Caso de Estudio
ERG Raises Red Flag, Changing Management Trajectory
by Frances Bynum, OD
Desafío
Diagnosing with Confidence
DIAGNÓSTICO
Retinitis Pigmentosa
Testing Protocol
Flicker 16
Patient History
A 46-year-old White male with no family history of retinal or other concerning ocular disease presented for a routine exam. His visual acuity was 20/20 in both eyes. The only complaint that he had was some difficulty driving at night. He noted that it was challenging to see under these conditions.
Fundus examination revealed some pigment changes nasally on both eyes (Figure 1). Upon further investigation, I realized that these were mild bone spicules, so we proceeded to capture auto fluorescence images. As the FAF images show, the patient had quite a bit of retinal loss in the nasal aspect of both retinas (Figure 2). A visual field further confirmed the presence of the nasal defect (Figure 3).
Figure 1
Fundus OD Fundus OS
Figure 2
Auto Fluorescence OD Auto Fluorescence OS
Figure 3
Visual Field OD Visual Field OS
Why Was the ERG Performed?
We felt it was important to get a better understanding of the patient’s functional deterioration in this case, and we hoped the ERG would help paint a clearer picture that would make it easier to explain the findings to the patient and guide next steps when making a referral to the retinal specialist.
What Were the ERG Findings?
The Flicker 16 protocol (Figure 4) showed significantly decreased amplitudes and implicit times. The fundamental waveform was used in this instance due to the extremely low amplitudes. Importantly, the ERG also indicated that there is more severe functional vision loss than the visual field or the visual acuity represent in this case. Based on the combination of testing that was performed, I was able to confidently diagnose the patient with sector retinitis pigmentosa.
Figure 4
How Did the ERG Impact Next Steps?
Having certainty in this diagnosis prompted us to initiate important next steps, which included blood work for genetic testing. ERG also provided the information needed to determine eligibility for clinical trials that this patient may benefit from in the months ahead. Currently, there is no treatment for retinitis pigmentosa, but making the correct diagnosis and being able to direct my patient to the right specialists and services may be very helpful in the future — not only for himself, but for any children that he might have.
Finally, what I really liked about the ERG in this case was the color-coded print out of the results. This made it much easier to sit down and go over the findings with the patient. We talked about potential progression as well as his driving issues. I explained that he should refrain from driving at night or in low light conditions, such as cloudy or rainy days.
Why We Use RETeval
RETeval device makes me a better diagnostician and boosts my confidence managing disease progression. With ERG, I can monitor retinal function objectively, rather than relying too heavily on tests that require subjective patient responses.
Practice Protocol
When we first acquired the RETeval device, we focused on DR. We ran a DR Assessment on all patients who had both diabetes and signs of retinopathy. My technicians quickly learned how to use the RETeval, and it was so simple to implement into the practice flow. Because it’s portable and patients don’t have to move from room to room, we were able to start using the device on a variety of patients in whom structure and function was not really matching up. Now we have protocols for a host of diseases such as retinal vascular diseases, optic nerve disease including glaucoma and any unexplained vision loss in cataract patients.
Frances Bynum, OD
Northwest Tennessee Eye Clinic (Martin, TN)
Dr. Bynum is a Vision Source administrator and owner of a solo practice in a rural market. Her technical expertise has afforded her the ability to bring state-of-the-art procedures and technology into her practice, allowing patients to obtain a comprehensive range of services close to home. She’s a patient education advocate and believes that she and her patients can manage blinding eye diseases best when working as a team.