Assessment of the reproducibility and repeatability of a method of grading macular subretinal fluid using optical coherence tomography SE Benson, PG Schlottmann, C Bunce, W Xing and DG Charteris Abstract Aim To devise a quantative method for the measurement of the extent of macular subretinal fluid using optical coherence tomography (OCT), and to assess the interobserver and intraobserver agreement for this grading system. Methods Observational cohort series. Patients were a cohort who underwent retinal detachment surgery over an 18-month period. All patients had OCT scan at 6 weeks after surgery. The scans were graded by two independent observers experienced in OCT interpretation and each grader was masked to the others findings. Observer 1 then regraded the scans on a later day masked to his previous findings. The interobserver and intraobserver agreement was assessed using weighted Kappa (Kw) statistics. Results In all, 116 patients were analysed. Both the intraobserver and interobserver agreement was very high, with Kw being 0.9631 and 0.9070, respectively. Conclusions The grading system for assessment of the extent of macular subretinal fluid using OCT appears to have very good reproducibility and repeatability. We propose that this grading system would be clinically useful when applied to pathologies visible on OCT scan of the macula. Eye (2006) 20, 1030–1033. doi:10.1038/sj.eye.6702073; published online 9 September 2005 Keywords: optical coherence tomography; macula; grading; subretinal fluid Introduction Optical coherence tomography (OCT) is a useful noninvasive tool for detecting macular pathologies, the morphology of which in some cannot be seen on clinical examination. 1 Persistent subretinal fluid has been identified by OCT in patients who have undergone successful retinal detachment surgery. 2–6 This fluid often cannot be seen on slit-lamp clinical examination, is not detected by fluorescein angiography and is associated with poor vision and upon its resolution with visual improvement. Other studies from our group (data in preparation) have determined the incidence, pattern, and duration of persistent subretinal fluid in patients having undergone vitrectomy/ gas and scleral buckle procedures for retinal detachment. The results of these studies have raised the question that the extent of subretinal fluid involvement of the macula may also affect the extent to which patients recover following retinal detachment surgery. We have therefore devised a grading system to assess the extent of macular subretinal fluid on OCT and we here present our findings on the reproducibility and repeatability of such a grading system. Materials and methods Patients were a cohort of those recruited to other studies undertaken in the vitreoretinal research unit at Moorfields Eye Hospital, the aims of which were to assess the OCT appearance of the macula following retinal detachment surgery. Both the original studies Received: 8 June 2005 Accepted: 7 July 2005 Published online: 9 September 2005 Financial support provided by Pfizer No conflicting relationship exists for any of the above authors Moorfields Eye Hospital, City Road, London, UK Correspondence: S Benson, VR Research Fellow, Moorfields Eye Hospital, City Road, London EC1V 2PD, UK Tel: þ 44 20 7566 2283; Fax: þ 44 20 7566 2285. E-mail: sarah.benson@ moorfields.nhs.uk Eye (2006) 20, 1030–1033 & 2006 Nature Publishing Group All rights reserved 0950-222X/06 $30.00 www.nature.com/eye CLINICAL STUDY