Electroretinography (ERG) is a well-established diagnostic procedure for objectively evaluating retinal function. In this study, ERG in beagle dogs, which are a popular experimental animal, was performed to determine the normal range of ERG variables and assess differences between the left and right eyes. ERG findings including rod, combined rod-cone, single-flash cone, and 30-Hz flicker responses were recorded with an LED-electrode in 43 sedated beagle dogs. The subjects were divided into young (< 1 year old), adult (1~5 years old), and senile animals (> or = 6 years old). Normal ERG ranges were obtained. Significant differences in b-wave amplitude along with b/a ratio of the combined rod-cone response were found between the young and adult animals as well as young and senile dogs. No significant differences were observed between the left and right eyes. ERG variables in beagle dogs differed by age due to age-related retinal changes. Thus, we propose that normal ERG ranges should be determined according to age in each clinic and laboratory using its own equipment because each institution usually has different systems or protocols for ERG testing.
Aging ; Animals ; Dogs/*anatomy & histology ; Electrodes/veterinary ; Electroretinography/methods/*veterinary ; Female ; Male

PURPOSE: To investigate the characteristics of the waveform generated by blue and red light stimulations in a dark-adapted electroretinogram (ERG) and those of cone responses in the dark-adapted condition. METHODS: The study subjects were 52 persons (88 eyes) with no previous medical history. The author recorded b-waves (rod response) with red light stimulation and the x-waves (dark-adapted cone response) that appeared before the b-waves. The author also recorded b-waves with blue light stimulation, which had the same amplitude as the b-waves from the red light stimulation. The differences with respect to age and gender were studied. Waveforms of the dark-adapted cone ERGs were recorded by using a digital subtraction technique. RESULTS: The x-wave always appeared before the b-wave with 0 dB (2.4 cd.s/m2) red stimulation. With blue stimulation, a b-wave equivalent to the b-wave stimulated with the red light of 0 dB intensity appeared at an average of -14.57 dB. The implicit time for the b-wave was delayed significantly for the male group. There were no significant differences between different age groups. The dark-adapted cone ERG demonstrated the waveform of a negative response followed by a series of oscillatory potentials (OPs) and a positive response. CONCLUSIONS: The cone responses were followed by the rod responses with red light stimulation of 0 dB in the dark-adapted ERG. The waveforms of the cone ERGs were obtained in dark adaptation with red and blue light stimulation.
Adolescent ; Adult ; Child ; Dark Adaptation/*physiology ; *Electroretinography ; Female ; Humans ; Male ; Middle Aged ; Photic Stimulation/*methods ; Retina/*physiology

The multifocal visual electrophysiology is an objective and non-invasive method to examine visual function. It can examine many tiny areas of retina at the same time and have a particular advantage in diagnosing the early diseases of ocular fundus. This paper introduces the design of multifocal visual electrophysiology examining system. The system uses multidisplay technology exclusively owned by Windows 98 or above operating system to control graphics stimulator which generates specified hexagonal array. The white or black transition of each hexagon controlled by a binary m-sequence stimulates corresponding area of retina. The specified Burian-Allen electrode is used to extract the mixed signal originated from many areas of retina. The signal is amplified and A/D transformed. The computer separates the mixed signal through fast m-transform and gets the response of each area of retina. The fast m-transform is a fast computation of cross-correlations with binary m-sequences and can reduce cross-correlation computation to a single Fast Walsh Transform. So a lot of time can be saved.
Electrophysiology ; Electroretinography ; methods ; Humans ; Image Processing, Computer-Assisted ; Signal Processing, Computer-Assisted ; Systems Analysis ; Visual Perception ; physiology

OBJECTIVETo characterize dark-adapted and light-adapted oscillatory potentials (OPs) in human electroretinogram (EGR) elicited by flashing light stimulation of the same intensity.

METHODSDark- and light-adapted ERGs of normal eyes were studied. The frequency spectra of the extracted dark-adapted OPs and light-adapted OPs were analyzed by a fast Fourier transform. The peak frequency, latency and total power of the OPs were determined.

RESULTSThe averaged peak frequency, latency, and power of the dark-adapted OPs was 125.3∓9.93 Hz, 41.7∓3.56 ms, and 9.25∓5.55 (V·s)(2), as compared with 79.5∓6.79 Hz, 50.8∓5.36 ms, and 3.56∓2.18 (V·s)(2) for light-adapted Ops, respectively, showing significant differences in the parameters between dark- and light-adapted Ops (P<0.001).

