AIMS/BACKGROUND: Interrupted corneal sutures are used routinely by many cataract and corneal surgeons. A slim compact knot facilitates burial and allows atraumatic suture removal, with decreased risk of wound dehiscence. The size and morphology of knots tied in different configurations were investigated. METHODS: 10-0 nylon suture material was used to tie knots on porcine corneal cataract sections using 2/1/1 (reef and granny), 3/1/1, and 1/1/1/1 (slip knot) configurations. 10-0 Mersilene was used to tie 2/1/1 reef knots. Scanning electron micrographs of the knots were digitised and their maximal lengths and widths estimated. In addition, the area of each knot was calculated and used as an index of its volume. RESULTS: 2/1/1 reef knots were significantly smaller in all dimensions compared with the other knots (all p < 0.03) except for the maximal width of 2/1/1 granny knots which were no wider than the 2/1/1 granny knots. The Mersilene knots were larger than the nylon ones. CONCLUSION: The use of 2/1/1 reef knots is recommended for corneal suturing.