Identification and genetic characterization of Angiostrongylus cantonensis isolated from the human eye.

Angiostrongylus cantonensis, or the rat lungworm, is the causative agent of human angiostrongyliasis associated with eosinophilic meningitis or meningoencephalitis. Additionally, this nematode can cause ocular angiostrongyliasis, though this is rare. The worm can cause permanent damage to the affected eye and sometimes even blindness. Genetic characterization of the worm from clinical samples is limited. In the present study, we investigated the genetics of A. cantonensis recovered from a patient's eye in Thailand. We sequenced two mitochondrial genes (cytochrome c oxidase subunit I, or COI, and cytochrome b, or cytb) and nuclear gene regions (66-kDa protein and internal transcribed spacer 2, or ITS2) from a fifth-stage larva of Angiostrongylus sample that was surgically removed from the human eye. All sequences of the selected nucleotide regions were highly similar (98-100%) to the sequences of A. cantonensis in the GenBank database. The maximum likelihood and neighbor-joining trees of the COI gene indicated that A. cantonensis was closely related to the AC4 haplotype, whereas the cytb and 66-kDa protein genes were closely clustered with the AC6 and Ac66-1 haplotypes, respectively. In addition, the phylogeny of the concatenated nucleotide datasets of the COI and cytb revealed that the worm was closely related to the Thai strain and strains from other countries. This study confirms the identification and genetic variation of the fifth-stage larvae of A. cantonensis recovered from a patient's eye in Thailand. Our findings are important for future research on the genetic variation of A. cantonensis that causes human angiostrongyliasis.

Clinical Course and Optical Coherence Tomography of Ocular Angiostrongyliasis: A Case Report.

Purpose: To report the clinical course and optical coherence tomography (OCT) findings of ocular angiostrongyliasis. Methods: A 36-year-old female with a history of ingesting regular raw freshwater shrimp and other raw food presented with acute unilateral painless visual loss in the right eye. Her right eye's best-corrected visual acuity (BCVA) was 1 ft of the count finger. Fundus examination showed vitritis, generalized retinal pigment epithelial alteration, and a moving roundworm in the vitreous at the 6 o'clock position. Macular OCT of her right eye showed thinning of the retina, loss of the external limiting membrane and ellipsoid zone, subretinal hyper-reflective material clumping, and hyper-reflective foci at the superficial choroidal layer. Results: The patient was administered oral and topical prednisolone. The roundworm, identified as Angiostrongylus cantonensis, was wholly extracted from the vitreous using a 23G sclerotomy port and pars plana vitrectomy. The final BCVA was 1 ft of the count finger. Conclusion: This case report describes an infrequent presentation and illustrates the clinical course and OCT findings of ocular angiostrongyliasis.

Causes of visual impairment in Thai diabetic patients in the visual rehabilitation clinic.

BACKGROUND: Visual disability from diabetic retinopathy is one of many public health problems. Knowing the causes of blindness and low vision in diabetic patients will help in policy planning in order to reduce diabetic complications and prevent blindness. OBJECTIVE: To study the causes of visual impairment, blindness and related factors in diabetic patients who registered at the visual rehabilitation clinic, Siriraj Hospital, Mahidol University, Bangkok. MATERIAL AND METHOD: A retrospective study of 133 diabetic patients who registered at the visual rehabilitation clinic between January 2007 and December 2010 was conducted. The patients were divided into 2 groups: a low vision group (VA in the better eye < 6/18-3/60) and a blindness group (VA in the better eye < 3/60--No light perception). The history of diabetic mellitus, associated systemic diseases, laboratory investigations, ocular changes and treatment were recorded. The causes of visual impairment and blindness were collected and analyzed. RESULTS: Of a total of 133 diabetic patients, 93 cases (69.9%) were in a low vision group and 40 cases (30.1%) were in a blindness group. The causes of visual impairment were proliferative diabetic retinopathy (84.6%), retinal detachment (37.2%), macular edema and scar (25.9%), optic atrophy (143%), neovascular glaucoma (11.7%) and vitreous hemorrhage (4.9%). Tractional retinal detachment (p-value < 0.001) and optic atrophy (p-value = 0.021) were the associated factors causing blindness in visual disability patients with statistical significance. Optic atrophy (38 eyes) occurred post vitrectomy in 19 eyes. CONCLUSION: Visual disability in diabetic patients is caused by the complications of diabetic retinopathy and its management. The prevention of disease progression, especially macular edema and proliferative diabetic retinopathy, will decrease the rate of visual impairment and blindness.

Correlation between body mass index and ocular parameters.

Purpose: To investigate the relationship between BMI and selected ocular parameters. Subjects and methods: Fifty-three left eyes of normal weight subjects and 67 age-sex matched overweight subjects were studied. Inclusion criteria for the normal weight and overweight groups included BMI between 18.5-22.9 and 23.0-29.9 kg/m2, respectively. Subjects with a history of systemic disease, ocular disease or surgery, or disability were excluded. All subjects underwent a medical history interview, arterial blood pressure, height, weight, waist circumference and hip circumference measurements, and BMI and waist-hip ratio calculation. The intraocular pressure (IOP) and anterior corneal curvature were measured by non-contact tonometry and corneal topography, respectively. Measurement of anterior and posterior segment parameters of the eye, including central corneal thickness, anterior chamber depth (ACD), anterior chamber angle, macular thickness (MT), ganglion cell thickness (GCT), retinal nerve fiber layer thickness, cup to disc ratio, and choroidal thickness was performed by enhanced depth-imaging optical coherence tomography. Results: There was a positive correlation between ACD and BMI (Univariate analysis; ß =0.198, P=0.030, Multivariate analysis; ß =0.410, P=0.005) and between BMI and IOP (Univariate analysis; ß =0.269, P=0.003). The IOP of the overweight group was found to be significantly higher than of the normal weight group (12.80±3.40 and 11.86±2.12 mm Hg, respectively, P=0.002). Also, there was a significant difference found between the GCT and the MT of the two groups (P=0.036 and 0.009, respectively). Conclusion: It was found that BMI strongly correlated with ACD and IOP. Also, the degree of obesity was found to be a significant factor; therefore, the relationship between these ocular parameters and the severity of obesity should be further investigated.