Neuro-Ophthalmology Service, Cullen Eye Institute, Baylor College of Medicine, 6565 Fannin NC-205, Houston, TX 77030, USA. E-mail: foroozan{at}bcm.tmc.edu
SIR, A 58-yr-old woman with dermatomyositis was evaluated for painless bilateral visual loss of 2 weeks duration. Three months prior to neuro-ophthalmic evaluation she developed multiple systemic symptoms including joint pain and stiffness, a rash on the arms, back and chest, fevers and weakness of the upper and lower extremities, which required hospitalization and treatment with intravenous corticosteroids. Laboratory evaluation showed an elevated creatine kinase of 201 U/l (normal range: 26140). This prompted a thigh muscle biopsy which showed chronic inflammation consistent with dermatomyositis. The remainder of her laboratory evaluation was normal and did not reveal evidence of another collagen vascular disease. She had no prior history of hypertension, diabetes mellitus or cardiovascular disease.
She was discharged on 40 mg of oral prednisone which was gradually tapered over the next 3 months. The day after completing the prednisone taper she reported blurred vision in both eyes that gradually progressed over the next 4 days. During this time she also noted increasing weakness and pain in the extremities. She restarted 40 mg of prednisone per day and saw an ophthalmologist who noted bilateral optic disc oedema, without retinopathy, and referred her for neuro-ophthalmic evaluation.
Her visual acuity was 20/20 OD and 20/25 OS, and there was a left relative afferent pupillary defect. She identified 7 of 10 Ishihara pseudoisochromatic colour plates with the right eye and 2 of 10 with the left eye. Automated perimetry revealed superior and inferior arcuate visual field defects on the right and an inferior altitudinal defect on the left (Fig. 1). Dilated fundoscopy revealed resolving pallid optic disc oedema, with opacification of the superior and inferior retinal nerve fibre layer, on the left more than the right (Fig. 2). The remainder of the fundus examination was normal in each eye, without cotton wool spots or haemorrhages. Contrast-enhanced magnetic resonance imaging (MRI) of the brain and orbits was normal, without optic nerve enhancement. Her prednisone was increased to 60 mg per day and she reported no additional deterioration of vision. She returned 1 month later and her visual acuity and fields were stable. Her optic disc oedema had completely resolved, and the remainder of the fundus examination was normal.
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Retinopathy is believed to be more common in children with dermatomyositis because accompanying vasculitis is more common at a younger age [2]. In the prior reports retinopathy has been clinically evident with fundoscopy, but one report suggested that intravenous fluorescein angiography (IVFA) may show more vascular involvement than is clinically obvious [5]. Despite this suggestion we were not able to find a patient who had evidence of involvement on IVFA without fundoscopically evident retinopathy.
The precise incidence of visual loss in dermatomyositis is not known, and in prior reports decreased vision has been attributed to retinopathy and infarction within the retinal nerve fibre layer [6]. Intraretinal haemorrhages and macular exudates have also been described as causing decreased vision in patients with dermatomyositis [6]. The retinopathy and visual loss appear to be reversible in most patients but persistent visual loss has also been noted despite treatment with corticosteroids and other immunosuppressive agents [6].
Optic neuropathy has been described in patients with dermatomyositis, but only in association with retinopathy [2]. We were unable to find a prior report of a patient with dermatomyositis who had optic nerve involvement without retinopathy using the following search terms: dermatomyositis, optic disc, vision, blindness, retinopathy (Pub Med, www.ncbi.nlm.nih.gov June 2003).
The timing of this patient's visual loss, 1 day after discontinuing prednisone and in association with increasing myalgias and weakness, suggests that reactivation of the dermatomyositis was the cause of her visual loss. The relative afferent pupillary defect, dyschromatopsia, visual field defects and pallid optic disc oedema in the absence of retinopathy are evidence that the visual loss was from an optic neuropathy and not a retinopathy. Fortunately, reinstitution of corticosteroid therapy led to stabilization of her optic neuropathy with resolution of optic disc oedema and stabilization of visual function. She had no history of vascular disease, simultaneously swollen optic nerves and a relatively large cup-to-disc ratio in each eye, all of which would be extremely unusual for another cause of optic neuropathy such as non-arteritic ischaemic optic neuropathy [7]. We cannot totally exclude the presence of subclinical retinopathy and we did not perform IVFA, however there were no cotton wool spots or intraretinal haemorrhages characteristic of ocular involvement in patients with dermatomyositis.
It is not clear why retinopathy did not develop in this patient. Perhaps prior treatment with corticosteroids somehow protected the retinal vascular circulation. Spontaneous regression of retinal neovascularization has been noted in juvenile dermatomyositis, months after the initial fundus findings were documented [8]. The retinopathy in our patient may have been present prior to initial ophthalmic evaluation and disappeared by the time fundoscopy was performed, however her visual loss occurred just 2 weeks prior to neuro-ophthalmic assessment, during which time visual-impairing retinopathy would be expected to persist.
Optic neuropathy may occur in the absence of retinopathy in a patient with dermatomyositis. The absence of retinopathy does not preclude visual loss and should not delay the institution of corticosteroid therapy.
The author has declared no conflicts of interest.
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