Feasibility of screening for diabetic retinopathy at an Australian pathology collection service: a pilot study

OBJECTIVE

To evaluate the feasibility of a novel diabetic retinopathy (DR) screening model using a pathology collection centre (PCC) as a screening site.

DESIGN AND SETTING

Cross-sectional pilot study conducted in one urban PCC in Victoria between 1 September 2009 and 15 March 2010. Trained pathology staff screened participants for DR using undilated, non-stereoscopic colour fundus photography.

PARTICIPANTS

Participants were patients who spoke English, were aged at least 12 years, had type 1 or type 2 diabetes, and did not undertake biannual DR screening.

MAIN OUTCOME MEASURES

Proportion of patients who do not participate in biannual DR screening; proportion of patients who accept DR screening while attending a PCC; proportion of gradable images; patient acceptance of the screening model; and effectiveness of the follow-up pathway.

RESULTS

Over 6 months, 289 English-speaking patients with diabetes attended the PCC, of whom 99 (34.3%) had not undertaken biannual DR screening. Of these, 93 (93.9%) accepted our screening service. Overall, retinal images were sufficient for interpretation in 88 patients (94.6%) and the median time for photography was 6 minutes (interquartile range, 10 minutes). Two, eight and six cases of minimal, mild and moderate non-proliferative DR (NPDR) in the worst eye were found, respectively. Dissemination of screening results to treating doctors and patients was found to be suboptimal and will need to be revised.

CONCLUSION

DR screening in one urban PCC appears to be a feasible alternative for diabetic patients who do not undertake biannual screening for DR.

Frequency and risk factors of non-retinopathy ocular conditions in people with diabetes: the Singapore Malay Eye Study

AIM

To investigate the frequency and risk factors of non-retinopathy ocular conditions in persons with diabetes.

METHODS

A population-based cross-sectional study of 3176 Malay persons aged between 40 and 79 years in Singapore was conducted. Cataract, glaucoma, refractive errors, age-related macular degeneration, dry eye, epiretinal membrane, ocular hypertension and retinal conditions were assessed based on standardized interviews, clinical examinations and laboratory investigations.

RESULTS

A total of 768 participants (24.2%) had diabetes. People with diabetes were more likely to have cortical cataract (52.1 vs. 37.3%, P < 0.001), ocular hypertension (10.9 vs. 7.4%, P = 0.002) and epiretinal membrane (17.2 vs. 10.1%, P < 0.001) compared with those without diabetes. The odds of having cortical cataract (odds ratio 1.63, 95% CI 1.20-2.20) and epiretinal membrane (among those with previous cataract surgery: odds ratio 1.63, 95% CI 1.20-2.20) were significantly higher in people with diabetes compared with those without. The population attributable risks for cortical cataract and epiretinal membrane because of diabetes were 8.7 and 9.0%, respectively. In persons with diabetes, hypertension and high cholesterol were the major risk factors associated with non-retinopathy eye complications such as ocular hypertension (odds ratio 1.18, 95% CI 1.04-1.33) and retinal emboli (odds ratio 1.99, 95% CI 1.05-3.80).

CONCLUSION

Our results allow clinicians to better inform patients with diabetes that they are more likely to have cortical cataract and epiretinal membranes (those with previous cataract surgery) in addition to diabetic retinopathy. Two modifiable risk factors-blood pressure and cholesterol associated with ocular hypertension and retinal emboli, respectively-are also risk factors for non-retinopathy ocular conditions in persons with diabetes.

Cataract conversion assessment using lens opacity classification system III and Wisconsin cataract grading system

PURPOSE

To propose a general conversion approximation algorithm and illustrate its application to two cataract classification systems, the Lens Opacity Classification System III (LOCS III) and Wisconsin Cataract Grading System (Wisconsin system).

METHODS

Lens opacity of 3265 participants (78.7% response rate) aged 40 to 80 years from the Singapore Malay Eye study were assessed both clinically during slit-lamp examination using LOCS III, and via slit-lamp and retro-illumination photographic grading using the Wisconsin system. Collapsed contingency tables were used to convert between the LOCS III and Wisconsin System.

RESULTS

The conversion between the two cataract classification systems is affected by the direction of transformation. The conversion algorithm was validated and explained with an application example.

CONCLUSIONS

An approximate conversion algorithm for any two cataract grading systems was proposed and applied to the LOCS III and Wisconsin system. These findings provide general ways to pool and compare cataract prevalence using different grading systems in epidemiological studies.

Acceptance, attitudes, and beliefs of Singaporean Chinese toward an ocular implant for glaucoma drug delivery

PURPOSE

We investigated patients' attitudes and perceptions toward a subconjunctival implant as a novel ocular drug delivery method for glaucoma.

METHODS

We recruited 344 Chinese patients with primary open angle or angle closure glaucoma currently on topical antiglaucoma medication for a minimum of six months from specialist glaucoma clinics. Sociodemographic data, and information about patients' general and ocular health were collected. Beliefs about medicines, glaucoma, eye drops, and self-reported adherence were assessed by trained interviewers using validated questionnaires. A description about the implant was provided and patients subsequently were assessed on their understanding and acceptance.

RESULTS

Of the 344 Chinese patients enrolled, 216 (62.8%) would accept the implant as a replacement for their current eye drops. Of those who accepted the implant, 99 (45.8%) were willing to accept it at similar costs, while 40 (18.5%) and 20 (9.3%) patients were willing to pay 1.5 and 2 times the cost of their present medication, respectively. Patients who accepted the implant had more severe glaucoma (P = 0.015) and felt that the implant was more helpful than eye drops (P < 0.001). Beliefs toward medicines, glaucoma, eye drops, self-reported adherence, and sociodemographic factors did not have a significant impact on the patients' decisions.

CONCLUSIONS

An ocular drug implant would be an acceptable alternative to topical eye drops for subgroups of glaucoma patients.

A randomized, single-center study of equivalence of 2 intraocular lenses used in cataract surgery

PURPOSE

To compare the outcomes of 2 intraocular lenses (IOLs) for the treatment of age-related cataracts.

DESIGN

Prospective, randomized trial.

PARTICIPANTS

Patients with age-related cataracts were recruited and randomized to receive phacoemulsification and implantation of either the AcrySof SA60AT lens (Alcon, Inc, Fort Worth, TX) or the low-cost Tecsoft Flex lens (Fred Hollows Foundation, Tilganga, Nepal). A total of 300 patients were available for description and analysis (148 in the AcrySof group and 152 in the Tecsoft group).

METHODS

Patients underwent phacoemulsification and implantation of the AcrySof SA60AT lens or the Tecsoft Flex lens. They were followed up and examined at baseline, 1 week, 1 month, 6 months, and 12 months after cataract surgery.

MAIN OUTCOME MEASURES

Uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (BDVA), incidence of posterior capsule opacification (PCO), Visual Function Index questionnaire results, and safety of the implanted IOLs.

RESULTS

No significant difference (P>0.05) was found in UDVA and BDVA after surgery between the 2 groups. The equivalence test of the 95% confidence intervals showed that both lenses had an equal improvement of UDVA and BDVA as well as similar rates of PCO after cataract surgery. There was no significant difference between the 2 groups with regard to visual functioning or the incidence of adverse surgical events during (P>0.05) or after (P>0.05) the surgery.