CONCLUSIONSCompared with dark-adapted OPs, light-adapted Ops is characterized by a lower peak frequency and a lower power with a prolonged latency.

Adaptation, Ocular ; physiology ; Adult ; Dark Adaptation ; physiology ; Electroretinography ; methods ; Female ; Humans ; Male ; Oscillometry ; Retina ; physiology ; Young Adult

OBJECTIVETo investigate the characteristics of multifocal electroretinograms (mf-ERG) of different phases in diabetic retinopathy (DR) and its clinical significance.

METHODSMultifocal electroretinograms in patients with DR (I - II stage) were tested with VERIS IV system.

RESULTSIn I - II stage, the absolute values of N1, P1 and N2 response densities, and the N1-P1 and P1-N2 response densities were attenuated is a field of about 45 degrees in diameter.

CONCLUSIONAs a new objective and quantitative examination for spatial visual function, multifocal electroretinograms may be valuable in the diagnosis of diabetic retinopathy.

Aged ; Diabetic Retinopathy ; pathology ; physiopathology ; Electroretinography ; methods ; Female ; Humans ; Male ; Middle Aged ; Retina ; pathology ; physiopathology ; Time Factors

PURPOSE: To evaluate the clinical usefulness of binocular multifocal electroretinography (mfERG) by comparing results with conventional monocular mfERG in patients with monocular macular disease. METHODS: mfERG testing was conducted on 32 patients with monocular macular disease and 30 normal subjects. An initial mfERG was simultaneously recorded from both eyes with two recording electrodes under binocular stimulation. A second mfERG was subsequently recorded with conventional monocular stimulation. Amplitudes and implicit times of each ring response of the binocular and monocular recordings were compared. Ring ratios of the binocular and monocular recording were also compared. RESULTS: In the macular disease group, there were no statistical differences in amplitude or implicit time for each of the five concentric rings between the monocular and binocular recordings. However, with binocular simulation, the ring ratios (ring 1 / ring 4, ring 1 / ring 5) were significantly reduced in the affected eye. In the normal control group, there were no statistical differences in any parameters between the monocular and binocular recordings. CONCLUSIONS: Binocular mfERG could be a good alternative to the conventional monocular test. In addition, given that the test needs stable fixation of the affected eye during the binocular test, the reliability of the test results could be improved, especially for patients with monocular macular disease.
Adult ; Aged ; Aged, 80 and over ; Electroretinography/*methods ; Female ; Humans ; Male ; Middle Aged ; Prospective Studies ; Vision, Binocular/physiology ; Vision, Monocular/physiology ; Visual Acuity/*physiology ; Wet Macular Degeneration/*diagnosis/*physiopathology

Dengue fever is a viral disease that is transmitted by mosquitoes and affects humans. In rare cases, dengue fever can cause visual impairment, which usually occurs within 1 month after contracting dengue fever and ranges from mild blurring of vision to severe blindness. Visual impairment due to dengue fever can be detected through angiography, retinography, optical coherence tomography (OCT) imaging, electroretinography, event electroencephalography (visually evoked potentials), and visual field analysis. The purpose of this study is to report changes in the eye captured using fluorescein angiography, indocyanine green, and OCT in 3 cases of dengue fever visual impairment associated with consistent visual symptoms and similar retinochoroidopathic changes. The OCT results of the three patients with dengue fever showed thinning of the outer retinal layer and disruption of the inner segment/outer segment (IS/OS) junction. While thinning of the retina outer layer is an irreversible process, disruption of IS/OS junction is reported to be reversible. Follow-up examination of individuals with dengue fever and associated visual impairment should involve the use of OCT to evaluate visual acuity and visual field changes in patients with acute choroidal ischemia.
Adult ; Dengue/*complications/diagnosis/physiopathology ; Electroretinography ; Female ; Fluorescein Angiography ; Fundus Oculi ; Humans ; Tomography, Optical Coherence/*methods ; Vision Disorders/*diagnosis/etiology/physiopathology ; *Visual Acuity ; *Visual Fields

