Changes in ocular astigmatism with age: A longitudinal study.

PURPOSE: To investigate changes in astigmatism with age. Are changes from with-the-rule (WTR) in younger ages to against-the-rule (ATR) in older patients mediated through oblique astigmatic axes or spherical prescriptions, and at what ages do these changes occur? METHODS: Prescription data were gathered retrospectively from one optical practice belonging to a large multiple group in the UK. Longitudinal assessments were made of the changes in astigmatism for 326 patients (mean age at first prescription 46 years, range 28-69 years) and 640 eyes through their recorded prescription history (median 20 years of prescription data per participant, IQR 19-22 years, range 18-29 years). RESULTS: Changes in small degrees of astigmatism (0.25 or 0.50 DC) from WTR to ATR were more than three times more likely to pass through an oblique cylinder axis as through a spherical prescription (56 vs. 16, χ 1 2 = 22.2, p < 0.0001). For patients aged 28-40 years at their first recorded eye examination, 55% (92/167) of eyes had an onset of astigmatic changes at a mean of 44 years (SD 6.2) and 41% (68/167) of eyes had no change until after a mean of 54 years (SD 4.6). Compared with a measured prevalence of oblique astigmatism in the literature of 11%-19%, 36% (232/640) of the eyes in this study had an oblique cylinder prescribed at least once in their refraction history and of these oblique cylinders, 78% were transient in nature. CONCLUSIONS: The change in ocular astigmatism with age, from WTR to ATR, was more than three times more likely (56 vs. 16) to pass through oblique cylinder axes as through a spherical prescription. Changes in oblique astigmatism have been implicated in complaints with new spectacles, so given this prevalence of oblique cylinder axes (232/640, 36%), continuing professional development is needed regarding reconciling these oblique changes with previous prescriptions.

Distance spectacle-wearing habits in older patients in England.

PURPOSE: To report the proportion of older people in England who wear distance spectacles full time, part time and rarely, and to investigate factors that influence how much the distance vision (DV) correction is worn. METHODS: A two-part questionnaire investigating the spectacle-wearing habits of older people was developed and completed by 322 participants (age 72 years ±7.7, range 60-94). A subcohort of 209 DV correction wearers with a mean spherical equivalent (MSE) of <±4.00DS was selected for a logistic regression to investigate which factors influence how much the DV correction is used. RESULTS: In total, 43% of emmetropic, and 55% of pseudophakic, DV spectacle wearers wear their correction full time. Lens type, MSE and the age that participants first wore a DV correction significantly predicted DV correction wearing habit (adjusted R2 = 0.36), with lens type being the strongest predicting factor and progressive users wearing their spectacles 37% more than those using single vision lenses. CONCLUSIONS: Many patients appear to consider convenience more important than being spectacle independent at distance, with lens type the most significant influencing factor of how much those with low/moderate refractive error wear their distance correction. Many emmetropes and pseudophakes choose to wear their progressive or bifocal spectacles full time, and the emmetropia provided by cataract surgery does not provide independence from full-time spectacle wear for many patients. The optometrist has a key role in discussing both choice of spectacle lens correction and the refractive outcome options of cataract surgery with patients.

Developing refractive management recommendations for patients undergoing cataract surgery: A Delphi study.

PURPOSE: Currently, there are no UK optometric guidelines regarding the pre and postoperative refractive management of patients undergoing cataract surgery. This study used a Delphi method to gain consensus on best practice. METHODS: Eighteen recommendations targeted areas of concern/variability in advice that were highlighted in an earlier focus group study of refractive management for patients who had received cataract surgery. These covered three topics: preoperative target refraction discussions, postoperative refractive management and driving advice postoperatively. The recommendations were then developed using evidence from optometry and ophthalmology clinical expertise and the research literature. Eighteen recommendations underwent a process of agreement and modification using a Delphi study consisting of a panel of 22 highly experienced optometrists (N = 11, 25 years mean clinical experience) and ophthalmologists (N = 11, 17 years mean clinical experience) who rated and commented upon the importance and feasibility of each recommendation. The responses were considered by the research team and the recommendations modified and/or removed prior to a second Delphi round of responses to a modified series of recommendations. Consensus of opinion was defined as greater than 80% of panellists 'agreed' or 'strongly agreed' on the recommendation for both importance and feasibility. RESULTS: Fourteen of the 18 recommendations reached consensus in the first round. A second round of the Delphi method saw 17 modified recommendations scored and commented upon by 20 clinicians. Fifteen recommendations reached consensus after two rounds of the Delphi method. CONCLUSIONS: Recommendations to guide the pre and postoperative refractive management of patients undergoing cataract surgery were agreed between highly experienced optometrists and ophthalmologists using a 2-round Delphi method. Patients would benefit from consistent target refraction discussions, postoperative refractive management and driving advice, and recommendations were of particular benefit to less experienced optometrists.

