The electroretinogram can play a central role in diagnosing cases with autoimmune retinopathy (AIR). Patients with AIR frequently present with photopsias, night blindness, decreased central vision, and narrowed or scotomatous visual fields and may be mistaken as having retinitis pigmentosa.^4,14 Making the situation more complicated, a few retinitis pigmentosa (RP) patients may develop AIR as a complication of their underlying disease (see below). Very often, the patient swears that his or her vision was normal a year before but now has noticeable changes. On examination, patients frequently have minimal retinal changes, and many are referred to neuro-ophthalmology clinic for evaluation. Most AIR patients develop a diffuse panretinal atrophy, which on viewing manifests as a blond fundus with mild to severe retinal vessel attenuation, and often a fine pigmentation or granularity to the subretinal space. A large majority of AIR patients have blond fundi with diffuse atrophy, and they do not have bone spicule–like dark pigment deposits. The signs and findings in AIR are often subtle and confusing, but an electoretinographic study will demonstrate severe retinal dysfunction in the face of often minimal changes in the fundus (figures 58.1A and 58.1B). Many patients have negative or greatly reduced waveforms in the dark-adapted bright-flash electroretinogram (ERG). The above findings alone do not give a diagnosis of AIR, but is the first step in establishing a more firm diagnosis.

Figure 58.1.  

Cases of CAR syndrome. A, Case 1. Eighty-four-year-old man who was found to have colon carcinoma in October 1994. No vision in OD from advanced glaucoma. Found to have CAR in April 1994. Relatively low doses of prednisone gave good visual recovery. Larger doses would be used today. (See also color plate 26.)

Figure 58.1.  

(continued) B, Case 2. Seventy-one-year-old woman with ovarian carcinoma found in October 2002. Vision was severely diminished six months later. She was placed on 60mg prednisone, 100mg Immuran, and 100mg cyclosporine. ERG values increased, while Goldmann visual fields remained the same on follow-up visit. Fundus showed diffuse atrophy without pigment deposits. (See also color plate 27.)

Autoimmune retinopathy is a complex subject because there are many variations on the theme. Rare patients have cancer-associated retinopathy (CAR syndrome), and even rarer is melanoma-associated retinopathy (MAR syndrome). There has even been a report of AIR associated with a teratoma.²⁸ Because different combinations of antiretinal antibodies have different levels of pathogenicity and because of other factors such as blood-retinal barrier integrity and family history of autoimmune diseases, can influence the severity. Most AIR patients present without cancer, but an associated carcinoma needs to be ruled out if the patient has newly diagnosed autoimmune retinopathy. If a patient has a carcinoma or melanoma and then presents with visual dysfunction, the diagnosis is much easier but still needs to be confirmed with a thorough evaluation, including ERG. Because many of these cases are treatable with immunosuppression, which can have significant side effects, it is important to be as certain as possible of the diagnosis.

Autoimmune complications also can occur in patients with RP, and the most typical form shows up as severe cystoid edema of the posterior pole or macula. Some patients will have severe striae (wrinkles) of the macular area (not cellophane retinopathy, which has more of a mild shimmer effect). These patients typically complain of having noticeable loss of visual field over a short period of time, and if their kinetic visual fields are followed over a year, there is noticeable contraction of their isopters every 3–4 months. This subgroup of RP patients has been termed “CAR-like syndrome,” since they have the same findings as CAR patients but do not have carcinomas. Most patients fall into the category of simplex RP, but have the additional findings of cystoid edema, retinal striae, diffuse retinal atrophy with minimal to no pigment deposits, and faster progression than occurs in typical RP (figure 58.2).

Figure 58.2.  

Forty-two-year-old woman with CAR-like syndrome and severe cystic edema of the posterior pole and no pigment deposits in the periphery. This patient had antirecoverin antibodies with bands of activity to seven other retinal proteins. There was no history of cancer. (See also color plate 28.)

To better understand the role of antiretinal antibodies in RP, we evaluated a group of 521 RP patients by doing Western blots on their serum. Fifty-one patients had antibody immunoreactivity in the range of 23 to 26kDa, and those in turn had dot-blot antirecoverin testing. Eight of 51 patients had immunoreactivity to recoverin.¹⁰ Since antirecoverin antibodies have been shown to be associated with CAR syndrome and cytotoxicity has been demonstrated in cell retinal cell cultures, these antibodies in RP patients are likely to be contributing to the patients' pathology.