Use of vision tests in clinical decision making about cataract surgery: results of a national survey

Glaucoma and glare

PURPOSE

To determine whether a purpose-built glare tester, in combination with new glare-specific questions, can better assess glaucoma patients' experience of glare and visual disability than visual acuity (VA) or visual fields alone.

PATIENTS AND METHODS

Consecutive patients attending for visual fields in a single glaucoma clinic from 03/06/2019-01/11/2019 underwent VA assessment using a Brightness Acuity Tester as a glare source, examination for media opacities, and completed the VFQ-25 with four additional glare-related questions. One hundred and sixteen eyes (64 patients) were included for analysis. The amount of disability glare (VA reduction due to glare) was compared according to presence/absence of media opacity and glaucoma severity. Subjective glare symptoms were compared with objective disability glare measurement using a Bland-Altman plot.

RESULTS

Patients with advanced-severe glaucoma had significantly worse disability glare than those with mild-moderate glaucoma. VA reduction due to glare from mild-moderate to acute-severe glaucoma (mean -3.4 letters, P = 0.01, CI -0.8, -6.0) was of almost identical magnitude to that due to presence of any media opacity (mean -3.3 letters, P = 0.03, CI -0.4, -6.2). There was a trend towards greater disability glare in more symptomatic patients, with good agreement between subjective and objective glare measurements for those with few glare signs or symptoms, but progressively more variation either side of agreement as either measurement worsened.

CONCLUSIONS

Glaucoma is associated with objective and subjective acuity reduction in the presence of glare. We demonstrated an increase in disability glare in patients with more severe glaucoma. The worse the glare symptoms or signs, the more variable the agreement between objective and subjective assessments.

Relationship Between Acuity and Contrast Sensitivity: Differences Due to Eye Disease

Purpose

Visual acuity (VA) and contrast sensitivity (CS) characterize different aspects of visual function. Whereas VA is a standard test in routine eye exams and clinical trials, CS is often not included. We investigated the pathology-specific dissociation between VA and CS by quantifying and comparing the relationship between these two measures in common ocular pathologies.

Methods

VA and CS data were assembled from 1113 subjects, including groups with cataract (n = 450), age-related macular degeneration (AMD; n = 232), glaucoma (n = 100), retinitis pigmentosa (RP; n = 87), and normal ocular health (n = 244). VA and CS were measured by the Early Treatment Diabetic Retinopathy Study chart and Pelli-Robson chart, respectively.

Results

Even when VA was relatively normal (<0.3 logMAR), the four ocular pathology groups showed quantitatively different mean CS deficits relative to normal controls, ranging from -0.01 log units for cataract to 0.23 log units for RP. When the entire range of VA was considered, the corresponding deficits in CS were noticeably different across these four groups, being least for cataract and progressively more severe for glaucoma, AMD, and RP. For every 1.0 logMAR loss of VA, the corresponding deficit in CS ranged from 0.22 logCS for cataract to 0.97 logCS for RP.

Conclusions

The quantitative relationship between VA and CS depends on the ocular pathology. CS appears to provide valuable complementary information to VA in the early detection of eye disease and when evaluating visual impairment.

Patients' maximum acceptable waiting time for cataract surgery: a comparison at two time-points 7 years apart

PURPOSE

To evaluate the maximum acceptable waiting time (MAWT) of cataract patients and assess the determinants of their perception of MAWT at two time-points 7 years apart.

METHODS

In 2007 (prior to the transformation of our cataract service to a day case unit) and 2014, 500 consecutive patients with cataract were asked to fill in a preoperative questionnaire addressing their MAWT to undergo cataract surgery. The patients' visual impairment (VF-14 score), education and social status were evaluated.

