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Biomedical subjects

W J Sah

Publications and source records attributed to W J Sah.

14 recordsLinked to original sources
PubMed2001

Amniotic membrane, tear film, corneal, and aqueous levels of ofloxacin in rabbit eyes after amniotic membrane transplantation.

PURPOSE: We evaluated ocular penetration and drug levels in tears after topical ofloxacin instillation in rabbit eyes with amniotic membrane transplantation (AMT). METHODS: Forty-eight New Zealand White rabbits were used. In the first set of experiments, 24 rabbits (24 eyes) were divided into four groups according to the epithelial removal or AMT. Topical ofloxacin was instilled four times every 15 minutes. One hour after the last eyedrop, the concentration of ofloxacin in the amniotic membrane, cornea, and aqueous humor was evaluated. In the second set of experiments, 24 rabbits were divided into six groups according to AMT (transplantation of lyophilized or fresh amniotic membrane) or duration of application. Ofloxacin ointment or two drops of ofloxacin were applied to the right eye, and then tear samples were collected after 0.5, 1, 2, 4, and 6 hours for the analysis of ofloxacin concentration. RESULTS: Mean ofloxacin concentrations in the cornea and aqueous humor were statistically higher in deepithelialized cornea regardless of AMT (p < 0.05). The mean tear levels of ofloxacin in the AMT groups were statistically higher than those in non-AMT groups (p < 0.05). There was no statistical significance in the tear level of ofloxacin between lyophilized amniotic membrane groups and fresh amniotic membrane groups nor between 1-hour amniotic membrane-attached groups and 6-hour amniotic membrane-attached groups. CONCLUSION: Amniotic membrane transplantation seems to interfere with the ocular penetration of topical ofloxacin in normal rabbit corneas but enhances ofloxacin penetration in corneas with epithelial defects. The ofloxacin level in tears was higher in eyes with AMT up to 1 hour after topical ofloxacin use. Therefore, it seems that amniotic membrane has some potential to act as an effective drug delivery system.

Administration, Topical↗
PubMed1998

Treatment of total hyphema with relatively low-dose tissue plasminogen activator.

The purpose of this study is to investigate the efficacy of tissue plasminogen activator (tPA) in the treatment of total hyphema following ocular trauma or intraocular surgery. Three patients (3 eyes) representing unresolved total hyphema for more than 5 days and uncontrolled high intraocular pressure received intracameral injections of 10 microgram of recombinant tPA. Intracameral tPA injection resulted in complete resolution of hyphema in all 3 eyes. Resolution occurred mostly within 24 to 48 hours after injection. Possible side effects of tPA injection, such as increased intraocular pressure and corneal edema, were not observed. However, 1 eye had vitreous hemorrhage after repeated injections of tPA. Intracameral injection of tPA seems to be a safe and effective method for the treatment of unresolved total hyphema. However, repeated intracameral tPA injections may cause unwanted complications such as vitreous hemorrhage.

Adult↗
PubMed1997

Five years results of photorefractive keratectomy for myopia.

PURPOSE: To evaluate the long-term stability, complications, and causative factors in eyes that had photorefractive keratectomy (PRK) for myopia. SETTING: Kangnam St. Mary's Hospital, Seoul, Korea. METHODS: This study evaluated the results of PRK in 201 myopic eyes with a consecutive 5 year follow-up. Preoperative myopia ranged from 2.25 to 12.50 diopters (D), with astigmatism of less than 1.50 D. The Excimer laser was set to a maximum correction of -6.50 D at a 5.0 mm diameter ablation zone. Patients with more than 7.00 D of myopia had double-pass PRK with two different ablation zone sizes (5.0 and 4.5 mm). The data were statistically analyzed using polynomial regression for evaluating long-term stability and myopic regression and Cox's proportional hazard model for evaluating causative factors. RESULTS: An uncorrected visual acuity better than 20/25 was achieved in 62.4% of eyes. The main complication after PRK was myopic regression. Mean refractive error 5 years after PRK was -2.43 +/- 1.90 D. It was -1.49 +/- 0.60 D in moderately myopic eyes (less than 6.50 D) and -3.55 +/- 2.31 D in highly myopic eyes (over 7.00 D). According to our evaluation, the possible causative factors for myopic regression were pre-PRK refraction (P < .0001) and post-PRK corneal haze (P = .01); their relative risks were 3.33 and 1.93, respectively. Multivariate analysis eliminated the corneal haze factor. CONCLUSION: Myopic regression occurred as long as 5 years after PRK, with the most important factor for myopic regression being pre-PRK refraction.

Adult↗
PubMed1996

Myopic regression after photorefractive keratectomy.

