Optical Coherence Tomography Angiography Analysis of Retinal and Choroidal Vascular Networks during Acute, Relapsing, and Quiescent Stages of Macular Toxoplasma Retinochoroiditis.

PURPOSE: To highlight the advantages of optical coherence tomography angiography (OCTA) in delineating the morphological features of the retinal and choroidal vascular network during acute, relapsing, and quiescent stages of macular toxoplasma retinochoroiditis. METHODS: This prospective study included patients presenting with both active and quiescent ocular toxoplasmoses. OCTA was obtained to diagnose and follow the subsequent vascular network changes at diagnosis and six months after acute presentation. RESULTS: Twenty-three eyes of 23 patients were included. In active lesions, OCTA showed extensive, well-delineated areas of intense hyposignal and perifoveal capillary arcade disruption in the parafoveal superficial capillary plexus (pSCP) and less extensive hyposignal in the parafoveal deep capillary plexus (pDCP). Signals of decreased deep capillary density and disorganization were also seen in the choroid. In nonactive lesions, OCTA demonstrated a homogenous and equally attenuated grayish hyposignal of the pSCP and pDCP and a partial restoration of the nonperfused choroidal areas. CONCLUSION: OCTA is a useful technique for vascular network analysis in toxoplasma retinochoroiditis. It allows the visualization of the different network changes and behaviors during the different stages of the infection.

Unilateral Acute Macular Toxoplasmic Chorioretinitis Associated with White Dot-Like Choroidal Involvement Demonstrated on Indocyanine Green Angiography

A 9-year-old otherwise healthy boy was examined due to a 4-day history of visual decline in his right eye. Ophthalmological examination revealed an area of active retinochoroiditis in the right macula. Indocyanine green angiography (ICGA) demonstrated multiple hypocyanescent dots surrounding the active lesion extending 360 degrees towards the equator. Optical coherence tomography angiography (OCTA) exhibited dark dots on the choriocapillaris slab over areas corresponding to the hypocyanescent dots detected with ICGA. Full systemic examination and laboratory investigations were carried out. Toxoplasma gondii serology was positive. The diagnosis of toxoplasmic chorioretinitis with white dot-like choroidal involvement was made. Trimethoprim/sulfamethoxazole, azithromycin, and oral prednisolone were administered orally. On repeated ICGA 2 weeks later, the scattered hypocyanescent dots were significantly fewer in number. A month later, right visual acuity was improved, the macular chorioretinitis focus had become inactive, an epiretinal membrane had formed, and the dark dots on the choriocapillaris slab of OCTA were markedly diminished. ICGA may be helpful to observe possible, subtle choroidal involvement in patients with toxoplasmic chorioretinitis.

Chorio-retinal toxoplasmosis: treatment outcomes, lesion evolution and long-term follow-up in a single tertiary center.

BACKGROUND: Ocular toxoplasmosis is a common cause of ocular inflammation worldwide. The aim of this study is to characterize the clinical outcomes and lesion evolution of patients with ocular toxoplasmosis and to compare the primary and reactivation subgroups. METHODS: A retrospective population-based cohort study at one uveitis-specialized tertiary referral center. Patients presenting with active ocular toxoplasmosis between the years 2007-2016 were included. Primary ocular toxoplasmosis and reactivations were compared. RESULTS: Included were 22 patients, 64% female with a mean age of 29 ± 18 years, 59% (n = 13) were primary, 9% (n = 2) congenital and 32% (n = 7) reactivations. Visual acuity improved from 0.38 ± 0.44 to 0.20 ± 0.27 LogMAR (P = 0.026) after a mean of 37 ± 33 months. Initial lesion size was 2.38 ± 1.1 optic disc areas, reducing to 1.56 ± 1.24 following 2 months (34% reduction, P = 0.028) and to 1.17 ± 0.87 disc areas following one year (51% reduction, P = 0.012). Patients with macula-threatening lesions had worse visual acuity (0.50 ± 0.46 vs. 0.05 ± 0.07 LogMAR, P = 0.047). Primary and reactivation subgroups had similar presentations, visual outcomes and recurrence rates (all P > 0.05). CONCLUSIONS: In this population, primary ocular toxoplasmosis was the most common presentation. Lesion size reduced during the initial months with limited change thereafter and a third of cases recurred. Macula-threatening lesions were associated with worse visual acuity, and no significant differences were seen between the primary and reactivation subgroups.

