A questionnaire, the Catquest, was developed using classical test theory by the Swedish National Cataract Register in 1994. The questions had been picked out through a pre-study in cataract patients using 37 questions about daily life activities. The questions chosen for the questionnaire were the most decisive questions, concerning activities frequently performed, weighted high by the patients, and affected by a cataract extraction¹. The Catquest questionnaire was shown to have a good validity and a high reliability² according to classical test theory. In Catquest a certain score sum before surgery was compared to a certain score sum after surgery in each area of evaluation and individually for each patient³. Many studies were performed by use of the Catquest questionnaire.^4-12                                                                                                                  
In 2007 the Catquest database with more than 20,000 completed questionnaires was used to revise and construct a new modern questionnaire by use of Item-Response Theory (Rasch analysis)¹³. This new questionnaire is a valid short-form visual disability instrument that is ideal for the measurement of patient-reported outcomes of cataract surgery. From a clinical viewpoint, the advantages with this instrument include that it measures disability, gives interval scoring, has high precision, is short and minimizes response burden, is sensitive to changes after cataract surgery, has high effect size, and has good targeting.¹⁴ The instrument is translated into English, German, Dutch and Greek languages and validation studies are ongoing.

References, Catquest and Catquest-9SF.

1. Lundström M, Fregell G, Sjöblom A. Vision related daily life problems in patients waiting for a cataract extraction. Br J Ophthalmol. 1994;78:608-611.

2. Lundström M, Roos P, Jensen S, Fregell G. Catquest questionnaire for use in cataract surgery care: Description, validity and reliability. J Cataract Refract Surg 1997;23:1226-1236.

3. Lundström M, Stenevi U, Thorburn W, Roos P. Catquest questionnaire for use in cataract surgery care: Assessment of surgical outcomes. J Cataract Refract Surg 1998;24:968-974.

4. Lundström M, Stenevi U, Thorburn W. Outcome of cataract surgery considering the pre-operative situation. – A study of possible predictors of the functional outcome. Brit J Ophthalmol. 1999;83:1272-1276.

5. Lundström M, Brege KG, Florén I, Stenevi U, Thorburn W. Impaired visual function following cataract surgery assessed using the Catquest questionnaire. J Cataract Refractive Surg. 2000;26:101-108.

6. Lundström M, Stenevi U, Thorburn W. Cataract surgery in the very elderly. J Cataract Refractive Surg. 2000;26:408-414.

7. Lundström M, Stenevi U, Thorburn W. Quality of life aspects of first and second eye cataract surgery. An analysis of five years data collected by the Swedish National Cataract Register. J Cataract & Refract Surg. 2001;27:1553-1559

8. Lundström M, Stenevi U, Thorburn W. The Swedish National Cataract Register – A nine-year review. Acta Ophthalmol Scand. 2002;80:248-257.

9. Kobelt G, Lundström M, Stenevi U. Cost-effectiveness of cataract surgery: Method to assess cost-effectiveness using registry data. J Cataract & Refract Surg 2002; 28:1742-1749.

10. Lundström M, Brege KG, Florén I, Lundh B, Stenevi U, Thorburn W. Cataract surgery and quality of life in patients with age-related macular degeneration (AMD). Brit J Ophthalmol 2002;86:1330-1355.

11. Lundström M & Wendel E. Duration of self-assessed benefit of cataract extraction – a long-term study. Br J Ophthalmol 2005;89:1017-1020.

12. Lundström M, Albrecht S, Nilsson M, Åström B. Patients benefit from bilateral same-day cataract extraction – a randomised clinical study. J Cataract Refract Surg. 2006; 32:826-830.

13. Lundström M, Pesudovs K. Catquest-9SF patient outcomes questionnaire. Nine-item short-form Rasch-scaled revision of the Catquest questionnaire. J Cataract Refract Surg. 2009;35:504-513.

14. Lundström M, Behndig A, Kugelberg M, Montan P, Stenevi U, Pesudovs K. The outcome of cataract surgery measured with the Catquest-9SF. Acta Ophthalmol. 2011 Dec;89(8):718-23.