Mental health support across the sight loss pathway: a qualitative exploration of eye care patients, optometrists, and ECLOs.

BACKGROUND: The process of becoming visually impaired or blind is undoubtedly a highly emotional experience, requiring practical and psychological support. Information on mental health support provision in the UK across the sight-loss pathway, however, is largely unknown, especially amongst healthcare practitioners that are often sought after for advice: the referring optometrist and eye clinic liaison officer (ECLO). This study aims to ascertain the perceived accessibility and quality of mental health support across the sight-loss pathway. METHODS: Semi-structured individual interviews were conducted with patients with a diagnosed eye condition who had received care from a hospital eye service, referring optometrists, and ECLOs. Following interview transcription, results were synthesised in a narrative analysis. RESULTS: A total of 28 participants were included in the analysis, of which 17 were participants with various eye conditions, five were referring optometrists, and five were ECLOs. After analysis, three broad themes emerged: (1) The emotional trauma of diagnosis (2) Availability of mental health support; (3) The point where mental health support is most needed across the sight-loss pathway. Several patients reporting that they had received no offer of support nor were they signposted to any possible sources. Referring optometrists and ECLO's agreed. CONCLUSION: It is important that referring optometrists are aware of the need for mental health support services and can signpost to local support services including the third sector anytime during the referral process. Future large-scale, UK-wide research into referral practice and signposting for mental health support for patients is warranted, to identify how services can be improved in order to ensure that the wellbeing of patients is maintained.

Pathological eating behaviours and risk of retinopathy in diabetes: a systematic review and meta-analysis.

Background: Diabetes mellitus can cause several long-term macrovascular and microvascular complications including nephropathy, neuropathy, and retinopathy (DR). Several studies have reported positive associations between eating pathologies and DR; however, these studies have not been aggregated and sub-grouped into type of pathological eating behaviour, and the differences in risk according to type of eating behaviour is unknown. The aim of this review, therefore, was to aggregate risks of DR in populations with and without pathological eating behaviours, stratified according to eating behaviour. Methods: A systematic review and meta-analysis was conducted. Major databases and grey literature were search from inception until 1/6/2021. Studies reporting the prevalence of pathological eating behaviours (against a control group with no pathological eating behaviours) in diabetic people with and without DR were included. Odds ratios were calculated from primary data. Results: Seven studies with eight independent outcomes with a total of 1162 participants were included. The odds ratio of DR in the total pooled analysis was 2.94 (95%CI 1.86-4.64; p = <0.001; I2 = 29.59). Two types of eating behaviour yielded enough data for sub-group analysis. Eating disorder not otherwise specified yielded an odds ratio of 2.73 (95%CI 1.81-4.10; p = <0.001; I2 = 0.00), and binge eating disorder yielded an non-significant odds ratio of 0.92 (95%CI 0.31-2.77; p = 0.887;I2 = 0.00). Discussion: The likelihood of DR increases almost three times in the presence of pathological eating behaviours. More studies are required to confirm this in clinical populations stratified by eating disorder. Practitioners working with people with diabetes should closely monitor eating behaviours to preclude this risk. Supplementary Information: The online version contains supplementary material available at 10.1007/s40200-022-00980-x.

Surface tilt measured with the EyeSys videokeratoscope: influence on corneal asymmetry.

PURPOSE: To investigate whether the apparent corneal asymmetry in the EyeSys videokeratoscope (VK EyeSys Laboratories, Houston, TX) image is a result of the cornea being tilted in relation to the instrument and to examine the possibility of deducing this tilt from a single captured image. METHODS: Videokeratoscopic images were captured with and without a front surface conicoidal contact lens (experiment 1). An image was captured with central fixation followed by image capture with fixation 10 degrees off center. These two images were used to calculate the angle of tilt with central fixation. The approximate tilt of the cornea derived from a single captured image was determined by the use of a mathematical model applied to some of the ring images (experiment 2). Twenty-four subjects were used in each of the above experiments. RESULTS: The mean tilt for the first group of subjects with the contact lens on the cornea was 2.8 degrees, whereas the tilt for the cornea alone was 3.2 degrees (experiment 1). The corneal tilt for the second group of subjects was 3.3 degrees, and the approximate tilt derived from a single captured VK image, using the equation, was 3.2 degrees (experiment 2). CONCLUSIONS: The similarity of the tilt angle with and without the contact lens in place suggests that the apparent asymmetry seen in the VK images of human corneas may be largely an artifact arising from corneal tilt and not nasal/temporal asymmetry. The agreement of the corneal tilt derived from two VK images and the approximate tilt derived from a single image indicates that the latter may offer a quick and convenient way to determine the fixation adjustment required to eliminate corneal tilt.