Dengue fever is a viral disease that is transmitted by mosquitoes and affects humans. In rare cases, dengue fever can cause visual impairment, which usually occurs within 1 month after contracting dengue fever and ranges from mild blurring of vision to severe blindness. Visual impairment due to dengue fever can be detected through angiography, retinography, optical coherence tomography (OCT) imaging, electroretinography, event electroencephalography (visually evoked potentials), and visual field analysis. The purpose of this study is to report changes in the eye captured using fluorescein angiography, indocyanine green, and OCT in 3 cases of dengue fever visual impairment associated with consistent visual symptoms and similar retinochoroidopathic changes. The OCT results of the three patients with dengue fever showed thinning of the outer retinal layer and disruption of the inner segment/outer segment (IS/OS) junction. While thinning of the retina outer layer is an irreversible process, disruption of IS/OS junction is reported to be reversible. Follow-up examination of individuals with dengue fever and associated visual impairment should involve the use of OCT to evaluate visual acuity and visual field changes in patients with acute choroidal ischemia.
Adult ; Dengue/*complications/diagnosis/physiopathology ; Electroretinography ; Female ; Fluorescein Angiography ; Fundus Oculi ; Humans ; Tomography, Optical Coherence/*methods ; Vision Disorders/*diagnosis/etiology/physiopathology ; *Visual Acuity ; *Visual Fields

Hereditary vitreoretinopathies are potentially blinding inherited disorders characterized by an abnormal-appearing vitreous gel and associated retinal changes. Four of these disorders, Stickler's syndrome, Wagner's disease, erosive vitreoretinopathy, and Goldmann-Favre syndrome, exhibit marked syneresis of the vitreous gel. Erosive vitreoretinopathy has associated retinal pigment epithelial changes, poor night vision, visual field defects, and abnormal electroretinographic findings; symptoms not found in Stickler's syndrome. A 36-year-old man with progressive visual loss and a visual field defect had no systemic disease. His vitreous cavity was liquefied. Vitreous strands and a cataract were found in both eyes. Pronounced RPE degeneration was found superotemporally in both eyes and a bullous rhegmatogenous retinal detachment in the left eye accompanied two retinal tears. His visual field showed a ring scotoma in both eyes and the ERG finding was abnormal. We report one case of erosive vitreoretinopathy with retinal pigment epithelial changes, rhegmatogenous retinal detachment, visual field defects, abnormal electroretinographic findings, marked vitreous syneresis and cataract. These symptoms are distinct from previously described entities.
Adult ; Case Report ; Electroretinography ; Eye Diseases/*pathology ; Human ; Male ; Ophthalmologic Surgical Procedures/methods ; Retinal Diseases/*pathology ; Treatment Outcome ; Vision Disorders/diagnosis ; Visual Fields ; Vitreous Body/*pathology

OBJECTIVETo evaluate the experimental induction of posterior vitreous detachment (PVD) by intravitreous injection of hyaluronidase and perfluoroethane (C(2)F(6)).

METHODSFifteen rabbits (30 eyes) were divided into 3 experimental groups,the contralateral eyes in same animals served as the controls. Eyes in group A and B were received two vitreous injections of 15 IU of hyaluronidase at an interval of 5 d. The eyes in group C and all control eyes were injected with balanced salt solution (BSS). Seven days after injection, the experimental eyes in group A and C were received 0.5 ml of Fifteen rabbits (30 eyes) were divided into 3 experimental groups, the contralateral eyes in same animals served as the controls. Eyes in group A and B were received two vitreous injections of 15 IU of hyaluronidase at an interval of 5 d. The eyes in group C and all control eyes were injected with balanced salt solution (BSS). Seven days after injection,the experimental eyes in group A and C were received 0.5 ml of C(2)F(6) injection. The ocular and retinal signs were examined for 8 following weeks and then killed for histological examination.

RESULTFive eyes in group A (100.0%) showed complete separation of the vitreous cortex from the retina (PVD), three eyes in group B(60.0%) showed partial PVD, and no PVD was detected in group C and all control eyes. On electroretinogram no significant difference was found in amplitude and latency of a-(or b-) wave in both experimental and control eyes, between before and after experiments. No evidence of ocular or retinal toxicity was revealed by light or scanning electronic microscopy in all eyes.

CONCLUSIONVitreous injection of hyaluronidase combined with perfluoroethane, as a safety method, can induce posterior vitreous detachment without mechanical vitrectomy.

Animals ; Electroretinography ; Female ; Fluorocarbons ; pharmacology ; Hyaluronoglucosaminidase ; pharmacology ; Male ; Ophthalmologic Surgical Procedures ; methods ; Rabbits ; Vitreous Body ; drug effects ; surgery ; ultrastructure ; Vitreous Detachment ; etiology