Background: Glaucoma is the leading cause of irreversible blindness worldwide and is second only to cataracts asthemost common cause of blindness overall (14%). As the mainstay of treatment is early diagnosisand prevention of progression1.According to an estimate in the year 2006, there would be 60.5million people worldwide with open-angleglaucoma (OAG) andangle closure glaucoma (ACG)in 2010, increasingto79.6 million by 20202.Primary angleclosureglaucoma (PACG)is acommon form ofglaucoma in South India.The overall prevalence of primary angle closures(PACandprimaryangle-closureglaucoma)insouthernIndiais1.58%.3Laserperipheraliridotomy doneprophylactically in primary angle closure suspects. The purpose of laser peripheraliridotomy is to preservevisual function and maintain quality of life by preventing Acute angleclosure crisis/Primary angle closure glaucoma from developing4.Even done prophylactically inthe felloweyetoprevent anacute attackin a patient havingprimaryangle closureglaucoma. Laser peripheral iridotomy is a non-surgical, less expensive procedure. It is a cost effective-singleone-time intervention, as there ispoor compliance of patients in developing countries likeIndiaforfollow-up. Evenpatientswhoareoncertainmedications(likedecongestants, motion sicknessmedication,and anticholinergicagents)areatriskofAcuteangleclosure crisis5.It is essential to evaluate the response to laser iridotomy by studying changes inanteriorsegment morphology. Thesechanges can bequantified bygonioscopyand biometry.6 Objectives: 1.Tostudytheeffectivenessoflaseriridotomyasaprimarytherapyforprimary angleclosuredisease. 2.TostudythevariationinIOPchangesfollowingND-YAGlaser iridotomy. Studydesign: Prospective non-randomized interventional hospital-based study. Methods:Thisstudyincluded60eyes of 30 patients with primary angle closure disease (PACD) requiringLaserPeripheral iridotomy. They were subjected to a detailedOphthalmic examination visual evaluation, and complete examinationincludingvisualacuitymeasurementbyApplanationtonometer,peripheralanteriorchamberplusangleassessmentbyVan-Herick,andgonioscopyusinga Slitlamp, measurementofIntraocularpressurebeforeandafterLaserperipheraliridotomyandfollowed-upforaperiod of 6 months. Mainoutcomemeasures: Intraocularpressure(IOP) byApplanation tonometer. Results: This study included 60 eyes of 30 patients. Most patients (36.7%) belongedtotheagegroupof51-60yearsand61-70years (Mean) respectively.19(63.3%)patients were female and 11 (36.7%) were male patients. A family history of glaucomawaspresentin4(13.33%)patients. Outof30patients, 7(23.33%)haddiabetes,7(23.33%)had hypertension and 3(10%)had both. The study showeda statistically significant decrease in IOP(P 0.0001) post iridotomyafter4 weeks (21.10±9.51mmHgVs 13.83±3.22mmHg),(P <0.05) Interpretation Andconclusion: This study investigated the immediate IOP change and risk factors forIOPspikesafterlasertreatmentinPACGtreatedbyprophylacticLPI.Laserperipheral iridotomy can cause an acute and (usually) transient posttreatment rise inintraocular pressure (IOP) in some patients. To blunt IOP spikes in vulnerable casesantiglaucomamedicationscanbeaddedandPIenhancement(retreatment)canbedone. More laser energy used and shallower central anterior chamber depth werefound to be risk factors for IOP elevation of 8 mmHg or more beyond baseline afterLPI.