Comprender la electrorretinografía (ERG) de la retina
What is an electroretinogram (ERG) and why is it important?
The ERG assesses how retinal cells respond to light and reveals functional changes before visible symptoms appear. This data allows for early and personalized interventions.
The retina acts like the film in a camera, converting light into signals that travel to the brain. If the retinal cells aren't functioning properly, vision can deteriorate even before you notice it. The ERG records the intensity and timing of electrical responses, which helps to identify cell loss, retinal stress, or disease progression in early stages.
How does an ERG test work?
The procedure combines pupil dilation, light stimulation, and electrical sensors to obtain accurate measurements without pain.
Drops are applied to dilate the pupils and, in some cases, anesthetic drops to reduce discomfort during electrode placement. The patient observes flashes or light patterns of varying intensities and colors that activate different types of retinal cells. Small electrodes placed on or near the eye capture electrical activity, which is converted into curves that the specialist interprets.
Step-by-step process of an ERG test
The study usually lasts from 30 to 60 minutes and allows you to return to your daily activities immediately.
After explaining the procedure, the pupils are dilated and, if necessary, anesthetic drops are applied for greater comfort. Very thin electrodes are placed on the ocular surface or on nearby skin to capture retinal responses. The retina is exposed to sequences of flashes or patterns that activate cones, rods, and internal cells. The signals are captured in waves that reveal the strength and response time of the retina, key data for diagnosis.
Different types of ERG tests
There are several ERG modalities designed to evaluate specific regions or layers of the retina.
Evalúa la función global de toda la retina y es útil para retinopatía diabética o retinosis pigmentaria.
- Destello único: ráfagas aisladas permiten que la retina se recupere entre estímulos.
- Destellos repetidos: estímulos continuos valoran la respuesta bajo estimulación sostenida.
Usa un tablero de ajedrez alternante para medir la función de las células ganglionares, esenciales en la detección temprana de glaucoma.
Mapea regiones específicas, sobre todo la mácula, y es valioso para enfermedades que afectan la visión central, como enfermedad de Stargardt o toxicidad por hidroxicloroquina.
Comprender los resultados del ERG: ¿qué nos dicen las curvas?
Las curvas del ERG reflejan la salud de distintas capas retinianas y ayudan a precisar la naturaleza de un problema ocular.
La onda A representa la respuesta de los fotorreceptores, mientras que la onda B proviene de células internas como las bipolares. Amplitudes bajas o retrasos pueden indicar disfunción.
Amplitud disminuida o tiempo prolongado puede sugerir retinosis pigmentaria, daño por diabetes o estrés celular. Estos hallazgos se combinan con otras pruebas para definir el plan de manejo.
El papel del ERG en el diagnóstico y seguimiento de enfermedades retinianas
El ERG aporta datos objetivos que permiten vigilar condiciones crónicas y ajustar tratamientos a tiempo.
Enfermedades genéticas como la retinosis pigmentaria muestran cambios tempranos en el ERG, lo que facilita un seguimiento cercano.
Functional abnormalities may appear on the ERG before there is visible damage to the retina, providing an opportunity to intervene.
PERG detects ganglion cell involvement, helping to slow the progression of glaucoma through timely therapies.
Medications such as hydroxychloroquine can cause retinal damage. Regular ERG monitoring allows for early detection of changes.
What to expect before, during, and after your ERG test
Knowing the stages of the test helps reduce anxiety and prepare properly.
The specialist explains the procedure, answers questions, and applies drops to dilate the pupils. The electrodes are placed and the person is instructed to look at flashes or patterns while electrical responses are recorded. Slight sensitivity to light may occur, but this will soon disappear. The patient can resume their normal activities and have the results reviewed at a follow-up appointment.
Benefits of ERG in retinal health management
The ERG offers key advantages that improve detection, monitoring, and therapeutic decision-making.
Identify problems before vision loss becomes obvious. It provides unbiased measurements based on the actual electrical activity of the retina. Comparing results across different visits allows for the evaluation of treatment effectiveness and progression. The findings guide medication adjustments, surgical interventions, or lifestyle changes.
Frequently Asked Questions about the ERG
The following answers common questions to help you feel informed and at ease.
No. The placement of electrodes and exposure to light stimuli are painless procedures. Any mild discomfort is usually brief. The entire study takes between 30 and 60 minutes, and the patient can resume their activities immediately. Yes. The ERG is very sensitive and can reveal retinal dysfunction even when vision appears normal. If an abnormality is detected, the specialist may request additional studies or repeat the ERG to monitor the condition more accurately. People with unexplained visual changes, a family history of retinal diseases, prolonged use of drugs with ocular risk, or a diagnosis of diabetes or glaucoma benefit from this objective test.
Your trusted retina specialist for advanced ERG testing
Electroretinography provides valuable information that helps protect your eye health and preserve your vision. Our team combines cutting-edge technology with personalized care to offer accurate diagnoses and customized treatment plans. We are committed to your visual well-being at every stage of your life.
El Dr. Fernández y su equipo son profesionales, atentos y siempre están pendientes de los pacientes. Tratan a cada paciente como a una persona digna de atención personal y dedicación completa.
SS
The practice is impeccable. Drs medical skills gave me extra years of vision when I had no hope. Staff are professional and kind.
Vantura Henderson
Great front desk staff! The office is immaculate! The ophthalmology exam was thorough and precise. Highly recommend this place.
Wajeeha Faizi
Recibimiento cálido. Pruebas de preparación cuidadosas. Examen profesional con el Dr. Fernandes, quien me explicó lo que estaba haciendo en cada paso del proceso.
karen cook
Very compassionate providers. They take their time to explain everything and go the extra mile to ensure you’re educated. Even after hours, they’ll help in emergencies.
Adam Rashed