Herpes simplex virus and pterygium in Taiwan.

PURPOSE: To evaluate the presence of herpes simplex virus (HSV) in pterygia to study the possible association between HSV and pterygia in Taiwan, a tropical country with a high prevalence of pterygium. METHODS: Sixty-five pterygia, 10 normal conjunctiva, 8 conjunctival nevi, and 2 malignant conjunctival melanomas were obtained. Clinical histories were recorded for each patient. HSV detection was accomplished by polymerase chain reaction amplification of viral sequences. HSV-positive specimens underwent subsequent DNA in situ hybridization. Results were statistically analyzed. RESULTS: By using polymerase chain reaction, HSV was detected in 3 (5%) pterygia, and no conjunctival control displayed HSV. All 3 HSV-positive pterygia studies were DNA in situ hybridization negative. There was no statistically significant correlation between pterygium and the presence of HSV. CONCLUSIONS: HSV is not associated with pterygium formation in Taiwan; the pathogenesis of pterygia is still incompletely understood.

Multiphoton fluorescence and second harmonic generation microscopy for imaging infectious keratitis.

The purpose of this study is to demonstrate the application of multiphoton fluorescence and second harmonic generation (SHG) microscopy for the ex-vivo visualization of human corneal morphological alterations due to infectious processes. The structural alterations of both cellular and collagenous components can be respectively demonstrated using fluorescence and SHG imaging. In addition, pathogens with fluorescence may be identified within turbid specimens. Our results show that multiphoton microscopy is effective for identifying structural alterations due to corneal infections without the need of histological processing. With additional developments, multiphoton microscopy has the potential to be developed into an imaging technique effective in the clinical diagnosis and monitoring of corneal infections.

Multiphoton fluorescence and second harmonic generation imaging of the structural alterations in keratoconus ex vivo.

PURPOSE: To demonstrate the application of multiphoton fluorescence (MF) and second harmonic generation (SHG) microscopy for ex vivo characterization of the structural alterations of human corneas due to keratoconus. METHODS: Buttons of keratoconic corneas derived from penetrating keratoplasty were sent for structural analysis with a custom-built multiphoton microscope. Fluorescence detected within the cytoplasm and the SHG signal obtained from collagen were used to demonstrate the morphologic changes in the corneal specimens. RESULTS: The fluorescent epithelial cells around the apical area were elongated and were aligned parallel to the adjacent collagen fibers. Parallel and centripetal distribution patterns of stromal collagen bundles were demonstrated at different depths within the keratoconic corneas. CONCLUSIONS: MF and SHG microscopy provides three-dimensional structural analysis of keratoconus ex vivo. It may provide important morphologic information for the investigation of the pathogenesis of keratoconus and may have potential in a clinical setting as an in vivo diagnostic and monitoring system for advancing keratoconus.

Amniotic membrane transplantation for persistent corneal ulcers and perforations in acute fungal keratitis.

PURPOSE: To report the therapeutic effect and complications of amniotic membrane transplantation (AMT) in acute fungal keratitis. METHODS: Diagnosis of fungal keratitis was confirmed by cultures in 23 eyes of 23 patients. The indications to perform AMT were to promote reepithelialization in non-healing ulcers or to prevent corneal perforation. Antifungal agents were administered throughout the whole course of hospitalization. Repeated cultures were performed immediately before AMT. The main outcome measurements were epithelial healing rate, necessity of therapeutic penetrating keratoplasty (TPK), and persistence of infection. RESULTS: During a mean follow-up time of 20.6 months +/- 23.22 (6-65 months) AMT was performed during the active phase of the keratitis (fungal culture was still positive) in 16 patients (69.6%), and during the inactive phase (fungal culture negative) in 7 patients (30.4%). Single-layer AMT was performed in 17 patients, and double-layer AMT was performed in 6 patients with corneal perforation and anterior chamber collapse. Complete epithelialization was observed in 12 patients (75%) in the active group and in 7 patients (100%) in the inactive group. Treatment failure requiring TPK was experienced in 4 patients (25%) in the active group. Persistent fungal keratitis was noted in 2 patients (8.7%) in that group. The final visual acuity improved in 17 cases, worsened in 2 cases, and remained unchanged in 4 cases. Twelve of the 23 eyes (52.2%) in this study preserved useful vision (20/400 and better) with or without subsequent surgeries. CONCLUSION: AMT is effective in promoting epithelialization and preventing corneal perforations in acute fungal keratitis, and there is no risk of rejection. However, the risk of persistent or recurrent infection necessitates continued antifungal treatment and patient monitoring.

Medical treatment for combined Fusarium and Acanthamoeba keratitis.