Measurement of corneal curvature in young and older normal subjects.

PURPOSE: A decrease in the vertex radius occurs with aging. The aim of this study was to investigate whether the degree of flattening from the vertex to the periphery of the cornea, ie, the surface profile, also changes with age. METHODS: A "p" value (a parameter that denotes the rate of flattening from the apex to the limbus) and vertex radius were measured in the horizontal meridian in a group of young and older subjects using the EyeSys videokeratoscope and the Topcon autokeratometer. RESULTS: With EyeSys data, horizontal vertex radius and p value were computed by means of plotting a graph of r2 (sagittal radius) versus y2 (perpendicular distance from the instrument optical axis). For Topcon data, previously derived equations were used. Mean vertex radii in the younger Topcon autokeratometer group was 7.91+/-0.31 and for the EyeSys videokeratoscope was 7.98+/-0.31. For the older group, Topcon mean vertex radii was 7.68+/-0.22 and EyeSys mean was 7.74+/-0.24. Mean p value in the younger group was 0.66+/-0.09 for the Topcon and 0.78+/-0.07 for the EyeSys. In the older group, mean vertex radii was 0.74+/-0.07 for the Topcon and 0.86+/-0.07 for the EyeSys. CONCLUSION: Vertex radius decreased with age, demonstrating a steepening of the cornea, and confirming previous results. The p value increases with age, indicating a shift toward a more spherical surface. The rate of change in the vertex radius and p value with age are predicted.

Comparison of videokeratoscope and autokeratometer measurements on ellipsoid surfaces and human corneas.

BACKGROUND: Various studies have compared the accuracy and repeatability of autokeratometers and videokeratoscopes using calibrated convex surfaces. We investigate the agreement between the Topcon KR-3500 autokeratometer and the EyeSys videokeratoscope on human corneas and calibrated convex surfaces. METHODS: Measurements were obtained from 30 convex ellipsoidal buttons and 20 right eyes of 20 young normal human subjects. Vertex radius and p-values were compared for the two instruments. RESULTS: The two instruments showed excellent agreement on convex buttons. The human data showed no such relationship. For vertex radius, a good level of agreement was obtained only for surfaces whose p-values were near unity. Repeatability was also calculated and was shown to be better with the Topcon autokeratometer than with the EyeSys videokeratoscope. Editing the EyeSys data to encompass the same corneal area as that of the Topcon improved its repeatability, although it did not reach the level of the Topcon autokeratometer. CONCLUSIONS: The Topcon autokeratometer and the EyeSys videokeratoscope showed reasonable agreement for surface topography on convex conicoidal plastic test buttons but not for human corneas. Alterations in the data-capture mechanisms of videokeratoscopes could improve their ability to accurately image paraboloidal surfaces.

Binocular recognition summation in the peripheral visual field: contrast and orientation dependence.

Spatial frequency thresholds for recognition were measured for binocular and monocular viewing conditions at two contrast levels (95% and 7%). Measurements were obtained at the fovea and at four different eccentric retinal locations. Each eccentric retinal location was 8 degrees from the fovea, one on the horizontal axis (180 degrees ), and the other three in the superior field on retinal axes of 90 degrees, 45 degrees and 135 degrees. For the superior and horizontal retinal locations, the orientations of the gratings tested were horizontal (180 degrees ) and vertical (90 degrees ). For the retinal points on the oblique axes, the orientations of the gratings were 45 degrees and 135 degrees. Measurements were also obtained at the fovea for all four different grating orientations at both levels of contrast. Recognition threshold was defined as the highest spatial frequency at which luminance gratings were perceived vertically. At the fovea, binocular summation ratios (binocular spatial frequency/monocular spatial frequency) showed no significant differences for gratings of either contrast levels or for any orientation (p>0.05). In the superior periphery, significantly higher summation ratios were shown by low contrast vertical gratings (p<0.05), and in the horizontal periphery by low contrast horizontal gratings (p<0.05). On the oblique axis, low contrast gratings that were parallel to the oblique meridian showed higher summation ratios compared to those at right angles to it. High contrast gratings, at least at 8 degrees eccentricity, did not show this effect. Data suggest that meridional organisation of the retina (e.g. vertical gratings seen maximally in the superior field) occurs for resolution and that it is evidenced closer to the fovea than previously shown.

