title: Functional and anatomic consequences of subretinal dosing in the cynomolgus macaque.
abstract: OBJECTIVE
  To characterize functional and anatomic sequelae of a bleb induced by subretinal injection.
  
  
  METHODS
  Subretinal injections (100 μL) of balanced salt solution were placed in the superotemporal macula of 1 eye in 3 cynomolgus macaques. Fellow eyes received intravitreal injections (100 μL) of balanced salt solution. Fundus photography, ocular coherence tomography, and multifocal electroretinography were performed before and immediately after injection and again at intervals up to 3 months postinjection. Histopathologic analyses included transmission electron microscopy and immunohistochemistry for glial fibrillary acidic protein, rhodopsin, M/L-cone opsin, and S-cone opsin.
  
  
  RESULTS
  Retinas were reattached by 2 days postinjection (seen by ocular coherence tomography). Multifocal electroretinography waveforms were suppressed post-subretinal injection within the subretinal injection bleb and, surprisingly, also in regions far peripheral to this area. Multifocal electroretinography amplitudes were nearly completely recovered by 90 days. The spectral-domain ocular coherence tomography inner segment-outer segment line had decreased reflectivity at 92 days. Glial fibrillary acidic protein and S-cone opsin staining were unaffected. Rhodopsin and M/L-cone opsins were partially displaced into the inner segments. Transmission electron microscopy revealed disorganization of the outer segment rod (but not cone) discs. At all postinjection intervals, eyes with intravitreal injection were similar to baseline.
  
  
  CONCLUSIONS
  Subretinal injection is a promising route for drug delivery to the eye. Three months post-subretinal injection, retinal function was nearly recovered, although reorganization of the outer segment rod disc remained disrupted. Understanding the functional and anatomic effects of subretinal injection is important for interpretation of the effects of compounds delivered to the subretinal space.
  
  
  CONCLUSIONS
  Subretinal injection is a new potential route for drug delivery to the eye. Separating drug effects from the procedural effects is critical.
authors.affiliation: Comparative Ophthalmic Research Laboratories, University of Wisconsin, USA. tmnork@wisc.edu
authors.forename: T Michael
authors.initials: TM
authors.lastname: Nork
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Murphy
authors.forename: Charlene B Y
authors.initials: CB
authors.lastname: Kim
authors.forename: James N
authors.initials: JN
authors.lastname: Ver Hoeve
authors.forename: Carol A
authors.initials: CA
authors.lastname: Rasmussen
authors.forename: Paul E
authors.initials: PE
authors.lastname: Miller
authors.forename: Hugh D
authors.initials: HD
authors.lastname: Wabers
authors.forename: Michael W
authors.initials: MW
authors.lastname: Neider
authors.forename: Richard R
authors.initials: RR
authors.lastname: Dubielzig
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: McCulloh
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Christian
mesh_terms: D000085:Acetates / Q000008:administration & dosage*; D000818:Animals; D004338:Drug Combinations; D016503:Drug Delivery Systems; D004596:Electroretinography; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007150:Immunohistochemistry; D058449:Intravitreal Injections; D008252:Macaca fascicularis; D008854:Microscopy, Electron; D008903:Minerals / Q000008:administration & dosage*; D009887:Ophthalmoscopy; D055355:Opsins / Q000378:metabolism; D012160:Retina / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D012243:Rhodopsin / Q000378:metabolism; D012965:Sodium Chloride / Q000008:administration & dosage*; D041623:Tomography, Optical Coherence
chemical_list: D000085:Acetates; C030660:BSS solution; D004338:Drug Combinations; D005904:Glial Fibrillary Acidic Protein; D008903:Minerals; D055355:Opsins; D012965:Sodium Chloride; D012243:Rhodopsin