Activation of toxoplasma retinochoroiditis during pregnancy and evaluation of ocular findings in newborns.

The purpose of this study was to evaluate patients with activation of toxoplasma retinochoroiditis during pregnancy and ocular findings in newborns. A total of 17 pregnant patients who were clinically and serologically diagnosed with ocular toxoplasmosis were retrospectively reviewed. After birth, ocular findings for all infants were recorded. The mean age of the patients was 29.08 ± 5.71 years. In all cases, activation was present in only one eye. In 13 cases, anterior uveitis was associated with posterior uveitis. Visual acuity in all cases prior to treatment was 0.3 ± 0.21 and increased to 0.55 ± 0.29 after treatment. The mean gestational age of the patients was 19.76 ± 8.71 weeks at the time of hospital admission. No case of toxoplasmic ocular involvement was identified in the infants on postnatal examination. In the case of toxoplasma retinochoroiditis during pregnancy, appropriate treatment and follow-up is very important to protect the newborns and to prevent impaired vision in mothers.

Microhabitat Selection and Eyefluke Infection Levels in the Western Mosquitofish (Gambusia affinis).

Several trematode species infect the eyes of fish as second intermediate hosts. In most cases the definitive host is a piscivorous bird. Studies of a few species have shown an increase in transmission due to decreased visual acuity of the fish host. However, this may vary depending on trematode microhabitat choice within the eye. Some trematode species are found in the lens, some are found in the vitreous humor, and others have been reported from the retina. Here we report 3 genera of eyeflukes in 3 locations of the eye in the intermediate fish host, Gambusia affinis . Clinostomum metacercariae were found attached to the outer sclera within the eye orbit, and Diplostomum metacercariae were found in the lens. Posthodiplostomum metacercariae were confirmed by histology to reside between the choroid and pigmented retina. Posthodiplostomum metacercariae were found in both eyes of all 20 fish examined and in high intensities (up to 27 metacercariae per eye). High trematode intensities between the choroid and pigmented retina found in this study may disrupt vision in this fish host. Our study is the first to document the microhabitat of all 3 trematode metacercariae within the eye of G. affinis .

Quality of life assessment in ocular toxoplasmosis in a Colombian population.

OBJECTIVE: To assess the quality of life in patients with ocular toxoplasmosis. METHODS: The participants were 29 otherwise healthy patients with retinochoroidal lesions consistent with Toxoplasma infection. The controls were 29 gender and age-matched people with normal visual function who came from the same socioeconomic and educational background as the participants. The authors used the version of the National Eye Institute 25-item visual function questionnaire (NEI VFQ25). RESULTS: Patients with ocular toxoplasmosis had statistically significant lower scores than controls for all the subscales, except for color vision. Patients with bilateral lesions were more affected in the mental health, difficulties role, and specific vision subscales. The median of the compound score for the participants was 79 (range 35-99) and for the controls was 95 (range 72-98). CONCLUSIONS: People with ocular toxoplasmosis have worse vision-related quality of life than people without the condition, especially if they have bilateral lesions and more recurrences.

Perceptual visual filling-in of toxoplasmic retinochoroiditis scotomas.

UNLABELLED: Perceptual visual filling-in of toxoplasmic retinochoroiditis chronic scotomas was studied in 13 patients. Although there is deficit of visual inputs, patients with such chronic lesions perceive the region in the visual field uninterrupted. Targets were programmed to appear just outside the edge of the retinal lesion, and healthy retinal areas in the same eye. The results showed no significant difference in perceptual filling-in latencies (P>0.05). CONCLUSIONS: (i) neural mechanisms of filling-in at the blind spot are probably involved explaining this perceptual phenomenon; (ii) any neuronal changes occurring at the edge of the lesion only affected filling-in within the scotoma area.