RESULTS

The mean MAWT was 3.2 months in both periods, whereas the actual waiting time decreased significantly by 1.7 months (p < 0.001). Patients who had self-noted visual impairment were nearly four times (p < 0.001) more likely to accept only an MAWT of <3 months in 2007. In both periods, patients with a VF-14 score lower than the mean were more likely to accept a shorter MAWT (p = 0.002 and p = 0.034). Living together with children or having relatives close by was associated with a greater acceptance of an MAWT longer than 3 months (p = 0.002 and p = 0.023).

CONCLUSION

Reducing the actual mean waiting time had no impact on the mean MAWT. Patients with poor tolerance of waiting had greater self-reported difficulty with vision. Social support was also a strong predictor from the patients' perspective. The VF-14 score had a greater impact than clinical visual acuity (VA) testing. Considering the implementation of standards for waiting lists, objective criteria to guarantee a transparent system should be taken into account.

Which factors influence patients' maximum acceptable waiting time for cataract surgery? - a questionnaire survey

PURPOSE

To evaluate patients’ maximum acceptable waiting time (MAWT) and to assess the determinants of patient perceptions of MAWT.

METHODS

A total of 500 consecutive patients with cataract were asked to fill out a preoperative questionnaire, addressing patients’ MAWT to undergo cataract surgery. Patients’ visual impairment (VF-14 score), education, profession and social status were evaluated, and an ophthalmologic examination was performed. Univariate analysis included Spearman’s correlation test, unpaired Student’s t-test and the Mann–Whitney U test. Univariate and multivariate associations were calculated using unconditional logistic regression.

RESULTS

The mean MAWT was 3.17 ± 2.12 months. The mean VF-14 score was 72.10 ± 22.54. Between VF-14 score and MAWT, there was a significant correlation (r = 0.180, p = 0.004). Patients with higher education (high school, university) accepted significantly longer MAWT (3.92 ± 2.38 months versus 3.02 ± 2.00 months, p = 0.009). Patients who had self-noticed visual impairment were nearly four times (OR: 3.88, 95% CI = 2.07–7.28, p < 0.001) more likely to accept only MAWT of <3 months.

CONCLUSIONS

Patients with low tolerance for waiting had greater self-reported difficulty with vision. Patients’ acceptance of waiting was not associated with clinical visual acuity measures. Education, ability to work, living independently and taking care of dependents were also strong predictors from patients’ perspective. Considering the implementation of standards for waiting lists, these facts should be taken into account.

Cataract surgery and quality of life implications

Cataract surgery in the developed world has undergone a revolution over the last 20 years. An operation which used to require a stay in hospital and long visual rehabilitation is now a quick day-case procedure with immediate benefits. As with any surgery there is an associated morbidity, but there is now the potential to provide cataract surgery at an earlier stage of cataract maturation and save patients from a period of severe visual impairment. This article reviews the new techniques available to measure the impact that cataracts have not only on a patient's visual acuity but also their general physical health, function, cognition, and emotional well-being. New research is described that takes into account these more holistic tests and how they can be used to judge the best time to refer and operate on a patient with cataracts.

The effect of the randomized trial of patching regimens for treatment of moderate amblyopia on pediatric ophthalmologists: 3-year outcome

PURPOSE

To investigate whether the recommendations of the randomized trial of patching regimens for treatment of moderate amblyopia in children have been adopted by pediatric ophthalmologists 3 years after publication.

METHODS

An identical questionnaire to that emailed 3 years ago (6 months after publication of the randomized trial) was emailed to 560 members of the American Association for Pediatric Ophthalmology and Strabismus.

RESULTS

One hundred seven (20%) responses were received. Fifty-five percent of respondents had decreased their prescribed patching regimens at least sometimes as compared with 28% (p = 0.0005) in 2003. There was no significant increase in the prescription of near visual tasks or only 2 hour patching regimens.

CONCLUSIONS

Our study suggests that pediatric ophthalmologists may be prescribing fewer patching hours in 2006 in comparison to 2003. However, the majority of ophthalmologists are still reluctant to patch for only 2 hours, and there has not been a significant increase in prescribing near visual tasks during patching.