Visual Predictors of Postural Sway in Older Adults.

Purpose: Accurate perception of body position relative to the environment through visual cues provides sensory input to the control of postural stability. This study explored which vision measures are most important for control of postural sway in older adults with a range of visual characteristics. Methods: Participants included 421 older adults (mean age = 72.6 ± 6.1), 220 with vision impairment associated with a range of eye diseases and 201 with normal vision. Participants completed a series of vision, cognitive, and physical function tests. Postural sway was measured using an electronic forceplate (HUR Labs) on a foam surface with eyes open. Linear regression analysis identified the strongest visual predictors of postural sway, controlling for potential confounding factors, including cognitive and physical function. Results: In univariate regression models, unadjusted and adjusted for age, all of the vision tests were significantly associated with postural sway (P < 0.05), with the strongest predictor being visual motion sensitivity (standardized regression coefficient, ß = 0.340; age-adjusted ß = 0.253). In multiple regression models, motion sensitivity (ß = 0.187), integrated binocular visual fields (ß = -0.109), and age (ß = 0.234) were the only significant visual predictors of sway, adjusted for confounding factors, explaining 23% of the variance in postural sway. Conclusions: Of the vision tests, visual motion perception and binocular visual fields were most strongly associated with postural stability in older adults with and without vision impairment. Translational Relevance: Findings provide insight into the visual contributions to postural stability in older adults and have implications for falls risk assessment.

Investigating target refraction advice provided to cataract surgery patients by UK optometrists and ophthalmologists.

PURPOSE: To determine whether UK optometrists and ophthalmologists provide target refraction advice to patients prior to cataract surgery, and when this should first be discussed. METHODS: Optometrists and ophthalmologists were asked to complete a survey of two clinical vignettes (both older patients with cataract; a pre-operative myope who routinely read without glasses and a patient using a monovision approach), plus multiple choice and short answer questions either using hard copy or online. RESULTS: Responses were obtained from 437 optometrists and 50 ophthalmologists. Optometrists who reported they would provide target refraction advice were more experienced (median 22 years) than those who would leave this to the Hospital Eye Service (median 10 years). The former group reported it was in the patients' best interest to make an informed decision as they had seen many myopic patients who read uncorrected pre-operatively, and were unhappy that they could no longer do so after surgery. Inexperienced optometrists reported that they did not want to overstep their authority and left the decision to the ophthalmologist. The ophthalmologists estimated their percentage of emmetropic target refractions over the last year to have been 90%. CONCLUSION: Currently, some long-term myopes become dissatisfied after cataract surgery due to an emmetropic target refraction that leaves them unable to read without glasses as they did prior to surgery. Although experienced optometrists are aware of this and attempt to discuss this issue with patients, less experienced optometrists tend not to. This suggests that target refraction needs greater exposure in university training and continuing professional development. To provide patients with the knowledge to make informed decisions regarding their surgery, we suggest an agreed protocol within funded direct referral schemes of initial target refraction discussions by optometrists to introduce the idea of refractive outcomes and outline options, with further discussion with the ophthalmologist to clarify understanding.

What are the causes of non-tolerance to new spectacles and how can they be avoided?