CONCLUSIONS

The Tecsoft Flex IOL is a low-cost suitable alternative that is similar to the AcrySof IOL in terms of safety and visual outcomes.

Evaluation of item candidates for a diabetic retinopathy quality of life item bank

PURPOSE

We are developing an item bank assessing the impact of diabetic retinopathy (DR) on quality of life (QoL) using a rigorous multi-staged process combining qualitative and quantitative methods. We describe here the first two qualitative phases: content development and item evaluation.

METHODS

After a comprehensive literature review, items were generated from four sources: (1) 34 previously validated patient-reported outcome measures; (2) five published qualitative articles; (3) eight focus groups and 18 semi-structured interviews with 57 DR patients; and (4) seven semi-structured interviews with diabetes or ophthalmic experts. Items were then evaluated during 3 stages, namely binning (grouping) and winnowing (reduction) based on key criteria and panel consensus; development of item stems and response options; and pre-testing of items via cognitive interviews with patients.

RESULTS

The content development phase yielded 1,165 unique items across 7 QoL domains. After 3 sessions of binning and winnowing, items were reduced to a minimally representative set (n = 312) across 9 domains of QoL: visual symptoms; ocular surface symptoms; activity limitation; mobility; emotional; health concerns; social; convenience; and economic. After 8 cognitive interviews, 42 items were amended resulting in a final set of 314 items.

CONCLUSIONS

We have employed a systematic approach to develop items for a DR-specific QoL item bank. The psychometric properties of the nine QoL subscales will be assessed using Rasch analysis. The resulting validated item bank will allow clinicians and researchers to better understand the QoL impact of DR and DR therapies from the patient's perspective.

Association between myopia and diabetic retinopathy: a review of observational findings and potential mechanisms

A protective, but inconsistent association between myopia and a decreased risk of diabetic retinopathy (DR) has been suggested in several studies. However, it is unclear whether the structural, or the refractive components of myopia; or both, is the main contributor to this protective relationship. This paper provides a comprehensive review of existing evidence on the association between myopia, and its structural (axial length [AL], anterior chamber depth [ACD]) and refractive (lens biometry and corneal curvature [CC]) components, with DR. 11 studies consisting of 7230 subjects from 1960 to April 2012, were reviewed. A longer AL was the only variable associated with a lower risk and severity of DR. Therefore, the available evidence suggests that AL is the main contributor to the protective influence of myopia on DR observed in earlier studies. Further investigations are now needed to determine the mechanisms by which AL protects against DR.

Visual impairment, age-related eye diseases, and cognitive function: the Singapore Malay Eye study

OBJECTIVE

To describe the associations of visual impairment and major age-related eye diseases with cognitive function in an older Asian population.

METHODS

A population-based, cross-sectional study of 1179 participants aged 60 to 80 years from the Singapore Malay Eye study was conducted. Visual acuity was measured using the logMAR vision chart. Cataract and age-related macular degeneration were graded using the Wisconsin Cataract Grading System and the Wisconsin Age-Related Maculopathy Grading System, respectively. Glaucoma was diagnosed using the International Society Geographical and Epidemiological Ophthalmology criteria. Diabetic retinopathy was graded using the modified Airlie House classification system. Cognitive dysfunction was defined as a locally validated Abbreviated Mental Test using education-based cutoff scores.

RESULTS

After adjusting for age, sex, education level, income, and type of housing, persons with visual impairment before refractive correction (odds ratio [OR]=2.59; 95% CI, 1.89-3.56) or after refractive correction (OR=1.96; 95% CI, 1.27-3.02) and those with visual impairment due to cataract (OR=2.75; 95% CI, 1.35-5.63) were more likely to have cognitive dysfunction. Only moderate to severe diabetic retinopathy was independently associated with cognitive dysfunction (OR=5.57; 95% CI, 1.56-19.91) after controlling for concurrent age-related eye diseases. No significant independent associations were observed between cataract, age-related macular degeneration, or glaucoma and cognitive dysfunction.

CONCLUSIONS

Older persons with visual impairment, particularly those with visual impairment due to cataract, were more likely to have cognitive dysfunction. Furthermore, among the major age-related eye diseases, only diabetic retinopathy was associated with cognitive dysfunction.

Language barrier and its relationship to diabetes and diabetic retinopathy

Background

Language barrier is an important determinant of health care access and health. We examined the associations of English proficiency with type-2 diabetes (T2DM) and diabetic retinopathy (DR) in Asian Indians living in Singapore, an urban city where English is the predominant language of communication.

Methods

This was a population-based, cross-sectional study. T2DM was defined as HbA1c ≥6.5%, use of diabetic medication or a physician diagnosis of diabetes. Retinal photographs were graded for the severity of DR including vision-threatening DR (VTDR). Presenting visual impairment (VI) was defined as LogMAR visual acuity > 0.30 in the better-seeing eye. English proficiency at the time of interview was assessed.

Results

The analyses included 2,289 (72.1%) English-speaking and 885 (27.9%) Tamil- speaking Indians. Tamil-speaking Indians had significantly higher prevalence of T2DM (46.2 vs. 34.7%, p < 0.001) and, among those with diabetes, higher prevalence of DR (36.0 vs. 30.6%, p < 0.001), VTDR (11.0 vs. 6.5%, p < 0.001), and VI (32.4 vs. 14.6%) than English speaking Indians. Oaxaca decomposition analyses showed that the language-related discrepancies (defined as the difference in prevalence between persons speaking different languages) in T2DM, DR, and VTDR could not be fully explained by socioeconomic measures.

Conclusions

In an English dominant society, Tamil-speaking Indians are more likely to have T2DM and diabetic retinopathy. Social policies and health interventions that address language-related health disparities may help reduce the public health impact of T2DM in societies with heterogeneous populations.

The importance of rating scales in measuring patient-reported outcomes

Background

A critical component that influences the measurement properties of a patient-reported outcome (PRO) instrument is the rating scale. Yet, there is a lack of general consensus regarding optimal rating scale format, including aspects of question structure, the number and the labels of response categories. This study aims to explore the characteristics of rating scales that function well and those that do not, and thereby develop guidelines for formulating rating scales.

Methods

Seventeen existing PROs designed to measure vision-related quality of life dimensions were mailed for self-administration, in sets of 10, to patients who were on a waiting list for cataract extraction. These PROs included questions with ratings of difficulty, frequency, severity, and global ratings. Using Rasch analysis, performance of rating scales were assessed by examining hierarchical ordering (indicating categories are distinct from each other and follow a logical transition from lower to higher value), evenness (indicating relative utilization of categories), and range (indicating coverage of the attribute by the rating scale).

Results

The rating scales with complicated question format, a large number of response categories, or unlabelled categories, tended to be dysfunctional. Rating scales with five or fewer response categories tended to be functional. Most of the rating scales measuring difficulty performed well. The rating scales measuring frequency and severity demonstrated hierarchical ordering but the categories lacked even utilization.

Conclusion

Developers of PRO instruments should use a simple question format, fewer (four to five) and labelled response categories.