Principles of disability glare measurement: an ophthalmological perspective

Disability glare describes the loss of retinal image contrast as a result of intraocular light scatter, or straylight. It has increasingly important modern implications such as with cataract and refractive surgery or high-intensity lighting. However, its measurement has proven difficult despite many varying approaches. This article aims to explain the principles and problems associated with glare testing that are important for assessment and use of glare measures. After defining disability glare, this article discusses the importance of its measurement to current clinical practice. It explains the principles and mechanisms that underlie disability glare and its measurement. Finally, some examples of available glare tests are described to illustrate the principles discussed.

Capabilities of potential vision test measurements

PURPOSE

To determine the usefulness of a battery of potential vision tests (PVTs) including potential acuity meter (PAM), laser interferometer (LI), critical flicker/fusion frequency (CFF), superilluminated pinhole at distance (SPH(d)) and near (SPH(n)), and optimal reading speed (ORS) by their independence of the effects of cataracts and sensitivity to macular disease (MD).

SETTING

Department of Optometry, University of Bradford, Bradford and Leeds General Infirmary, Leeds, United Kingdom.

METHODS

Potential vision test measurements were determined in 76 patients with age-related cataract and no other eye disease, 52 patients with MD and clear ocular media, and 28 patients with normal, healthy eyes.

RESULTS

Potential vision tests were independent of the degrading effects of cataract up to a visual acuity (VA) level of 20/200 or worse (CFF), 20/125 (ORS and SPH), and 20/40 (PAM and LI). A high degree of association was found between PVT scores and distance VA in the MD group for SPH(d) (r2 = 0.93), SPH(n) (r2 = 0.89), and PAM (r2 = 0.71). A moderate correlation was found for LI (r2 = 0.55), CFF (r2 = 0.50), and ORS (r2 = 0.45).

CONCLUSIONS

Potential acuity meter and LI showed very limited independence to moderate/dense cataracts and inaccurate predictions in patients with MD. Superilluminated pinhole was relatively unaffected by moderate/dense cataract and yet provided accurate predictions in the presence of MD and clear ocular media. Critical flicker/fusion frequency showed the greatest ability to bypass cataracts, although its ability to predict VA in patients with early MD was limited. The ORS was relatively unaffected by moderate/dense cataract, but its poor ability to predict VA in MD may limit its clinical suitability as a PVT.

Impact of differences between eyes on binocular measures of vision in patients with cataracts

PURPOSE

To assess the association of stereopsis with differences between eyes (better minus worse eye value) and the binocular value of visual acuity and contrast sensitivity, and to analyse binocular summation or inhibition phenomena owing to differences between eyes.

METHODS

A cohort of 137 patients with bilateral cataracts (visual acuity of 0.3 LogMAR or worse in both eyes) was followed up through first- and second-eye cataract surgery. The patients were recruited from the ophthalmology departments of two teaching hospitals. Visual acuity, contrast sensitivity (monocular and binocular), and stereopsis were measured preoperatively, after first- and second-eye surgery. Multiple linear regression and local correlation analyses were used.

RESULTS

Stereopsis was most strongly influenced by visual acuity in the postoperative period after first-eye surgery (standardized coefficients of 0.382 for difference between eyes and 0.356 for binocular visual acuity) and by contrast sensitivity in the postoperative period after second-eye surgery (standardized coefficients of 0.353 for the difference between eyes and -0.312 for binocular contrast sensitivity). After first-eye surgery, the correlation of the differences between eyes with stereopsis was stronger (between 0.4 and 0.5) when the differences were greater than 0.4 logMAR units for visual acuity. Slight binocular summation was found for contrast sensitivity.

CONCLUSIONS

When assessing the indication for and outcomes of cataract surgery, analysis of visual function should include measures of both eyes, rather than measures of the operative eye only, as differences between eyes (better minus worse eye value) may play an important role in binocular measures such as stereopsis.