PURPOSE: To investigate non-tolerance cases from several UK practices to determine their likely causes and how they might have been avoided. METHODS: Patient complaint and refraction data were collected from non-tolerance recheck examinations. For one practice, clinical data were also collected retrospectively to investigate the quality of the eye examinations. RESULTS: Data for 279 rechecks were gathered from 10 practices and a recheck frequency of 2.3% was found. The mean patient age was 60 (SD 16) years, with cylinder changes responsible for 38% of prescription-related causes of rechecks, overplusing or underminusing 26%, and underplusing or overminusing just 11%. An assessment of 242 recheck corrections found that 40% were unsatisfactory (e.g., failed to address initial or recheck symptoms, N = 45) and retrospective analysis of 217 case records showed many limitations (e.g., 61% or 28% recorded no uncorrected or habitual visual acuity (VA) at either initial examination or recheck). CONCLUSIONS: Given that overplus-underminus was a much bigger proportion of prescription-related cases than overminus-underplus (26% vs. 11%), the refraction mantra of "maximum plus for maximum VA" should be balanced by increased teaching of the problems of overplusing and underminusing, and the use of prescribing guidelines. In addition, continuing professional development regarding the basics of the recheck examination, refraction, visual acuity and prism determination is needed. Changes of oblique cylinders should be carefully considered in older patients as this is a common cause of non-tolerance. In addition, if the "if it ain't broke, don't fix it" and related maxims had been applied to all patients who were asymptomatic at the original examination, one third of all non-tolerance cases could have been avoided. Finally, it would seem appropriate for practices to develop a system to deal better with non-tolerance cases. Perhaps an experienced clinician should examine all patients with non-tolerance and provide feedback to the original clinician.

What are patients' beliefs about, and experiences of, adaptation to glasses and how does this affect their wearing habits?

PURPOSE: It is well known that some patients experience difficulties adapting to new glasses. However, little is known about what patients themselves understand of the adaptation process, and how this influences their attitudes and the decisions they make when adapting to a new pair of glasses. Nor is it understood whether these factors affect their wearing habits. METHODS: We conducted four focus groups. Participants were 22 glasses wearers (mean ± SD age 43 ± 14 years, range 21-71 years) who reported they: (1) wore spectacle correction for distance vision (single vision, bifocal or progressive lenses); (2) had struggled to get used to a new pair of glasses and (3) sometimes chose not to wear their distance correction. Focus groups were audio recorded, transcribed verbatim and analysed thematically. RESULTS: We identified three themes. Trust is about how participants' trust in their optometrist and themselves influences the likelihood of them adapting successfully to new glasses. Conflict describes how the advice patients have received about adapting to glasses can conflict with what they have experienced and how this conflict influences their expectations. Part of Me explores how participants' experiences and feelings about their glasses are important to adaptation and this includes physical, visual, emotional and behavioural aspects. CONCLUSIONS: The traditional optometric perspective of adaptation to glasses is much narrower than that held by patients, and significantly underestimates the physical, behavioural and emotional adaptation that patients must go through in order to feel fully comfortable wearing their glasses. Patients should receive significantly more information about adaptation, including symptoms that may be experienced and why these happen, practical tips to aid adaptation, and when and how to raise concerns. Patients should also receive information about the day-to-day effects of blur adaptation to avoid them not wearing their glasses, including for vision-critical tasks such as driving.

When is refraction stable following routine cataract surgery? A systematic review and meta-analysis.

PURPOSE: We systematically reviewed the literature to investigate when refraction is stable following routine cataract surgery implanting monofocal intraocular lenses. Current advice recommends obtaining new spectacles 4-6 weeks following surgery. Due to advancements in surgical techniques, we hypothesised that refractive stability would be achieved earlier, which could have major short-term improvements in quality of life for patients. METHODS: Medline, CINAHL, AMED, Embase, Web of Science and the Cochrane Library were searched with key words chosen to find articles, which assessed refraction following uncomplicated cataract surgery. Citation chains and the reference lists of all included papers were searched. Unpublished literature was identified using OpenGrey (www.opengrey.eu). The review considered studies that measured refraction at regular intervals following surgery until stability was achieved. RESULTS: The search identified 6,680 papers. Two reviewers independently screened the abstracts and nine papers were found to fit the criteria, of which five were included in the meta-analysis. The quality of the papers was evaluated using the Methodological Index for Non-Randomised Studies (MINORS) instrument. Meta-analysis of 301 patients' data of spherical, cylindrical and spherical equivalent correction were performed using Review Manager 5 (RevMan 5.3) (https://revman.cochrane.org/). Refraction at 1-week versus the gold standard of 4-weeks showed no significant difference for sphere data (effect size and 95% confidence interval of; ES = 0.00, 95% CI: -0.17, 0.17; p = 1.00), cylindrical data (ES = +0.06; 95% CI: -0.05, 0.17; p = 0.31), and spherical equivalent (ES = -0.01; 95% CI: -0.12, 0.10; p = 0.90). Heterogeneity was non-significant (I2  < 25%) for all refractive elements. Data were similar for 2- versus 4-weeks post-surgery. Acquired data from one study highlighted a small number of patients with very unstable cylindrical corrections at 1-week post-operatively. CONCLUSIONS: No statistical difference was found when comparing sphere, cylindrical and spherical equivalent values at 1- and 4-weeks post cataract surgery. This suggests that new glasses could be provided 1-week after surgery. However, from a clinical perspective, a small number of patients (~7%) from an acquired dataset (N = 72) showed very unstable cylindrical corrections at 1-week. Further work is needed to determine why this is the case and how these patients can be detected.