Determinants of informed consent in a cataract surgery clinical trial: why patients participate

OBJECTIVE

To identify the determinants of patients' decision-making for participation in a cataract surgery clinical trial in a tertiary care hospital.

DESIGN

Prospective observational study.

PARTICIPANTS

We interviewed by questionnaire 40 patients scheduled to have cataract surgery.

METHODS

The data collected from patients included attitudes about informed consent, evaluation of the provision of information, and sociodemographic variables.

RESULTS

Overall, 20 (50%) patients consented to enter the trial. All patients (n = 20;100%) in the consenting group expected positive implications compared to 6 (30%) in the nonconsenting group, who expected negative implications (p = 0.008). The majority of patients (90%) in the nonconsenting group felt that the degree of risk incurred by undergoing trial treatment was moderate to high. The perceived burden imposed on daily life by participating was seen by the nonconsenting group to be moderately higher in 11 patients (55%) compared to 3 patients (15%) in the consenting group (p = 0.026). Of the nonconsenting patients, 50% were dissatisfied with the attitudes of medical experiments as compared to 2% of those who did consent (p = 0.023).

CONCLUSION

The major reasons for participation in a cataract surgery trial were (i) expected positive implications resulting from involvement; and (ii) satisfaction with the attitudes of medical experiments. Patients who refused to enter the trial felt that the degree of risk as well as the burden imposed on daily life by participating were high. Demographic variables did not have any impact on a patients' decisions to accept or decline entry into the trial.

The impact of cataract, cataract types, and cataract grades on vision-specific functioning using Rasch analysis

PURPOSE

To determine the impact of cataracts and their types and grades on vision-specific functioning.

DESIGN

Prospective population-based cross-sectional study.

METHODS

The Singapore Indian Eye Study examined 3400 of 4497 (75.6% response rate) ethnic Indians 40 years of age and older living in Singapore. Three thousand one hundred sixty-eight (93.2%) fulfilled inclusion criteria with complete information for final analysis. Cataracts were assessed on slit-lamp examination and were graded according to the Lens Opacity Classification System III. Vision-specific functioning scores were explored with the Visual Function scale, validated using Rasch analysis.

RESULTS

Two hundred sixty-nine (8.5%) and 740 (23.4%) of the study participants had unilateral and bilateral cataracts, respectively, and 329 (10.4%), 800 (25.2%), and 128 (4.1%) participants had nuclear, cortical, and posterior subcapsular (PSC) cataracts, respectively. In multivariate linear regression models, the presence of bilateral rather than unilateral cataract (β = -0.12; 95% confidence interval, -0.20 to 0.00) was associated independently with poorer vision-specific functioning, even after adjusting for undercorrected refractive error (β = -0.11; 95% confidence interval, -0.21 to 0.00). Bilateral nuclear, cortical, and PSC cataracts also were associated with poorer vision-specific functioning (β = -0.31, -0.15, and -1.15, respectively), with combinations of them having even greater impact. Significantly poorer vision-specific functioning occurred at Lens Opacity Classification System grades 4 (nuclear opalescence), 5 (nuclear color), 3 (cortical), and 1 (PSC) or higher.

CONCLUSIONS

People with bilateral but not unilateral cataracts experience difficulty with performing vision-specific daily activities independent of refractive error, with PSC cataracts and cataract combinations having the greatest impact. Cataract types cause poorer vision-specific functioning beginning at different severity grades.

Prevalence and risk factors of diabetic retinopathy in migrant Indians in an urbanized society in Asia: the Singapore Indian eye study

PURPOSE

To describe the prevalence of and risk factors for diabetic retinopathy (DR) in Indian persons living in a newly urbanized society in Asia.

DESIGN

Population-based study.

PARTICIPANTS

Ethnic Indians aged ≥40 years living in Singapore.

METHODS

The Singapore Indian Eye Study was conducted between 2007 and 2009. All participants underwent an extensive ophthalmic examination, including retinal photographs obtained after pupil dilation. These images were graded for the presence and severity of DR using the modified Airlie House classification system. Diabetes was defined as hemoglobin A1c level of ≥6.5%, use of diabetic medication, or a physician diagnosis of diabetes. Risk factors were measured using questionnaires, clinical assessments, or laboratory tests.

MAIN OUTCOME MEASURES

Any DR, diabetic macular edema (DME), or vision-threatening DR (VTDR).

RESULTS

Among the 3400 participants, the age-standardized prevalence was 33.6% (95% confidence interval [CI], 31.4-35.8) for diabetes and 10.5% (95% CI, 9.3-11.8) for DR. Among those with diabetes only, the age-standardized prevalence was 30.4% (95% CI, 26.5-34.8) for any DR, 7.2% (95% CI, 5.3-9.7) for DME, and 7.1% (95% CI, 5.4-9.5) for VTDR. In multivariate analysis, independent risk factors for any DR were younger age (odds ratio [OR], 0.98; 95% CI, 0.96-1.00, per year increase), longer diabetes duration (OR, 1.09; 95% CI, 1.07-1.11 per year increase), higher hemoglobin A1c (OR, 1.23; 95% CI, 1.13-1.34 per percent increase), higher systolic blood pressure (OR, 1.01; 95% CI, 1.00-1.02 per 1-mmHg increase), lower diastolic blood pressure (OR, 0.97; 95% CI, 0.96-0.99 per 1-mmHg increase), history of previous stroke (OR, 2.16; 95% CI, 1.12-4.16), and insulin treatment (OR, 2.99; 95% CI, 1.84-4.87). Similar independent risk factors, except for blood pressure, were found for VTDR. Additionally, persons with lower income and living in smaller houses were associated with VTDR.

CONCLUSIONS

One in 3 migrant Indians living in newly urbanized Asian societies have diabetes and 1 in 10 has DR. This is similar to rates reported in Western populations and significantly higher than those reported in India.

Impact of diabetic retinopathy on patients' beliefs about diabetes

BACKGROUND

The aim was to compare beliefs about diabetes and determine their associations with psychological well-being, self-management behaviour and glycaemic control in those with and without diabetic retinopathy (DR).

METHODS

We recruited 400 patients with diabetes aged 18 years or more from specialised eye clinics, as part of the Diabetes Management Project (DMP). Two-field retinal photographs were taken to assess DR and detailed clinical and psychological well-being examinations were performed following standardised procedures. Glycaemic control was determined using glycated haemoglobin levels. We assessed beliefs about diabetes (diabetes-specific version of the Revised Illness Perception Questionnaire [IPQ-R]), self-management behaviour (Summary of Diabetes Self Care Activities [SDSCA]) questionnaire) and depression and anxiety (the Hospital Anxiety and Depression Scale [HADS]).

RESULTS

Patients with DR (n = 256, 64 per cent) believed that they experienced more symptoms related to their diabetes, that diabetes had a greater impact on their life and that this condition was more unpredictable compared with those without DR (p < 0.05 for all). Patients with DR were also more engaged in glucose testing compared with those without DR. Furthermore, negative beliefs about diabetes were significantly associated with higher levels of depression and anxiety (p < 0.01) but not glycaemic control, regardless of DR and other diabetic complications.

CONCLUSIONS

Patients with DR had more negative beliefs about diabetes than those without. We identified strong and consistent associations between negative beliefs and psychological outcomes regardless of diabetic complications. These findings suggest that management for patients with DR could include strategies to address negative beliefs about diabetes and manage the emotional implications of diabetes in addition to medical treatment.