Ocular toxoplasmosis: the role of retinal pigment epithelium migration in infection.

Our aim was to study the migration of retinal pigmented epithelium (RPE) into the retinal layer during infection of C57BL/6 mice with Toxoplasma gondii. Eyes from infected and non-infected animals were analyzed on the 60th day of infection by light and transmission electron microscopy. Non-infected eyes showed a normal morphology. In contrast, we observed free parasites in the retinal vasculature, the presence of mononuclear inflammatory infiltrate (MNII) and parasites in the vasculature of choroids in infected eyes. No inflammatory infiltrate was observed; RPE cells were identified near the MNII in nuclear and plexiforme layers. RPE cells were also found on the ganglion cell layer and in the outer segments of the photoreceptor. The morphology showed that RPE cells caused a discontinuity in the nuclear and plexiforme layers. Clusters of parasites were found surrounded by RPE cells and MNII in the inner plexiforme layers. Ultrastructural analysis showed that RPE cells migrated through the epithelium into the inner retinal layers. We did not observe Toxoplasma cysts in many eyes in which pathological changes were detected. Only 8.3% of the animals had Toxoplasma cysts in the inner nuclear layer in the absence of inflammatory cells. The migration of RPE cells can be triggered by a disruption of the RPE monolayer or injury to the neural retina, as in the case of toxoplasmosis.

Laser photocoagulation around the foci of toxoplasma retinochoroiditis: a descriptive statistical analysis of 35 patients with long-term follow-up.

Thirty-five patients with toxoplasma retinochoroiditis, receiving medical treatment and then treated with laser photocoagulation around the foci, were retrospectively evaluated for the risk of recurrence of the retinochoroiditis with a Kaplan-Meier representation. The recurrence rates with 95% symmetric confidence intervals were: at 1 year, 12.7 + or - 13%, at 2 years, 19.8 + or - 15%; at 3 years, 24.0 + or - 16%; at 4 years, 33.3 + or - 19%; at 5,6 and 7 years, 53.5 + or - 21%; at 8 and 9 years 66. 8 + or - 22%. With the data provided by our series, it is not possible to show the efficacy of laser photocoagulation as a prevention of recurrence in toxoplasma retinochoroiditis. Moreover, because of their heterogeneity, the recurrence rates from the literature cannot provide precise data for a comparison. Concerning the laser-induced thermal damage, the potential therapeutic mechanism of the laser procedure is discussed.

Ultrastructure of the midgut of Phrixocephalus cincinnatus (Wilson), a blood-feeding parasitic copepod of flatfishes.

Phrixocephalus cincinnatus is a blood-feeding copepod parasite inhabiting the choroid of the eye of the Pacific sanddab Citharichthys sordidus off the coast of southern California. The present study examined the fine structure of the midgut using both light and electron microscopy. The anterior midgut or stomach was lined with a tall columnar epithelium. The apical surfaces of the cells formed vesicles that pinched off and entered the gut lumen. Posteriorly, the midgut consisted of 2 morphologically distinct cell types; vacuolar and nonvacuolar. These cells probably were different developmental and functional stages of a single kind of columnar epithelial cell. The nonvacuolar cells possessed basally located nuclei, rough endoplasmic reticulum, and long microvilli indicative of an absorptive function. The vacuolar cells were characterized by short microvilli, endocytic vesicles, primary and secondary lysosomes, well-developed rough endoplasmic reticulum, and Golgi apparatus, suggesting that they were active in endocytosis as well as the synthesis of digestive and lysosomal enzymes. Distension of the apical surface of vacuolar cells with enzyme-containing vesicles resulted in the liberation of the distal part of the cell into the gut lumen. Subsequent lysis of the cell membrane released enzyme-containing vesicles, suggesting that digestive enzymes are discharged by apocrine secretion of the vacuolar cells. Both vacuolar and nonvacuolar cells absorb nutrients resulting from the extracellular digestion of host blood.

