Letters to the Editor Will improvement of knowledge lead to improvement of compliance with glaucoma medication? Kaweh Mansouri 1 and Tarek Shaarawy 2 1 Jules Gonin Eye Hospital, University of Lausanne, Switzerland 2 Glaucoma Sector, Department of Oph- thalmology, University of Geneva, Swit- zerland doi: 10.1111/j.1755-3768.2009.01513.x Editor, W e read with interest the paper by Hoevenaars et al. (2008). The authors are to be complimented for designing an extensive study attempting to find out whether addressing specific items of improved knowledge of glau- coma leads to better compliance. In their study, 44 randomly selected oph- thalmologists each selected four consec- utive patients (n = 166) to complete a structured questionnaire. The results could not show a statistically significant correlation between the total level of knowledge and compliance. The authors conclude that it would be ‘unli- kely that further improving knowledge will greatly improve compliance with glaucoma medication’. They recom- mend that strategies on enhancing com- pliance should not focus on further improving knowledge and that a patient education programme will not be of added value in improving compliance. We beg to differ with their conclu- sions. Firstly, their counterintuitive findings are in contradiction to most of the published literature, which shows a positive correlation between better understanding of glaucoma and compli- ance (MacKean & Elkington 1983; Zimmerman & Zalta 1983; Khandekar et al. 2005). Recently, this relationship was shown to have a risk ratio (RR) of 2.05 [95% confidence interval (CI) 1.07–3.93] in a study of 105 Omani and a RR of 4.54 (95% CI 1.45–14.16) in 200 Swiss glaucoma patients (K. Mansouri et al., unpublished). However, because most studies on com- pliance lacked sufficient power to assess the effect of patient knowledge and compliance, a significant majority of participants did not have an accurate viewpoint of glaucoma, thus reducing the numbers available for analysis (Konstas et al. 2000). The educational level of patients is also positively corre- lated with better compliance (Sleath et al. 2006): several studies have demon- strated that less formally educated indi- viduals, particularly those with less than secondary education, were more unlikely to be familiar with glaucoma (Gasch et al. 2000; Lau et al. 2002; Olthoff et al. 2005; Hoevenaars et al. 2006). Also, patients with chronic dis- ease (including glaucoma) frequently complain of a lack of information (Osterberg & Blaschke 2005; Mansouri et al. 2006), making this a major barrier to improving compliance. Interestingly enough, Hoevenaars et al.’s recent rec- ommendation is also in contradiction of an earlier report by the same group that analysed the same cohort for socioeco- nomic determinants, which suggested that ‘better provision of information to patients … could reduce their risk of becoming blind … and improve compli- ance’(Hoevenaars et al. 2006). Their study suffers from a number of limitations that might have contrib- uted to the surprising findings: (1) The definition of non-compliance (one missed dose in the past 4 weeks) is unusual. Most reports use a less strict criterion of one or more doses in the past week. (2) The definition of ‘total level of knowledge’ (some questions were too complex for an average patient) does not necessarily reflect useful knowl- edge of glaucoma. (3) The response rate was relatively low, with only 166 out of 240 targeted patients (69.1%) and 73% of ophthal- mologists participating compared to the reported 85% of patients. Eleven patients did not fill in the number of doses missed and a further 12 were excluded for various reasons, reducing the effective response rate to 59.5%. (4) It could further be argued that selecting only four patients per prac- tice could lead to potential selection bias and chance. (5) Furthermore, the issue of dyscom- pliance (how to correctly instill drops), an important part of achieving a treatment response, was not addressed in the study. It can be rea- sonably argued that dyscompliance could be reduced by adequate educa- tion and the provision of instillation aids through the healthcare provider. (6) We believe that the study design does not allow the authors to arrive at the above-mentioned conclusions. The authors should have conducted an interventional trial with a study group receiving education on glau- coma and a control group not receiv- ing any additional education. Even in the absence of these short- comings, the conclusion drawn would still not be justified: the authors them- selves demonstrate that three out of 22 items showed a significant positive cor- relation with compliance (such as patients knowing that eyedrops cannot repair glaucoma damage), and a fur- ther 19 items showed a positive relation with compliance while not being signifi- cant. Therefore, we would like to cau- tion practitioners and policy-makers to interpret these conclusions carefully and in the context of the other pub- lished literature. Nevertheless, we appreciate the effort invested by the authors to address an often neglected field of glaucoma research. References Gasch AT, Wang P & Pasquale LR (2000): Determinants of glaucoma awareness in a general eye clinic. Ophthalmology 107: 303–308. Hoevenaars JG, Schouten JS, van den Borne B, Beckers HJ & Webers CA (2006): Socio- economic differences in glaucoma patients’ knowledge, need for information and expectations of treatments. Acta Ophthal- mol Scand 84: 84–91. Hoevenaars JG, Schouten JS, van den Borne B, Beckers HJ & Webers CA (2008): Will improvement of knowledge lead to improvement of compliance with glaucoma medication? Acta Ophthalmol 86: 849–855. Khandekar R, Shama Mel-S & Mohammed AJ (2005): Noncompliance with medical treatment among glaucoma patients in Oman – a cross-sectional descriptive study. Ophthalmic Epidemiol 12: 303–309. Konstas AG, Maskaleris G, Gratsonidis S & Sardelli C (2000): Compliance and viewpoint of glaucoma patients in Greece. Eye 14: 752–756. Lau JT, Lee V, Fan D, Lau M & Michon J (2002): Knowledge about cataract, glau- coma, and age related macular degeneration in the Hong Kong Chinese population. Br J Ophthalmol 86: 1080–1084. Acta Ophthalmologica 2009 468