Higher-order wavefront aberrations in retinitis pigmentosa

PURPOSE

The purpose of this study was to characterize higher-order wavefront aberrations associated with posterior subcapsular (PSC) cataracts in patients with retinitis pigmentosa (RP).

METHODS

Wavefront aberrations were measured by Shack-Hartmann (SH) aberrometry in eight patients with RP who had PSC cataracts, 10 patients with RP who had minimal or no PSC cataracts, and 16 age-equivalent visually normal control subjects. Higher-order wavefront aberrations for 3-mm and 6-mm pupil diameters were defined as the root mean square (RMS) of the wavefront aberration functions.

RESULTS

For a 6-mm pupil diameter, the mean RMS for total higher-order wavefront aberrations was significantly larger for the patients with RP than for the control subjects, both for patients with PSC cataract (F = 17.30, p < 0.001) and for those with minimal or no PSC cataract (F = 4.80, p < 0.05). The mean RMS for third-order aberrations was not significantly different for patients with RP than for the control subjects. However, the mean RMS for fourth-order aberrations was significantly larger for the patients with RP than for the control subjects, both for patients with PSC cataract (F = 8.85, p < 0.01) and those with minimal or no PSC cataract (F = 5.07, p < 0.05). There were no significant differences in higher-order aberrations between the patients with RP and the control subjects for a 3-mm pupil diameter.

CONCLUSIONS

Increased higher-order wavefront aberrations were present in patients with RP with and without clinically observable PSC cataracts. The measurement of wavefront aberrations in patients with RP provides an objective and quantitative method for detecting and monitoring disease-related changes in the optics of the eye.

The prioritization of patients on waiting lists for cataract surgery: validation of the Western Canada waiting list project cataract priority criteria tool

PURPOSE

To assess the validity of the Cataract Priority Criteria Score (PCS), developed by the Western Canada Waiting List (WCWL) Project to determine patient prioritization for cataract surgery.

METHODS

Ophthalmologists assessed consecutive patients with the PCS and a visual analogue scale of urgency (VAS Urgency). Patients were mailed questionnaires pre- and post-surgery. Outcome measures were the Visual Function Assessment (VFA), EuroQol (EQ-5D), and best-corrected visual acuity.

RESULTS

The sample of 253 patients was 58% female (mean age, 73.7 years); 166 completed pre-and post-surgery VFA. The correlation of the PCS and VAS Urgency was 0.65 (p = 0.000). Adjusting for age, first or second eye surgery, and post-operative complication, the PCS predicted improvement in the VFA and visual acuity (p < .05).

CONCLUSIONS

These data provide some evidence to support the convergent and predictive validity of the PCS. Multiple patient outcomes should be used in the evaluation of the validity of priority scores.

The Bristol cataract listing survey: profile of listed patients with visual acuity 6/12 or better

INTRODUCTION

The aim of this study was to assess the vision-related quality of life (VR-QOL) in patients with good distance Snellen visual acuity (VA) who are listed for cataract surgery.

METHODS

An observational cross-sectional prospective study of patients listed for cataract surgery. VA and VR-QOL data using the VCMI questionnaire were collected on patients attending preoperative assessment during June 2002.

RESULTS

A total of 397 cataract patients were listed during this month. Following exclusions there were 378 eligible individuals, 210 (56%) of whom had a VA of 6/12 or better in the eye scheduled for surgery. Of these, 40% patients had only mild VR-QOL impairment. More than half of the patients with good VA (6/12 or better) in the surgery eye and mild VR-QOL impairment described their vision as poor in this eye. However, most of these patients were not dissatisfied with their overall level of vision.

CONCLUSION

A significant number of patients listed for cataract surgery with VA of 6/12 or better had only mild VR-QOL impairment and were not dissatisfied with their overall level of vision. The decision to list a patient for surgery may have been based on the patient's perception of monocular vision rather than their quality of life.

