Abstract
A 36-year-old woman presented with acute vision loss and was found to have disc oedema and retinitis pigmentosa (RP). She presented with a history of acute, painless vision loss in her left eye over a period of 10 days. Her best-corrected visual acuity was 20/50, N6 in the right eye (OD) and 20/160, N6 in the left eye (OS). She was found to have a swollen optic disc and the examination of her fundus showed changes suggestive of RP. The diagnosis of RP was confirmed by electroretinogram, and after ruling out demyelinating changes in the central nervous system and other possible infectious causes of papillitis, she was treated with intravenous steroids followed by a course of oral steroid therapy. Following treatment, her visual acuity improved to 20/60. Acute vision loss may occur in patients with RP and prompt steroid therapy may result in partial visual recovery.
Background
Retinitis pigmentosa (RP) is primarily a degenerative disease affecting the rod photoreceptors in the retina. The optic disc in RP may show optic atrophy, classically described as a ‘waxy pallor’ of the disc, and is thought to be a consequence of photoreceptor degeneration. Optic disc drusen have also been reported and are thought to be the end result of axonal degeneration.1 The presence of disc oedema in cases of RP is uncommon. The present report describes a rare presentation of acute unilateral vision loss associated with disc oedema in RP and demonstrates that in such cases, a partial recovery of vision may be achieved after steroid therapy.
Case presentation
A 36-year-old woman presented with sudden, painless loss of vision in the left eye over the past 10 days. She had a similar episode of vision loss in the right eye 7 years ago and had partial recovery of vision after treatment with oral steroids.
On examination, her best-corrected visual acuity (BCVA) was 20/50, N6 in the right eye (OD) and 20/160, N6 in the left eye (OS). Both the pupils were sluggishly reacting to light. Anterior segment examination was within normal limits. Fundus examination showed an attached retina, with vascular attenuation and pigmentary changes in the mid periphery, in both eyes. There was optic disc pallor in OD, however, OS had disc oedema (figure 1A, B). A clinical diagnosis of RP with possible papillitis in the left eye was made.
Figure 1.
Fundus findings on presentation showing optic atrophy in OD (A) and disc oedema in OS (B) with bilateral vascular attenuation and pigmentary changes. Resolution of disc oedema seen after treatment (C and D).
Investigations
An electroretinogram (ERG) showed decreased rod responses with relative preservation of cone function, confirming the diagnosis of RP (figure 2). MRI of the brain was performed with gadolinium contrast, which showed no enhancement of either optic nerve, and no demyelinating plaques or other intracranial lesions. In view of the atypical presentation, a systemic work up was advised to rule out infectious causes. The complete blood picture and erythrocyte sedimentation rate were normal. HIV ELISA, venereal disease research laboratory and Mantoux tests were negative, chest X-ray was normal and serum ACE was within normal limits (22 IU/mL). Serum rheumatoid arthritis factor and C reactive protein were within normal limits.
Figure 2.
Electroretinogram showing decreased scotopic responses suggestive of retinitis pigmentosa.
Differential diagnosis
In view of the patient's medical history and the clinical presentation, the diagnosis of RP and an associated papillitis was made. ERG, HVF and MRI of the brain with gadolinium contrast helped in confirming the diagnosis. A complete systemic work up ruled out any infectious aetiology. Another possible differential diagnosis was Leber's hereditary optic neuropathy (LHON). Genetic testing was also carried out and the patient tested negative for the three common mutations associated with LHON, namely, G3460A, G11778A and T114484C.
Treatment
The patient was treated with intravenous methylprednisolone 1 g/day in two divided doses for 3 days, followed by oral steroids (1 mg/kg/day) in tapering doses; her disc oedema regressed and visual acuity improved to 20/60, N6 in the affected eye.
Outcome and follow-up
The patient gradually recovered vision in her left eye over 1 month. The disc oedema gradually resolved. Two months after presentation, her BCVA was 20/40, N6 OD, and that of OS was 20/60, N6. Fundus examination showed bilateral optic atrophy, with pigmentary changes and vascular attenuation as seen previously (figure 1C, D).
Visual field testing was performed using Humphrey Visual Field Analyzer (HFA, Carl Zeiss Meditec, Dublin, California, USA) with the central 30–2 SITA program, which showed peripheral field loss with central small islands of vision in both eyes (figure 3). Spectral-domain optical coherence tomography (OCT; Cirrus HD-OCT, Carl Zeiss Meditec AG, Dublin, California, USA) showed a normal foveal scan in OD, and foveal thinning in OS (central foveal thickness 137 microns). OCT of the optic nerve head showed thinning of the peripapillary retinal nerve fibre layer in both eyes. Genetic testing to rule out LHON was also performed, and the patient tested negative for the three common mutations associated with LHON, namely, G3460A, G11778A and T114484C.
Figure 3.
Visual field testing in both eyes revealed severe peripheral vision loss with small preserved central islands of vision.
Discussion
Disc oedema in patients with RP is rare and the exact cause is not known. There are previously published reports documenting disc oedema in RP but the aetiology and association with vision loss have not been established.2 3 In a case report, Villa et al2 describe a patient with RP with bilateral chronic vision loss with bilateral disc oedema, which remained unresolved over a period of 1 year. In this case, no treatment was offered as the patient was not symptomatic. Another previously published report documents unilateral disc oedema in a patient with bilateral juvenile RP, which partly resolved spontaneously, but details about the onset and progression of vision loss have not been clearly elucidated.3
Our patient presented with acute, unilateral, painless vision loss, with no neurological signs or symptoms. There were no lesions seen on neuroimaging. We also ruled out the common infective causes of papillitis and LHON. Intravenous steroid treatment resulted in resolution of disc oedema and definite visual recovery.
The disappearance of the oedema with steroid use and visual recovery suggests an inflammatory component. Our patient also gave a history of a similar episode in the other eye, 7 years earlier, with partial recovery of vision. We postulate that there may have been acute loss of vision with possible disc oedema at that time also, however, we were unable to retrieve any previous examination reports.
Sachdev et al4 reported a patient with Bardet-Biedl syndrome with bilateral disc oedema and sudden loss of vision and postulated that the cause of the oedema may have been inflammation due to accelerated degeneration of the photoreceptors.
Recent studies5 have demonstrated presence of inflammatory cells in the vitreous and pro-inflammatory cytokines in the aqueous and vitreous of patients with RP, and have suggested a causative role of chronic inflammation in RP. We propose that acute exacerbation of inflammation may lead to disc oedema causing sudden vision loss, which may be superimposed on the otherwise chronic visual deterioration seen in such cases. Treatment directed at reducing the potential damage by inflammatory mediators may help in limiting the degree of visual loss. Therefore, prompt institution of steroids would help to decrease the potential damage to the optic nerve and help in at least partial recovery of vision. However, loss of the visual field that occurs due to degeneration of the photoreceptors in the mid-periphery will not be affected by this treatment.
Learning points.
Acute exacerbation of inflammation may be present in retinitis pigmentosa and may cause a papillitis-like picture with disc oedema and acute vision loss.
Detailed investigations are necessary to rule out any associated neurological or systemic causes of disc oedema.
Prompt steroid therapy may result in partial visual recovery.
Footnotes
Contributors: All the authors were involved in diagnosis and management of the patient. The manuscript was prepared by authors PPC and MT and the review of literature was performed by author PPC.
Competing interests: None declared.
Patient consent: Obtained.
Provenance and peer review: Not commissioned; externally peer reviewed.
References
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