Early retinal arteriolar changes and peripheral neuropathy in diabetes

OBJECTIVE

To examine the association between early retinal arteriolar abnormalities and diabetic peripheral neuropathy (DPN).

RESEARCH DESIGN AND METHODS

Data from 608 people (aged 40-80 years) with diabetes from the population-based Singapore Malay Eye Study were analyzed. Participants underwent binocular two-field digital retinal photography and quantitative sensory testing. DPN was defined as an abnormal response to a monofilament or neurothesiometer test. Quantitative changes of retinal vascular caliber and arteriolar bifurcation geometry were measured using a computer-based program. Qualitative retinal signs of retinopathy and retinal arteriolar wall signs were graded by standardized methods.

RESULTS

DPN was present in 155 people (25.5%). After adjusting for age, sex, diabetes duration, HbA(1c), cardiovascular risk factors, antihypertensive medication use, and peripheral arterial disease, people with suboptimal arteriolar caliber (odds ratio 1.94 [95% CI 1.22-3.10]), larger arteriolar branching coefficient (1.58 [1.03-2.42]), diabetic retinopathy (1.82 [1.20-2.75]), and focal arteriolar narrowing (2.92 [1.48-5.76]) were more likely to have DPN. Participants with a greater number of retinal microvascular signs were more likely to have DPN than those without retinal changes (6.11 [2.11-17.71] for two or more signs and 3.47 [1.18-10.21] for one sign compared with none).

CONCLUSIONS

Individuals with diabetes with early retinal arteriolar abnormalities are more likely to have DPN, independent of hyperglycemia and major vascular risk factors. These data support the hypothesis that early microvascular dysfunction, evident in the retina, is an independent risk factor for DPN.

Impact of migration and acculturation on prevalence of type 2 diabetes and related eye complications in Indians living in a newly urbanised society

Background

Health of migrants is a major public health challenge faced by governments and policy makers. Asian Indians are among the fastest growing migration groups across Asia and the world, but the impact of migration and acculturation on diabetes and diabetes-related eye complications among Indians living in urban Asia remains unclear.

Methodologies/Principal Findings

We evaluated the influence of migration and acculturation (i.e., migration status and length of residence) on the prevalence of type-2 diabetes mellitus (T2DM) and diabetes-related eye complications (diabetic retinopathy (DR) and cataract), among first-generation (defined as participant born in India with both parents born in India, n = 781) and second-generation (participants born in Singapore with both parents born in India, n = 1,112) Indian immigrants from a population-based study of Adult Indians in Singapore. Diabetes was defined as HbA1c≥6.5%, use of diabetic medication or a physician diagnosis of diabetes. Retinal and lens photographs were graded for the presence of DR and cataract. Compared to first generation immigrants, second generation immigrants had a higher age- and gender-standardized prevalence of T2DM (34.4% versus 29.0%, p<0.001), and, in those with T2DM, higher age- and gender-standardized prevalence of DR (31.7% versus 24.8%, p<0.001), nuclear cataract (13.6% versus 11.6%, p<0.001), and posterior sub-capsular cataract (6.4% versus 4.6%, p<0.001). Among first generation migrants, longer length of residence was associated with significantly younger age of diagnosis of diabetes and greater likelihood of having T2DM and diabetes-related eye complications.

Conclusion

Second generation immigrant Indians and longer length of residence are associated with higher prevalence of diabetes and diabetes-related complications (i.e., DR and cataract) among migrant Indians living in Singapore. These data highlight potential worldwide impacts of migration patterns on the risk and burden of diabetes.

Global prevalence and major risk factors of diabetic retinopathy

OBJECTIVE

To examine the global prevalence and major risk factors for diabetic retinopathy (DR) and vision-threatening diabetic retinopathy (VTDR) among people with diabetes.

RESEARCH DESIGN AND METHODS

A pooled analysis using individual participant data from population-based studies around the world was performed. A systematic literature review was conducted to identify all population-based studies in general populations or individuals with diabetes who had ascertained DR from retinal photographs. Studies provided data for DR end points, including any DR, proliferative DR, diabetic macular edema, and VTDR, and also major systemic risk factors. Pooled prevalence estimates were directly age-standardized to the 2010 World Diabetes Population aged 20-79 years.

RESULTS

A total of 35 studies (1980-2008) provided data from 22,896 individuals with diabetes. The overall prevalence was 34.6% (95% CI 34.5-34.8) for any DR, 6.96% (6.87-7.04) for proliferative DR, 6.81% (6.74-6.89) for diabetic macular edema, and 10.2% (10.1-10.3) for VTDR. All DR prevalence end points increased with diabetes duration, hemoglobin A(1c), and blood pressure levels and were higher in people with type 1 compared with type 2 diabetes.

CONCLUSIONS

There are approximately 93 million people with DR, 17 million with proliferative DR, 21 million with diabetic macular edema, and 28 million with VTDR worldwide. Longer diabetes duration and poorer glycemic and blood pressure control are strongly associated with DR. These data highlight the substantial worldwide public health burden of DR and the importance of modifiable risk factors in its occurrence. This study is limited by data pooled from studies at different time points, with different methodologies and population characteristics.

Republished article: The impact of diabetic retinopathy: understanding the patient's perspective

Understanding the impact of a condition from the patient's perspective is important, and different types of patient-reported outcomes or instruments are available to help with this. This review article summarises the current evidence on the impact of diabetic retinopathy (DR) and its associated vision impairment on patient-reported outcomes. We have included research that has used a range of outcome measures to assess the impact of DR on generic health-related quality of life, utility, vision-functioning and vision-specific quality of life. This review also offers clarification on frequently misused psychometric terminologies to help clinicians and researchers better understand the literature associated with patient-reported outcome research. Overall, the evidence suggests that DR, particularly in its vision-threatening stages, has a substantial, negative impact on the patient. However, our understanding of the impact of DR is currently restricted due to limitations inherent in currently available patient-reported outcome measures. We conclude by discussing potential directions for future research in this area, such as item banking and computer adaptive testing.

The impact of diabetic retinopathy and diabetic macular edema on health-related quality of life in type 1 and type 2 diabetes

PURPOSE

To assess the impact of diabetic retinopathy (DR) and diabetic macular edema (DME) on health-related quality of life (HRQoL) in type 1 and type 2 diabetes using the EuroQoL EQ-5D generic multi-attribute utility instrument (MAUI).

METHODS

In this cross-sectional study, 577 patients with diabetes were recruited from specialized eye clinics in Melbourne, Australia. Each patient underwent clinical, biochemical, and anthropometric assessments. The severity of combined DR and DME (no DR/DME; mild NPDR [nonproliferative DR (NPDR)] and/or mild DME; moderate NPDR and/or moderate DME; and vision-threatening DR (VTDR) (severe NPDR or PDR and/or severe DME) in the worse eye was calculated. EQ-5D utility measures were the main outcome. Because the distribution of the utility measures was skewed, independent associations were explored using multivariate quantile regression models (five quintiles, namely 15th, 30th, 45th, 60th, 75th) ranging from poorest to highest HRQoL.