Extent and effect of surface tilt on the data display of the EyeSys videokeratoscope.

AIMS: This study examined the occurrence, magnitude, and the consequences of a possible tilt between the corneal surface and optical axis of the EyeSys videokeratoscope. METHODS: Initially, a theoretical model was developed to calculate the angle of tilt. The predictions of the model were verified empirically using a convex conicoid surface and were found to predict the tilt to within 0.5 degree of the actual tilt. The likely effects of the tilt on the corneal power were also examined. The angle of tilt was then measured on the human cornea and the effect of neutralising the tilt on the videokeratoscopic data display was observed. RESULTS: The angle of tilt was found to lie between 1 degree and 6 degrees in a temporal direction. CONCLUSION: When the corneal tilt on the human subjects was neutralised, then a reduction in the nasal/temporal asymmetry was observed.

A comparison of sampling efficiency and internal noise level in young and old subjects.

Contrast detection in different levels of external visual noise allows a given loss in contrast sensitivity to be attributed to either an increase in the internal noise of the visual system, a decrease in sampling efficiency, or both. Sampling efficiency indicates how effectively the available stimulus information is utilized by the visual system. The aim of this study is to investigate the effect of normal ageing on sampling efficiency and internal noise. Contrast thresholds for sine-wave gratings of 6 c/deg were measured in the presence of four (including zero) levels of externally added visual noise in young and older healthy observers. Results showed that sampling efficiencies were significantly lower for the older group compared to the younger, while the internal noise showed no significant change. The implications of the data for the relative contribution of the optical and neural systems on visual function loss with ageing are discussed. Our results suggest that the neural system plays a major role in the loss of contrast sensitivity with ageing in normal, healthy eyes.

Accuracy and repeatability of the Topcon K-3500 autokeratometer on calibrated convex surfaces.

The vertex (apical) radius and the p value of 30 conicoidal convex surface plastic buttons were measured using the Topcon KR-3500 autokeratometer. The vertex radius was found using the equations derived in the introduction. The results were compared to those derived by the Form Talysurf technique, which was considered to give a precise indication of both the vertex radius and p value. The results revealed a good agreement between the two methods of measurement. The autokeratometer displayed a tendency to underread the vertex radius, compared to the Talysurf result, but the maximum difference was 0.02 mm (95% confidence interval). For the p value, the autokeratometer could over- or underread with a maximum difference of 0.035. The largest coefficient of repeatability for the two observers using the Topcon autokeratometer was found to be 0.033 mm for vertex radius and 0.068 for the p value.

A comparison of binocular summation in young and older patients.

Binocular and monocular contrast sensitivities were measured at two spatial frequencies of 1 and 6 c/deg in 8 young (mean age 22.6 +/- 3.8 years) and 18 older subjects with normal healthy eyes (mean age 58.4 +/- 7.3 years). Data were analysed as binocular summation ratios defined as binocular CS/"best eye' CS. Binocular summation ratios were higher for the younger group (1.46 and 1.48 for 1 and 6 c/deg respectively) compared to the older group who demonstrated a spatial frequency dependence (1.31 and 1.13 at 1 c/deg and 6 c/deg respectively). The results are discussed in terms of age-related cortical cell loss and increased monocular sensitivity differences between the two eyes.

A comparison of binocular summation in the peripheral visual field in young and older patients.

PURPOSE: To measure binocular and monocular thresholds to a light detection task in order to investigate binocular summation in the central and peripheral visual fields. The study also aims to investigate any differences in the magnitude of binocular summation in young and older subjects with healthy eyes. METHODS: Binocular and monocular thresholds were measured at eccentricities of 0, 5, 15, 25 and 40 degrees nasally and temporally, using the Humphrey Field Analyser. Binocular summation ratios were computed as the binocular sensitivity divided by the "best" monocular sensitivity. RESULTS: Binocular and monocular sensitivities declined with increasing eccentricity. Binocular summation ratios were shown to be significantly higher for the younger group compared to the older group at all eccentricities. CONCLUSIONS: Using this test, the binocular performance is shown to be lower for the older group at all eccentricities. Results are discussed in terms of age-related cortical cell loss and increased monocular sensitivity difference.

