CERA

Science and research

Patient-reported outcome questionnaires

A number of patient-reported outcome measures (PROMs) to assess vision-related quality of life (VRQoL) have been developed and validated at CERA, including questionnaires, computerised adaptive testing (CATs) systems, a health state index, and utility measures.

Impact of Vision Impairment Questionnaire (IVI)

The IVI is a questionnaire that measures the impact of vision impairment on VRQoL. It contains 28 items with 3-4 response options using Likert scaling, ranging from not at all to a lot. Items 1-15 have an additional response don’t do this for other reasons. The IVI comprises three vision-specific subscales: ‘reading and accessing information’, ‘mobility and independence’ and ‘emotional well-being’.

It has been extensively validated in populations with different levels of vision impairment and various eye conditions, including age-related macular degeneration, glaucoma, cataract and diabetic retinopathy.

This questionnaire is now managed by the Singapore Eye Research Institute, a collaborator of CERA. Please contact [email protected] if you would like a pdf copy of the following:

  • Impact of Vision Impairment Questionnaire
  • Scoring guide of the Impact of Vision Impairment Questionnaire
Main publications

Original version of IVI – 32 items

[1] Weih LM, Hassell JB, Keeffe JE. Assessment of the impact of vision impairment. Investigative Ophthalmology & Visual Science. 2002 Apr; 43(4):927-35.

Rasch analysis of IVI – 28 items

[2] Lamoureux EL, Pallant JF, Pesudovs K, Hassell JB, Keeffe JE. The Impact of Vision Impairment Questionnaire: an evaluation of its measurement properties using Rasch analysis. Investigative Ophthalmology & Visual Science. 2006 Nov; 47(11):4732-41.

Rasch analysis of domain structure of the IVI

[3] Lamoureux EL, Pallant JF, Pesudovs K, Rees G, Hassell JB, Keeffe JE. The impact of vision impairment questionnaire: an assessment of its domain structure using confirmatory factor analysis and Rasch analysis. Investigative Ophthalmology & Visual Science. 2007 Mar; 48(3):1001-6.

Pooled item calibrations – 28 items

[4] Goldstein JE, Fenwick EK, Finger RP, Gothwal V, Jackson ML, Lamoureux EL, Rees G, Massof R. Calibrating the Impact of Vision Impairment (IVI): Creation of a Sample-Independent Visual Function Measure for Patient-Centered Outcomes Research. Transl Vis Sci Technol. 2018 Nov; 7(6): 38.

Publications using other language versions of the IVI

Mandarin (Simplified)

[5] Fenwick EK, Ong PG, Sabanayagam C, Rees G, Xie J, Holloway E, Cheng CY, Wong TY, Lim B, Tan PC, Lamoureux EL. Assessment of the psychometric properties of the Chinese Impact of Vision Impairment questionnaire in a population-based study: findings from the Singapore Chinese Eye Study. Qual Life Res. 2016 Apr;25(4):871-80.

German

[6] Finger RP, Fenwick E, Marella M, Dirani M, Holz FG, Chiang PP, Lamoureux EL. The impact of vision impairment on vision-specific quality of life in Germany. Investigative Ophthalmology & Visual Science. 2011 Jun 1;52(6):3613-9.

Melanesian

[7] O’Connor PM, Scarr BC, Lamoureux EL, Le Mesurier RT, Keeffe JE. Validation of a quality of life questionnaire in the Pacific Island. Ophthalmic Epidemiology. 2010 Dec;17(6):378-86.

Telugu and Hindi

[8] Gothwal VK1, Reddy SP, Fathima A, Bharani S, Sumalini R, Bagga DK, Sudharman PM. Assessment of the impact of keratoconus on VRQoL. Investigative Ophthalmology & Visual Science. 2013 Apr 23;54(4):2902-10.

Thai

[9] Ratanasukon M, Tongsomboon J, Bhurayanontachai P, Jirarattanasopa P. The Impact of Vision Impairment (IVI) Questionnaire; Validation of the Thai-Version and the Implementaion on VRQoL in Thai Rural Community. PLoS One. 2016 May 18;11(5):e0155509.

Brief Impact of Vision Impairment Questionnaire (B_IVI)

The original 28-item IVI was shortened to 15 items (the Brief IVI or B_IVI) using traditional and Rasch analysis techniques. It is a valid and reliable questionnaire for measuring the impact of vision impairment on vision-related QoL and has similar psychometric properties to the original 28-item IVI. The B_IVI can be used to provide an overall measure of vision-related QoL, and it also contains two subscales which provide measures of visual functioning and emotional well-being.

