The Endophthalmitis Population Study of Western Australia (EPSWA): first report

BACKGROUND/AIM: Over the period of 19 years to 1999, cataract surgery numbers increased 6% per annum in Western Australia (WA), promoted by the convenience, efficacy, and general safety of outpatient phacoemulsification surgery. Although endophthalmitis is an uncommon complication, it is a major cause of post-cataract surgery blindness. The present population study investigates not only the prevalence of endophthalmitis but provides an accurate incidence of endophthalmitis in WA over the same period. METHODS: Using the hospital morbidity data system (HMDS) of the WA Record Linkage Project, and cross validating against three independent databases (anaesthetic and microbiological databases and surgeons' logbooks) the authors examined 698 case notes that were potentially cases of endophthalmitis for the period 1980 to June 1999. As the database linkage was incomplete for 1999, only the 188 confirmed cases to 1998 were included in the present study. Additional case note validation was performed to confirm the correct codes for the cataract surgical procedure. RESULTS: Despite changes in surgical technique and prophylaxis over the study period of 19 years, the incidence of endophthalmitis remained largely unchanged, averaging one in 500 surgical cases overall. However, the incidence fluctuated over time and varied with the location of surgery ranging from 0.65 per 1000 operations to 16.4 per 1000 operations. CONCLUSION: These data highlight previously undescribed temporal and geographic variations in the incidence of endophthalmitis. It is uncertain whether the wide variation in prophylactic practices throughout the ophthalmic community has any bearing on the incidence of endophthalmitis.     

Determinants of intraocular pressure and its association with glaucomatous optic neuropathy in Chinese Singaporeans: the Tanjong Pagar Study

PURPOSE: To examine the relationship between intraocular pressure (IOP), anthropomorphic, demographic, socioeconomic, systemic, and ocular factors and glaucomatous optic neuropathy (GON) in Chinese people. METHODS: Chinese people (n = 2000), aged 40 to 79 years, were selected from the Singapore electoral register. Of the 1717 considered eligible for examination, 1232 participated, representing a response rate of 71.8%. IOP was estimated with Goldmann applanation tonometry. The drainage angle was assessed with static and dynamic gonioscopy. The optic nerve was examined at high magnification through a dilated pupil with a fundus contact lens or a +78-D lens. Static automated visual field testing was performed on subjects with suspected glaucoma. GON was diagnosed on the basis of structural and functional abnormalities of the optic nerve. RESULTS: The main independent determinants of higher IOP were higher systolic blood pressure (P < 0.001), quadrants of any peripheral anterior synechiae (PAS, P = 0.02) and width of the drainage angle (P = 0.049). A 100- micro m increase in corneal thickness was associated with an increase in mean IOP of 1.5 to 1.8 mm Hg (P < 0.001). Odds of GON increased 1.2 times per 1-mm Hg increase in screening IOP. A clear association between corneal thickness and GON was not identified. CONCLUSIONS: Clinical IOP estimates are related to systolic blood pressure and corneal thickness. Variation in IOP with angle width may suggest that trabecular compaction significantly contributes to causes of the increase in IOP, independent of angle-closure. GON is an IOP-related phenomenon among Chinese Singaporeans.     

Congenital orbito-palpebral cyst in a case of Fraser syndrome

A seven-year-old girl was referred to our clinic with absent eyelids and a mass which was gradually increasing in size from the right orbit. The child was diagnosed to have Fraser syndrome (cryptophthalmos, abnormal genitalia, mental deficiency, renal agenesis and abnormal ears). On examination, there was cryptophthalmos and a cystic swelling arising from the right orbit. The cyst was removed. On gross examination, there was a posterior eyeball with normal optic nerve. Placed in the anterior part of the eyeball was a cyst measuring about 2 cm in diameter filled with a yellow-coloured fluid. The cavity of the eyeball was communicating with the cyst. The cyst wall was lined by a single layer of epithelium. The posterior eyeball had well developed sclera, choroid, retina and optic nerve. There have been many reports of cryptophthalmos in Fraser syndrome. The most common eye deformity described with cryptophthalmos is microphthalmia or anophthalmia. To the author's knowledge, there is one other report of cystic eyeball with cryptophthalmos in the literature. The cyst seems to be due to a surface ectodermal anomaly, rather than a neuro-ectodermal anomaly where there is failure of invagination of the primary optic cup during development. The cyst wall in those cases has inverted retinal elements. In our case, differentiation of retinal elements was present in the posterior eyeball. The abnormality seemed to lie in the derivatives of surface ectoderm, namely the eyelids and the anterior segment structures.     

