taken from optical coherence tomography (OCT) scans. The coefficients of repeatability of each of these were confirmed in a sub-study. A systematic objective MP spatial profile classification technique was implemented throughout. The feasibility of applying this to MP measurements obtained with different techniques such as HFP and fundus autofluorescence (FAF) was also explored in a sub-study. The results showed that measures of MP optical density (MPOD) over the central retinal area were statistically significantly increased in South Asian and black compared to white subjects, whereby ethnicity explained around 10% of the variation (P < 0.0005). Non-exponential MP spatial profiles (ring-like and central dip respectively) were significantly more prevalent in South Asian and black compared with white subjects (χ2 (4, n = 226) = 13.4, P = 0.009). Integrated MPOD up to 1.8º was significantly increased in ring-like and central dip compared to exponential profiles (P < 0.0005) irrespective of ethnicity. South Asian and black individuals presented thinner central retinas and wider foveas compared to white individuals (P < 0.0005). However, while accounting for these ethnic variations, foveal architecture provided no predictive values for the MP spatial profile phenotype

Do ethnic variations in foveal morphology explain variations in macular pigment spatial density distribution?

Abstract from the 2016 ARVO Annual Meeting

Role of advanced technology in the detection of sight-threatening eye disease in a UK community setting.

Background/aims: To determine the performance of combinations of structural and functional screening tests in detecting sight-threatening eye disease in a cohort of elderly subjects recruited from primary care. Methods: 505 subjects aged ≥60 years underwent frequency doubling technology (FDT) perimetry, iVue optical coherence tomography (iWellness and peripapillary retinal nerve fibre layer (RNFL) scans) and intraocular pressure with the Ocular Response Analyzer, all performed by an ophthalmic technician. The reference standard was a full ophthalmic examination by an experienced clinician who was masked to the index test results. Subjects were classified as presence or absence of sight-threatening eye disease (clinically significant cataract, primary open-angle glaucoma, intermediate or advanced age-related macular degeneration and significant diabetic retinopathy). Univariate and multivariate logistic regression analyses were used to determine the association between abnormal screening test results and the presence of sight-threatening eye disease. Results: 171 subjects (33.8%) had one or more sight-threatening eye diseases. The multivariate analysis found significant associations with any of the target conditions for visual acuity of <6/12, an abnormal FDT and peripapillary RNFL thickness outside the 99% normal limit. The sensitivity of this optimised screening panel was 61.3% (95% CI 53.5 to 68.7), with a specificity of 78.8% (95% CI 74.0 to 83.1), a positive predictive value of 59.5% (95% CI 53.7 to 65.2) and an overall diagnostic accuracy of 72.9% (95% CI 68.8 to 76.8). Conclusions: A subset of screening tests may provide an accurate and efficient means of population screening for significant eye disease in the elderly. This study provides useful preliminary data to inform the development of further larger, multicentre screening studies to validate this screening panel

Does foveal anatomy influence macular pigment and its spatial profile? A bi-racial study

Abstract from the 2014 European Association for Vision and Eye Research Conference