RESULTS

Median age of the participants was 66 years (range, 26-90 years). Of the 577 participants, 223 (38.7%) had no DR/DME, 35 (6.1%) had mild NPDR/DME, 127 (22.0%) had moderate NPDR/DME, and 192 (33.3%) had VTDR. In adjusted models, neither presence nor severity of DR/DME was significantly associated with any quantile of the EQ-5D. In contrast, the presence of diabetic complications (other than DR) (β = -0.153; SE = 0.052; P < 0.001), other nonocular comorbidities (β = -0.115; SE = 0.038; P < 0.01), and higher body mass index (β = -0.007; SE = 0.002; P < 0.001) were all associated with worse HRQoL.

CONCLUSIONS

Using a generic MAUI, the EQ-5D, the authors found that the presence or severity of DR/DME and concomitant vision loss were not associated with any quantile of HRQoL. These findings suggest that the EQ-5D lacks sensitivity in assessing the impact of the severity of DR/DME on HRQoL parameters and that condition-specific instruments may better capture the full impact of the association.

The prevalence and risk factors of ocular trauma: the Singapore Indian eye study

PURPOSE

To describe the prevalence and risk factors of ocular trauma in an urban Southeast Asian population.

METHODS

A population-based survey of 3,400 (75.6% response rate) adults of Indian ethnicity aged 40-80 years residing in Singapore was conducted in 2007-2009. An age-stratified (10-year age group) random sampling procedure was performed to select participants. Ocular trauma was defined as any eye injury requiring medical attention and any history of ocular trauma was documented using a standardized and validated questionnaire comprising seven questions. Potential risk factors associated with ocular trauma included age, gender, socioeconomic status, occupation, housing type, alcohol consumption, smoking, diabetes mellitus, hypertension and history of falls.

RESULTS

Ocular trauma was reported in 5.1% (n = 162; 95% confidence interval [CI] 4.3-6.1%) of the study population, of whom 26.5% (n = 43) required hospitalization. A total of 42.0% (n = 68) of cases resulted from a blunt object, 36.4% (n = 59) from a sharp object, and 15.4% (n = 25) from chemical burns. After adjusting for age and sex, men had a higher prevalence of ocular trauma (7.1% vs. 3.0%, age-adjusted odds ratio [OR] 2.2, 95% CI 1.6-3.1). A history of cigarette smoking was associated with higher likelihood of ocular trauma (OR 1.6, 95% CI 1.1-2.4) but not consumption of alcohol (OR 1.0, 95% CI 0.6-1.6).

CONCLUSIONS

One in twenty Indian adults in this urban Southeast Asian population had a history of ocular trauma, similar to the prevalence reported in Malays living in Singapore. Men and cigarette smokers were more likely to have incurred ocular trauma.

Literacy is an independent risk factor for vision impairment and poor visual functioning

PURPOSE

People with limited literacy are at increased risks of chronic systemic conditions. The authors therefore investigated the independent contribution of limited literacy on visual impairment and visual function in a large eye survey in Singapore.

METHODS

The authors undertook a population-based, cross-sectional study of Asian Malays (≥ 40 years old). Visual impairment was defined as logMAR (logarithm of minimal angle of resolution) visual acuity > 0.30 in the better-seeing eye. Information regarding reading and writing literacy levels and other independent variables, including sociodemographic measures (e.g., education, income), were obtained from a standardized interview. Visual functioning was assessed using a modified and validated version of the Vision-Specific Functioning Scale using Rasch analysis.

RESULTS

Of the 3280 participants, 553 (16.9%) had inadequate reading literacy and 688 (21.0%) had inadequate writing literacy. In multivariate analysis, persons with inadequate reading literacy were more likely to have presenting visual impairment (odds ratio [OR] = 2.66; 95% confidence interval [CI] = 1.91 to 3.72; P < 0.001), best-corrected visual impairment (OR = 2.59; 95% CI = 1.70 to 3.96; P < 0.001), and poorer visual functioning (β coefficient = 0.58; 95% CI = 1.57 to 3.02; P < 0.001), even controlling for education, income, and other patients' characteristics. Similar associations were found for inadequate writing literacy.

CONCLUSIONS

Inadequate literacy is independently associated with visual impairment and poorer visual functioning. Interventions that address literacy may help to reduce socioeconomic disparities in visual impairment.

Racial differences in the prevalence of diabetes but not diabetic retinopathy in a multi-ethnic Asian population

PURPOSE

To compare the prevalence and risk factors of diabetes (DM) and diabetic retinopathy (DR) in a multi-ethnic Asian population of Chinese, Malays, and Indians in Singapore.

METHODS

A total of 2919 individuals participated in a population-based, cross-sectional study in Singapore of Chinese (n = 1633), Malays (n = 658), and Indians (n = 628) aged 40 to 95 years, with retinal photographs, graded using the Early Treatment Diabetic Retinopathy Study (ETDRS) severity scale. DM was defined as fasting plasma glucose ≥ 7 mmol/L, self-reported physician-diagnosed diabetes, and use of glucose-lowering medication.

RESULTS

The overall age-standardized prevalence of diabetes was 13.8% (Chinese, 11.5%; Malays, 17.1%; and Indians, 21.6%; P < 0.0001). Among persons with diabetes (n = 401), the overall age-standardized prevalence of DR was 25.4% (20.1%, 24.8%, and 28.9% in Chinese, Malays, and Indians, respectively; P = 0.290). In multivariate analysis, longer diabetes duration (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.01-1.09, per year increase), higher glycated hemoglobin (OR 1.25; 95% CI, 1.01-1.54, per 1% increase), and serum creatinine levels (OR, 1.01; 95% CI, 1.00-1.03, per mg/dL increase) were the independent risk factors of DR in the whole population. Race was not found to be associated with DR (OR, 1.35; CI, 1.00-1.83). The associations of major risk factors with DR were similar among the three ethnic groups.

CONCLUSIONS

There was a significant difference in the prevalence of diabetes between Chinese, Malays, and Indians. The main risk factors of DR, similar among the three ethnic groups, are longer diabetes duration, higher hbA1c, and higher creatinine levels. No significant racial differences were found in the prevalence of DR among persons with diabetes.

Differential association of serum lipids with diabetic retinopathy and diabetic macular edema

PURPOSE

To assess the association of serum lipids with diabetic retinopathy (DR), diabetic macular edema (DME), and macular thickness in adults with diabetes.

METHODS

Diabetic patients aged ≥ 18 years were prospectively recruited from specialized eye clinics in Melbourne, Australia. Fasting total-C (cholesterol), triglyceride, HDL-C, non-HDL-C, and LDL-C were assessed. DR was graded from fundus photographs and classified into mild, moderate, severe nonproliferative, and proliferative DR and separately graded for the presence of DME, including clinically significant macular edema (CSME). Macular thickness was assessed using optical coherence tomography (OCT).