BACKGROUND AND OBJECTIVE: Myopic photorefractive keratectomy (PRK) using the 193 nm excimer laser is an effective and precise surgical procedure to correct myopia, but not without complications, such as corneal haze, over- or undercorrection, halo, glare, and myopic regression. Among these, myopic regression, which can reduce uncorrected visual acuity, is the most common and progressive long-term complication. PATIENTS AND METHODS: We evaluated 228 eyes that received successful myopic PRK with the Summit excimer laser (ExciMed UV 200LA, 5.0 mm optical zone) and followed up more than three years at Kangnam St. Mary's hospital. Two hundred twenty eight eyes were divided into 3 groups according to the degree of preoperative myopia and correction: Group I, 79 eyes of moderate myopia (-2.25 to-6.75 diopters [D]) with full correction; Group II, 110 eyes of high myopia (-7.00 to -12.50 D) with full correction by two-zone ablation; Group III, 29 eyes of high myopia (-7.00 to -12.00 D) with partial correction of 6.00 D. Retrospective analysis of the data was performed with statistical evaluation of the incidence of myopic regression, regression formula, coefficient of parameters, and cumulative hazard of regression in each group. RESULTS: An incidence of myopic regression greater than 1.00 D was noted in 40.5%, 83.3%, and 18.2% of patients in Group I, II, and III, respectively. The regression formula obtained from the repeated measure ANOVA was Y = 2.13 -0.47 InX, Y = 3.02 -0.82 InX, and Y = 3.69 -0.50 InX, in Group I, II, and III, respectively. The amount of correction was a statistically significant correlation factor to the myopic regression (Pearson's correlation coefficient = 0.78, P < 0.001). The amount of preoperative myopia may act as a negative correlation factor to the myopic regression. According to the Kaplan-Meyer survival table, the cumulative correlation hazard was significantly higher in high myopia with full correction than in moderate myopia with full correction. CONCLUSION: Our results indicated that the incidence and amount of myopic regression have a tendency to be dependent on the amount of correction, but may be reduced as the preoperative myopia increases, if the amount of correction is the same. A longer term and more detailed study of PRK using a 6.0 mm optical zone will be needed to determine how the amount of preoperative myopia and would profiles affect the myopic regression.

Adult↗
PubMed1994

Excimer laser photorefractive keratectomy for myopia: two-year follow-up.

We evaluated the results of photorefractive keratectomy (PRK) with an excimer laser on 45 consecutive myopic eyes (23 patients) that were followed two years or more. The myopic range was from -2.00 diopters (D) to -6.00 D with astigmatism less than 1.50 D. Uncorrected visual acuity better than 20/25 was achieved in 88.9% of all cases two years postoperatively. Best corrected visual acuity was equal to or better than preoperatively in 95.6% of eyes. The difference between the attempted and achieved correction was within +/- 1.00 D in 91.1% two years postoperatively. Keratometric readings and central corneal thickness showed a gradual restoration until six months postoperatively and then stabilized. The cornea was clear in 66.7% of the eyes. The most common subjective complaint was decreased night vision two years after PRK. From our experience, excimer laser PRK is a predictable and effective surgical method to correct myopia up to -6.00 D in a single-step procedure.

Adult↗
PubMedDate not supplied

Acridine orange staining for rapid diagnosis of Acanthamoeba keratitis.

Acanthamoeba keratitis is uncommon, but one of the most severe infectious diseases of the cornea. Delayed diagnosis or misdiagnosis as bacterial or herpes simplex keratitis leads to extensive corneal inflammation and profound visual loss. Therefore, accurate and rapid diagnosis of Acanthamoeba keratitis is essential for successful treatment and good prognosis. We evaluated the usefulness of acridine orange staining from corneal scrapings and contact lens solutions for the rapid diagnosis of four consecutive cases of Acanthamoeba keratitis. Gram stain and culture on nonnutrient agar plates with Escherichia coli overlay were also made. Corneal scrapings stained with acridine orange revealed yellow-to-orange polygonal, cystic structures consistent with the appearance of Acanthamoeba among inflammatory cells and the corneal epithelial cells. The contact lens case solutions of two patients also showed numerous cysts with double wall. Some organisms from the third patient were identified as Acanthamoeba castellani and others as Acanthamoeba lugdunensis. Based on the acridine orange staining results in four cases of Acanthamoeba keratitis, this stain is recommended as a simple and reliable method for the rapid diagnosis of this disease.

Acanthamoeba↗
PubMedDate not supplied

Three-year results of photorefractive keratectomy for myopia.

We evaluated the results of single-step photorefractive keratectomy (PRK) on 35 consecutive myopic eyes (19 patients) with follow up of 3 years or more. The range of preoperative myopia was from -2.00 diopters (D) to -6.00 D with astigmatism of less than 1.50 D. The excimer laser used in this study was the ExciMed UV 200LA, (Summit Technology), which was set to a maximum correction of -6.00 D at a 5.0-mm diameter ablation zone. Uncorrected visual acuity better than 20/25 was achieved in 82.9% of eyes. Spectacle corrected visual acuity was equal to or better than that of preoperative levels in 94.3%. The difference between attempted and achieved correction was within 1.00 D in 60.0% of eyes. The myopic regression curve was Y = 3.679-0.6876 log (X). If the regression remains constant, we expect that refraction at 5 years after PRK would be -1.48 D. Trace corneal haze was present in 12 eyes (34.3%). At three years the most common subjective complaint was mild decreased night vision with asthenopia. The findings suggest that myopic regression can occur as long as 3 years after PRK.

