Epidemiology of pterygium in aged rural population of Beijing, China.

BACKGROUND: Pterygium is a common ophthalmic disease and an important public health problem. It may be affected by many factors such as age, gender, ultraviolet radiation exposure, and time spent outdoors. This study aimed to investigate the prevalence of pterygium and evaluate the risk factors for the development of pterygium in the aged rural population of Beijing. METHODS: The investigation is a population-based cross-sectional study. Participants from 198 villages of 13 suburban districts, aged 55 - 85 years old, were invited to complete a medical record, and 37 067 individuals were taken external ocular and fundus photos at Beijing ocular disease survey in 2008-2009. The information was uploaded by Internet and diagnosed with stages and grades by ophthalmological specialists. The prevalence, stages and grades of pterygia were observed. RESULTS: Of the 37 067 individuals, 1395 (3.76%) had pterygium. There was a significantly higher prevalence in male (5.13%) than in female (3.17%, P = 0.000). The prevalence rate increased obviously with ages (chi(2) = 7.939, P = 0.019) in rural Beijing. The average prevalence of 5.91% in Daxing and Fangshan districts with low latitude and low precipitation was significantly higher than that in Miyun and Huairou districts with high latitude and deep precipitation (3.17%, P = 0.000). The majority of the pterygia (43.5%) were in active stage and 46.5% pterygia involved pupil area corneas. CONCLUSIONS: There is a statistically significant association between latitude and precipitation of habitation region and pterygium formation. Solar radiation, especially ultraviolet exposure represents a significant environment hazard to pterygium development.

[Morphological characteristics in corneal smear of acanthamoeba keratitis].

OBJECTIVE: To study the morphological characteristics in corneal smear of acanthamoeba keratitis. METHODS: Experimental study. From May 1991 to December 2007, in Department of Microbiology, Beijing Institute of Ophthalmology, Beijing Tongren Hospital, 159 cases with acanthamoeba keratitis were analyzed for the laboratory results and clinical data. Giemsa's stained smear and wet-mount preparation of 159 cases were observed, all the results of cytology be photographed as the records. RESULTS: Among the 159 cases with acanthamoeba keratitis, 131 patients (82.4%) were positive on smear, and 110 cases (69.2%) were positive in culture of amoeba. The detection positive rate of smear was apparently higher than culture. Typical trophozoites, pre-encystment trophozoites, mature cysts and empty cysts could be observed by smear. So it is an important method for the clinical diagnosis. The edema and dissolved corneal epithelial cells, exudate cells, arthrospores or chlamydoconidium of mycelial fungus, vacuoles, lipid droplet and medicine crystallization should be differentiated with the pathogen. The movement of trophozoites could mainly be observed through wet-mount preparation. CONCLUSION: The detection of typical features of trophozoites, pre-encystment trophozoites, mature cysts and empty cysts by corneal smear is important for the etiological diagnosis of acanthamoeba keratitis.

Effect of topical application of terbinafine on fungal keratitis.

BACKGROUND: Fungal keratitis is a rare but serious corneal disease that may result in loss of vision. The poor prognosis might be due to limited treatment option. This study aimed to evaluate the clinical efficacy of 0.25% terbinafine eye drops comparing with 5% natamycin suspension on fungal keratitis. METHODS: A retrospective clinical trial was performed on 90 patients presenting with direct smear and/or culture positive fungal keratitis at Beijing Tongren Hospital, Beijing, China from January 2006 to May 2008. Corneal ulcers were categorized as mild or severe. Forty-five patients were treated with topical terbinafine and the next 45 cases received topical natamycin hourly. RESULTS: Filamentous fungi were found in corneal scrapings among all 90 cases. Fungal cultures were positive in 64 patients (71%). Species of Fusarium and Aspergillus were the principal isolates. Forty (89%) patients showed favorable response to terbinafine, while forty-two (93%) patients exhibited favorable response to natamycin (P > 0.05). The mean course of treatment was significantly showed in the terbinafine treatment group than natamycin group ((26.5 +/- 11.2) days versus (19.3 +/- 6.4) days; P < 0.05). In terbinafine group, twenty patients with ulcers smaller than 4 mm had favorable outcome, while 20 of 25 patients with ulcers more than 4 mm in diameter had favorable response (P < 0.05). Twenty-seven patients with depth of infiltration less than half of stroma thickness had favorable response to terbinafine, while 13 of 18 patients with depth of infiltration more than half of stroma responded to terbinafine. This difference was statistically significant (P < 0.05). CONCLUSIONS: Our findings suggest that topical terbinafine is an effective antifungal drug for the management of filamentous mycotic keratitis, particularly in cases with smaller and shallower ulcers. Its mean duration of treatment was longer than natamycin.

[Ultrastructure study of pathogen of acanthamoeba keratitis].