This questionnaire is now managed by the Singapore Eye Research Institute, a collaborator of CERA. Please contact [email protected] if you would like a pdf copy of the following:

  • Brief Impact of Vision Impairment Questionnaire
  • Scoring guide of the Brief Impact of Vision Impairment Questionnaire
Main publications

Development and validation of the B_IVI

[1] Fenwick EK, Man RE, Rees G, Keeffe J, Wong TY, Lamoureux EL. Reducing respondent burden: validation of the Brief Impact of Vision Impairment questionnaire. Qual Life Res. 2016 Aug 24. [Epub ahead of print] PMID: 27558785

Impact of Vision Impairment Very Low Vision (IVI-VLV)

The IVI-VLV is a valid and reliable measure of VRQoL in persons with very low vision. It is derived from the original IVI. All items of the IVI-VLV are preceded by “How much does your eyesight….” and use the same rating scale with the following four response options: Not at all, a little, some of the time, and a lot. In addition, all items have a Don’t do this for other reasons option.

It has two subscales: 1. Emotional Wellbeing (EWB) and 2. Activities of Daily Living, Mobility and Safety (ADLMS). The EWB subscale contains 12 items, and the ADLMS subscale 16 items (a total of 28 items for the IVI-VLV). The IVI-VLV can differentiate between different levels of VRQoL in participants, and measurement is unaffected by almost all levels of general or mental health.

The questionnaire is the first instrument to measure VRQoL in persons with severe vision loss whose VRQoL is not captured by available instruments. The IVI-VLV meets all requirements of the Rasch model, and proposed quality criteria for health status questionnaires, such as content validity, internal consistency, reliability, no floor or ceiling effects and good interpretability.

Please contact [email protected] if you would like a pdf copy of the following:

  • Impact of Vision Impairment Very Low Vision Questionnaire
  • Scoring guide of Impact of Vision Impairment Very Low Vision Questionnaire
Main publications

Development and validation of the IVI-VLV

[1] Finger RP, Tellis B, Crewe J, Keeffe JE, Ayton LN, Guymer RH. Developing the impact of Vision Impairment-Very Low Vision (IVI-VLV) questionnaire as part of the LoVADA protocol. Investigative Ophthalmology &Visual Science. 2014 Sep 4;55(10):6150-8.

Impact of Vision Impairment for Children (IVI_C)

The Impact of Vision Impairment for Children (IVI-C) is a validated VRQoL questionnaire, the items for which were primarily developed from focus groups with children with vision impairment. Focus groups with associated adults (non-specialised class teachers, specialised teachers and parents of children with vision impairment) were also undertaken.

The IVI-C contains 24 items each of which have 5 Likert responses ranging from Always to Never plus an additional, No, for other reasons. Six of the items are reversed scored to reduce response bias. There is a banner heading at the top of each of the five pages of items, “The questions are all about how things are for you because of your eyesight”.

The banner should be read out before the set of items on the page are read. The IVI_C focuses on interaction and classroom dynamics and was the first paediatric VRQoL questionnaire developed primarily from the perspectives of children. It has been used in India, South-East Asia and the Pacific, the Caribbean, UK and the USA.

This questionnaire is now managed by the Singapore Eye Research Institute, a collaborator of CERA. Please contact [email protected] if you would like a pdf copy of the following:

  • Impact of Vision Impairment Questionnaire for Children
  • Scoring guide of the Impact of Vision Impairment Questionnaire for Children
Main publications

Development of the original version of the IVI_C (28 items)

[1] Cochrane G, Lamoureux E, Keeffe J. Defining the content for a new quality of life questionnaire for students with low vision (The impact of vision impairment on children: IVI_C). Ophthalmic Epidemiology. 2008 Mar; 15(2):114-20.

Rasch analysis of the IVI_C (24 items)

[2] Cochrane GM, Marella M, Keeffe JE, Lamoureux EL. The Impact of Vision Impairment for Children (IVI_C): validation of a vision-specific pediatric quality of life questionnaire using Rasch analysis. Investigative Ophthalmology & Visual Science. 2011 Mar; 52(3):1632-40.

Publications using other language versions of the IVI_C

Telugu and Hindi

[3] Gothwal, Vijaya K.; Sumalini, Rebecca; Irfan, Shaik Mohammad; et al. Rasch Analysis of Impact of Vision Impairment for Children Questionnaire Optometry and Vision Science  2013 Aug; 90(8): 820-7

Impact of Vision Impairment in Residential Care (IVI-RC)

A residential care-specific version of the IVI was developed for use in the Residential Ocular Care (ROC) study, which is a large randomised controlled trial to assess the effectiveness of a tailored eye care model for people living in residential care. The IVI-RC comprises 28 items across three separately scored scales, namely Reading and Accessing Information, Mobility and Independence, and Emotional well-being.

