Do visual fields need to be considered in classification criteria within visually impaired shooting?

Classification within the sport of vision impairment (VI) shooting is based upon the athlete's visual function. This study aimed to determine whether more than one class of competition is needed within VI shooting on the basis of visual field loss. Qualification scores of 23 elite athletes were obtained at World Championship events in prone and standing shooting disciplines. Visual field data were obtained from classification data and from assessment at events. A standardized scoring protocol determined whether athletes had function (≥10 dB) or no function (<10 dB) at locations between 0-60 degrees eccentricity along 10 meridia. Visual field function was not associated with shooting performance in prone or standing disciplines (p > 0.05). Having measurable visual field function beyond 30 degrees made no difference to athletes' ability to shoot competitively in prone (p = 0.65) or standing disciplines (p = 0.47), although a potential impact on qualification was observed in the standing discipline. There was no evidence that loss of visual field function at any specific location adversely affected ability to shoot competitively. There is currently no evidence to consider visual fields in classification within prone or standing VI shooting, although further research is needed as the sport grows.

Rifle Shooting for Athletes With Vision Impairment: Does One Class Fit All?

Revised evidence-based classification criteria introduced for shooting for athletes with vision impairment (VI shooting) suggest that athletes with impaired contrast sensitivity (CS) and visual acuity (VA) should be eligible for inclusion in the sport but should all eligible athletes compete against each other in the same "class" or is more than one class necessary? Twenty-five elite VI shooting athletes took part in the study. Two measures of visual function were assessed under standardized conditions: VA (using an ETDRS logMAR letter chart, and/or a BRVT chart) and CS (using both a Pelli-Robson chart and a Mars number chart). Shooting performance, in both prone and standing events, was measured during an international VI shooting competition. Fourteen of the 25 athletes had measurable VA, and for CS, 8 athletes had measurable function with the Pelli-Robson chart and 13 with the Mars chart. The remaining athletes had function not numerically measurable by the charts and were considered to have no residual vision. There was no indication that shooting performance varied with visual function, and individuals that had residual vision had no advantage over those without vision for either prone or standing shooting. The modifications made to VI shooting, including the use of auditory tones to guide the gun barrel, appear to have successfully rendered the sport equitable for all eligible athletes. Only one class is necessary for athletes. An improved method of measuring CS in athletes with profound VI would be advantageous.

Contrast Sensitivity Is a Significant Predictor of Performance in Rifle Shooting for Athletes With Vision Impairment.

Purpose: In order to develop an evidence-based, sport-specific minimum impairment criteria (MIC) for the sport of vision-impaired (VI) shooting, this study aimed to determine the relative influence of losses in visual acuity (VA) and contrast sensitivity (CS) on shooting performance. Presently, VA but not CS is used to determine eligibility to compete in VI shooting. Methods: Elite able-sighted athletes (n = 27) shot under standard conditions with their habitual vision, and with their vision impaired by the use of simulation spectacles (filters which reduce both VA and CS) and refractive blur (lenses which reduce VA with less effect on CS). Habitual shooting scores were used to establish a cut-off in order to determine when shooting performance was 'below expected' in the presence of vision impairment. Logistic regression and decision tree analyses were then used to assess the relationship between visual function and shooting performance. Results: Mild reductions in VA and/or CS did not alter shooting performance, with greater reductions required for shooting performance to fall below habitual levels (below 87% of normalized performance). Stepwise logistic regression selected CS as the most significant predictor of shooting performance, with VA subsequently improving the validity of the model. In an unconstrained decision tree analysis, CS was selected as the sole criterion (80%) for predicting 'below expected' shooting score. Conclusion: Shooting performance is better predicted by losses in CS than by VA. Given that it is not presently tested during classification, the results suggest that CS is an important measure to include in testing for the classification of vision impairment for athletes competing in VI shooting.

Functional visual fields: a cross-sectional UK study to determine which visual field paradigms best reflect difficulty with mobility function.

