title: Comparative study of the safety and efficacy of the Ahmed glaucoma valve model M4 (high density porous polyethylene) and the model S2 (polypropylene) in patients with neovascular glaucoma.
abstract: OBJECTIVE
  To prospectively evaluate the safety and efficacy of the Ahmed glaucoma valve model M4 (High density porous polyethylene plate; Medpor) compared with the model S2 (polypropylene plate).
  
  
  METHODS
  Mexican patients with neovascular glaucoma were randomly included for each group (M4 and S2). They were operated on using conventional techniques and creating a sub-episcleral tunnel to place the valve tube in the anterior chamber. After one year of follow-up, the results were evaluated with respect to a post-operative reduction in pressure, changes in visual acuity, the need for drugs, and complications, as well as the demographic characteristics of each group. Each operation using the M4 valve was performed by a single surgeon (FGC). Those operated on using the S2 model had their surgery performed by the staff surgeons at the Glaucoma Department of the Mexican Association to Prevent Blindness (APEC).
  
  
  RESULTS
  Each group (M4 and S2) contained 21 eyes of 21 Mexican patients with a diagnosis of neovascular glaucoma, leading to a total of 42 patients undergoing surgery. The mean preoperative intraocular pressure (IOP) was 43.5 (±11.8), and 42.24 (±12.84) mmHg for the M4 and S2 groups, respectively. After one year of follow-up, the IOP reported was 18.9 (±9.7) mmHg for the final 18 patients in the M4 group, and 16.38 (±9.76) mmHg for the 21 patients in the S2 group.
  
  
  CONCLUSIONS
  The design of a drainage valve device such as that of Ahmed has characteristics such as moderate control of IOP, thanks to the valve component in the immediate post-operative period, which makes them safer than other non-valve devices. This avoids an excess of flat chambers and the presence of low IOPs, which can lead to bleeding in the early post-operative period due to the weak desmosomal junctions of the newly formed vessels, with the advantage of maintaining suitable control of IOP from the first day after surgery.
  
  
  CONCLUSIONS
  Further studies with longer follow-up with a larger number of patients are needed to evaluate the effectiveness of this porous coating in the control of neovascular glaucoma.
authors.affiliation: Hospital Dr. Luis Sánchez Bulnes, Asociación para Evitar la Ceguera en México, Coyoacan, México. Electronic address: fegica@hotmail.com.
authors.forename: F
authors.initials: F
authors.lastname: Gil-Carrasco
authors.affiliation: Servicio de Glaucoma, Hospital Dr. Luis Sánchez Bulnes, Coyoacan, México.
authors.forename: J
authors.initials: J
authors.lastname: Jiménez-Román
authors.affiliation: Hospital Dr. Luis Sánchez Bulnes, Asociación para Evitar la Ceguera en México, Coyoacan, México.
authors.forename: M
authors.initials: M
authors.lastname: Turati-Acosta
authors.affiliation: Servicio de Glaucoma, Hospital Dr. Luis Sánchez Bulnes, Coyoacan, México.
authors.forename: H
authors.initials: H
authors.lastname: Bello-López Portillo
authors.affiliation: Servicio de Glaucoma, Hospital Dr. Luis Sánchez Bulnes, Coyoacan, México.
authors.forename: C G
authors.initials: CG
authors.lastname: Isida-Llerandi
mesh_terms: D000328:Adult; D000368:Aged; D003131:Combined Modality Therapy; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D020327:Glaucoma Drainage Implants / Q000009:adverse effects; D015355:Glaucoma, Neovascular / Q000188:drug therapy / Q000601:surgery*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009883:Ophthalmic Solutions / Q000627:therapeutic use; D020959:Polyethylene; D011126:Polypropylenes; D016062:Porosity; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology; D011446:Prospective Studies; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D009883:Ophthalmic Solutions; D011126:Polypropylenes; D020959:Polyethylene
keywords: Ahmed valve; Glaucoma neovascular; Implante valvular de Ahmed; Intraocular pressure; Neovascular glaucoma; Polietileno poroso; Presión intraocular; Tunelización subepiescleral