The usefulness of Vistech and FACT contrast sensitivity charts for cataract and refractive surgery outcomes research

AIM

To investigate the repeatability and sensitivity of two commonly used sine wave patch charts for contrast sensitivity (CS) measurement in cataract and refractive surgery outcomes.

METHODS

The Vistech CS chart and its descendant, the Functional Acuity Contrast Test (FACT), were administered in three experiments: (1) Post-LASIK and age matched normal subjects; (2) Preoperative cataract surgery and age matched normal subjects; (3) Test-retest repeatability data in normal subjects.

RESULTS

Contrast sensitivity was similar between post-LASIK and control groups and between the Vistech and FACT charts. The percentage of subjects one month post-LASIK achieving the maximum score across spatial frequencies (1.5, 3, 6, 12, 18 cycles per degree) were (50, 33, 13, 13, 0 respectively) for FACT, but only (0, 0, 13, 4, 0 respectively) for Vistech. A small number of cataract patients also registered the maximum score on the FACT, but up to 60% did not achieve the minimum score. Test-retest intraclass correlation coefficients varied from 0.28 to 0.64 for Vistech and 0.18 to 0.45 for FACT. Bland-Altman limits of agreement across spatial frequencies were between +/-0.30 and +/-0.85 logCS for Vistech, and +/-0.30 to +/-0.75 logCS for FACT.

DISCUSSION

The Vistech was confirmed as providing poorly repeatable data. The FACT chart, likely because of a smaller step size, showed slightly better retest agreement. However, the reduced range of scores on the chart due to the smaller step size led to ceiling (post-LASIK) and floor (cataract) effects. These problems could mask subtle differences between groups of patients with near normal visual function as found post-refractive or cataract surgery. The Vistech and FACT CS charts are ill suited for refractive or cataract surgery outcomes research.

Potential vision testing--the relationship between visual acuity and Vernier acuity in the presence of simulated cataract

To evaluate the utility of a computer controlled two-bar Vernier acuity measurement as a predictor of visual function in the presence of cataract we measured logMAR visual acuity and Vernier acuity in a group of 40 young normal observers under various levels of dioptric blur (0-3 D in dioptre steps). The Vernier thresholds were resistant to dioptric blur up to 2 D, but performance degraded with blur of 3 D for non-optimised Vernier stimulus parameters. The stimulus parameters, bar length and bar separation, were further investigated in two subjects under conditions of blur. By extending the Vernier bar length and increasing the bar separation the effect of blur could be further reduced even under the most blurred condition. The relationship between visual acuity and Vernier acuity was determined. Vernier acuity was measured in the presence of Vistech cataract simulating lenses and a prediction of visual acuity was made for three observers, two with no ocular abnormality and one with age-related maculopathy. The cataract simulating lenses affected the measured visual acuity in all three subjects, but had less effect on Vernier acuity. Predicted visual acuities were all within six letters (0.12 log units) of the visual acuity without the simulated cataract. As expected, the subject sufferng from age-related maculopathy, whilst showing similar levels of Vernier acuity to the two ocularly healthy subjects at 1.5 degrees of retinal eccentricity, showed much poorer Vernier acuity for stimuli presented at fixation.

Randomised comparison of three methods of administering a screening questionnaire to elderly people: findings from the MRC trial of the assessment and management of older people in the community

OBJECTIVE

To compare three different methods of administering a brief screening questionnaire to elderly people: post, interview by lay interviewer, and interview by nurse.

DESIGN

Randomised comparison of methods within a cluster randomised trial.

SETTING

106 general practices in the United Kingdom.

PARTICIPANTS

32 990 people aged 75 years or over registered with participating practices.

MAIN OUTCOME MEASURES

Response rates, proportion of missing values, prevalence of self reported morbidity, and sensitivity and specificity of self reported measures by method of administration of questionnaire for four domains.