OBJECTIVES: To develop an appropriate method of assessing visual field (VF) loss which reflects its functional consequences, this study aims to determine which method(s) of assessing VF best reflect mobility difficulty. SETTING: This cross-sectional observational study took place within a single primary care setting. Participants attended a single session at a University Eye Clinic, Cambridge, UK, with data collected by a single researcher (HS), a qualified optometrist. PARTICIPANTS: 50 adult participants with peripheral field impairment were recruited for this study. Individuals with conditions not primarily affecting peripheral visual function, such as macular degeneration, were excluded from the study. PRIMARY AND SECONDARY OUTCOME MEASURES: Participants undertook three custom and one standard binocular VF tests assessing VF to 60°, and also integrated monocular threshold 24-2 visual fields (IVF). Primary VF outcomes were average mean threshold, percentage of stimuli seen and VF area. VF outcomes were compared with self-reported mobility function assessed with the Independent Mobility Questionnaire, and time taken and patient acceptability were also considered. Receiver operating characteristic (ROC) curves determined which tests best predicted difficulty with mobility tasks. RESULTS: Greater VF loss was associated with greater self-reported mobility difficulty with all field paradigms (R2 0.38-0.48, all P<0.001). All four binocular tests were better than the IVF at predicting difficulty with at least three mobility tasks in ROC analysis. Mean duration of the tests ranged from 1 min 26 s (±9 s) for kinetic assessment to 9 min 23 s (±24 s) for IVF. CONCLUSIONS: The binocular VF tests extending to 60° eccentricity all relate similarly to self-reported mobility function, and slightly better than integrated monocular VFs. A kinetic assessment of VF area is quicker than and as effective at predicting mobility function as static threshold assessment.

Functional visual fields: relationship of visual field areas to self-reported function.

PURPOSE: The aim of this study is to relate areas of the visual field to functional difficulties to inform the development of a binocular visual field assessment that can reflect the functional consequences of visual field loss. METHODS: Fifty-two participants with peripheral visual field loss undertook binocular assessment of visual fields using the 30-2 and 60-4 SITA Fast programs on the Humphrey Field Analyser, and mean thresholds were derived. Binocular visual acuity, contrast sensitivity and near reading performance were also determined. Self-reported overall and mobility function were assessed using the Dutch ICF Activity Inventory. RESULTS: Greater visual field loss (0-60°) was associated with worse self-reported function both overall (R2 = 0.50; p < 0.0001), and for mobility (R2 = 0.64; p < 0.0001). Central (0-30°) and peripheral (30-60°) visual field areas were similarly related to mobility function (R2 = 0.61, p < 0.0001 and R2 = 0.63, p < 0.0001 respectively), although the peripheral (30-60°) visual field was the best predictor of mobility self-reported function in multiple regression analyses. Superior and inferior visual field areas related similarly to mobility function (R2 = 0.56, p < 0.0001 and R2 = 0.67, p < 0.0001 respectively). The inferior field was found to be the best predictor of mobility function in multiple regression analysis. CONCLUSION: Mean threshold of the binocular visual field to 60° eccentricity is a good predictor of self-reported function overall, and particularly of mobility function. Both the central (0-30°) and peripheral (30-60°) mean threshold are good predictors of self-reported function, but the peripheral (30-0°) field is a slightly better predictor of mobility function, and should not be ignored when considering functional consequences of field loss. The inferior visual field is a slightly stronger predictor of perceived overall and mobility function than the superior field.

The relationship between visual function and performance in rifle shooting for athletes with vision impairment.

BACKGROUND: Paralympic sports provide opportunities for those who have an impairment that might otherwise be a barrier to participation in regular sporting competition. Rifle shooting represents an ideal sport for persons with vision impairment (VI) because the direction of the rifle can be guided by auditory information when vision is impaired. However, it is unknown whether those with some remaining vision when shooting with auditory guidance would be at an advantage when compared with those with no vision at all. If this were the case then it would be necessary for those with and without remaining vision to compete in separate classes of competition. MATERIALS AND METHOD: The associations between shooting performance and 3 measures of visual function thought important for shooting were assessed for 10 elite VI shooters currently classified as VI. A conventional audiogram was also obtained. RESULTS: The sample size, though small, included the majority of European VI shooters competing at this level. The relationships between visual functions and performance confirmed that individuals with residual vision had no advantage over those without vision when auditory guidance was available. Auditory function was within normal limits for age, and showed no relationship with performance. SUMMARY: The findings suggest that rifle-shooting athletes with VI are able to use auditory information to overcome their impairment and optimise performance. Paralympic competition should be structured in a way that ensures that all shooters who qualify to compete in VI shooting participate within the same class irrespective of their level of VI.

The Level of Vision Necessary for Competitive Performance in Rifle Shooting: Setting the Standards for Paralympic Shooting with Vision Impairment.

