Sir,

We read with great interest Sandfeld et al's1 recent correspondence regarding bilateral papillitis in ocular toxoplasmosis. Although they highlight that only a few microorganisms are required to incite a detrimental inflammatory response in the optic nerve, they argue that the relatively preserved visual function in their case tends to refute this hypothesis. We agree and feel that the simultaneous, symmetrical, and bilateral nature would also refute this hypothesis. The serology confirms an active toxoplasma infection, but we wonder what the proposed mechanism for the disc swelling in both eyes was. We would be interested to find out whether they performed a B-scan to rule out a posterior scleritis, which we feel could explain the clinical picture. We describe a similar presentation of bilateral disc swelling with normal visual function secondary to posterior scleritis.

Case report

A 59-year-old Caucasian man presented with bilateral, painful red eyes of 3 weeks duration. The functions of the pupils, colour vision, and optic nerve were all normal. His corrected visual acuities were 20/20 bilaterally.

Examination revealed bilateral diffuse anterior scleritis with quiet anterior chambers (Figure 1a and b) and bilateral disc swelling (Figure 1c and d). His CRP and ESR were raised (41 and 97, respectively), ANA was weakly positive and IgG was mildly raised. The rest of his autoimmune screen and his urine dip were normal. CXR revealed probable longstanding right basal atelectasis.

Figure 1
figure 1

(a, b) Anterior segment images showing diffuse anterior scleritis. (c, d) Fundus view illustrating disc oedema and associated haemorrhages.

Full size image

Neuroimaging failed to demonstrate any intracranial or orbital lesions although the paranasal sinus mucosa was thickened, consistent with sinusitis. B-scan ultrasound confirmed the diagnosis of posterior scleritis, showing a diffuse posterior scleral thickening (2.4 mm). High-dose prednisolone (1 mg/kg) led to resolution of the disc swelling over the following week. The steroid doses were tapered and steroid-sparing immunosuppressants commenced.

Comment

Posterior scleritis is a rare condition notorious for its non-specific presentation leading to frequent misdiagnosis.2, 3, 4 Despite the negative c-ANCA, the likely systemic association in this case was thought to be ‘limited’ Wegener's granulomatosis, although the steroid-sensitive nature of the condition would seem to contradict this.

Posterior scleritis may be associated with disc swelling in up to 17% of patients.5 Although visual loss is typically severe, posterior scleritis may also occur with normal vision. B-scan ultrasound is the key investigation in diagnosing the condition; it is non-invasive and readily available in most eye units. As in the previous case of toxoplasmosis and bilateral disc swelling, adjuvant signs should be closely examined for, as in this case the anterior scleritis suggested the diagnosis and in the former case the vitritis suggested the inflammatory aetiology.