This questionnaire is now managed by the Singapore Eye Research Institute, a collaborator of CERA. Please contact [email protected] if you would like a pdf copy of the following:

  • Impact of Vision Impairment Questionnaire in Residential Care
  • Scoring guide of the Impact of Vision Impairment Questionnaire in Residential Care
Main publications

[1] REK Man, ATL Gan, M Constantinou, EK Fenwick, EE Holloway, EA Finkelstein, M Coote, J Jackson, G Rees, EL Lamoureux. Effectiveness of an Innovative and Comprehensive Eye Care Model for Individuals in Residential Care Facilities:  Results of the Residential Ocular Care (ROC) Multi-Centered Randomized Controlled Trial. Br J Ophthalmology. 2020. Epub ahead of print.

[2] Rees G, McCabe M, Xie J, Constantinou M, Gan A, Holloway E, Man RE, Jackson J, Fenwick EK, Lamoureux E. High vision-related quality of life indices reduce the odds of depressive symptoms in aged care facilities. Aging Ment Health. 2019. 8: 1-9.

Analysis of the IVI instruments

We recommend that Rasch analysis is conducted on the raw responses from any of the IVI instruments in order to:

  1. Assess the psychometric properties of the IVI and its three domains, such as scale precision, unidimensionality, item fit, targeting, and differential item functioning, to ensure the IVI fits the Rasch model;
  2. Convert ordinal scores into those approximating interval-level measurement. Only interval measures can be used in parametric testing. Rasch analysis also improves measurement precision and increases sensitivity when assessing changes over time.

Should you require assistance with Rasch analysis or input in designing your study, please do not hesitate to contact Prof Ecosse Lamoureux on [email protected].

Digital IVI

We are phasing out our paper-pencil questionnaires to a digital format. Digital versions of our IVI instruments can be supplied to you via a web link which you can run from a computer or tablet. After taking the items, overall and subscale scores are automatically computed and the data are stored on our secure server and can be provided to you in an excel spreadsheet.

The digital format is strongly recommended as it mitigates the need for data entry and calculation of raw scores.

Vision and Quality of Life Index (VisQoL)

The VisQoL is a health state measure (or index) and has a descriptive system that covers six dimensions: physical well-being, independence, social well-being, self-actualisation, and planning and organisation. Each question is preceded by “Does my vision…” and each dimension has between five and six response categories, ranging from, for example, no effect to unable to do. Two dimensions also have a ‘non-applicable’ option.

Analysis

The health states defined by the VisQoL responses can be translated into VisQoL index values using an available value set derived from surveys using the time trade off method. The value set was generated during instrument validation, using a range of health states in a vision-impaired and vision-unimpaired sample. Item scores were combined using a multiplicative model and the scale of the index ranges from 0-1, where 0.0 represents the worst imaginable vision-related health state, i.e. blindness, and 1.0 represents the best imaginable vision-related health state, i.e. perfect vision. Health states rated worse than blindness are represented by negative values. In order to obtain utilities, the VisQoL index values can be either mapped to the Australian Quality of Life (AQoL) utilities, or the VisQoL can be used as part of the AQoL-7D questionnaire.

For a copy of the VisQoL, visit here.

Main publications

[1] Peacock S, Misajon R, Iezzi A, Richardson J, Hawthorne G, Keeffe J. Vision and quality of life: development of methods for the VisQoL vision-related utility instrument. Ophthalmic Epidemiology. 2008 Jul-Aug; 15(4):218-23.

[2] Misajon R, Hawthorne G, Richardson J, Barton J, Peacock S, Iezzi A, Keeffe J. Vision and quality of life: the development of a utility measure. Investigative Ophthalmology & Visual Science. 2005 Nov; 46(11):4007-15.

Publications using other language versions of the VisQoL

German

[3] Finger RP, Kortuem K, Fenwick E, von Livonius B, Keeffe JE, Hirneiss CW. Evaluation of a vision-related utility instrument: the German vision and quality of life index. Investigative Ophthalmology & Visual Science. 2013 Feb; 54(2):1289-94.

Telugu and Hindi

[4] Gothwal VK, Bagga DK. Vision and Quality of Life Index: validation of the Indian version using Rasch analysis. Investigative Ophthalmology & Visual Science. 2013 Jul; 54(7):4871-81.