The aim of this study was to investigate the level of vision impairment (VI) that would reduce performance in shooting; to guide development of entry criteria to visually impaired (VI) shooting. Nineteen international-level shooters without VI took part in the study. Participants shot an air rifle, while standing, toward a regulation target placed at the end of a 10 m shooting range. Cambridge simulation glasses were used to simulate six different levels of VI. Visual acuity (VA) and contrast sensitivity (CS) were assessed along with shooting performance in each of seven conditions of simulated impairment and compared to that with habitual vision. Shooting performance was evaluated by calculating each individual's average score in every level of simulated VI and normalizing this score by expressing it as a percentage of the baseline performance achieved with habitual vision. Receiver Operating Characteristic curves were constructed to evaluate the ability of different VA and CS cut-off criteria to appropriately classify these athletes as achieving 'expected' or 'below expected' shooting results based on their performance with different levels of VA and CS. Shooting performance remained relatively unaffected by mild decreases in VA and CS, but quickly deteriorated with more moderate losses. The ability of visual function measurements to classify shooting performance was good, with 78% of performances appropriately classified using a cut-off of 0.53 logMAR and 74% appropriately classified using a cut-off of 0.83 logCS. The current inclusion criteria for VI shooting (1.0 logMAR) is conservative, maximizing the chance of including only those with an impairment that does impact performance, but potentially excluding some who do have a genuine impairment in the sport. A lower level of impairment would include more athletes who do have a genuine impairment but would potentially include those who do not actually have an impairment that impacts performance in the sport. An impairment to CS could impact performance in the sport and might be considered in determining eligibility to take part in VI competition.

Agreement among optometrists and ophthalmologists in estimating limbal anterior chamber depth using the van Herick method.

PURPOSE: To evaluate the inter-observer agreement for measuring limbal anterior chamber depth (LACD) using the van Herick test in community optometrists, glaucoma specialist optometrists and ophthalmologists. METHODS: The study was divided into two phases. In the first phase, a random sample of 100 UK community optometrists were given an opportunity to select and grade eight digital slit-lamp images of anterior chamber angles using the original van Herick 4 point grading scale. The images were included in a clinical decision making study using computerised virtual case vignettes. In the second phase, hospital-based glaucoma specialist optometrists and glaucoma sub-specialist ophthalmologists graded the LACD of the right eye using a 7-point % grading scale in 57 consecutively presenting patients with suspect glaucoma. Inter-observer agreement was assessed using linearly weighted kappa (κw ). RESULTS: Inter-observer agreement for community optometrists was moderate, with a mean κw for grading photographic images of 0.50 (95% confidence interval (CI) 0.43-0.57). Overall, ninety-two percent of observations were within one grade of the actual grade, although grading of narrow angles was associated with a 13% false negative error rate (based on a ≤ grade 2 threshold). For Phase 2 of the study, pairwise comparisons between optometrists and ophthalmologists showed that agreement was moderate to substantial (mean κw  = 0.54-0.65) with a false negative rate of 1.9% (based on a ≤ 25% threshold). Grading accuracy of specialist optometrists and ophthalmologists were equivalent. CONCLUSIONS: In summary, the present study found that community optometrists showed moderate inter-observer agreement for grading LACD. Glaucoma specialist optometrists showed moderate to substantial agreement with weighted kappa values that were equivalent to sub-specialist ophthalmologists. The augmented 7-point % grading scale is intuitive and potentially offers greater accuracy for grading narrow angles than the traditional 4-point scale for grading LACD.

The impact of postgraduate training on UK optometrists' clinical decision-making in glaucoma.

PURPOSE: To investigate the impact of a postgraduate training module on optometrists' clinical decision-making in relation to the diagnosis and management of primary open-angle glaucoma. METHODS: A group of United Kingdom community optometrists (n = 53) were assessed immediately before and again 3 months after completing a 3-day didactic postgraduate university module on the diagnosis and management of glaucoma. A smaller control cohort (n = 20), who did not receive the intervention, was recruited and completed the same assessments on two occasions, separated by approximately 3 months. The assessments comprised: knowledge of five key features of the optic disc in glaucoma, performance on a computer program (Discus) that assessed the ability to differentiate normal from glaucomatous discs and a clinical decision-making exercise using case-based scenarios. RESULTS: The scores for the knowledge of important disc features for the intervention cohort significantly increased from a median of 2/5 to 5/5 post-intervention (p < 0.001). For the control cohort, the difference in median scores between the two tests was not significant. Analysing the performance of the intervention cohort using the Discus program showed no significant improvement in ability to diagnose a glaucomatous disc following the intervention [mean area under the receiver operating characteristic curve pre-intervention = 0.85 (95% CI: 0.76-0.91), post-intervention = 0.84 (95% CI: 0.76-0.91)]. Similarly, there were no statistically significant differences in mean areas under the receiver operating characteristic curve between tests for the control cohort, although both cohorts compared favourably with a previously published Discus data set from a panel of experts in disc analysis (mean area = 0.87). For the clinical decision-making exercise the median test score for the intervention cohort was unchanged pre- and post-intervention. CONCLUSION: The results of the present study suggest that a traditional didactic approach, in isolation, is unlikely to be suited to training optometrists to achieve or develop the clinical competencies required for glaucoma detection and management. Consideration should be given to the development of specialist postgraduate training that is more practice-based, provides opportunities for active learning and includes strategies for feedback and reinforcement.

