Classification Criteria for Toxoplasmic Retinitis.

PURPOSE: To determine classification criteria for toxoplasmic retinitis. DESIGN: Machine learning of cases with toxoplasmic retinitis and 4 other infectious posterior uveitides / panuveitides. METHODS: Cases of infectious posterior uveitides / panuveitides were collected in an informatics-designed preliminary database, and a final database was constructed of cases achieving supermajority agreement on diagnosis, using formal consensus techniques. Cases were split into a training set and a validation set. Machine learning using multinomial logistic regression was used on the training set to determine a parsimonious set of criteria that minimized the misclassification rate among the infectious posterior uveitides / panuveitides. The resulting criteria were evaluated on the validation set. RESULTS: Eight hundred three cases of infectious posterior uveitides / panuveitides, including 174 cases of toxoplasmic retinitis, were evaluated by machine learning. Key criteria for toxoplasmic retinitis included focal or paucifocal necrotizing retinitis and either positive polymerase chain reaction assay for Toxoplasma gondii from an intraocular specimen or the characteristic clinical picture of a round or oval retinitis lesion proximal to a hyperpigmented and/or atrophic chorioretinal scar. Overall accuracy for infectious posterior uveitides / panuveitides was 92.1% in the training set and 93.3% (95% confidence interval 88.2, 96.3) in the validation set. The misclassification rates for toxoplasmic retinitis were 8.2% in the training set and 10% in the validation set. CONCLUSIONS: The criteria for toxoplasmic retinitis had a low misclassification rate and seemed to perform sufficiently well for use in clinical and translational research.

Ocular parasitoses: A comprehensive review.

Parasitic infections of the eyes are a major cause of ocular diseases across the globe. The causative agents range from simple organisms such as unicellular protozoans to complex metazoan helminths. The disease spectrum varies depending on the geographic location, prevailing hygiene, living and eating habits of the inhabitants, and the type of animals that surround them. They cause enormous ocular morbidity and mortality not because they are untreatable, but largely due to late or misdiagnosis, often from unfamiliarity with the diseases produced. We provide an up-to-date comprehensive overview of the ophthalmic parasitoses. Each section describes the causative agent, mode of transmission, geographic distribution, ocular pathologies, and their management for common parasites with brief mention of the ones that are rare.

Intraocular parasitic infections.

A parasite is a living organism that receives some of its basic nutritional requirements through intimate contact with another living organism. When the parasite reaches the eye, ocular complications occur due to mechanical, immunologic, or allergic reactions. When an ophthalmologist detects a parasite in the eye, it is often difficult to identify the exact organism. Lack of methodological uniformity in management of ocular parasitosis emphasizes the need for standardization, including construction of a management algorithm. Knowledge on immunoreactivity in systemic parasitology has grown remarkably, but translational research from bench to bedside needs to be improved. Newer molecular diagnostic techniques are essential for ophthalmic application. Many parasitic worms are developing resistance to available drugs, necessitating discovery of the next generation of anti-parasitic agents. The aim of this review is to understand the existing literature on ocular parasitosis, to highlight diagnostic and therapeutic advances, and to analyze the management algorithm on ocular parasitosis.

A case of keratoconjunctivitis due to ewingella americana and a review of unusual organisms causing external eye infections

We report the isolation of Ewingella americana from the conjunctivae of a 38 year old female physician with keratoconjunctivitis associated with the use of soft contact lens. The patient was treated sucessfully with topical ciprofloxacin. The source of the infection remains unknown. All contact lens cleaning materials used by the patient were sterile. Since the patient was a physician, and this organism has been recorded as a cause of nosocomial infections, we checked whether cases of Ewingella americana had been reported, but none were identified. We have identified 39 bacterial species, 27 fungi, 4 viruses, 7 protozoa, 4 helminths, and 2 arthropods which rarely have been associated with keratitis or conjunctivitis. Infectious diseases specialists and ophthalmologists must be aware of the many different causes of this illness, including ewingella americana. This organism is a rare bacterial cause of keratoconjunctivitis not previously reported in Brazil. It should be added to the list of unusual cases of external eye infections.

A review of the spectrum of clinical ocular fundus findings in P. falciparum malaria in African children with a proposed classification and grading system.

Ocular fundus pathology in Plasmodium falciparum malaria is common and has prognostic significance. We have made a collaborative effort to document the ocular features in several populations. Based on examination of 735 patients in Malawi, Kenya and The Gambia by direct and indirect ophthalmoscopy with dilated pupils, we have determined that the 5 distinct clinical features (in order of frequency) include retinal whitening, haemorrhages, unique vessel abnormalities, papilloedema, and cotton wool spots. Photographs and descriptions of these are presented, along with a proposed grading scheme.