Laboratory investigations on viral and Chlamydia trachomatis infections of the eye: Sankara Nethralaya experiences.

ABSTRACT

PURPOSE: To review our experiences on the laboratory investigations of viral and chlamydial conjunctivitis, congenital cataract and acute retinal inflammations seen from 1990 to 1998 at Sankara Nethralaya, Chennai, India. METHODS: Conjunctival swabs/scrapings from 1061 patients with conjunctivitis were investigated. Nested polymerase chain reaction (nPCR) and restriction fragment length polymorphism (RFLP) techniques were applied on 74 conjunctival swabs during the 1996 outbreak of acute viral conjunctivitis. The occurrence of Rubella virus in 86 lens aspirates of congenital cataract was investigated. Tests were performed for the association of Herpes simplex virus (HSV), Varicella zoster virus (VZV) and Cytomegalovirus (CMV) with acute retinal inflammation in 32 patients. RESULTS: The causative agents of conjunctivitis were Adenovirus in 13.8%, HSV in 2.2% and C. trachomatis in 20.9% of the patients. Epidemics were due to Adenovirus type 4 in 1991, type 3 in 1992-93 and type 7a in 1996. PCR was 37.9% more sensitive in detecting Adenovirus than virological methods. RFLP identified the conjunctivitis epidemic strain of 1996 as Adenovirus 7a. Rubella virus was isolated from 8.1% of lens aspirates from congenital cataract. Nineteen of the 32 patients with acute retinitis had confirmed virus infections (VZV 8; HSV 5; and CMV 6) and the rapid detection of the virus agent helped institute specific chemotherapy resulting in useful vision in some patients. CONCLUSION: Laboratory investigations for diagnosis of viral and C. trachomatis ocular infections were useful in establishing the aetiology and determining the incidence of causative agents of specific ocular diseases.