PURPOSE: Acanthamoeba and fungal keratitis are rare ocular infections. We report cases of combined Fusarium and Acanthamoeba keratitis and the clinical course of medical treatment. METHODS: We reviewed the medical records of patients treated for culture-proven Acanthamoeba keratitis at a referral centre, during 2001-2006. RESULTS: Eleven consecutive patients were treated for culture-proven Acanthamoeba keratitis during the 5 years, two of whom had combined fungal infections. A 29-year-old man presented with ground-glass corneal oedema and epitheliopathy caused by contact lens use. The other patient, a 7-year-old girl, had eye trauma that led to a feathery corneal infiltrate. Both cases were treated with topical 0.02% polyhexamethylene biguanide (PHMB), 0.1% propamidine, 1% clotrimazole and 5% natamycin. Therapeutic keratoplasty was not required in either case. CONCLUSIONS: Timely identification of the pathogen, with repeated culture and smear if necessary, as well as adequate dosage to prevent recurrence is highly recommended in order to preclude the need for therapeutic penetrating keratoplasty.

Overview of laser refractive surgery.

Since approval of the use of the excimer laser in 1995 to reshape the cornea, significant developments in the correction of refractive errors such as myopia, hyperopia, and astigmatism have been achieved. Combined with other advanced ophthalmological instruments (e.g. anterior segment imaging systems, the femtosecond laser, wavefront-guided customized ablation) and the knowledge accumulated concerning the basic science of refractive errors (e.g. biomechanics and wound healing of the cornea, higher-order aberrations), laser refractive surgery has promisingly outshone other conventional techniques (e.g. radial keratotomy [RK], automated lamellar keratectomy [ALK]) in terms of both safety and efficacy. Photorefractive keratectomy (PRK) produces stable and predictable results with a safe profile. Similarly, laser in situ keratomileusis (LASIK) is also safe and efficacious with the additional advantages of rapid visual recovery and minimal postoperative pain. The choice between the two methods is made only after thoughtful discussion between the surgeon and the patient. Despite these advances, certain limitations and complications do exist. There are also specific and controversial circumstances for which studies should be conducted to make further breakthroughs and avoid annoying complications. In this review, the basic knowledge, surgical issues, and clinical outcomes, of laser refractive surgery, as well as complex cases, will be presented.

Acanthamoeba keratitis presenting as dendritic keratitis in a soft contact lens wearer.

Acanthamoeba keratitis is a rare cause of corneal infection in Taiwan, which can result in devastating visual outcomes. A 37-year-old woman, who wore soft contact lenses, suffered from severe pain in her left eye. Biomicroscopy revealed dendritic keratitis, radial keratoneuritis, and fine keratic precipitates on her cornea. Culture, using non-nutrient agar plate seeded with Escherichia coli, resulted in heavy growth of Acanthamoeba. The inpatient treatment, including topical neomycin-polymyxin B and metronidazole (0.5%) eyedrops, oral ketoconazole, and then oral prednisolone, successfully controlled the corneal infection. The best-corrected visual acuity was 0.9 without any evidence of recurrence of infection after 21 months of follow up. Acanthamoeba keratitis can present as dendritic keratitis, which mimics herpes simplex infection, thus, delays appropriate treatment. Early diagnosis and judicious treatment are essential for restoring the vision and avoiding the subsequent need of penetrating keratoplasty.

Annual database of intraocular lens power in a Taiwanese population.

BACKGROUND: To derive a unique database of intraocular lens (IOL) power for Taiwanese, an ethnic group with a strikingly high prevalence of myopia. METHODS: A retrospective series of 3068 cases visiting Chang Gung Memorial Hospital, Linkou for cataract removal and posterior chamber IOL implantation between July 1999 and June 2000 was reviewed. The distribution of IOL powers and a possible age-correspondence was analyzed by one-way analysis of variance (ANOVA) test and multiple regression. RESULTS: Using the SRK/II linear regression formula, with an "A" constant of 118.5, the mean predicted IOL power required for emmetropia was 20.0 +/- 5.1 diopter (D). The mean IOL power for males was 19.8 +/- 5.1 D. The mean IOL power for females was 20.1 +/- 5.1 D. Moreover, ANOVA results documented a statistically significant tendency of age-dependence for IOL power distribution in the 3 groups (male, female, and male and female; F=24.53, p<0.05; F=16.39, p<0.05; F=40.54; p<0.05, respectively). In particular, it statistically significantly differed among decades over 40 years indicating that IOL power increased with age. However, the implanted IOL power decreased with age in patients younger than 40 years old. Multiple regression analysis showed that age, but not gender, was statistically significantly correlated to the IOL power distribution (p<0.05). CONCLUSION: We provide a unique database of IOL power for cataract surgeries in Taiwan. An age-related correspondence of the database of IOL powers was also documented in this study, which can therefore be regarded further cross-sectional evidence for the age-dependence prevalence of myopia.