Rickettsia rickettsii infection as an unusual cause of pediatric retinitis: A case report.

Purpose: To report a case of infectious pediatric retinitis attributed to Rocky Mountain spotted fever which is rarely reported in the United States. Observations: A previously healthy 14-year-old male return traveler from Mexico was admitted to the pediatric ICU with septic shock and a diffuse rash. He subsequently complained of blurry vision and was found to have evidence of retinitis on exam. Infectious workup revealed high titers of rickettsial IgM and IgG antibodies. He was treated successfully with 14 days doxycycline and followed up in clinic with improvement in his visual complaints and retinitis. Conclusions and importance: Rickettsioses are worldwide endemic zoonotic infections caused by Gram negative obligate intracellular bacteria and spread to humans by infected ticks. Rickettsial infections, including Rocky Mountain spotted fever caused by Rickettsia rickettsii, are a cause of infectious retinitis, and atypical and zoonotic infections should remain on the differential diagnosis for patients presenting with rash, systemic illness, and visual complaints, even if the patient's travel or exposure history do not immediately suggest a likely rickettsial infection. In general, the ocular manifestations of rickettsial infection improve with systemic doxycycline treatment of the underlying infection.

Light scatter causes the grayness of detached retinas: implications for vision loss in retinal detachment.

OBJECTIVE: To investigate the cause of the gray appearance of the detached retina. METHODS: The effects of ex vivo bovine retinas and Scotch (3M, Minneapolis, Minn) tape on light scattering were predicted based on mathematical modeling and examined empirically on an optical bench. Images were collected with a CCD [charged-coupling device] camera connected to a microcomputer with an image grabber. The clarity of the image was calculated as the standard deviation, sigma. RESULTS: Calculations predicted a gaussian distribution of laser light scattering with increased diffusion with increasing distance from the medium to the target. The image clarity, sigma, increased rapidly in the first 50 micro m of separation of the retina and tape from the test target and the rate of increase diminished thereafter. Removal of the outer retina with an excimer laser improved retinal transparency. CONCLUSIONS: Data explain that the gray appearance of the detached retina results from light scattering. This phenomenon likely results, at least in part, because of the irregular outer retinal surface at the level of the photoreceptors. Clinical Relevance The findings suggest that visual loss in retinal detachment may result, in part, from optical properties of the detached retina and have implications for visual recovery and subretinal surgery.