title: Pathogenic implications of subretinal gas migration through pits and atypical colobomas of the optic nerve.
abstract: OBJECTIVE
  To describe subretinal migration of gas and silicone oil in a series of patients with congenital cavitary optic disc anomalies and to further clarify the pathogenesis of the associated maculopathy.
  
  
  METHODS
  Medical records of 4 female patients, aged 8 to 34 years, who developed subretinal gas migration after vitreous surgery for macular detachment associated with cavitary optic disc anomalies were reviewed. A theoretical model was used to calculate the pressure differential required to induce subretinal gas migration through an optic pit.
  
  
  RESULTS
  The 4 patients had bilateral atypical optic nerve colobomas or a unilateral large optic pit. A definite defect in the tissue overlying the disc excavation could be seen in one eye, and intraoperative drainage of subretinal fluid through the disc anomaly was possible in all cases. Subretinal migration of gas or silicone oil was seen intraoperatively in one case and first appeared between 1 and 17 days postoperatively in the remaining cases. Theoretical calculations suggest that the pressure differential required for migration of gas through a small defect in the roof of a cavitary disc lesion is within the range of expected fluctuations in cerebrospinal fluid pressure.
  
  
  CONCLUSIONS
  These observations provide clinical confirmation of a defect in tissue overlying cavitary optic disc anomalies and imply interconnections between the vitreous cavity, subarachnoid space, and subretinal space. We theorize that intermittent pressure gradients resulting from normal variations in intracranial pressure play a critical role in the pathogenesis of retinopathy associated with cavitary disc anomalies.
authors.affiliation: Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan School of Medicine, Ann Arbor 48105, USA. markwj@umich.edu
authors.forename: T Mark
authors.initials: TM
authors.lastname: Johnson
authors.forename: Mark W
authors.initials: MW
authors.lastname: Johnson
mesh_terms: D000328:Adult; D015170:Cerebrospinal Fluid Pressure; D002648:Child; D003103:Coloboma / Q000378:metabolism*; D004058:Diffusion; D005260:Female; D005466:Fluorocarbons / Q000378:metabolism*; D006801:Humans; D007429:Intraocular Pressure; D008954:Models, Biological; D009898:Optic Disk / Q000002:abnormalities*; D016684:Prone Position; D012160:Retina / Q000378:metabolism*; D012163:Retinal Detachment / Q000601:surgery; D012164:Retinal Diseases / Q000209:etiology*; D012189:Retrospective Studies; D012827:Silicone Oils / Q000378:metabolism*; D014792:Visual Acuity; D014821:Vitrectomy
chemical_list: D005466:Fluorocarbons; D012827:Silicone Oils; C042852:perflutren