Electroretinographic findings in transplant chorioretinopathy

Abstract

Aim: Transplant chorioretinopathy is a rare complication following solid organ or bone marrow transplantation and can result in severe vision loss. This series presents electroretinogram (ERG) results in patients with this condition.

Methods: Patients who presented with bilateral vision loss following bone marrow or solid organ transplantation were identified. A complete ophthalmologic examination, fundus photography, and fluorescein angiography (FA) were performed. Full-field ERG was obtained in all patients and a multifocal ERG (mfERG) was obtained in two patients.

Results: Four patients were identified. All patients had bilateral vision loss and displayed a characteristic pattern of mottled hyperfluorescence on FA. Three patients developed progressive vision loss ranging from 20/60 to hand motions whereas one retained 20/40 vision. All patients exhibited moderate to severe cone dysfunction, while the degree of rod abnormalities was varied. Two patients with severe cone dysfunction showed mild clinical changes initially, but later developed progressive vision loss and chorioretinal atrophy.

Conclusion: Transplant chorioretinopathy patients undergoing ERG testing show cone dysfunction with a variable degree of rod dysfunction. ERG abnormalities preceded the visual acuity and clinical changes in two patients, suggesting that ERG may be a helpful predictor of the clinical course in this rare disease.

Keywords: ERG; chorioretinopathy; electroretinogram; mfERG; transplant.

Figure 1

Representative normal waveforms full-field and multifocal electroretinograms (mfERG) are presented. A) The normal full-field electroretinogram (ERG): The vertical marks denote the stimulus flash. In brief, the following parameters were measured. 30 Hz flicker: In a light-adapted patient, cone responses are evoked by a stimulus flickering at 30 Hz. Photopic single flash: In a light-adapted patient, a bright white flash stimulus evokes primarily a cone-mediated response, the so-called “cone-ERG”. Scotopic oscillatory potentials (OPs): In a dark-adapted patient, a variable response in the positive deflection felt to arise from amacrine cells. These responses are diminished in eyes with ischemia. The scotopic single flash: In the dark-adapted eye, is maximal response, a bright single white flash stimulus. In a dark-adapted eye, a rod-isolated response is obtained that occurs after a dark-adapted patient received dim white and or blue flash that is below cone threshold. In so doing, the resulting waveform is almost exclusively a b-wave. B) The normal mfERG: The typical waveform of the primary mfERG response is a biphasic wave with an initial negative deflection followed by a positive peak. There may be a second negative deflection after the peak. The preferred designation is to label these three peaks N1, P1, and N2, respectively. There similarity in this waveform with the conventional ERG. Amplitude is measured in nanovolts and time in milliseconds. The data reporting consists of a trace array, ring averages (a concentric ring of averages), and topographic representation of amplitudes and P1 latencies (implicit times).

Figure 2

A 71-year old Caucasian male with a history of cardiac transplantation. A) Color fundus photograph shows retinal pigment epithelial (RPE) changes. B–E) Fluorescein angiogram reveals areas of mottled hypo- and hyperfluorescence with multiple areas of leakage in later frames. F) Time domain optical coherence tomography line scans reveal shallow subfoveal detachments.

Figure 3

Full-field electroretinogram (ERG) of the patient depicted in Figure 1. A control tracing is included for comparison. There are decreased photopic and scotopic amplitudes bilaterally. The implicit times are also prolonged.

Figure 4

A 45-year-old Caucasian male with a history of bone marrow transplantation following treatment for multiple myeloma. A) On initial presentation, visual acuity was 20/40. Fundus examination was significant for small drusen-like deposits in the macula. B) Multifocal electroretinogram (ERG) performed at presentation was notable for severely decreased central cone amplitudes. C) The trace array reveals central tracings with reduced amplitude and increased implicit times. The topographic amplitude map discloses depressed central amplitude. The ring averages reveal abnormal latencies in the central group of tracings (1 and 2) compared to the concentric outer groups (5 and 6). The topographic P1 latency map disclosed increased implicit times centrally (red and yellow) compared with outer areas. Three years later, the visual acuity has decreased to 20/400, and there is diffuse pigmentary atrophy.