Experiences following cataract surgery - patient perspectives.

PURPOSE: Most patients report being highly satisfied with the outcome of cataract surgery but there are variable reports regarding the impact of cataract surgery on some real-world activities, such as fall rates. We hypothesised that adaptations to changed refractive correction and visual function may cause difficulties in undertaking everyday activities for some patients and used a series of focus groups to explore this issue. METHOD: Qualitative methods were used to explore patients' experiences of their vision following cataract surgery, including adaptation to vision changes and their post-surgical spectacle prescription. Twenty-six participants took part in five focus groups (Mean age = 68.2 ± 11.4 years), and the data were analysed using thematic analysis. RESULTS: We identified three themes. 'Changes to Vision' explores participants' adaptation following cataract surgery. While several had problems with tasks relying on binocular vision, few found them bothersome and they resolved following second eye surgery. Participants described a trial and error approach to solving these problems rather than applying solutions suggested by their eyecare professionals. 'Prescription Restrictions' describes the long-term vision problems that pre-surgery myopic patients experienced as a consequence of becoming emmetropic following surgery and thus needing spectacles for reading and other close work activities, which they did not need before surgery. Very few reported that they had the information or time to make a decision regarding their post-operative correction. 'Information Needs' describes participant's responses to the post-surgical information they were given, and the unmet information need regarding when they can drive following surgery. CONCLUSION: The findings highlight the need for clinicians to provide information on adaptation effects, assist patients to select the refractive outcome that best suits their lifestyle, and provide clear advice about when patients can start driving again. Patients need to be provided with better guidance from clinicians and prescribing guidelines for clinicians would be beneficial, particularly for the period between first- and second-eye surgery.

Subjective Verticality Is Disrupted by Astigmatic Visual Distortion in Older People.

Purpose: There is little research evidence to explain why older adults have more problems adapting to new spectacles incorporating astigmatic changes than younger adults. We tested the hypothesis that astigmatic lenses oriented obliquely would lead to errors in verticality perception that are greater for older than younger adults. Methods: Participants included 12 young (mean ± SD age 25.1 ± 5.0 years) and 12 older (70.2 ± 6.3 years) adults with normal vision. Verticality perception was assessed using a computer-based subjective visual vertical (SVV) task, under static and dynamic (in the presence of a moving peripheral distractor) conditions and when viewing targets through the near refractive correction (control condition), and two forms of astigmatic lenses oriented in the vertical, horizontal, and oblique meridians. Results: The older group demonstrated much greater dynamic SVV errors (e.g., 3.4° for the control condition) than the younger group (1.2°, P = 0.002), larger errors with vertical and horizontal astigmatic lenses (older group 4.1°and 5.2° for toric and magnifier lenses vs. younger group 1.2° and 1.4°, respectively, P < 0.001), and a larger influence of the oblique astigmatic lenses (older group 5.6° vs. younger group 2.1°, P<0.001). Conclusions: Astigmatic lenses produced little or no errors in SVV in young adults, but large static and dynamic SVV errors in older adults. This indicates a greater reliance on visual input with increased age for SVV, and helps explain why oblique astigmatic refractive corrections can cause dizziness in older patients and why they report greater difficulties adapting to new spectacles with astigmatic changes.

Development and Validation of the Vision-Related Dizziness Questionnaire.