Does optometrists' self-reported practice in glaucoma detection predict actual practice as determined by standardised patients?

PURPOSE: Questionnaires are commonly used as a proxy measure of clinical practice; however their application in a variety of healthcare settings has found significant self-reporting bias. The aim of this study is to estimate the validity of self-reporting as a measure of optometrist case-finding practice for glaucoma and the appropriate referral of suspects. METHODS: Two complementary approaches were used: (1) a sample of optometrists (N=34) on an ophthalmic list in West London were visited incognito by Standardised Patient (SP) volunteers aged over 54 who were trained to identify the components of a standard Sight Test. Optometrists from the same list were then invited to participate in a structured face-to-face interview regarding their case finding practice for glaucoma. The findings from the two sources were compared. (2) as part of a national glaucoma survey of optometrists, respondents (N=1264) were asked in a free text question for the information that they would include in a referral letter for suspect glaucoma. The responses were compared to the content of a sample of glaucoma referral letters (N=571) obtained from consultant ophthalmologists across the UK. In each case, the degree of correspondence ('match') between reported practice and actual practice was assessed by chi-square analysis. RESULTS: For the SP study there was incomplete correspondence between the questionnaire and SP reports in several areas e.g. questions relating to a complete history and symptoms, measurement of intra-ocular pressure and visual fields. Complete correspondence was found for questions asking about the routine assessment of ocular health and refraction. For the referral study, correspondence between survey findings and referral letters was obtained for IOP only. No correspondence was found for disc assessment, visual fields or family history of glaucoma. CONCLUSIONS: The overall findings from both studies indicate that self-reported clinical practice questionnaires overestimate routine tests undertaken by optometrists in practice. Although there was a good correspondence for mandatory tests, correspondence was poor for discretionary tests. These findings should be borne in mind in all questionnaire studies that report current practice in glaucoma case-finding.

A national survey of diagnostic tests reported by UK community optometrists for the detection of chronic open angle glaucoma.

PURPOSE: In the UK, the majority of cases of chronic open angle glaucoma are detected by community optometrists following a routine sight test. However, there is potential for variability in case finding strategies used. The aim of this study was to carry out a national web-based survey to determine current diagnostic tests used by optometrists in glaucoma case finding. METHODS: Optometrists on the Association of Optometrists (AOP) electronic database were invited to participate. The survey was open for 16 weeks between April and July 2008. RESULTS: A total of 1875 optometrists were eligible to enter the survey, of which 1264 answered the questions relating to diagnostic equipment. Respondents were asked to indicate their usual method of examining the optic nerve head. Direct ophthalmoscopy only was used by 25% with the majority (62%) using a combination of direct and slit-lamp binocular indirect methods. The vast majority of optometrists (78%) used non-contact tonometry to measure intraocular pressure, with only 16% routinely using a Goldmann or Perkins applanation tonometer. The perimeter most frequently used was either one of the Henson range of instruments (39%) or the Humphrey Field Analyser (22%). A smaller number of optometrists (<5%) had access to more specialised imaging equipment, such as HRT, GDx or OCT. CONCLUSIONS: The results of the survey demonstrate that UK optometrists are well equipped to carry out case finding for chronic open angle glaucoma, although there is a lack of standardisation with respect to equipment used.

Barriers perceived by UK-based community optometrists to the detection of primary open angle glaucoma.

PURPOSE: This paper aims to identify the barriers to case-finding for primary open angle glaucoma (POAG) as perceived by community optometrists in the United Kingdom (UK). METHODS: An anonymous, online survey to investigate the current mode of optometric practice for the detection of POAG was developed. The survey included a free-text question relating to barriers to case-finding for the disease. Optometrists on the Association of Optometrists (AOP) electronic database were invited to participate. The survey was open for 16 weeks between April and July 2008. RESULTS: A total of 1680 responses was received to the survey, of which 1293 (77%) answered the free-text question relating to perceived barriers. Eighty-eight per cent of these reported one or more barriers to the detection of glaucoma in the community, most commonly: time constraints limiting the options for repeat testing and lack of financial remuneration to perform the additional tests required. Barriers were less frequently reported in Scotland, with 23.4% of optometrists reporting no barriers compared to only 12% in England, 6% in Northern Ireland and 4% in Wales. CONCLUSION: In general, UK optometrists believed that their ability to detect POAG in the community is hampered by time and financial constraints. However, barriers were significantly fewer in Scotland, where optometrists have different contractual terms of service with the NHS than their counterparts in the rest of the UK.