Purchase this article with an account.
W.C. Lara, B.L. Jordan, G.M. Hope, W.W. Dawson, R.A. Foster, S. Kaushal; Fast Oscillations of the Electro-oculogram in Cystic Fibrosis . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4957.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose:The purpose of this abstract is to verify that electro-oculogram (EOG) fast oscillations (FOs) are significantly reduced in cystic fibrosis (CF) patients with known genotypes compared to normals. Methods:CF patients were genotyped to provide for comparisons between the different mutations in the chloride channel CFTR. Six CF patients and six normals underwent a full visual exam, including: medical history, visual acuity, intraocular pressures, slit lamp examination, and dilated fundus exam. Electroretinograms (ERGs) were recorded by analysis of potentials from the corneal apices using DTL microfiber electrodes. Methods of stimulation and recording were consistent with current international standards. Retinal signals were measured under photopic, scotopic, and 30 hertz flicker conditions. EOGs were measured across the canthal dipole. Patients followed light emitting diodes cycling at 1 cycle per second, movement subtended a total of 30° of arc. FOs were measured at 1 minute intervals under conditions of light and dark. Slow oscillations (SOs) were measured for a total of 20 minutes after the initiation of the light phase. The ratios of the averaged EOG FO RMS voltages (light/dark) under these conditions were analysed by conventional t-test. Results:The entire ocular exam including the retina was found to be normal in patients with CF. The standard ERG measurements were normal when adjusted for age. However, there was a statistically significant (p<0.05) reduction in FO amplitudes in CF patients when compared to normals. Conclusions:EOG FOs and SOs are believed to be caused by changes in RPE chloride membrane conductances. Patients with Best’s Disease, a disease that results from mutations in the chloride channel protein bestrophin, have a known reduction in the light peak of the SOs, yet have preserved FOs. Patients with CF are known to have gene mutations that result in the misfolding of CFTR, a cAMP dependent membrane chloride channel. This channel is known to be expressed on the basolateral surface of the RPE. One abstract reported that the FOs in non-genotyped CF patients were significantly reduced compared to normals. We have confirmed these findings and additionally have determined the genotype of our CF patients. This suggests that the FOs are correlated with the activity of the CFTR channels. The reduction in the FO amplitudes did not result in any significant visual disturbance. It is conceivable that in certain pathologic states that lead to RPE dysfunction, the FOs may be a useful clinical marker to monitor RPE metabolism.
This PDF is available to Subscribers Only