RESULTS

A total of 500 participants (median age, 65 years) were examined. DR, DME, and CSME were present in 321 (66.2%), 149 (33.0%), and 68 (15.0%) patients, respectively. Serum lipid levels were not related to DR or DME. In multivariate models adjusted for traditional risk factors and lipid medications, persons with higher total-, LDL-, and non-HDL-C were more likely to have CSME (odds ratio of 1.54, 1.49, and 1.63 per 1-SD increase, respectively; all P < 0.05). No association was found for serum lipids with macular thickness, as assessed by OCT. The pattern of these associations remained similar in both type 1 and type 2 diabetes, although it was statistically significant only in type 2 diabetes.

CONCLUSIONS

Serum lipids are independently associated with the CSME, but not with DR, mild or moderate DME, or macular thickness. These data reflect the different impact of hyperlipidemia in the pathogenesis of DR and DME and may explain the discrepancies in previous studies.

The impact of the severity of vision loss on vision-related quality of life in India: an evaluation of the IND-VFQ-33

PURPOSE

To validate the 33-item Indian Vision Functioning Questionnaire (IND-VFQ-33), a vision-specific scale, and determine the relationship between the severity of vision impairment (VI) and vision-related quality of life (VRQoL).

METHODS

In this cross-sectional, observational study 273 participants with VI from cataract were recruited from a South Indian eye hospital. Participants underwent a clinical examination and completed the IND-VFQ-33 scale. The psychometric properties of the IND-VFQ-33 and its subscales were assessed using Rasch analysis, exploring key indices such as instrument unidimensionality, discriminant ability, and targeting of item difficulty to patient ability.

RESULTS

Rasch analysis demonstrated the validity of the IND-VFQ-33 to assess VRQoL through four subscales (i.e., vision-specific mobility, activity limitation, psychosocial impact, and visual symptoms), but not as an overall measure. In adjusted multivariate analysis models, those with severe VI and blindness reported significantly poorer vision-specific mobility and activity limitation (mean change, -18.82, P = 0.007 and -29.48, P < 0.001, respectively) compared with those with no VI. These decrements in vision-specific functioning were both clinically significant. Lack of schooling and schooling up to completion of primary school were associated with poorer vision-specific mobility and visual symptoms, respectively.

CONCLUSIONS

Using a psychometrically valid IND-VFQ, only severe VI and blindness led to a clinically meaningful decline in vision-specific mobility and activity limitation. This finding reflects the current protocol for cataract surgery referral in developing or transitional countries, where priority is given to patients with at least moderate to severe VI.

The impact of cataract surgery questionnaire: re-evaluation using Rasch analysis

PURPOSE

The Impact of Cataract Surgery (ICS) questionnaire was designed to assess cataract surgery outcomes. The aim of this study was to describe the psychometric properties of the ICS questionnaire using the Rasch model in a cataract population.

METHODS

Ninety-one patients waiting to undergo cataract surgery in the first or second eye at the Flinders Medical Centre, Adelaide, South Australia self-administered the four-item ICS questionnaire. Rasch analysis was performed to assess behaviour of response categories, ability to differentiate between participants' visual abilities (person separation; minimum acceptable 2.0), if items measure a single underlying construct [i.e. unidimensionality assessed by fit statistics and further by principal components analysis (PCA)] and matching of item difficulty to participant ability (targeting; ideal < 0.5 logits). Adequate person separation was defined as basic requirement for a measure, failing which further assessment such as PCA was not performed.

RESULTS

The four-item ICS questionnaire did not meet the required measurement properties (person separation zero). Response categories did not behave as intended, requiring the collapsing of categories for one item (read ordinary newspaper-size print). One item misfit (estimating distance) indicating that it was not measuring the same construct as other items. However, person separation failed to improve following the deletion of this item. Targeting was -0.46 logits, indicating that the item difficulty was well suited to the visual abilities of the participants.

CONCLUSION

In its present form, the ICS is unsuitable for visual disability assessment in patients awaiting cataract surgery. Other, better visual function questionnaires are available and preferred.

Are obesity and anthropometry risk factors for diabetic retinopathy? The diabetes management project

PURPOSE

To investigate the relationship between anthropometric parameters and diabetic retinopathy (DR) in adults with diabetes.

METHODS

Five hundred participants with diabetes were recruited prospectively from ophthalmology clinics in Melbourne, Australia. Each underwent an eye examination, anthropometric measurements, and standardized interview-administered questionnaires, and fasting blood glucose and serum lipids were analyzed. Two-field fundus photographs were taken and graded for DR. Height; weight; body mass index (BMI); waist, hip, neck, and head circumferences; and skinfold measurements were recorded.

RESULTS

A total of 492 patients (325 men, 66.1%) aged between 26 and 90 years (median, 65) were included in the analysis: 171 (34.8%), 187 (38.0%), and 134 (27.2%) with no DR, nonproliferative DR (NPDR), and proliferative DR (PDR), respectively. After multiple adjustments, higher BMI (odds ratio [OR], 1.06; 95% confidence interval [CI],1.01-1.11; P = 0.02) was significantly associated with any DR. Obese people were 6.5 times more likely to have PDR than were those with normal weight (OR, 6.52; 95% CI, 1.49-28.6; P = 0.013). Neck circumference (OR, 1.05; 95% CI, 1.00-1.10; P = 0.03) and waist circumference (OR, 1.12; 95% CI, 1.03-1.22; P = 0.01) were significantly associated with any DR. BMI (OR, 1.04; 95% CI, 1.00-1.08; P = 0.04) and neck circumference (OR, 1.04 95% CI, 1.01-1.08; P = 0.04) were also positively associated with increasing severity levels of DR.

CONCLUSIONS

Persons with diabetes with higher BMI and larger neck circumference are more likely to have DR and more severe stages of DR. These data suggest that obesity is an independent risk factor for DR.

The impact of vision impairment on vision-specific quality of life in Germany

PURPOSE

To validate the German-translated Impact of Vision Impairment (IVI) questionnaire, a vision-specific quality of life (QoL) scale, and determine the relationship between the severity of vision impairment, ocular conditions, and VRQoL.

METHODS

This cross-sectional study was clinic based, with 184 patients with low vision recruited from an outpatient clinic at a German eye hospital. Participants underwent a clinical examination and completed the German IVI scale. The validity of the IVI scale was assessed using Rasch analysis. The main outcome measure was the overall functional and emotional score provided by the IVI.

RESULTS

Overall, there were more female (n = 111, 60.3%) than male participants. Participants' mean ± SD age and visual acuity in the better eye were 69.0 ± 15.5 years and. 0.41 ± 0.35 logMAR, respectively. The main cause of vision loss was age-related macular degeneration (n = 54, 29.3%). Rasch analysis demonstrated the validity of the German IVI to assess VRQoL through two subscales: vision-specific functioning and emotional well-being. In adjusted multivariate analysis models, those with mild or moderate/severe vision impairment reported significantly poorer vision-specific functioning (mean change, -6.5, P = 0.018 and -11.98, P < 0.001 for mild and moderate to severe VI, respectively) and emotional well-being (mean change, -2.35; P = 0.043 and -3.13, P = 0.004 for mild and moderate/severe VI respectively) compared with non-visually impaired patients.

CONCLUSIONS

Using a psychometrically valid German IVI, even mild vision impairment was independently associated with poor VRQoL. These findings reinforce the importance of early preventative and rehabilitative efforts to prevent longitudinal deterioration in vision loss.