OBJECTIVE: To observe the ultrastructure of the strains of acanthamoeba isolated from acanthamoeba keratitis (AK), the morphologic changes of acanthamoeba after culture with 0.02% chlorhexidine, and ultrastructure characteristics of acanthamoeba in corneal tissue of AK. METHODS: It was a experimental study. The ultrastructure of acanthamoeba strains cultured with 0.02% chlorhexidine was observed with scanning electron microscope (SEM). The excited cornea tissues from AK were observed with transmission electron microscope (TEM). RESULTS: Cultured acanthamoeba trophozoites were approximately 15 - 45 microm in diameter, appeared irregularly round or oval in shape, with rough surface and intrusion of cytoplasm. The trophozoite propagated by ways of binary division. The acanthamoeba cysts were approximately 10 - 25 microm in diameter, round in shape and with a plica-like surface. The acanthamoeba could change from trophozoite to cyst. The amoeba emerging through ostioles could turn into trophozoite and left an empty cyst. After cultured with 0.02% chlorhexidine for 24 hours, the trophozoite and cyst collapsed and distorted. However, after clinical treatment with 0.02% chlorhexidine, only the cysts could be seen in corneal tissue of AK. Ecto-and endo-cystic walls were preserved, but the cytoplasma was aggregated and the sub-cytoarchitecture were degenerated or disappeared. DISCUSSION Chlorhexidine at a concentration of 0.02% kills acanthamoeba trophozoites and cysts in vitro. Chlorhexidine (0.02%) also kills trophozoites and inhibits the activity of cysts in corneal tissues. However, it should be noticed that the inactive cysts can stay in the cornea for a long time and may cause an immuno-pathologic inflammation of the cornea.

[Molecular characteristics of Acanthamoeba strains from keratitis patients].

OBJECTIVE: To study the molecular characteristics of Acanthamoeba strains isolated from keratitis patients. METHODS: Twenty six Acanthamoeba strains were isolated from corneal ulcers between 1994 and 2002. Partial genome DNA sequences of all strains of Acanthamoeba were amplified using PCR and then the PCR products were sequenced. The partial DNA sequences were analyzed by software Clustal X and MEGA2. The results of Acanthamoeba obtained from Beijing Tongren Hospital were compared with strains from other countries and districts. RESULTS: Of 26 Acanthamoeba strains isolated from the patients, 25 (96%) were 18S rDNA (Rns) genotype T4 and one (4%) was T3. These results were similar to those obtained from other countries and districts. CONCLUSIONS: According to the Rns genotype classification criterion, most of Acanthamoeba strains isolated from keratitis patients in Beijing are genotype T4 and only few of these strains are genotype T3. The Acanthamoeba infecting the cornea might belong to the specific 18S rDNA genotype.

Etiological analysis on ocular fungal infection in the period of 1989 - 2000.

BACKGROUND: This study was to review the distribution and shifting trend of fungal of culture specimens isolated from eyes of patients at the Beijing Institute of Ophthalmology, Tongren Hospital, Beijing, China. METHODS: The fungal culture-positive rate, the distribution and change of isolates of 2609 specimens collected in a 12-year period (1989 - 2000) were retrospectively analyzed. RESULTS: In 775 positive cultures, 707 specimens (91.2%) were from the cornea, 22 (2.8%) from the conjunctiva, 15 (1.9%) from the anterior chamber, 9 (1.2%) from the vitreous body, 3 (0.4%) from the lacrimal sac, and 19 (2.5%) from other parts of the eye. The average culture-positive rate was 29.7%. The ratio of the positive cultures in the first half year (from January to June) to those in the second half (from July to December) was 1:2.1. The main genus cultured was Fusarium sp (58.7%), followed by Aspergirum sp (16.8%). The percentage of Fusarium sp was increased from 53.6% (1989 - 1994) to 60.2% (1995 - 2000), whereas the percentage of Aspergirum sp was decreased from 22.3% (1989 - 1994) to 15.1% (1995 - 2000). CONCLUSIONS: Fusaruim sp is one of the most predominant pathogens of ocular fungal infection in northern China and its incidence tends to increase, but that of Aspergirum sp to decrease. It is very important to recognize the distribution and shifting trend of pathogenic fungi in the diagnosis, prevention and treatment of fungal keratitis.

[In vitro fluoroquinolone resistance in ocular bacterial isolates].

OBJECTIVE: To assess the in vitro resistance of ocular bacterial isolates to fluoroquinolone that are commonly used in the treatment of ocular infection. METHODS: Ocular bacterial isolates (n = 347) from Beijing Institute of Ophthalmology were tested for their resistance to ofloxacin, ciprofloxacin and norfloxacin. In vitro susceptibility testing was determined by the Kirby-Bauer disk diffusion method. RESULTS: The total number of ocular bacterial isolates was 347 from January, 1999 to December, 2000 including gram-positive cocci 192 (55.3%), gram-negative cocci 16 (4.6%), gram-positive bacilli 44 (12.7%), gram-negative bacilli 89 (25.7%), Nocardia 6 (1.7%). The percentage of resistance in total ocular bacterial isolates to ofloxacin, ciprofloxacin and norfloxacin was 28.5%, 25.9% and 34.9% respectively. The resistance of streptococcus species to ofloxacin (5.9%) and ciproloxacin (11.8%) was significantly lower than gentamycin (52.9%) and tobramycin (70.6%) (P < 0.01), and to norfloxacin (23.5%) was significantly lower than tobramycin (P < 0.01). Pseudomonas showed significantly lower resistance to ciprofloxacin (6%) ofloxacin (14.0%) and norfloxacin (14.0%) than gentamycin (42.0%) (P < 0.01 and P < 0.05). The percentage of resistance in staphylococcus species to norfloxacin (46.8%) was higher than gentamycin (30.8%) and tobramycin (27.6%) (P < 0.05 and P < 0.01 separately). The resistance of gram-positive bacilli to ofloxacin, ciproloxacin and norfloxacin. was equivalent (P > 0.05). CONCLUSIONS: The fluoroquinolones, ofloxacin and ciprofloxacin have higher overall in vitro efficacy on most of the ocular bacteria than gentamycin and tobramycin, but ofloxacin and ciprofloxacin are equivalent to gentamycin and tobramycin in efficacy against staphylococcus species.