Manami Kuze

The multifocal electroretinogram in retinal detachment.

We evaluated the retinal electrophysiologic function in both the detached and attached areas of eyes with retinal detachment, and assessed the functional recovery of these areas after surgery by quantifying the results, obtained from multifocal electroretinograms. Multifocal electroretinographic recordings and central 0°, to 30°, visual field tests were performed preoperatively and 2 weeks 1, 3 and 6 months postoperatively in 12 patients with unilateral retinal detachment. Each patients response to the multifocal electroretinogram and the visual field test was classified into two groups: group A, the response from the attached area; and group B, that from the detached retinal area. Individual mean deviation and percentage mean deviation were calculated for each group. All retinal detachments were successfully reattached by the conventional scleral buckling method. The retinal sensitivity in the visual field test of all the patients in group B greatly improved. However, the percentage mean deviation in the response density of the multifocal electroretinogram in group B was −81% preoperatively and −63% at 6 months postoperatively. Thus, the improvement was confined within narrow limits. The response density of the multifocal electroretinogram in group A was very low, and never improved beyond −50% of percentage mean deviation. In the eyes with retinal detachment, electroretinogram response in both the attached and detached areas was more disturbed, than predicted by means of the visual field test during the course of this study.

Time-Dependent Course of Electroretinograms in the Spontaneous Diabetic Goto-Kakizaki Rat

PurposeThis study evaluates the relevance to human retinopathy of electroretinograms (ERGs) from the spontaneously diabetic Goto-Kakizaki (GK) rat.MethodsStarting from 4 weeks of age, we obtained ERGs every 4 weeks from six GK rats and seven Wistar (control) rats, and from two GK and two Wistar rats at 14 days of age. The a-wave, b-wave, and oscillatory potentials (OPs) were recorded after stimulation with a single bright flash. We compared the amplitudes and implicit times and measured a-wave latencies to evaluate photoreceptor function.ResultsThe amplitudes of the a-wave, b-wave, and OPs (O1 and O2) of the GK rats were reduced between 4 and 48 weeks of age. The time-dependent courses of change in a-wave, b-wave, and O2 amplitude did not differ between the two groups. The a-wave latencies in GK rats were significantly prolonged, but not the implicit times of OPs. At 14 days of age, the a-wave amplitudes were significantly smaller in GK than in Wistar rats.ConclusionFunctional abnormalities of photoreceptors might be induced by inheritable degeneration at an early age in the GK rat. Although hyperglycemia would cause retinal hypoxia, it would not be severe enough to disturb the generation of OPs. Jpn J Ophthalmol 2006;50:211–216

Comparison Between Dawson, Trick, and Litzkow Electrode and Contact Lens Electrodes Used in Clinical Electroretinography

PURPOSE To determine the reliability of the Dawson, Trick, and Litzkow (DTL) electrode in electroretinographic recordings (ERG) in subjects of all ages, we evaluated ERG responses obtained with the contact lens (CL) and DTL electrodes and estimated a DTL/CL ratio for each sample. METHODS Seventy-nine volunteers aged 2-84 years (79 normal eyes) were recruited for the study. Electroretinographic recordings elicited by monocular single-flash stimuli delivered by an automatic ERG recording system were recorded using both CL and the DTL electrodes (CL-ERG and DTL-ERG, respectively). RESULTS The relative amplitude of the DTL-ERG to the CL-ERG was 79.6-99.8% (mean = 93.4%) for the a-wave and 84.4-106.3% (mean = 92.3%) for the b-wave. The relative latency of the DTL-ERG to the CL-ERG was 86. 0-107.6% (mean = 98.2%) for the a-wave and 96.1-113.0% (mean = 97. 9%) for the b-wave. The a- and b-wave amplitudes differed significantly between DTL and CL electrodes only in the 40- to 49-year-old age groups (P <.05). Regression analysis indicated moderate to strong relationships between the electrodes for amplitude (a-wave, r = 0.690; b-wave, r = 0.824) and latency (a-wave, r = 0.667; b-wave, r = 0.725). CONCLUSION The DTL electrode has as high stability as the conventional CL electrodes for ERG recordings in most age groups.

Ultrasound biomicroscopy for membranous congenital cataract.

376 CAN J OPHTHALMOL—VOL. 43, NO. 3, 2008 thalmic arterial occlusions in children younger than 12 years old.4,5,6 The first describes the case of an 11-yearold girl with unilateral visual field loss due to a branch retinal artery occlusion in the right eye and no underlying cause found after extensive investigations.4 The second describes the case of a 7-year-old girl with spontaneous occlusion of the right ophthalmic artery and a negative systemic work-up.5 The third describes the case of an 8-yearold boy with a CRAO and no definite etiology, but a 4-day history of flu-like symptoms led the authors to attribute the pathology to a postviral vasculitis.6 In our instance, we hypothesize that the prolonged retinal occlusion led to both macular and disc edema, resulting in severe ischemic damage. Though retinal arterial obstruction is rare in children, our case highlights the importance of including this in the differential diagnosis of acute vision loss.

Changes in electroretinogram oscillatory potentials during dark adaptation.