Ultrastructure of the holdfast of Phrixocephalus cincinnatus (Wilson), a blood-feeding parasitic copepod of flatfishes.

Phrixocephalus cincinnatus is a parasitic copepod inhabiting the eye of flatfishes. Specimens of infected Pacific sanddabs Citharichthyes sordidus were collected from Santa Monica Bay, California, and the copepods were fixed and examined using standard light and transmission electron microscopy. The holdfast consisted of numerous, intertwined rootlets originating from the cephalothorax of the parasite and embedded in the choroid of the host's eye. A large hematoma, extravasated blood, and necrotic host cells surrounded the holdfast. Electron microscopy revealed that the rootlets were encased with a trilaminar cuticle consisting of an outer epicuticle and an external and internal procuticle. The outer surface of the epicuticle was covered with microvillosities that contacted host tissue. In regions where host macrophages contacted the cuticle, the external layer of procuticle was expanded by large, cholesterol-like crystal deposits. Internally, the rootlets were comprised of at least 3 types of large cells. Epithelial cells contacted the internal layer of procuticle and contained numerous mitochondria. The cytoplasm of stellate cells was dominated by rough endoplasmic reticulum or large vacuoles. Ovoid cells contained distinct proteinaceous granules of unknown chemical composition. These observations revealed that the rootlets are structurally complex and suggest that the holdfast may be actively involved with molecular exchange between parasite and host.

Biomicroscopic and histopathologic considerations regarding the feasibility of surgical excision of subfoveal neovascular membranes.

Surgical excision of subfoveal neovascular membranes may result in recovery of excellent visual acuity in patients with presumed ocular histoplasmosis but not in patients with age-related macular degeneration. To provide an explanation for this discrepancy, I analyzed the clinical and histopathologic findings in five patients with presumed ocular histoplasmosis. These findings provide evidence that the new vessels arising in the choroid in these patients usually grow within the subsensory retinal space and not in the subpigment epithelial space, as occurs in patients with age-related macular degeneration. In presumed ocular histoplasmosis, the new vessels are partly engulfed by a monolayer of proliferating retinal pigment epithelium. Surgical excision of this membrane permits reapproximation of the retinal receptors and native pigment epithelium and may be associated with remarkable return of visual acuity.

Visual results after surgical removal of subfoveal choroidal neovascular membranes.

PURPOSE: The authors report their experience with the surgical removal of subfoveal choroidal neovascularization. Correlations between preoperative characteristics and final postoperative visual acuity are explored. METHODS: A retrospective study of 159 consecutive patients was performed between February 1990 and August 1993. Follow-up of 2 or more months was available for 147 eyes: presumed ocular histoplasmosis syndrome, 67 eyes; age-related macular degeneration, 41 eyes; myopia, 10 eyes; multifocal choroiditis, 9 eyes; idiopathic, 8 eyes; angioid streaks, 4 eyes; and miscellaneous, 8 eyes. RESULTS: Sixty-seven eyes had presumed ocular histoplasmosis syndrome: mean follow-up was 10.5 months. Visual acuity was stable or improved in 56 (83%) eyes and 20/40 or greater in 21 (31%) eyes. Mean interval to best visual acuity was 3 months. A recurrence rate of 37% had no significant effect on final visual outcome (P = 0.952). Forty-one eyes had age-related macular degeneration: mean follow-up was 15 months. Visual acuity was improved in only five (12%) eyes and was 20/40 or greater in only two (5%) eyes. The interval to best visual acuity was 5 months. A recurrence rate of 27% had not significant effect on final visual outcome (P = 0.31). The visual results and recurrence rates for eyes with less common disorders are presented. CONCLUSION: The surgical excision of subfoveal choroidal neovascularization may stabilize or improve visual acuity in selected cases. Patients with focal disorders of the retinal pigment epithelium-Bruch's membrane complex appear to have a better surgical outcome than those with diffuse disease.

Ophthalmological study of the lesions induced by the filarial worm with dermal microfilariae, Monanema martini, in its murid hosts.