Diabetic Retinopathy Utility Instrument (DRU-I)

The DRU-I comprises five quality of life dimensions, including Visual symptoms, Activity limitation/mobility, Lighting and glare, Socio-emotional well-being, and Inconvenience, each rated as no, some, or a lot of difficulty. The DRU-I was developed using discrete choice experiment (DCE) methods and assesses disutilities associated with vision-threatening DR and clinically significant macular oedema, and associated vision impairment. It has the potential to assess the cost-effectiveness of DR interventions from a patient perspective and inform policies on resource allocation relating to DR.

This questionnaire is now managed by the Singapore Eye Research Institute, a collaborator of CERA. Please contact [email protected] if you would like a pdf copy of the following:

  • Diabetic Retinopathy Utility Instrument
  • Scoring guide of the Diabetic Retinopathy Utility Instrument
Main publications

Development and validation of the DRU-I

[1] Fenwick EK, Bansback N, Gan ATL, Ratcliffe J, Burgess L, Wong TY, Lamoureux EL. Validation of a novel diabetic retinopathy utility index using discrete choice experiments. Br J Ophthalmol. 2020 Feb;104(2):188-193.

Item banks and computerised adaptive tests (CATs)

We have several item banks and CATs available to measure the impact of eye conditions and vision impairment on a range on quality of life outcomes. Please contact [email protected] if you would to know more about our CAT instruments.

What are item banks and CAT?

An item bank  is a pool of items (questions) that measures a latent construct such as ‘visual functioning’ and usually contains far more items than would normally be included in a single paper-based questionnaire. The items are all calibrated on the same scale (like a ruler) using Item Response Theory methods. CAT is a method for administering items from a calibrated item bank. It iteratively chooses the questions asked based on the examinee’s impairment level by presenting targeted items (i.e. those that will provide the greatest amount of information) to the respondent.

Subsequent items are selected based on the examinee’s previous responses and selection proceeds until a pre-defined stopping criterion (e.g. measurement precision or number of items) is reached.  For example, if a person has no difficulty with ‘cooking a meal’, the next selected item would be a more difficult task such as ‘reading the newspaper’. Conversely, if ‘negotiating stairs’ is a challenge, an easier task like ‘watching TV’ will be presented.

What are the benefits of item banking and CAT compared to traditional paper-pencil questionnaires?

Having items spread across (tapping into) different levels of the construct and calibrated on the same scale means that items which best target the participant’s ability level can be selected. Similarly, even though participants may answer different items (the combination of which depends on the participant’s level of the underlying construct) the scores are meaningful in the same terms as they are taken from the larger calibrated bank of items.

Moreover, item banks are flexible, meaning that new items can be added to suit changes in disease management or the instruments/technologies employed in daily life. This strategy ensures that items are tailored to the individual’s level of impairment and, as such, test takers perceive this technology  to be more “empathetic”. Therefore, compared to paper-pencil questionnaires with a fixed set of items, CATs require fewer items and less time to arrive at equally precise scores, reduce test taker burden by asking relevant questions and tailoring the test to test-taker ability level. CAT also facilitates integration of results of psychometric tests promptly into the therapeutic process by providing real-time feedback.

How do they work in practice?

We will provide you with a web link for each CAT which can be administered on a tablet or laptop. At the completion of the CAT test, a Rasch-scaled score is automatically computed and the data are stored on our secure server and can be provided to you in an excel spreadsheet. Our CATs therefore mitigate the need for data entry and calculation of Rasch-scaled scores.

The Impact of Vision Impairment CAT (IVI-CAT)

We have developed CATs for the overall IVI (IVI-CAT); Vision-specific functioning (VSF-CAT); and Emotional well-being (EWB-CAT). On average, the IVI-CAT requires only 10 items to get a highly precise score estimate of VRQoL, corresponding to a 65% reduction in items from the paper-pencil version (n=28 items).

The VSF-CAT requires only 10-11 items on average to get stable score estimates of vision-specific functioning (equivalent to a 53% item reduction). All eight items are required for the EWB-CAT as the item pool is small.

Main publication

Development and validation of the IVI-CAT

[1] EK Fenwick, BS Loe, J Khadka, REK Man, G Rees, EL Lamoureux. Optimizing measurement of VRQoL: a computerized adaptive test for the Impact of Vision Impairment questionnaire (IVI-CAT). Qual Life Res. 2020 Mar;29(3):765-774.

