Retinitis pigmentosa is a group of hereditary disorders that cause the degeneration of photoreceptor cells in the retina leading to progressive vision loss.1 Congenital toxoplasmosis is an acquired disease resulting from transplacental transmission of Toxoplasma gondii and is characterized by damage to the eyes, nervous system, skin and ears. We describe a rare case of retinitis pigmentosa and congenital toxoplasmosis occurring together in the same patient.
An eight-year-old male presented to our center with complaints of decreased night vision. His best-corrected visual acuity was 5/200 in both eyes. Anterior segment examination was unremarkable in both the eyes. Fundus evaluations in both the eyes showed bony spicules pigmentation especially in the mid-peripheral retina, arteriolar attenuation and waxy disc pallor of the optic disc typical of retinitis pigmentosa. There were well-defined punched out healed chorio-retinal scar suggestive of congenital toxoplasmosis in both the eyes [Fig. 1]. The family history revealed he had two unaffected siblings with the father suffering from retinitis pigmentosa [Fig. 2]. Electroretinography (ERG) was performed that revealed reduction of a and b wave amplitude in both eyes on dim scotopic flash ERG, moderate scotopic flash ERG and moderate photopic flash ERG with the maximum reduction in response observed in the dim scotopic step. A detailed systemic examination did not show any abnormality. On the basis of our clinical suspicion, serological analysis for TORCH group of organisms was sent. The reports revealed positive IgG titers for toxoplasmosis. On the basis of history, physical examination and investigation, a diagnosis of retinitis pigmentosa with congenital toxoplasmosis was made.
Retinitis pigmentosa is a group of inherited disorders that may be seen in isolation or in association with systemic disease.1 Night blindness is often the first symptom experienced by these patients or they may experience loss of peripheral visual field. The disease occurs in a prevalence of between 1/3000 and 1/5000 causing visual impairment anywhere from infancy to mid 30s to 50s.2 Our patient had the features of typical retinitis pigmentosa. Congenital toxoplasmosis is a disease whose severity is determined by the timing of infection-whether occurring in the first or the third trimester. The acquisition of the organism in the third trimester often results in subclinical infection.3 The ocular clinical picture consists of chorioretinitis, strabismus, nystagmus, microcornea, cataract, retinal detachment, optic atrophy and pthisis.4 The diagnosis is clinched by the classic triad of convulsions, chorioretinitis and cerebral calcification.
We presume that the patient had subclinical or atypical5 congenital toxoplasmosis which was discovered only on ocular examination for his complaint of night blindness. So, we made a diagnosis of retinitis pigmentosa with congenital toxoplasmosis. An extensive medline search involving keywords retinitis pigmentosa, toxoplasmosis, congenital retinal diseases showed such a combination has never been reported in literature earlier. Macula could be involved in retinitis pigmentosa in three different ways. Atrophic maculopathy has least prognosis while the cystoid macular edema is rarely benefited by oral acetazolamide. Cellophane type of macular involvement progresses very slowly and has intermediate visual prognosis. This case shows the unique association of coloboma occurring in the macular area in a patient of retinitis pigmentosa as a result of congenital toxoplasmosis infection that worsened the visual potential and prognosis of the patient.
The cause or the reason for the co-existence of these two different etiological diseases is not known though it might be co-incidental. So, we conclude that such macular pathology can occur in a case of retinitis pigmentosa, which can affect the ocular morbidity and lead to earlier and accelerated deterioration of vision.
1. Madhavan C, Bhende P, Gopal L, Vasanthi SB, Kumaramanickavel G. Retinitis pigmentosa patients with sickle cell disease and dextrocardia and situs inversus syndrome Indian J Ophthalmol. 2001;49:193–5
2. Pagon RA. Retinitis pigmentosa Surv Ophthalmol. 1988;33:137–77
3. Nussenblatt RB, Belfort R Jr. Ocular toxoplasmosis. An old disease revisited JAMA. 1994;271:304–7
4. Mets MB. Eye manifestations of intrauterine infections Ophthalmol Clin North Am. 2001;14:521–31
5. Smith JR, Cunningham ET Jr. Atypical presentations of ocular toxoplasmosis
Curr Opin Ophthalmol. 2002;13:387–92