Study of the long term effects of different modalities of treatment of retinoblastoma on retinal function using flash and pattern electroretinographies

Azza Mohamed Ahmed Said ; Amira Mohamed ElGohary 


Abstract


Purpose: To describe the long term effects of different modalities of treatment of retinoblastoma on retinal function using both flash and pattern electroretinographies (FERG and PERG) and to correlate these results with the tumor size and location. Subjects and methods: A case - control study was performed on 75 eyes of 60 children treated successfully from retinoblastoma by different treatment modalities. Diagnosis, treatment and follow up of those patients were done in Ocular Oncology Unit, Ophthalmology department, Ain Shams University in the period from January 1999 to December 2003. The retinoblastoma eyes were divided into six study groups according to treatment modality, size and location. Evaluation of retinal function in those growing population of retinoblastoma survivors was started on March 2008 till May 2009 using FERG and PERG guided by International Society for Clinical Electrophysiology of Vision (ISCEV) standardized basic protocols. All data were collected and analyzed statistically. Results: Under scotopic, photobic and maximum combined conditions; there was a highly statistically significant difference in the mean a and b- waves implicit times and amplitudes of FERG in the chemoreduction group with or without the use of focal laser therapy, treating tumors affecting the fovea (P-values ≤ 0.01) and a statistically significant difference in treating peripherally located tumors when compared with the results of the control group (P-values ≤ 0.05). There was a highly statistically significant reduction in mean a- and b- waves amplitudes and a highly statistically significant increase in mean implicit times in the EBRT groups treating tumors less than 10 disc diameters (DD) in size either involving the fovea or peripherally located (P-values ≤ 0.01) . More statistically significant abnormalities in mean amplitudes and implicit times of the waveforms of FERG with poor formation of the oscillatory potentials in the EBRT group treating large tumors involving the macula (more than 10 DD in size) (P-values ≤ 0.001) . PERG show abnormalities in all study groups more profound in EBRT group treating large macular tumors however; these abnormalities were not statistically significant when compared to the control group (P-values > 0.05). Conclusion: FERG and PERG provide objective assessment of retinal function in successfully treated retinoblastoma patients. In those patients; abnormal ERG responses were correlated to large tumor size, use of EBRT and retinal toxic effects of the chemotherapeutic regimens with partial dysfunction of the photoreceptor and inner retinal layers. Further histopathological and electron microscopic studies are needed to correlate these electrophysiological results with evidence of signal transmission dysfunction within the retina, vascular injuries and/ or retinal atrophy.


Other data

Keywords retinoblastoma;electroretinograph;intravenous chemotherapy;external beam radiotherapy
Issue Date 2012
Publisher Journal of the Egyptian Ophthalmological Society
Source Journal of the Egyptian Ophthalmological Society 2012; 105 (2):277-288.
Journal Journal of the Egyptian Ophthalmological Society 
URI http://research.asu.edu.eg/123456789/958


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