PURPOSE: To develop and validate the first patient-reported outcome measure (PROM) to quantify vision-related dizziness. Dizziness is a common, multifactorial syndrome that causes reductions in quality of life and is a major risk factor for falls, but the role of vision is not well understood. METHODS: Potential domains and items were identified by literature review and discussions with experts and patients to form a pilot PROM, which was completed by 335 patients with dizziness. Rasch analysis was used to determine the items with good psychometric properties to include in a final PROM, to check undimensionality, differential item functioning, and to convert ordinal questionnaire data into continuous interval data. Validation of the final 25-item instrument was determined by its convergent validity, patient, and item-separation reliability and unidimensionality using data from 223 patients plus test-retest repeatability from 79 patients. RESULTS: 120 items were originally identified, then subsequently reduced to 46 to form a pilot PROM. Rasch analysis was used to reduce the number of items to 25 to produce the vision-related dizziness or VRD-25. Two subscales of VRD-12-frequency and VRD-13-severity were shown to be unidimensional, with good psychometric properties. Convergent validity was shown by moderately good correlations with the Dizziness Handicap Inventory (r = 0.75) and good test-retest repeatability with intra-class correlation coefficients of 0.88. CONCLUSION: VRD-25 is the only PROM developed to date to assess vision-related dizziness. It has been developed using Rasch analysis and provides a PROM for this under-researched area and for clinical trials of interventions to reduce vision-related dizziness.

The Visual Impact of Lens-Induced Astigmatism is Linked to Habitual Axis.

PURPOSE: Many studies have assessed the visual impact of astigmatism by inducing it using loose trial lenses at set axes. There are conflicting opinions and some confusion about the results, but the reduction in vision is typically least with lens-induced with-the-rule astigmatism. In this study, we determined whether a participant's habitual astigmatism influences the impact of lens-induced astigmatism on distance visual acuity (VA). METHODS: Participants included 35 adults (age range 19-79, average 41.3 ± 15.4 years), who were either astigmats (≥0.75DC; N = 21) or non-astigmatic controls (N = 14). Distance VA was measured using an automated FrACT (Freiburg VA) system with the participant's habitual correction, and then with the addition of a +1.00DC lens at either 90 or 180 degrees (control) or at and perpendicular to the axis of habitual astigmatism (astigmats). RESULTS: The reduction in VA with induced astigmatism was significantly affected by whether the participant was a with-the-rule astigmat, against-the-rule astigmat, or non-astigmat (p = 0.006). Lens-induced astigmatism axis ≈ 180 (160-20°) reduced the VA less than axis ≈ 90 (70-120°) in the control group (reduction in mean VA of 0.32 SD ± 0.10 with 95% confidence intervals of [0.27,0.37] compared to 0.42 ± 0.09 [0.37,0.47] logMAR) and with-the-rule astigmats (reduction in VA of 0.31 SD ± 0.06 [0.27,0.35] compared to 0.45 SD ± 0.12 [0.38,0.52] logMAR). The against-the-rule astigmats had a very similar reduction in VA with the ≈+1.00DC axis 180 condition compared to the ≈+1.00DC axis 90 condition (reduction in VA of 0.26 SD ± 0.09 [0.21,0.31] compared to 0.25 SD ± 0.14 [0.17,0.33] logMAR). CONCLUSIONS: The impact of lens-induced astigmatism was dependent on the refractive status of the participants. When investigating the impact of lens-induced astigmatism, it is important to consider the participants' habitual axis of astigmatism.

The addition of stripes (a version of the 'horizontal-vertical illusion') increases foot clearance when crossing low-height obstacles.

Trips over obstacles are one of the main causes of falling in older adults, with vision playing an important role in successful obstacle negotiation. We determined whether a horizontal-vertical illusion, superimposed onto low-height obstacles to create a perceived increase in obstacle height, increased foot clearances during obstacle negotiation thus reducing the likelihood of tripping. Eleven adults (mean ± 1 SD: age 27.3 ± 5.1 years) negotiated obstacles of varying heights (3, 5, 7 cm) with four different appearance conditions; two were obstacles with a horizontal-vertical illusion (vertical stripes of different thickness) superimposed on the front, one was a plain obstacle and the fourth a plain obstacle with a horizontal black line painted on the top edge. Foot clearance parameters were compared across conditions. Both illusions led to a significant increase in foot clearance when crossing the obstacle, compared to the plain condition, irrespective of obstacle height. Superimposing a horizontal-vertical illusion onto low-height obstacles can increase foot clearance, and its use on the floor section of a double-glazing door frame for example may reduce the incidence of tripping in the home. Practitioner Summary: Low-height obstacles such as the floor section of a double-glazing door frame are potential tripping hazards. In a gait lab-based study we found that a horizontal-vertical illusion superimposed onto low-height obstacles led to significantly higher foot clearances; indicating their potential as a useful safety measure.