Binocular summation in the fovea and peripheral field of anisometropic amblyopes.

PURPOSE: Binocular performance in the central and peripheral visual fields was compared for normal and anisometropic amblyopes. METHODS: Binocular and monocular thresholds to a light detection task were measured along the four principal meridia in 10 young normal subjects and 10 anisometropic amblyopes using the Humphrey's Visual Field Analyser. Thresholds were obtained at the fovea and at retinal eccentricities of 5 masculine, 10 masculine, 15 masculine, 25 masculine, 40 masculine and 55 masculine on the horizontal, vertical and oblique meridia of 45 masculine and 135 masculine. RESULTS: Binocular summation ratios (binocular sensitivity/ 'best' monocular sensitivity) were calculated for all the eccentricities. In the normal group, the mean binocular summation ratio for the fovea and the peripheral field was not significantly different. In the amblyopic group, subjects showed no or minimal binocular summation in the foveal region but reached normal ratios in the periphery. DISCUSSION: Results are discussed in terms of tolerance to interocular sensitivity differences in the periphery and selective losses in cortical cells.

The prevalence and risk factors for cataract in rural and urban India

Purpose: To report the prevalence and risk factors of cataract and its subtypes in older age group. Methods: A total of 6617 subjects were recruited from both rural and urban areas. A detailed history including data on demographic, socioeconomic and ocular history was obtained. Lens opacity was graded according to the Lens Opacity Classification System III (LOCS III). Results: Cataract was present in 1094 of the rural and 649 subjects in the urban population. Monotype subtype cataracts were found in 32% and 25% in rural and urban population and 12.68% and 18.6% were mixed cataracts in the rural and urban groups. In baseline characteristics history of diabetes, alcohol intake and presence of age-related macular degeneration were the risk factors in urban group. On multivariate analysis, the only significant risk factors for any cataract in subjects ?60 years were increasing age in both rural [odds ratio (OR), 1.07] and urban (OR, 1.08) population, and HbA1c (OR, 1.14) in rural population. Overweight (OR, 0.6) was found to be a protective factor, and lower social economic status (OR, 1.52) a risk factor for cataract in urban population. A significant urban–rural difference was found in the prevalence of cataract and its subtypes (P ? 0.05). Conclusion: We found the risk factors for any cataract in older age group to be increasing age and HbA1c in rural group. Age and lower social economic status were found to be the risk factors in urban arm. A statistically significant difference was found on comparison of the prevalence of cataract and its subtypes between the rural and urban population.

Binocular performance in patients with unilateral cataract using the Regan test: binocular summation and inhibition with low-contrast charts.

Recent reports have shown that binocular contrast sensitivity is an important indicator for assessing the visual function of a unilateral cataract. Binocular sensitivity, assessed in terms of binocular summation and inhibition, is dependent on the difference between the two eyes. Maximum binocular summation, obtained when the sensitivities of two eyes are equal, decreases if they are made unequal. Further increases in the monocular difference produce binocular inhibition, defined as a binocular sensitivity which is lower than the monocular. The aim of this study was to investigate whether the binocular effects in unilateral cataract that have been shown using laboratory-based equipment can be demonstrated using commercially available Regan charts. Binocular scores were compared with monocular scores in 16 unilateral cataract patients and 16 aged-matched normals using a high-contrast chart (96%) and a low-contrast (11%) chart. Normal subjects showed binocular summation with both charts. The cataractous patients showed no summation at high contrast and binocular inhibition with low-contrast charts. The implications of binocular inhibition at low contrast are discussed.

The clinical characteristics of Asian and Caucasian patients on Bradford's Low Vision Register.

AIM: To analyse the clinical characteristics of patients on the Bradford Low Vision Register with regards to the type (partially sighted or blind), sex, race, causes and age at registration. METHODS: All the data were obtained from the Morley Street Resource Centre, which keeps records of all registrations in the Bradford Metropolitan District. Information including postcode, date of birth, age, gender, ethnic group, degree, date of registration, cause of registration and age at registration were entered into a database. RESULTS: Of all registrations, 64% were blind and 36% were partially sighted. Asians were younger at registration and there were a significantly lower number of females compared to Caucasians. When data were analysed for the different age groups, in the older group of over 65 years, Asians showed significantly more diabetic retinopathy (26.1%) compared to Asians (7.8%), while Caucasians demonstrated significantly more glaucoma (C: 29.3%; A: 17.4%). In the younger age group (<30 years), the leading causes for Asians were retinitis pigmentosa and nystagmus while for Caucasians it was congenital cataracts and optic atrophy. The proportion of Asians registered was significantly lower than expected from the projected population estimates in Bradford. CONCLUSIONS: The study indicates significant differences in the clinical profiles of the two racial groups. The data do not follow the predictions from published population estimates, with Asians, especially females, being under-represented in the register.