RESULTS

The response rate was higher for the postal questionnaire than for the two interview methods combined (83.5% v 74.9%; difference 8.5%, 95% confidence interval 4.4% to 12.7%, P<0.001). The proportion of missing or invalid responses was low overall (mean 2.1%) but was greater for the postal method than for the interview methods combined (4.1% v 0.9%; difference 3.2%, 2.7% to 3.6%, P<0.001). With a few exceptions, levels of self reported morbidity were lower in the interview groups, particularly for interviews by nurses. The sensitivity of the self reported measures was lower in the nurse interview group for three out of four domains, but 95% confidence intervals for the estimates overlapped. Specificity of the self reported measures varied little by method of administration.

CONCLUSIONS

Postal questionnaires were associated with higher response rates but also higher proportions of missing values than were interview methods. Lower estimates of self reported morbidity were obtained with the nurse interview method and to a lesser extent with the lay interview method than with postal questionnaires.

The population requirement for cataract extraction: a cross-sectional study

PURPOSE

To examine the distribution in the population of indications for cataract extraction in order to relate demand for this procedure to the capacity for satisfying it.

METHODS

An age-stratified random population sample of 2783 individuals aged 55 years and over was taken from inner-city, urban and rural areas of Avon and Somerset. The requirement for cataract extraction was estimated on the basis of measures of vision-related quality of life, refracted visual acuity, and application of the Oxford Clinical Cataract Classification and Grading System. Data were also collected concerning suitability for surgery, including relative contraindications to surgery and whether participants considered their eyesight bad enough to merit surgery. Three sets of composite indications were defined.

RESULTS

Estimated prevalent requirements for cataract extraction for the three sets of composite criteria were: 29 per 1000 aged over 55 years (95% CI 20-41) for the most inclusive criterion; 17 per thousand (95% CI 10-27) for the intermediate criterion; and 7 per thousand (95% CI 3-14) for the most stringent criterion. These rates are equivalent to a national prevalent requirement for England of 384,000 for the most inclusive criterion. If the approximately 15% of individuals whose desire or fitness for surgery was questionable are removed from this estimate, the prevalent requirement, including the backlog from previous unsatisfied demand, becomes 325,000 individuals.

CONCLUSIONS

The findings suggest only a modest imbalance between supply and demand for cataract surgery. In particular there was a very small prevalence of untreated severe cataract, less than the annual health service surgical capacity, suggesting that the current National Health Service surgical capacity is adequate for cases of severe cataract.

The assessment of lens opacities in clinical practice: results of a national survey

AIM

To investigate the examination of lens opacities in routine ophthalmic clinical practice.

METHOD

A questionnaire survey was mailed to 703 consultant ophthalmologists in the UK. The surgeons were asked which lens feature(s) they assessed in their clinics when deciding whether to offer cataract surgery.

RESULTS

489 replies were received. A broad range of lens opacities was assessed, with differences between surgeons for some opacities with high prevalences in the population, particularly cortical opacities. Many (74% of 467) surgeons assessed one or more lens opacities (anterior subcapsular cataract, vacuoles, water clefts, coronary flakes, focal dots, retrodots, fibre folds) which may be visually important but which have received relatively little attention by researchers.

CONCLUSIONS

Some classes of lens opacity which are traditionally measured by researchers may be ignored in clinical practice and opacities which are traditionally ignored by some researchers are regarded as clinically important by a substantial number of surgeons.

Indications for cataract surgery

This review article will attempt to guide ophthalmologists in deciding the indications for cataract surgery. It will consider this year's visual function questionnaires, ancillary vision tests, and postoperative outcome measures to assess visual function. Cultural factors, age, and gender are a few of the confounding variables in trying to assess visual function. The indications for cataract surgery in the 21st century have evolved dramatically since cataract surgery was first performed in the 1700s. The physicians' dictum in the Hippocratic oath of "do no harm" has determined the indications for cataract surgery over time. Today, doing no harm means operating on cataracts earlier than previously, as this is technically easier than in previous years, when poorer surgical techniques prevailed. However, are we operating on cataracts too early? This review will attempt to highlight the relevant factors that will help to determine the indications for cataract surgery.