Facial skin rejuvenation

PURPOSE OF REVIEW: In recent years, many new products and techniques have arisen that are useful in the rejuvenation of facial skin. Most of the therapies are directed at improving the results of photoaging. These cutaneous changes occur from chronic exposure to ultraviolet B light (290 to 320 nm) associated with sunburn, and ultraviolet AII light (320 to 340 nm), and ultraviolet AI light (340 to 400 nm) associated with photoaging. Clinically chronic photoaging may result in fine wrinkles, texture abnormalities, pigment dyschromias, and actinic keratoses. RECENT FINDINGS: Many methods of patient assessment are available, but the most useful include the Fitzpatrick skin type classification and the Glogau photoaging scale. Although many therapies are available to reduce or even reverse many of these aging changes, patient education regarding lifestyle changes (especially smoking cessation) and sun avoidance need to be a critical foundation of treatment. Indeed, patient participation in their own skin care regimen is important for any program to be effective. Topical therapy including tretinoins, hydroxy acids, bleaching agents, and sunscreens are discussed herein. SUMMARY: The physician has an important role in understanding which treatment options are appropriate for mild, moderate, and severe photoaging, and in educating patients on the risks and benefits of each. This includes resurfacing modalities with microdermabrasion, chemical peels, and laser skin resurfacing.     

Preservation of neurological functions by nitric oxide synthase inhibitors following hemorrhagic shock

Excessive production of nitric oxide (NO) as result of inducible nitric oxide synthase (iNOS) induction has been implicated in the pathophysiology of hemorrhagic shock. Our aim was to study the effect of iNOS inhibitors, L-canavanine (50mg/kg) and N(G)-nitro- L-arginine methyl (L-NAME, 10mg/kg) and a resuscitation fluid, lactated Ringer's solution (3 times amount of blood lost), on survivability and neurological functions in rodents subjected to hemorrhagic shock. L-canavanine-treated rats had significantly higher survival rates (75%) compared to L-NAME-treated rats (44%) and lactated Ringer's solution-treated rats (40%), 72 h following hemorrhagic shock. A marked increase in the neurological performance was observed in L-canavanine-treated rats over the three-day period. Histological examinations also showed a reduction of degenerating neurons in L-canavanine-treated rats when compared to L-NAME-, lactated Ringer's solution- or un-treated rats. Mean arterial blood pressure (MABP), nitrate/nitrite level, glutamic oxalacetic transaminase (GOT) level, and blood gases were also significantly improved in L-canavanine-treated rats when compared to those of L-NAME-, lactated Ringer's solution- or un-treated rats. In conclusion, L-canavanine-treated rats were able to improve survivability, attenuate organ damage, and improve neurological outcome when compared to other treatment groups. It is therefore suggest that L-canavanine may be beneficial as a potentially useful therapeutic agent in treating neurological deficit as a result of hemorrhagic shock.     

Wavelet-based compression of medical images: filter-bank selection and evaluation

Wavelet-based image coding algorithms (lossy and lossless) use a fixed perfect reconstruction filter-bank built into the algorithm for coding and decoding of images. However, no systematic study has been performed to evaluate the coding performance of wavelet filters on medical images. We evaluated the best types of filters suitable for medical images in providing low bit rate and low computational complexity. In this study a variety of wavelet filters are used to compress and decompress computed tomography (CT) brain and abdomen images. We applied two-dimensional wavelet decomposition, quantization and reconstruction using several families of filter banks to a set of CT images. Discreet Wavelet Transform (DWT), which provides efficient framework of multi-resolution frequency was used. Compression was accomplished by applying threshold values to the wavelet coefficients. The statistical indices such as mean square error (MSE), maximum absolute error (MAE) and peak signal-to-noise ratio (PSNR) were used to quantify the effect of wavelet compression of selected images. The code was written using the wavelet and image processing toolbox of the MATLAB (version 6.1). This results show that no specific wavelet filter performs uniformly better than others except for the case of Daubechies and bi-orthogonal filters which are the best among all. MAE values achieved by these filters were 5 x 10(-14) to 12 x 10(-14) for both CT brain and abdomen images at different decomposition levels. This indicated that using these filters a very small error (approximately 7 x 10(-14)) can be achieved between original and the filtered image. The PSNR values obtained were higher for the brain than the abdomen images. For both the lossy and lossless compression, the 'most appropriate' wavelet filter should be chosen adaptively depending on the statistical properties of the image being coded to achieve higher compression ratio.