Binocular contrast summation and inhibition in amblyopia. The influence of the interocular difference on binocular contrast sensitivity.

The monocular contrast sensitivity loss in amblyopia is well documented. We investigated the influence of interocular sensitivity difference on binocular contrast sensitivity in amblyopia. Monocular and binocular contrast sensitivity functions of six amblyopes (three strabismic and three anisometropic) were measured. The monocular contrast sensitivity loss depended on the type of amblyope. Anisometropic amblyopes generally showed high frequency losses. Strabismic amblyopes showed losses at both low and high spatial frequencies. Binocular performance was assessed in terms of binocular ratios (binocular/non-amblyopic). A binocular ratio greater than 1 indicates binocular summation (binocular > monocular) while a ratio less than 1 shows binocular inhibition (binocular < monocular). In all subjects, the binocular ratio depended on the difference between the amblyopic and the non-amblyopic eye. Minimal interocular difference produced binocular summation, the magnitude of which decreased as the difference between the two eyes increased. Further increases in the monocular difference produced binocular inhibition. Anisometropic amblyopes showed a greater degree of binocular summation at low spatial frequencies compared to strabismic amblyopes. Both types of amblyopes showed binocular inhibition at high spatial frequencies. Clinical implications of binocular summation and inhibition in amblyopia are discussed.

Binocular and monocular detection of Gabor patches in binocular two-dimensional noise.

Contrast thresholds for detecting sine-wave Gabor patches in two-dimensional externally added random-pixel noise were measured. Thresholds were obtained for monocular and binocular signals in the presence of spatial correlated (identical) and uncorrelated (independent) noise in the two eyes. Measurements were obtained at four different spectral densities of noise (including zero). Thresholds were higher for monocular stimuli than for binocular, and higher in the presence of correlated noise compared to uncorrelated noise. The magnitude of binocular summation, similar in correlated and uncorrelated noise, decreased with increasing noise strength. The independent contributions of internal noise and sampling efficiency to detection were analysed. Sampling efficiencies were higher for binocular than for monocular viewing for both types of noise, with values being higher with uncorrelated noise. Binocular stimuli showed a lower equivalent noise level compared to the mean monocular case for both types of noise.

Binocular contrast sensitivity with monocular glare disability.

Glare disability plays an important part in the investigation and assessment of cataract. We investigated the effect of monocular glare disability on binocular contrast sensitivity. The magnitude of binocular summation was measured at different degrees of monocular glare disability. In the absence of glare, maximum binocular summation was shown. With increasing glare disability, the degree of binocular summation decreased steadily until binocular inhibition was produced. Binocular inhibition is defined as a reduction in binocular sensitivity to reach a level below the monocular. The clinical implications of binocular inhibition with monocular glare disability are discussed.

The effect of monocular defocus on binocular contrast sensitivity.

The monocular contrast sensitivity loss with defocus is well known. We measured binocular contrast sensitivity of sinewave gratings of 6 c/deg in the presence of different levels of monocular defocus. In the absence of defocus, the binocular sensitivity was about 42% higher than monocular. With increasing monocular defocus, the binocular sensitivity decreased steadily until it reached a level below the monocular, showing binocular inhibition. The clinical implications of binocular inhibition with monocular defocus are discussed.

Comparison of non-stereo polaroids and slides in detection of diabetic retinopathy.

Fundus photography plays an important role in detection and assessment of diabetic retinopathy. This study compared the detectability of diabetic retinopathy lesions on Polaroid prints and Ektachrome slides obtained with a non-mydriatic camera. The number of lesions detected with Ektachrome slides was higher compared to Polaroids. The method of viewing the Ektachrome slides was also shown to be important. Slides when projected onto a white screen revealed a higher number of lesions compared to the same slide viewed through a macroscope. If a non-mydriatic camera is used to screen diabetic retinopathy, judgement from a projected Ectachrome slide is recommended.