The filaria Monanema martini with skin-dwelling microfilariae induces in its natural murid hosts lesions similar to those in human onchocerciasis. This was demonstrated by histo-pathological studies but it appeared useful to evaluate the model by a clinical investigation. An ophthalmological analysis was performed on the two species of hosts, inoculated by one, two, or multiple doses of larvae, and with infections of at least one year duration. A total of 140 eyes was examined (anterior and posterior segments). We established a system for enumerating the different types and severities of lesions. We prepared a file for each eye and attempted to quantify our observations. The significant lesions were different in the two host species. In Arvicanthis niloticus, in which motile microfilariae were seen in the anterior segment, punctate keratitis was predominant. In Lemniscomys striatus, the posterior segment showed complete chorioretinal atrophy, similar to the final stage of onchocercal chorioretinitis in humans. M. martini represents in its natural hosts two complementary models for the study of the pathogenesis and treatment of human onchocerciasis.

The occurrence of Sphaerospora renicola K-stages in the choroidal rete mirabile of the common carp.

It is known from earlier studies that the so-called K-protozoa, the late presporogonic stages of Sphaerospora renicola, a parasite causing renal sphaerosporosis in common carp (Cyprinus carpio), accumulate in the swimbladder wall and give rise to the disease called myxosporean swimbladder inflammation. The present study indicates that in the case of intensive infection these parasites also occur in the rete mirabile of the choroid of the eye, causing haemorrhages and necrosis. The results suggest that the K-stages of S. renicola are located in the blood path just like the early presporogonic C-stages; however, as they get stuck in organs rich in capillaries, it is difficult to demonstrate them from the blood of the common carp.

Surgical management of subfoveal choroidal neovascularization.

BACKGROUND: Subfoveal choroidal neovascularization (CNV) usually is associated with a poor visual prognosis. Laser photocoagulation of certain subfoveal membranes secondary to age-related macular degeneration (ARMD) appears preferable to observation based on recent Macular Photocoagulation Study (MPS) findings but is associated with decreased vision. The authors explored the use of vitreoretinal surgical techniques as an alternative method of eradicating subfoveal CNV. METHODS: After vitrectomy, a small retinotomy technique was used to extract or disconnect from the choroidal circulation subfoveal CNV in 58 eyes. There were 33 eyes with ARMD, 20 eyes with presumed ocular histoplasmosis, and 5 eyes with miscellaneous etiologies. Five eyes also received subfoveal RPE patches. RESULTS: With limited follow-up, significant improvement in vision (defined as 2 Snellen lines) was achieved in 7 of 22 eyes with ARMD CNV removal (1 eye 20/20), 0 of 4 eyes with ARMD CNV removal and RPE patches, and 1 of 7 eyes with ARMD CNV disconnection. Significant improvement was achieved in 6 of 16 eyes with presumed ocular histoplasmosis removal and 0 of 4 eyes with presumed ocular histoplasmosis CNV disconnection. In 5 eyes with miscellaneous CNV, 2 improved (20/20 and 20/40). CNV recurred in 29%. CONCLUSIONS: Some patients with subfoveal CNV appear to benefit from surgical removal. Only rarely do eyes with ARMD improve. Longer-term follow-up and refined case selection are required before this approach can be widely recommended.

Disruption of the choroidoretinal interface by toxoplasma.

Toxoplasmosis is a common zoonotic infection of the retina caused by Toxoplasma gondii. The disease causes severe damage that affects the retina and subjacent choroid. Invasion of the retinal cells by the parasite leads to the major damage seen in the retina. Subsequent reactions to the invasion by toxoplasma leads to the influx of inflammatory cells. Although hypersensitivity reactions have been described to both toxoplasma and to retinal autoantigens, the major disruption of the choroidoretinal interface is probably secondary to the tissue invasion by the parasite. Patients with AIDS may show extensive necrosis of the retina in the absence of inflammatory cells. Healing of the active lesion leads to scar formation. Toxoplasma retinochoroiditis may be pigmented, nonpigmented or punched-out. Vascular anastomoses between the retina and choroid, retinal and subretinal neovascularization may occur in the aftermath of choroidoretinal interface disruption.