Spectral-domain optical coherence tomography in healed ocular toxoplasmosis

Abstract

IntroductionToxoplasmosis is the most common cause of infectiousretinitisinimmunocompetentindividuals.Theseroprevalenceof Toxoplasma gondii is different throughout the world.Among this positive population, only 1% has meaningfulchorioretinitis scars. Ocular toxoplasmosis is sometimes abenign and self-limiting disease. It can also cause central ortotal visual loss. Legal blindness occurs in nearly one quarterof the affected eyes. It is caused either directly byinvolvement of the macula or optic nerve or indirectly bycomplications secondary to inflammation [1, 2].Spectral-domainopticalcoherencetomography(SD-OCT)in active toxoplasmosis enabled identification of morpholog-ical features underestimated on clinical examination inpatients with ocular toxoplasmosis. Spectral-domain opticalcoherence tomography has revealed diffuse macular edema,vitreomacular traction, maculoschisis, focal choriocapillaris/choroidal relative hyper-reflectivity, and posterior vitreousdetachment [3].Typical congenital toxoplasmic retinochoroiditis presentsas a macular cicatricial lesion. SD-OCT in two cases ofhealed toxoplasmosis is reported for the first time.Material and methodsTwo consecutive cases of healed toxoplasmosis wereincluded. Elevated IgG levels for T. gondii were detectedusing enzyme-linked immunosorbent assay. SD-OCT wasperformed using Copernicus SD-OCT (Optopol, Poland).Three-dimensional imaging was also performed usingSD-OCT.Case reportsCase 1 A 24-year-old male presented with diminution ofvision in his left eye for past several years. His visual acuitywas20/20ODandcountingfingersOS.Slitlampexaminationresults were unremarkable for both eyes. Fundus examinationof his right eye wasnormal,but fundusexaminationof his lefteyerevealedalargehealedexcavatedscarattheposteriorpolehaving well-defined borders with central retinochoroidalatrophy and peripheral retinal pigment epithelial hyperplasia(Fig. 1a). SD-OCT of the left eye was performed. At thecenter of the lesion, a 6-mm horizontal scan showed splittingof retina at the level of outer nuclear layer. Discontinuation ofphotoreceptor layer, inner-segment–outer-segment junction,and hyper-reflective retinal pigment epithelium was observed(Fig. 1b). Retinal nerve fiber layer was found to be absent.Retinal thickness of 242 μm was observed prior to retinalsplitting. Retinal thickness at the edges of inner retinal layerbreak was observed to be 106 and 131 μm, respectively.Choriocapillaris/choroidal/scleral relative hyper-reflectivitywere also observed in the center of the lesion. On three-dimensional retinal imaging, an excavated scar was evident.The retinal pigment epithelium deformation map showedincreased retinal pigment epithelium thickness in the periph-eral area with loss of retinal pigment epithelium in the centerof the lesion (Fig. 1c).