Abstract: Objective  To evaluate the accuracy of three methods to caculate the length of foreign scleral materials (LSM) for posterior scleral reinforcement surgery. Design Evaluation of technique.  Participants 62 patients (65 eyes) with high myopia in Beijing Tongren Hospital from 2008-2010.  Methods All patients received revised Synder-Thompson posterior scleral reinforcement (PSR). The refraction, corneal curvature, anterior chamber depth and axial length (AL) were examined preoperatively. Three methods were used for calculation of the length of foreign scleral material. Method 1 and method 2 were based on geometric calculation of anterior chamber depth or corneal curvature. Method 3 was based on regression equation according to the actual length of foreign scleral material used during the surgery. Main Outcomes Measures Length of sclera material, corneal curvature, anterior chamber depth and axial length.  Results The actual length of sclera material in all 65 eyes was 47.8±4.0 mm. Mean length of foreign scleral materials in method 1, 2, 3 was 58.7±8.0 mm, 58.6±8.0 mm, 47.8±3.3 mm, respectively.  The regression equation of method 3: LSM=9.576+1.271×AL. All three methods were highly correlated with actual length of scleral material (r=0.822, 0.829, 0.835). Conclusions The regression equation method based on eyeball axial length can predict the length of scleral material more accurately than the other two methods based on geometric calculation of eyeballs. (Ophthalmol CHN, 2013, 22: 53-57)

Key words: posterior scleral reinforcement, foreign sclera length, axial length