title: Feasibility of laser-targeted photoocclusion of the choriocapillary layer in rats.
abstract: OBJECTIVE
  A new method, laser-targeted photoocclusion, was developed to occlude choroidal neovascularization while minimizing damage to the overlying retina. The ability to occlude normal choriocapillary layer in rats was evaluated as a first test of the feasibility of treating choroidal neovascularization with this method.
  
  
  METHODS
  A photosensitive agent, aluminum phthalocyanine tetrasulfonate, encapsulated in heat-sensitive liposomes, was administered intravenously along with carboxyfluorescein liposomes. A low-power argon laser (retinal power density of 5.7 W/cm2) locally released a photosensitizer bolus, monitored by the simultaneous release of carboxyfluorescein. A diode laser (operating at 675 nm with a retinal power density of 0.27 W/cm2) activated the photosensitizer with its release.
  
  
  RESULTS
  Vessels in the choriocapillary layer were occluded at day 3 after laser treatment and remained unchanged during the 30-day follow-up. Larger choroidal vessels and retinal capillaries remained perfused. Control experiments excluded possible effects of heat or activation of free photosensitizer. Pilot histologic studies showed no damage to the retinal pigment epithelium.
  
  
  CONCLUSIONS
  Laser-targeted photoocclusion caused selective occlusion of normal choriocapillaries while sparing overlying retinal pigment epithelium and retinal vessels. The method has potential as a treatment of choroidal neovascularization that may minimize iatrogenic loss of vision.
authors.affiliation: Johns Hopkins University School of Medicine, Wilmer Ophthalmological Institute, Baltimore, Maryland 21287-9131, USA.
authors.forename: S
authors.initials: S
authors.lastname: Asrani
authors.forename: S
authors.initials: S
authors.lastname: Zou
authors.forename: S
authors.initials: S
authors.lastname: D'Anna
authors.forename: G
authors.initials: G
authors.lastname: Lutty
authors.forename: S A
authors.initials: SA
authors.lastname: Vinores
authors.forename: M F
authors.initials: MF
authors.lastname: Goldberg
authors.forename: R
authors.initials: R
authors.lastname: Zeimer
mesh_terms: D000818:Animals; D002196:Capillaries / Q000187:drug effects* / Q000473:pathology; D002829:Choroid / Q000098:blood supply* / Q000187:drug effects / Q000473:pathology; D004337:Drug Carriers; D005240:Feasibility Studies; D005451:Fluorescein Angiography; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007211:Indoles / Q000627:therapeutic use*; D007834:Lasers; D008081:Liposomes; D008297:Male; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000473:pathology; D009942:Organometallic Compounds / Q000627:therapeutic use*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D051381:Rats; D013927:Thrombosis / Q000209:etiology / Q000473:pathology
chemical_list: D004337:Drug Carriers; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007211:Indoles; D008081:Liposomes; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; C048577:aluminum tetrasulfophthalocyanine; C024098:6-carboxyfluorescein