Abstract
Purpose: :
To characterize the clinical and functional findings of 7 patients with AINR positive by Western blot for auto-antibodies (Abs) recognizing carbonic anhydrase II (anti-CA-II+).
Methods: :
All AINR patients underwent exams inclusive of anterior chamber (A/C) and posterior biomicroscopy, macular and disc optical coherence tomography (OCT) with retinal nerve fiber layer (RNFL) analysis, Goldmann visual field (GVF), flash electroretinogram (ERG), and visual evoked potentials (VEPs). Two of 7 cases (none of whom paraneoplastic) were anti-CA-II+ alone, 5/7 had other auto-Abs, 2/5 recognizing alpha-enolase (anti-AE+).
Results: :
There was wide variability in age of onset (17-63 yo), presenting symptoms and severity (night blindness=5/7; decreased acuity=7/7, ranging from 20/25 to HM; photopsias=4/7). A/C cells were found in 4/7 patients, regardless of auto-Ab profile. Interocular disease asymmetry was seen in 4/7 cases. All cases had disc or atrophic/pigmentary juxtapapillary changes, and 6/7 had peripheral spots or patches of retinal/RPE atrophy. The 2 most severe cases (neither anti-AE+) had macular atrophy. A few bone spicules were seen only in 3/7 cases, 2 of whom both anti-CA-II and AE+. Rod ERGs ranged from non-recordable in 3/7 patients (2/2 for those with only anti-CA-II auto-Abs), barely recordable in 1/7, and normal in size in 3/7 (but 2/3 delayed). Cone ERGs were abnormal in 6/7 cases (mildly reduced and delayed in 1/7, markedly so in 4/7, and N/R in 1/7), normal in 1/7. When recordable, VEPs were always reduced and delayed. GVF changes ranged from enlarged blind spot only to marked constriction. Also OCTs were heterogeneous, with thinned and thickened areas within the same patient, some exhibiting photoreceptor loss but thickened RNFL. Only the case with normal rod/cone ERG amplitudes had a normal macular OCT. Disc RNFL analyses were instead abnormal in all cases, often asymmetric, with both thinned and thickened RNFL bundles within the same patient.
Conclusions: :
Patients with AINR and anti-CA-II+ auto-Abs present with variable severity and findings. The most constant are signs of retinal ganglion cell (RGC) compromise (disc, VEP and OCT changes, enlarged blind spots). Both rod and cone ERGs are affected, but rod ERGs can be often normal (3/7), whereas cone ERGs are so rarely (1/7 cases). These findings correlate well with the known CA-II expression in, and immunoreactivity in AINR patients against both photoreceptors and RGCs (Adamus et al. J. Autoimmun. 2009).
Keywords: electrophysiology: clinical • imaging/image analysis: clinical • autoimmune disease