title: Experimental studies on nonpenetrating filtration surgery using the CO2 laser.
abstract: BACKGROUND
  This study evaluated the use of a CO2 laser for performing deep sclerectomy in nonpenetrating filtration surgery.
  
  
  METHODS
  Three experimental models were performed: enucleated sheep and cow eyes (n=18) to determine optimal irradiation parameters, live rabbit eyes (n=20) to test feasibility, and cadaver eyes (40 procedures in 20 eyes) to study effects in human eyes tissue. After a half-thickness scleral flap was created, deep sclerectomy was performed by CO2 laser applications on the scleral bed down to the trabeculo-Descemet's membrane.
  
  
  RESULTS
  Fluid percolation was repeatedly achieved without penetration in sheep and cow eyes using scanned laser energy of 5-10 W at a pulse duration of 200 micros and a working distance of 35 cm. In live rabbits, deep sclerectomy was achieved without perforation in 19/20 eyes. Intraocular pressure was significantly decreased on the first postoperative day (10.3+/-5.1 mmHg lower, on average, than in the nonoperated fellow eye; P<0.001), and this persisted for 21 days. Operations on all cadaver eyes resulted in effective fluid percolation. Penetration of the scleral wall occurred in five cases only after repeated laser applications with high energy. Histologically, a thin sclerocorneal intact wall was demonstrated at the sclerectomy bed. Collateral tissue damage did not extend beyond 100 microm, and adjacent structures remained unharmed.
  
  
  CONCLUSIONS
  CO2 laser-assisted deep sclerectomy is a feasible and apparently safe procedure.
authors.affiliation: Department of Ophthalmology, Meir Hospital, Sapir Medical Center, 44281, Kfar-Saba, Israel. assia@netvision.net.il
authors.forename: Ehud I
authors.initials: EI
authors.lastname: Assia
authors.forename: Yigal
authors.initials: Y
authors.lastname: Rotenstreich
authors.forename: Irina S
authors.initials: IS
authors.lastname: Barequet
authors.forename: David J
authors.initials: DJ
authors.lastname: Apple
authors.forename: Mordechai
authors.initials: M
authors.lastname: Rosner
authors.forename: Michael
authors.initials: M
authors.lastname: Belkin
mesh_terms: D000818:Animals; D002245:Carbon Dioxide; D002417:Cattle; D003886:Descemet Membrane / Q000473:pathology / Q000601:surgery; D018463:Filtering Surgery / Q000379:methods*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D053685:Laser Therapy / Q000379:methods*; D011817:Rabbits; D012590:Sclera / Q000473:pathology / Q000601:surgery*; D012756:Sheep; D013524:Surgical Flaps; D014129:Trabecular Meshwork / Q000473:pathology / Q000601:surgery
chemical_list: D002245:Carbon Dioxide