Impact of early and late age-related macular degeneration on vision-specific functioning

AIM

To assess the impact of early and late age-related macular degeneration (AMD) on vision-specific functioning in Singapore Malays.

METHODS

AMD was assessed from fundus photographs. The following endpoints were considered for (a) AMD: no AMD, early AMD, and late AMD; (b) drusen: absence and presence; and (c) retinal pigment epithelium (RPE) abnormality: absence and presence. Vision functioning was assessed using the modified VF-11 scale validated using the Rasch analysis. The overall functioning score was used as the main outcome measure.

RESULTS

Retinal photographs and vision functioning data were available only for 3252 participants. After age standardisation, the prevalence of early AMD was 3.5% and late AMD 0.34%. In multivariate models, after adjusting for age, gender, education, level of income, smoking status, ocular condition and hypertension, only late AMD was independently associated with poorer vision functioning when compared with no AMD or early AMD (β (β regression coefficient)=-6.4 (CI -11.7 to -2.1; p=0.01)). Early AMD or its principal components, drusen or RPE abnormality, were not independently associated with vision functioning (p>0.05). In adjusted multinomial logistic regression models, people with late AMD were twice as likely (OR=2.23; 95% CI 1.16 to 7.11) to have low overall functioning than those without AMD.

CONCLUSIONS

Late AMD has a significant impact on visual functioning, but early AMD, drusen and RPE changes have no impact. These data highlight the importance of preventive public health strategies targeting patients with early AMD signs in order to prevent progression to late AMD when visual function is compromised.

The longitudinal impact of macular telangiectasia (MacTel) type 2 on vision-related quality of life

PURPOSE

To determine the longitudinal impact of idiopathic macular telangiectasia (MacTel) type 2 on vision-specific quality of life (QoL).

METHODS

Participants with MacTel type 2 and controls with no vision impairment were recruited at baseline. All underwent a full ophthalmic examination and the interview-administered 28-item Impact of Vision Impairment (IVI) questionnaire at baseline, to gather information on sociodemographic factors and vision-specific QoL. The MacTel patients were reassessed at 24 months.

RESULTS

For the MacTel participants (n = 22), the median (range) age and visual acuity were 64 years (45-87) and 20/32 (20/13-20/63) in the better eye, respectively. The corresponding median values in the control group (n = 38) were 57 years (41-68) and 20/25 or better in both eyes, respectively. Rasch analysis showed that the IVI and its three subscales had sufficient psychometric validity and possessed interval level estimates. The control group had almost twice the level of vision-specific QoL than did the MacTel group at baseline on all IVI scores (P < 0.001 for all). At 24 months, we found no significant change in any of the IVI scores in the MacTel group. Similarly, there was no significant difference in visual acuity in the better or worse eyes in that group after 2 years.

CONCLUSIONS

Persons with MacTel type 2 had poorer overall vision-related QoL than did healthy controls. Several aspects of vision-related QoL and distance visual acuity did not significantly change after 24 months. Longer follow-up assessment periods are needed to determine the longitudinal impact of this condition on vision-related QoL.

Persistence of patients receiving topical glaucoma monotherapy in an Asian population

OBJECTIVE

To determine the persistence rates of patients who started taking topical intraocular pressure (IOP)-lowering monotherapy in a Singapore eye hospital.

METHODS

This was a retrospective review of patients who started taking a single IOP-lowering medication between October 1, 2005, and September 30, 2006. Pharmacy dispensing records were traced for 3 years from the date of first prescription. A patient was defined as persistent if he or she was prescribed the same medication before or within 90 days after the previous prescription had lapsed during this period. Persistence was assessed after 1 and 3 years.

RESULTS

A total of 2781 patients started taking topical IOP-lowering monotherapy during the 1-year study period. The mean (SD) age was 61.1 (15.7) years; 50.2% were male, and most were Chinese (81.1%) or Singaporean residents (85.4%). After 1 year, only 22.5% of patients (626 of 2781) persistently received the same therapy, which decreased to 11.5% (320 of 2781) after 3 years. Prostaglandin analogues had better persistence rates at 1 year compared with timolol maleate (29.6% vs 23.7%; P = .004) and all other medications combined (29.6% vs 20.6%; P < .001). Those who were not persistent at year 1 were younger (P < .001) and more likely to not be Singaporean (P = .008), not receiving government subsidies (P < .001), and receiving unilateral therapy (P < .001).

CONCLUSIONS

In this hospital-based study, the persistence rate of patients who started taking topical IOP-lowering monotherapy was low after 1 (22.5%) and 3 years (11.5%). These rates are lower than in previous studies in Western countries and may have implications for glaucoma care in Singapore and other parts of Asia.

Psychometric properties of visual functioning index using Rasch analysis

PURPOSE

The visual functioning index (VFI) was one of the first questionnaires developed using classical test theory to assess outcomes of cataract surgery. However, it was not Rasch-validated. The objective of this study was to examine the psychometric properties of the VFI using Rasch analysis in patients with cataract.

METHODS

The 11-item VFI was self-administered to 243 patients (mean age 73.9 years) drawn from a cataract surgery waiting list. We examined the response category thresholds, item fit statistics, differential item functioning and unidimensionality for the VFI and its three subscales.

RESULTS

Category thresholds were ordered. The person separation and reliability were low, indicating the poor discriminatory ability of the VFI. No items misfit but there was suboptimal targeting of item difficulty to patient ability. On the whole the items in the VFI were too easy for the sample. Only one item showed moderate differential item functioning.

CONCLUSION

The VFI does not meet the stringent requirements of the Rasch model. However adding more items to suit the more able patients with cataract as well as those awaiting second-eye cataract surgery could optimize the VFI.

Managing depression in patients with vision impairment: a descriptive study of practitioners' beliefs and confidence

AIM

Depression is common in older adults with vision impairment yet it often remains unidentified and untreated. Eye health professionals (EHPs) and rehabilitation workers (RWs) may be able to assist in detecting depression. This study identified EHPs' and RWs' beliefs about depression and confidence in working with patients with vision impairment and depression.

METHODS

A self-administered cross-sectional survey of 94 EHPs and RWs assessed beliefs about the symptoms and treatment for depression, and confidence in working with depressed people with vision impairment.

RESULTS

Participants showed awareness of both the symptoms and treatment options for depression. However, some important misconceptions were identified and many symptoms of depression were commonly attributed to vision loss. Participants lacked confidence in communicating about depression with patients and their families.

CONCLUSIONS

Training programs are needed to enable EHPs and RWs to confidently identify depression and discuss appropriate treatment and referral options with their patients.

Smoking, socioeconomic factors, and age-related cataract: The Singapore Malay Eye study

OBJECTIVE

To describe the relationship of smoking, sex, and socioeconomic factors with age-related cataract in Malay adults in Singapore.

METHODS

In a population-based study, 3280 Malay individuals aged 40 to 80 years participated (78.7% response rate). All had interviews, systemic examination, and laboratory investigations. Lens opacity was graded from slitlamp and retroillumination photographs using the Wisconsin Cataract Grading System. Smoking-cataract associations were compared with the Blue Mountains Eye Study in Australia.

