Full thickness lateral eyelid defects following Moh's surgery can be challenging to repair. Complex anatomy, defect variability, and inadequate security make these eyelid reconstructions prone to cicatrical ectropion. The use of a simple horizontal oriented periosteal flap was first described in 1981 by Byron Smith and later elaborated on by others1,2. However no literature describes the design of a flap which attempts to optimize post-operative lateral eyelid position. A standardized flap design is needed in order to harness the many natural benefits of the flap and reduce complications. We present two fresh cadaveric dissections and 10 consecutive cases to illustrate to flap concepts. A traditional Tenzel flap incision is created to expose the periosteum of the lateral orbital rim as well as the edge of the temporalis fascia3. We then draw a central meridian from the upper puncta, through the pupil and reflect that line onto the lateral orbital rim. The superior aspect of the flap is started at the intersection of the central meridian and lateral rim and continues at a 40 degree angle superiorly out a distance X (which is the length needed to repair the defect). The width of the flap should measure 6-7 mm which compensates for primary contracture while maintaining strength of the periosteum. The periosteum is trimmed to fit and then secured to the lateral edge of the remaining tarsal plate with enough tension that the lid approximates the globe. If the flap is extended onto the temporalis fascia up to 50% of the posterior lamella of the lower eyelid can potentially be closed. Once the flap is secured, the Tenzel flap can simply be rotated to repair the anterior lamellar defect. The periosteal flap is an ideal flap to repair the lateral canthus due to its simplicity, reliability, and low risk. It can be designed to match the native eyelid contour, originates within the lateral orbit, is strong, and highly vascular2. Additionally if the flap loosens post-op it can be easily detached and better secured within the lateral orbit. We present a more standardized method of flap harvest in order to improve outcome and reduce ectropion. References: 1. Smith, B.C., Nesi, F.A. Practical Techniques in Ophthalmic Plastic Surgery. St. Louis: The C.V. Mosby Company, 1981. Pp. 92-95. 2. Weinstein GS, Anderson RL, Tse DT, Kersten RC. The use of a periosteal strip for eyelid reconstruction. Arch. Ophthalmol. 1985 Mar;103(3):357-359. 3. McCord, C.D. Jr., Codner, M.A. Eyelid and Periorbital Surgery, Vol.2, 1st Ed. St. Louis: Quality Medical Publishing, Inc., 2008. Pp. 600.