The Diabetic Retinopathy Quality of Life CAT (RetCAT)

We have developed and validated a series of item banks and CATs to measure the impact of diabetic retinopathy on quality of life (“RetCAT”). RetCAT comprises 279 items spread across 10 quality of life domains, including Visual Symptoms (n=18); Activity Limitation (n=84); Mobility (n=17); Emotional (n=45); Concerns (n=35); Convenience (n=20); Driving (n=15) and Lighting (n=10); Social (n=20); and Economic (n=15).

The psychometric properties of each item bank has been assessed using Rasch analysis, and the efficiency and measurement precision of the CATs has been evaluated in clinical populations. On average, stable score estimates can be obtained for each quality of life domain using approximately seven items  and taking 2 minutes to administer and answer.

Main publications

Developing content for QoL domains and items

[1] EK Fenwick, K Pesudovs, J Khadka, G Rees, M Dirani, TY Wong, EL Lamoureux. The impact of diabetic retinopathy on quality of life: qualitative findings from an item bank development project. Qual Life Res, 2012. 21(10): 1771-82.

[2] EK Fenwick, K Pesudovs, J Khadka, G Rees, TY Wong, EL Lamoureux. Evaluation of item candidates for a diabetic retinopathy quality of life item bank. Qual Life Res, 2013. 22(7): 1851-58.

Assessment of the psychometric properties of the QoL domains

[3] EK Fenwick, J Khadka, K Pesudovs, G Rees, TY Wong, EL Lamoureux. Diabetic retinopathy and diabetic macular edema quality-of-life item banks: development and initial evaluation using computerized adaptive testing. Invest Ophthalmol Vis Sci. 2017. 58(14): 6379-6387.

Evaluation of the RetCAT instrument

[4] EK Fenwick, J Barnard, A Gan, BS Loe J Khadka, K Pesudovs, REK Man, SY Lee, G Tan, TY Wong, EL Lamoureux. Computerised adaptive tests: Efficient and precise assessment of the patient-centered impact of diabetic retinopathy. Transl Vis Sci Technol. 2020 Jun 3;9(7):3.

The Glaucoma Quality of Life CAT (GlauCAT)

We have developed and validated a series of item banks and CATs to measure the impact of glaucoma on quality of life (“GlauCAT”). GlauCAT comprises 303 items spread across 12 quality of life domains, including Visual Symptoms (n=18); Ocular Comfort Symptoms (n=22); Activity Limitation (n=58); Mobility (n=20); Emotional (n=45); Concerns (n=45); General Convenience (n=23); Treatment Convenience (n=14); Driving (n=13); Lighting (n=9); Social (n=14); and Economic (n=22).

The psychometric properties of each item bank has been assessed using Rasch analysis, and the efficiency and measurement precision of the CATs has been evaluated in clinical populations. On average, stable score estimates can be obtained for each quality of life domain using approximately seven items  and taking 2 minutes to administer and answer.

Main publications

Developing content for QoL domains and items

[1] Khadka J, McAlinden C, Craig JE, Fenwick EK, Lamoureux EL, Pesudovs K. Identifying content for the glaucoma-specific item bank to measure quality-of-life parameters. J Glaucoma. 2015 Jan;24(1):12-9.

Assessment of the psychometric properties of the QoL domains

[2] Khadka J, Fenwick EK, Lamoureux EL, Pesudovs K. Item Banking Enables Stand-Alone Measurement of Driving Ability. Optom Vis Sci. 2016 Dec;93(12):1502-1512.

Language versions other than English

Our instruments are available in a variety of languages other than English. Please contact [email protected] for more information.

Instruments in development

We also have a few instruments in development:

Computerised adaptive tests for other eye conditions

CATs are also under development for age-related macular degeneration, other retinal diseases, refractive error, and myopia. If you would like more information on any of these upcoming CAT instruments, please email Prof Ecosse Lamoureux on [email protected].

Instrumental Activities of Daily Living Very Low Vision

An assessment of observed and timed performance on a range of instrumental activities of daily living appropriate for persons with very low vision.

Main publication

[1] Finger RP, McSweeney SC, Deverell L, O’Hare F, Bentley SA, Luu CD, Guymer RH, Ayton LN. Developing an instrumental activities of daily living tool as part of the low vision assessment of daily activities protocol. Investigative Ophthalmology & Visual Science. 2014 Nov; 55(12):8458-66.

Orientation & Mobility Assessment Very Low Vision

An assessment of observed performance on a range of orientation and mobility tasks appropriate for persons with very low vision.

Outcome measures for persons with very low vision

If you would like more information on these upcoming instruments, please email [email protected].