RESULTS

Of 2927 participants (89.2%) with gradable lens photographs, 1338 (45.7%) had cataract. After adjusting for age, sex, body mass index, hypertension, and diabetes, current smokers had a higher prevalence of nuclear cataract (odds ratio [OR], 2.06; 95% confidence interval [CI], 1.46-2.98), cortical cataract (OR, 1.33; 95% CI, 1.02-1.74), posterior subcapsular cataract (OR, 1.39; 95% CI, 1.02-1.91), or any cataract (OR, 1.48; 95% CI, 1.10-1.99). These associations were not seen in the Blue Mountains Eye Study. Primary or lower education (OR, 1.67; 95% CI, 1.06-2.64) and low monthly income (OR, 1.43; 95% CI, 1.09-1.87) were both associated with nuclear cataract, while small-sized public housing was associated with posterior subcapsular cataract (OR, 1.70; 95% CI, 1.28-2.25). Among men, 43.5% currently smoked compared with only 3.2% of women. The population attributable risk of nuclear cataract due to smoking was estimated to be 17.6% in men.

CONCLUSIONS

Smoking and indicators of low socioeconomic status were associated with cataract in Malay persons, with 1 in 6 nuclear cataract cases in men attributable to smoking. Smoking-cataract associations were stronger in Malay than in white persons.

Remediating serious flaws in the National Eye Institute Visual Function Questionnaire

PURPOSE

To test the assumption that the National Eye Institute Visual Function Questionnaire (NEI VFQ) measures visual functioning, assess the validity of its subscales, and, if flawed, revise the questionnaire and derive a shortened version with sound psychometric properties.

SETTING

Flinders Medical Centre, Adelaide, Australia.

METHODS

Patients from the cataract surgery waiting list self-administered and completed the 39-item NEI VFQ (NEI VFQ-39). Rasch analysis was applied, and the psychometric performance of the entire questionnaire and each subscale was tested. Instrument revision was performed in the context of Rasch analysis statistics.

RESULTS

Five hundred thirty-six patients (mean age 73.8 years) completed the questionnaire. Response categories for 2 question types were not used as intended so dysfunctional categories were combined. The NEI VFQ-39 and the 25-item version (NEI VFQ-25) had good precision but evidence of multidimensionality (more than 1 construct in 1 score), questions that did not fit the construct, suboptimum targeting of item difficulty to person ability, and dysfunctional subscales (8 NEI VFQ-39; 12 NEI VFQ-25). Questions could be reorganized into 2 constructs (a visual functioning scale and a socioemotional scale) that, after misfitting questions were removed, gave valid measurement of each construct and preserved 3 subscales. Removing redundancy from these long-form subscales yielded valid short-form scales.

CONCLUSIONS

Several NEI VFQ subscales were not psychometrically sound; as an overall measure, it is flawed by multidimensionality. This was repaired by segregation into visual functioning and socioemotional scales. Valid long and short forms of the scales could enhance application of the questionnaire.

Association of retinal vessel calibre with diabetic retinopathy in an urban Australian indigenous population

PURPOSE

To assess the relationship of retinal vessel diameter and diabetic retinopathy (DR) in a subgroup of participants recruited through the Darwin Region Urban Indigenous Diabetes study.

METHODS

Participants were examined as part of the Darwin Region Urban Indigenous Diabetes study. All participants with gradable fundus photographs were included in the current analysis. Assessment of retinal vascular diameter, including arteriolar diameter (central retinal arteriolar equivalent) and venular diameter (central retinal venular equivalent), was undertaken using a semi-automated retinal vascular imaging program. DR was graded according to the modified Early Treatment DR Study scale.

RESULTS

A total of 110 participants, 25 men and 85 women, with a mean age of 50.8 years were included in the analysis. The odds ratio for having DR for each standard deviation increase in central retinal venular equivalent was as high as 1.62 (95% confidence intervals 0.94, 2.80); however, this did not reach statistical significance (P = 0.08). Moreover, individuals with severe non-proliferative DR and proliferative DR were found to have narrower arteriolar diameters compared with those with no DR, but this was not statistically significant (-8.1 microm, 95% confidence intervals, -39.3 microm, 23.1 microm; P = 0.612).

CONCLUSION

Our data indicate a trend for narrower arteriole diameter and wider venular diameter with DR in this high-risk ethnic group, which concurs with overall trends seen in non-indigenous populations.

Vision-specific distress and depressive symptoms in people with vision impairment

PURPOSE

To determine the unique contribution of vision-specific distress in predicting depressive symptoms in people with vision impairment attending a tertiary eye care clinic.

METHODS

In this cross-sectional study, interview-administered surveys were conducted with 143 adult patients who had presenting visual acuity <0.3 logMAR. Depressive symptoms were assessed with the Patient Health Questionnaire-9 and vision-specific distress was assessed with the Impact of Vision Impairment (IVI) Questionnaire emotional well-being subscale. In addition, level of restriction of participation in common daily activities due to vision impairment was assessed with the IVI and measures of general physical health and social support were included.

RESULTS

Twenty-one (14.7%) of 143 participants reported clinically significant depressive symptoms and an additional 27.3% (n = 39) had mild depressive symptoms. Vision-specific distress was the strongest unique predictor of depressive symptoms (beta = 0.37, P < 0.001), with physical health (beta = -0.22, P < 0.01), age (beta = -0.18, P < 0.05), and experience of a negative life event (beta = 0.15, P < 0.05) also contributing significantly to depressive symptoms. Results also indicated that vision-specific distress mediates the impact of participation restriction due to vision impairment on depressive symptoms.

CONCLUSIONS

An assessment of vision-specific distress may be a useful tool with which to identify those at risk of depression or in need of early intervention in eye care or rehabilitation settings. Depression treatment approaches or depression prevention strategies for people with vision impairment may benefit from a focus on vision-specific distress.

Intentional and unintentional nonadherence to ocular hypotensive treatment in patients with glaucoma

OBJECTIVE

To determine the rate of intentional and unintentional nonadherence in glaucoma patients and to identify associations between adherence behavior and patients' beliefs.

DESIGN

Cross-sectional study.

PARTICIPANTS

One hundred thirty-one glaucoma patients using topical eye drops for at least 6 months.

METHODS

Interviewer-administered surveys.

MAIN OUTCOME MEASURES

Self-reported adherence and beliefs about glaucoma and its treatment were assessed using the Reported Adherence to Medication scale, the Brief Illness Perception Questionnaire, and the Beliefs about Medicines-Specific Questionnaire.

RESULTS

Overall, 59 (45%) participants reported some degree of nonadherence, among whom 39 (66.1%) reported unintentional nonadherence (e.g., forgetting), 10 (16.9%) reported intentional nonadherence (deliberate nonadherence), and 10 (16.9%) reported both forms of nonadherence. Compared with adherers, nonadherers were significantly younger, were less likely to have other nonocular health conditions or to use medicines other than their eye drops, and reported lower belief in the necessity of eye drops for glaucoma (P<0.05). Degree of unintentional nonadherence was associated with lower belief in necessity of eye drops, whereas degree of intentional nonadherence was associated with concerns about eye drops.

CONCLUSIONS

Strategies aimed at improving adherence in glaucoma patients need to address both intentional and unintentional dimensions. Interventions focused on eliciting and addressing patients' beliefs and concerns about their eye drops require evaluation.