PurposeTo investigate changes in the oscillatory potentials (OPs) of electroretinograms (ERGs) during dark adaptation (DA).MethodsERGs were recorded from ten normal subjects. Following 15 min of light adaptation, ERGs were recorded every 30 s for 20 min to follow the changes in the OPs during the course of DA. A 20-ms, 560-nm rectangular pulse of light was presented at 3.3 Hz to elicit the ERGs.ResultsThe latencies of OP1 and OP2 did not change significantly, but the amplitudes decreased slightly during DA. OP3 was not observed at 30 s, but appeared after 1 min of DA between OP2 and OP4. Similar results were obtained with stimulus durations of 10 to 100 ms in 10-ms steps. The amplitude of OP3 increased to 10 min of DA and then plateaued.ConclusionThe characteristics of OP3, which increases during DA, indicate that it is probably related to rod activity. Jpn J Ophthalmol 2005;49:420–422

Electrophysiological responses from intrinsically photosensitive retinal ganglion cells are diminished in glaucoma patients.

Purpose To record electroretinograms (ERGs) from intrinsically photosensitive retinal ganglion cells (ipRGCs) of glaucoma patients. Methods ERGs were recorded in 10 normal subjects and 15 patients with glaucoma. The ERG illumination system was built to achieve receptor-silent substitution, and comprised an optical diffuser and four-in-one light-emitting diodes. Results The ERG recordings of ipRGC from normal subjects showed an “on” response and an “off” response. The mean (±SD) implicit time for the on and off responses in normal subjects was 103.0 ± 24.9 and 337.9 ± 45.8 ms, respectively, with corresponding amplitudes of 7.7 ± 2.8 and 7.3 ± 3.4 μV, respectively. In glaucoma patients, the implicit time of the on and off responses was 135.0 ± 28.9 and 368.2 ± 17.3 ms, respectively. The corresponding amplitudes of the on and off responses in these patients were 0.47 ± 0.18 and 0.66 ± 0.32 μV, respectively. Conclusions The results demonstrate successful ERG recording of ipRGCs from advanced glaucoma patients, with marked reductions in amplitude, although not implicit time, compared with normal subjects.

Negative scotopic ERG and photopic ERG ON response impairment in a patient with normal dark adaptation

PurposeTo present ocular findings in a patient who showed negative scotopic electroretinogram (ERG) and reduced ON response, but normal dark adaptation.CaseAn 18-year-old Japanese male patient who complained of severe asthenopia. His corrected visual acuities were 1.2 in both eyes. His fundi were normal. He had normal contrast sensitivity and normal dark adaptation.MethodsThe patients underwent ERG (including the standard protocol and photopic long flash recordings).ResultsThe amplitudes of the rod ERG b-wave were reduced. The scotopic standard combined ERG response showed negative configuration. The photopic response to long flash revealed the reduced b-wave (ON response), while the amplitude of the first peak of the d-wave (OFF response) was within the normal range.ConclusionsPostsynaptic abnormalities in both the rod and cone ON-pathways, which are often found in patients with night blindness, were suggested in the ERG findings, but the dark adaptation of our patient was normal. Neuromuscular evaluation of the patient and ophthalmological evaluation, including ERG, of his parents were normal. To our knowledge, the ophthalmological and electrophysiological findings of our patient cannot be attributed to any known clinical entity.

Absolute Sensitivity of the Electroretinogram and of the Optic Nerve Action Potential in the Perfused Feline Eye

PURPOSE To assess and characterize the electroretinogram (ERG) and the optic nerve response (ONR) at threshold stimulus intensity in the isolated perfused cat eye. METHODS Eyes were enucleated from deeply anesthetized adult cats and arterially perfused with oxygenated serum-enriched tissue culture medium. Light stimuli of 20- to 400- msec duration from a xenon arc source, attenuated down to threshold intensities by neutral density filters, were delivered via a modified fundus camera in full dark adaptation. Vitreal ERGs and ONRs were amplified, digitized, averaged and analyzed using LabVIEW for Windows software. RESULTS The threshold intensities in log scot q/deg(2) per second for the negative scotopic threshold response (STR), for the ERG b-wave, and for the ONR were at 2.87+/-0.35, 3.53+/-0.35 and 1.78+/-0.48, respectively. CONCLUSION The in vitro perfused mammalian eye preparation exhibits remarkably low thresholds for the ERG and particularly for the ONR near the intensity required for the human psychophysical threshold.

Effects of the beta1-selective adrenergic antagonist betaxolol on electroretinography in the perfused cat eye.

The effects of the β1-selective adrenergic antagonist betaxolol on electroretinography (ERG) were studied in the isolated and arterially perfused cat eye. Betaxolol increased the perfusion flow rate, significantly at the administrations of more than 50μM concentrations and induced a dose-related, reversible increase in the amplitudes of both the a-wave and b-wave of ERG. These results suggest that the calcium-channel blocking mechanism of betaxolol has a beneficial influence on ocular blood flow and retinal electrical activity in response to light. As it is known that ERG is a good indicator of the functional integrity of the retina, this indicates that betaxolol could be an ideal drug for treating glaucoma in which ischemia is involved to some extent.