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. 1999 Jan;83(1):66–70. doi: 10.1136/bjo.83.1.66

Measuring the effectiveness of cataract surgery: the reliability and validity of a visual function outcomes instrument

D Lawrence 1, C Brogan 1, L Benjamin 1, D Pickard 1, S Stewart-Brown 1
PMCID: PMC1722791  PMID: 10209438

Abstract

AIMS—To assess test-retest reliability and validity of the "TyPE" patient self assessed visual function questionnaire, as part of a study in two hospitals measuring the effectiveness of cataract surgery. The American TyPE questionnaire had minor adaptations made for use in Britain.
METHODS—Test-retest reliability was assessed on 63 out of 378 adult cataract surgery patients in the study, using Spearman correlation coefficients and kappa coefficients of agreement. "Construct" validity was evaluated by comparing the association between changes in visual function questionnaire scores after surgery, with patients' perception of change in visual function obtained by independent interview of 24 patients.
RESULTS—The TyPE questionnaire items showed very good test-retest reliability. Average Spearman and kappa coefficients for 39 patients from hospital 1 were 0.93 and 0.84 respectively. Spearman and kappa coefficients of 0.9 and 0.81 were obtained for those nine patients in hospital 2 where both the test and retest questionnaires were filled in by the same people. However, for the 15 patients from hospital 2, where the questionnaire was filled in by different people in the retest, reliability was less good: the Spearman coefficients were still high, average 0.72, but the kappa coefficients were poor, 0.27. Good construct validity was exhibited, with a correlation of 0.79 between change in distance vision score from the questionnaires and the independent interview.
CONCLUSIONS—The adapted TyPE questionnaire is both very reliable and has good construct validity. The kappa coefficient should be used wherever possible to evaluate reliability. The test-retest reliability and validity and practicability of other visual function questionnaires have not been assessed adequately, and further development should be carried out of all such questionnaires, so that they may be introduced into routine clinical care.

 Keywords: reliability; validity; cataract outcomes; visual function; questionnaire

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Selected References

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  1. Cassard S. D., Patrick D. L., Damiano A. M., Legro M. W., Tielsch J. M., Diener-West M., Schein O. D., Javitt J. C., Bass E. B., Steinberg E. P. Reproducibility and responsiveness of the VF-14. An index of functional impairment in patients with cataracts. Arch Ophthalmol. 1995 Dec;113(12):1508–1513. doi: 10.1001/archopht.1995.01100120038005. [DOI] [PubMed] [Google Scholar]
  2. Desai P., Reidy A., Minassian D. C., Vafidis G., Bolger J. Gains from cataract surgery: visual function and quality of life. Br J Ophthalmol. 1996 Oct;80(10):868–873. doi: 10.1136/bjo.80.10.868. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Elliott D. B., Hurst M. A., Weatherill J. Comparing clinical tests of visual function in cataract with the patient's perceived visual disability. Eye (Lond) 1990;4(Pt 5):712–717. doi: 10.1038/eye.1990.100. [DOI] [PubMed] [Google Scholar]
  4. Gibson R. A., Sanderson H. F. Observer variation in ophthalmology. Br J Ophthalmol. 1980 Jun;64(6):457–460. doi: 10.1136/bjo.64.6.457. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Javitt J. C., Brenner M. H., Curbow B., Legro M. W., Street D. A. Outcomes of cataract surgery. Improvement in visual acuity and subjective visual function after surgery in the first, second, and both eyes. Arch Ophthalmol. 1993 May;111(5):686–691. doi: 10.1001/archopht.1993.01090050120041. [DOI] [PubMed] [Google Scholar]
  6. Laidlaw A., Harrad R. Can second eye cataract extraction be justified? Eye (Lond) 1993;7(Pt 5):680–686. doi: 10.1038/eye.1993.155. [DOI] [PubMed] [Google Scholar]
  7. Landis J. R., Koch G. G. The measurement of observer agreement for categorical data. Biometrics. 1977 Mar;33(1):159–174. [PubMed] [Google Scholar]
  8. Legro M. W. Quality of life and cataracts: a review of patient-centered studies of cataract surgery outcomes. Ophthalmic Surg. 1991 Aug;22(8):431–443. [PubMed] [Google Scholar]
  9. Mangione C. M., Phillips R. S., Seddon J. M., Lawrence M. G., Cook E. F., Dailey R., Goldman L. Development of the 'Activities of Daily Vision Scale'. A measure of visual functional status. Med Care. 1992 Dec;30(12):1111–1126. doi: 10.1097/00005650-199212000-00004. [DOI] [PubMed] [Google Scholar]
  10. Mordue A., Parkin D. W., Baxter C., Fawcett G., Stewart M. Thresholds for treatment in cataract surgery. J Public Health Med. 1994 Dec;16(4):393–398. doi: 10.1093/oxfordjournals.pubmed.a043019. [DOI] [PubMed] [Google Scholar]
  11. Schein O. D., Steinberg E. P., Cassard S. D., Tielsch J. M., Javitt J. C., Sommer A. Predictors of outcome in patients who underwent cataract surgery. Ophthalmology. 1995 May;102(5):817–823. doi: 10.1016/s0161-6420(95)30952-9. [DOI] [PubMed] [Google Scholar]
  12. Steinberg E. P., Tielsch J. M., Schein O. D., Javitt J. C., Sharkey P., Cassard S. D., Legro M. W., Diener-West M., Bass E. B., Damiano A. M. The VF-14. An index of functional impairment in patients with cataract. Arch Ophthalmol. 1994 May;112(5):630–638. doi: 10.1001/archopht.1994.01090170074026. [DOI] [PubMed] [Google Scholar]
  13. Wormald R. P., Wright L. A., Courtney P., Beaumont B., Haines A. P. Visual problems in the elderly population and implications for services. BMJ. 1992 May 9;304(6836):1226–1229. doi: 10.1136/bmj.304.6836.1226. [DOI] [PMC free article] [PubMed] [Google Scholar]

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