Aim: to do tailored lateral internal sphincterotomy extending up to upper end of fissure in patients having hypertonic 
internal sphincter (IAS) by technique has advantages of open and closed methods to keep continence. Clinical and 
anomanometric outcome will be assessed. 
Methods: 70 patients and 70 controls were subjected to anal manometric study. All patients had hypertonic IAS compared with controls. Sphincterotomy was done through 5-7mm perianal incision just lateral to lower edge of IAS. It extended up to upper end of  fissure. Sentinel tags, anal polyps and fibrotic fissure were excised. Results were assessed as persistence of symptoms, complications, healing, postoperative resting anal pressure (RAP) and 
recurrence. 
Results: Preoperative RAP significantly higher in patients (132.89 ± 6.61 cm H2o) than controls (79.64 ± 71, P >0.001). Sepsis of sphincterotomy wound occurred in 1.4%, bruising in 1.4%, transient minor soiling in 11.4% and no incontinence. In 97.2%, fissures healed within 6 weeks, postoperative RAP dropped significantly (78.09 ± 6.62 cm H2o, P >0.001). After 15.8 months mean follow up period, recurrence occurred in 4.3%. 
Conclusion: tailored lateral internal sphincterotomy is effective treatment of CAF with anal hypertonia. Our technique is 
safe and does not affect continence.