Purpose: The foveal function of patients with retinitis pigmentosa (RP) has been estimated by visual acuity (VA) or visual field (VF) tests. In the present study, the potential of optical coherence tomography (OCT) and focal electroretinogram (fERG) for monitoring macular function in RP patients was investigated.
Design: Cross-sectional observational study.
Methods: A total of 56 eyes of 56 patients with RP underwent ophthalmic examination including VA, VF, fERG, and OCT. Patients were morphologically divided into three groups by the appearance of photoreceptor inner/outer segment junction (IS/OS) that were depicted with OCT; type 1: no IS/OS visible, type 2: IS/OS was visible but the length was < or =2 mm, and type 3: IS/OS >2 mm was confirmed. Functional results for VA and fERG were compared and analysed based on the three groups.
Results: The average VA of type 1 patients was significantly lower than that of types 2 or 3 patients (P<0.001). There were no significant VA differences detected between types 2 and 3 patients. While most of the type 1 patients (21/22) showed non-recordable fERG, 3 out of 18 type 2 patients and none of type 3 patients showed non-recordable fERG. Significant differences of the fERG amplitudes were observed among the three groups (a-wave, b-wave, and OP, P<0.001 in all three components). However, the implicit time showed no difference between type 2 and 3.
Conclusions: Analysing the IS/OS with OCT and the amplitudes of fERG may be helpful for monitoring RP patients in addition to VA and VF.