title: Rod photopigment kinetics after photodisruption of the retinal pigment epithelium.
abstract: OBJECTIVE
  Advances in retinal imaging have led to the discovery of long-lasting retinal changes caused by light exposures below published safety limits, including disruption of the RPE. To investigate the functional consequences of RPE disruption, we combined adaptive optics ophthalmoscopy with retinal densitometry.
  
  
  METHODS
  A modified adaptive optics scanning light ophthalmoscope (AOSLO) measured the apparent density and regeneration rate of rhodopsin in two macaques before and after four different 568-nm retinal radiant exposures (RREs; 400-3200 J/cm(2)). Optical coherence tomography (OCT) was used to measure the optical path length through the photoreceptor outer segments before and after RPE disruption.
  
  
  RESULTS
  All tested RREs caused visible RPE disruption. Apparent rhodopsin density was significantly reduced following 1600 (P = 0.01) and 3200 J/cm(2) (P = 0.007) exposures. No significant change in apparent density was observed in response to 800 J/cm(2). Surprisingly, exposure to 400 J/cm(2) showed a significant increase in apparent density (P = 0.047). Rhodopsin recovery rate was not significantly affected by these RREs. Optical coherence tomography measurements showed a significant decrease in the optical path length through the photoreceptor outer segments for RREs above 800 J/cm(2) (P < 0.001).
  
  
  CONCLUSIONS
  At higher RREs, optical path length through the outer segments was reduced. However, the rate of photopigment regeneration was unchanged. While some ambiguity remains as to the correlation between measured reflectivity and absolute rhodopsin density; at the lowest RREs, RPE disruption appears not to be accompanied by a loss of apparent rhodopsin density, which would have been indicative of functional loss.
authors.affiliation: The Institute of Optics, University of Rochester, Rochester, New York, United States Center for Visual Science, University of Rochester, Rochester, New York, United States.
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Masella
authors.affiliation: Center for Visual Science, University of Rochester, Rochester, New York, United States Flaum Eye Institute, University of Rochester, Rochester, New York, United States.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Hunter
authors.affiliation: The Institute of Optics, University of Rochester, Rochester, New York, United States.
authors.forename: David R
authors.initials: DR
authors.lastname: Williams
mesh_terms: D000818:Animals; D003623:Dark Adaptation / Q000502:physiology*; D003720:Densitometry / Q000379:methods*; D008251:Macaca; D055214:Retinal Photoreceptor Cell Outer Segment / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000166:cytology / Q000378:metabolism*; D012243:Rhodopsin / Q000378:metabolism*; D041623:Tomography, Optical Coherence / Q000379:methods
chemical_list: D012243:Rhodopsin
keywords: dark adaptation; densitometry; light damage; retinal pigment epithelium; rhodopsin regeneration