Uveitis in Thailand : emphasis on clinical patterns and novel developments in diagnostics using intraocular fluid analysis

Abstract

In this thesis, we report on the so far unknown causes of uveitis in Thailand and describe their clinical manifestations. We found out that intraocular infections were the second most common cause of blindness and low vision in a tertiary center in northern Thailand. These infections predominantly consisted of CMV retinitis in HIV–infected patients. The spectrum of uveitis in northern Thailand included approximately 30% of HIV-infected patients with cytomegalovirus retinitis. Causes of HIV-negative uveitis seemed to be similar to those observed elsewhere in the Far East. However, PCR analysis of intraocular fluid revealed that CMV was the most frequent cause of infectious uveitis not only in HIV-positive patients but surprisingly also in HIV-negative patients. While CMV retinitis was most prevalent in HIV-positive patients, CMV-positive hypertensive anterior uveitis was typically present in HIV-negative patients. PCR analysis of intraocular fluids appeared to form a valuable diagnostic procedure as 45% of those examined exhibited positive results. We found out that positive intraocular HIV 1-RNA loads in HIV-positive patients with uveitis were predominantly present in the eyes of untreated patients with high plasma HIV loads. Further, we describe a novel infectious uveitis entity, namely HIV-induced anterior uveitis and report on its characteristics. Additionally we describe the clinical entities of HLA B27-associated AAU and ocular sarcoidosis in the Thai population and point out severe DRPE as an important masquerade of VKH disease. Principally, this thesis increases our knowledge in the field of uveitis in Southeast Asia and gives an account of the main uveitis entities present in this population. Based on the results reported in this thesis, future research should address the diagnostic role of Goldmann Witmer coefficient in patients with uveitis, which might assist the diagnosis of chronic ocular infections. Further exploration of clinical manifestations of ocular toxoplasmosis is desirable as the correct diagnosis makes the focused treatment possible. The presence of ocular sarcoidosis in Thailand could be clarified by a systemic study of radiologic and CT chest examinations in patients with uveitis and their diagnostic value in patients with uveitis could further be determined. The systematic taking of tissue biopsy and QuantiFeron tests could be further applied to determine the exact role of tuberculosis and sarcoidosis in Thai patients with uveitis. The study of human ocular tissues (using iris or retinal biopsies) might help to identify the exact cell population where HIV can replicate. Further analyses of intraocular HIV could determine whether the virus situated within the eye is distinct from the virus population present in the blood. Last, but not least, it would be valuable to expand the PCR facilities analyses and make the PCR analysis of intraocular fluids accessible to patients and ophthalmologists from the areas outside our hospital.