LAUSR

Editor, W e have read and reviewed the article entitled ‘Changes in choroidal thickness after intraocular pressure reduction following trabeculectomy’ by Kadziauskiene et al. (2016) with great interest. The authors evaluated the changes in peripapillary and subfoveal choroidal thickness (CT) after trabeculectomy. They assessed 37 eyes with open-angle glaucoma before trabeculectomy and at 1 week, 3 and 6 months postoperatively. The subfoveal and peripapillary CT was measured using enhanced depth imaging spectral-domain optical coherence tomography (SD-OCT). Kadziauskiene et al. showed that the medium subfoveal CT (IQR) increased from 182 (97) lm at baseline to 267 (107) lm at 1 week, 213 (97) lm at 3 months and 207 (91) lm at 6 months postoperatively. Furthermore, the peripapillary CT increased in all four quadrants at all follow-ups. We congratulate the authors for their precious study, and we would like to request more details and their valuable contributions to the article. It has been shown in many different studies that CT, which is the main parameters evaluated in the study, gets affected from many local, systemic and environmental factors (Nickla & Wallman 2010; Tan et al. 2016). We would like to ask Kadziauskiene et al. (2016) whether these parameters have been assessed. First, it has been mentioned that age range of patients included in the study was 30–83 years. Also, it is seen that 14 of 36 patients were female. It is known that menstrual cycle and pregnancy might significantly affect CT (Tan et al. 2016). We think that these points are required to be mentioned in the study. Second, many systemic diseases (hypertension, diabetes, hyperlipidaemia, and neurological, inflammatory and haematological diseases, etc.) and local diseases (strabismus, amblyopia, etc.) might affect CT. Furthermore, we are of the opinion that treatments used for these diseases might affect CT. Third, CT shows considerable diurnal variation and Kadziauskiene et al. (2016) have not mentioned if they took that point into consideration. The thickness of choroid is able to increase by 50% in an hour and increase its thickness by four times in a few days (Nickla & Wallman 2010). Subfoveal CT in healthy subjects has been researched by Usui et al. (2012). They evaluated subfoveal CT every 3 hr over a period of 24 hr. Usui et al. (2012) demonstrated that mean subfoveal CT was thickest (290.8 110.8 lm) at 3 am and thinnest (271.9 103.5 lm) at 6 pm. Additionally, the authors indicated in that study that CT’s diurnal variation was able to be up to 65 lm (range, 8–65 lm), and subfoveal CT in all eyes had a negative correlation with systolic blood pressure. Fourth, itmayhave apparent effect on CT that patients smoke, consume food or alcohol, caffeinated or non-caffeinated drinks, and exercise before OCT measurements. Also, body mass index (BMI) and systemic blood pressure results of patientsmay remarkably affect CT (Tan et al. 2016). We would like to ask authors whether all these factors have been considered in the study. Consequently, we would like to mention that it is of utmost importance in terms of scientific value of results obtained that all factors which may affect CT are reviewed and considered in preand postoperative period.