Monitoring Of Retinal Function Research Articles

Electroretinogram and visual field changes in a case of birdshot chorioretinopathy

This case report explores the role of the visual field perimetry and electroretinogram (ERG) in cases of non-infectious uveitis in the assessment and monitoring of retinal function and response to treatment. A 59-year-old Caucasian female presenting with bilateral posterior uveitis newly diagnosed as birdshot chorioretinopathy (BSCR) presenting with bilateral decrease in visual acuity and cystoid macular edema, as well as a paracentral scotoma in the right eye. The diagnosis and follow-up of the case was done using visual field perimetry, optical coherence tomography (OCT), and ERG. Baseline ERG showed a marked decrease in the amplitudes of the scotopic and photopic responses and a delay of peak times mainly in the right eye. Mycophenolate mofetil at 2g/day and oral prednisolone at 1g/kg/day were administered with gradual tapering of the corticosteroids. After 5months, there was a noticeable improvement in the visual acuity, macular edema in OCT, and an obvious increase in the amplitudes of the ERG associated with a decrease in peak times, particularly in the 30Hz photopic 3.0 Flicker of the right eye. This case report highlights the importance of the peak time and wave amplitudes of the 30Hz photopic DA 3.0 Flicker as being a sensitive parameter in the diagnosis and follow-up of BSCR.

Rod and rod mediated function in patients with beta-thalassemia major.

An electroretinographic (ERG) study was undertaken to test the hypothesis that scotopic retinal function is altered in transfused thalassemics on chronic Deferoxamine (DFO). ERG a- and b-wave responses and dark adapted visual thresholds were obtained from 11 patients with beta-thalassemia major, ages 7 to 38 (median 17) years. A quantitative model of the activation of phototransduction was fitted to the a-waves to estimate the gain of the transduction processes and the saturated amplitude of the rod photoresponse. From b-wave stimulus/response functions. the saturated b-wave amplitude and an index of b-wave sensitivity (log sigma ) were calculated. The patients' data were compared to those of normal subjects. The relations of the ERG parameters to age. average ferritin level, and duration of transfusion without DFO as well as other clinical parameters were examined. Longitudinal measures of b-wave responses and dark adapted visual thresholds. available for nine of the patients, were examined for significant change over time. For all patients both the gain and saturated amplitude of the rod response are normal. In two patients log sigma is below the 99% prediction interval for normal. One has low scotopic visual sensitivity. The duration of transfusion therapy unprotected by DFO chelation therapy was correlated with log a. These results suggest iron accumulation rather than DFO toxicity underlies scotopic dysfunction in older thalassemics. some of whom may have had extended periods of transfusion without the protection of chelation. Thus, monitoring of retinal function is recommended in such patients.