Normative database of retinal nerve fiber layer and macular retinal thickness in a Thai population

Purpose  To investigate the distribution of retinal nerve fiber layer (RNFL) and macular retinal thickness measured by optical coherence tomography (OCT) in a Thai population. Methods  We studied one eye each of 250 healthy subjects [age ≥ 18 years; spherical refractive error within ±6 diopters (D); astigmatism ≤3 D; no ocular pathology]. A complete eye examination, standard automated perimetry, and fast RNFL and macular thickness measurement by OCT were performed, and a disc photograph was taken. The distributions of both thicknesses, including their relationship with demographic data, were analyzed. Results  The mean ± SD age of the study population was 44.7 ± 12.2 years. The mean ± SD RNFL thickness was 109.3 ± 10.5 m, which was 10% thicker than that in the OCT normative database. RNFL decreased 2.3 m per decade (P < 0.001). Sex and spherical equivalent were not associated with RNFL thinning. The mean ± SD central foveal thickness was 183.2 ± 1.3 m. The macular thickness in the outer area was significantly thinner than that in the inner area (P < 0.001). The temporal regions were the thinnest among the four quadrants (P < 0.001). Thinning of all macular areas, except the center, was found to be associated with advancing age (P < 0.05). Conclusions  RNFL thickness in the measured Thai population was about 10% thicker than that in the original normative database. Macular thickness and RNFL thickness in the superior and inferior quadrants decreased with advancing age. Presented at the 6^th International Glaucoma Society Meeting, 28–31 March 2007, Athens, Greece     

Prospective comparison between conventional microbial work-up vs PCR in the diagnosis of fungal keratitis

Purpose

The PCR was compared with routine microbial studies for the detection of fungal pathogens in clinically suspected fungal keratitis.

Methods

A prospective nonrandomized study was undertaken at a tertiary eye care centre to evaluate 30 eyes of 30 patients with presumed fungal keratitis, both fresh and treated. Corneal scrapings were performed on each patient. The specimens were analysed by a semi-nested PCR assay using fungal-specific primers. PCR products were cloned and sequenced for identification, and compared with a conventional microbial work-up (smear and culture).

Results

Of the 30 samples, the PCR showed positivity in 93.3%, culture in 40%, and potassium hydroxide in 20%. Of the 28 PCR-positive cases, 12 were culture-positive and 16 were culture-negative. Two samples were both PCR and culture test negative. Culture-negative samples were PCR-positive in 16 of 18 (88.9%) cases. The PCR did not yield any false-negative findings in a culture-positive specimen. Both common and uncommon aetiologic fungi have been identified by DNA sequencing analysis.

Conclusion

The PCR was able to detect fungal DNA in a high proportion of culture-negative cases. Technical considerations of the PCR process include extraction of artifacts and amplification of non-pathogenic DNA. Nonetheless, our findings suggest that the PCR can be a useful adjunct to smear and culture in the rapid diagnosis of fungal keratitis, particularly in cases of failed detection from routine procedures.     

HLA-B27-associated acute anterior uveitis in the University Referral Centre in North Thailand: clinical presentation and visual prognosis

BACKGROUND: Acute anterior uveitis (AAU) is the most frequent type of uveitis encountered in the west. Although human leucocyte antigen (HLA)-B27-associated ankylosing spondylitis was reported in South East Asia, it is not known whether HLA-B27-associated ocular disease is prevalent in Thailand. METHODS: A prospective study of 100 unrelated blood donors and 121 consecutive patients with AAU was carried out. All people underwent HLA-B27 typing and full ocular examination. Radiological examination of the sacroiliac joints was conducted in patients with low back pain or arthralgias. RESULTS: The prevalence of HLA-B27 was 10% among the blood donors in contrast with 44% in the AAU group (p<0.001). The clinical characteristics of HLA-B27-associated AAU were similar to those published throughout the world (unilaterality in 74%, hypopyon in 31%, recurrent AAU in 64%). However, the increased intraocular pressure (IOP) was more common in the HLA-B-27-negative group (p = 0.03) than in their HLA-B27-positive counterparts. At least 15% of the HLA B27-positive group had radiological signs of ankylosing spondylitis. CONCLUSION: The prevalence of HLA-B27 in the population without uveitis in Thailand is about 10% and clinical characteristics of HLA-B27-positive AAU are similar to those reported in the west. In contrast with earlier reports, HLA-B27-negative AAU in Thailand was associated with increased IOP and should be further studied.     

Limbal stem cell and oral mucosal epithelial transplantation from ex vivo cultivation in LSCD-induced rabbits: histology and immunologic study of the transplant epithelial sheet

Purpose

To evaluate the results of cultivated limbal epithelial and oral mucosal epithelial transplantation (CLET and COMET) in limbal stem cell deficiency (LSCD)-induced rabbit model.

Materials and methods

Six New Zealand white rabbits were divided into two groups of three rabbits each. Limbal tissue was harvested from the first group, and oral mucosal biopsy was obtained from the second group. The tissues were cultured using an explant technique with amniotic membrane as a substrate and co-culture with the 3T3 fibroblast and air-lifting method. The right eye of each rabbit was induced to have LSCD using alkali burns. After three weeks, the LSCD-induced rabbit eyes were transplanted with the cultivated limbal and oral mucosal epithelial sheet in the first and second group, respectively. The transplanted eye was evaluated weekly post-operation. After 2 months, all transplanted eyes were enucleated and the epithelial morphology and phenotype of ocular surfaces were studied and compared with normal corneal and oral mucosal tissue.

Results

At 2-month post-transplantation, the eyes of four animals recovered with corneal transparency, one partially recovered, and one failed. The histology of the majority of transplanted eyes was stratified layers of corneal epithelia similar to normal rabbit cornea with some different findings such as goblet cells in the limbal region. Corneal epithelial thickening and stromal vascularization in two animals were observed. Phenotypic characterization of transplanted eyes showed a similar pattern of marker expression with the absence of p63 expression in the limbal or corneal epithelium in the COMET group.

Conclusions

The histology and phenotype of transplanted eyes after CLET and COMET were most likely to have similar characteristics as a normal healthy rabbit eye even though the COMET eyes have some inferior characteristics to the CLET eyes.

     

Psychometric utility of the international HIV dementia scale and Montreal Cognitive Assessment in HIV-associated asymptomatic neurocognitive impairment

Journal of NeuroVirology - There is a growing need for brief screening measures for HIV Associated Neurocognitive Disorders (HAND). We compared two commonly used measures (the Montreal Cognitive...