Adult↗
PubMedDate not supplied

Photorefractive keratectomy for undercorrected myopia after radial keratotomy: two-year follow up.

We evaluated the clinical results of excimer laser photorefractive keratectomy (PRK) on 18 myopic eyes of 13 patients with residual myopia after radial keratotomy. Follow up was 24 months or more and the time interval between radial keratotomy and PRK ranged from 12 to 94 months. Patients were divided into two groups for analysis based on their preoperative myopia: group 1 (-6.00 diopters (D) or less), group 2 (more than -6.00 D). Uncorrected visual acuity at 2 years follow up was 20/40 or better in 86% (group 1) and 50% (group 2). Mean manifest refractive change was from -3.55 D to -0.91 D in group 1 and from -7.44 D to -2.50 D in group 2. Predictability within 1.00 D between attempted and achieved correction was 71.4% (group 1) and 80% (group 2). Most complications were transient except decreased spectacle corrected visual acuity in one eye--a complication also reported by others. Glare (61%) and decreased vision at night (50%) were the most troublesome subjective symptoms. These results show that previous radial keratotomy may not influence the myopic correction of PRK. Planned two-stage myopic correction (PRK after radial keratotomy) in high myopia can be considered a useful technique.

Adult↗
PubMedDate not supplied

Some problems after photorefractive keratectomy.

We analyzed the data from 1821 patients (2920 eyes) who received photorefractive keratectomy (PRK) to investigate the postoperative complications which cause a significant decrease in visual acuity. A corneal haze of grade 2 or more developed in 9 patients (11 eyes, 0.38%) and corticosteroid-induced ocular hypertension occurred in 3 patients (4 eyes, 0.14%). Three patients (4 eyes) who had corneal haze of grade 2 or more underwent repeated photorefractive keratectomy and one patient (2 eyes) with steroid-induced ocular hypertension underwent trabeculectomies. A decrease of best spectacle corrected visual acuity of two lines or more was detected in 7 patients (8 eyes, 0.27%), caused by irregular astigmatism, steroid-induced cataract, incidental choroidal neovascular membrane, and an unknown origin. Good predictability and stabilization after photorefractive keratectomy was maintained at the 2 year follow-up. However, some subjective symptoms were reported by many patients and some complications occurred in a minority of eyes despite the excellent visual outcome in a large majority.

Cornea↗
PubMedDate not supplied

Photorefractive keratectomy in 202 myopic eyes: one year results.

We performed one-step procedures of photorefractive keratectomy (PRK) with the use of the excimer laser (193 nm) on 1519 myopic eyes during 1 year. From this group, we prospectively evaluated visual and refractive results of 202 (13%) consecutive myopic eyes that were followed for more than 1 year. Myopic eyes were divided into two groups according to the amount of myopia: group I, 135 eyes, 87 patients, less than -7.00 D, and group II, 67 eyes, 48 patients (-7.25 D to -13.50 D). The excimer laser system used was the ExciMed 200UV (Summit Technology, Inc, Waltham, Mass), the one-step computer program was fixed at a maximum ablation up to -6.00 D correction. Uncorrected visual acuity of 20/25 or better was achieved in 89.6% of eyes in group I and 47.8% in group II at 1 year. Best spectacle corrected visual acuity was equal to, or better than, the preoperative level in 93.8% of eyes. The difference between attempted and achieved refractive correction was within +/- 1.00 D in 91.4% in group I, and 51.7% in group II. The mean reduction of manifest (spherical equivalent) refraction in group II was 6.84 D at 1 year. Keratometric readings and central corneal thickness showed gradual changes until 6 months after surgery. Corneal haze disappeared in most of eyes at 1 year. The most common subjective complaint was glare and/or decreased vision at night or under dim light.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Phototherapeutic keratectomy in nine eyes with superficial corneal diseases.

We performed phototherapeutic keratectomy (PTK) in seven patients (nine eyes) with superficial corneal disease such as band keratopathy (one patient), Reis-Bückler's dystrophy (one patient, two eyes), granular dystrophy (two patients, three eyes), recurrent granular dystrophy (one patient), postinfection scar (one patient), and corneal scarring after pterygium removal (one patient). All patients received PTK after topical anesthesia with Pontocaine 0.5% and underwent epithelial removal with a surgical blade. We used methylcellulose 1.0% as a surface modulator before laser ablation. Focal ablation of the central cornea with an ablation zone of 5 mm was performed routinely in most eyes and a smoothing technique was applied only in two eyes. All patients were followed for more than 9 months. Uncorrected and corrected visual acuity were significantly improved in six patients (8 eyes) and a mild hyperopic shift occurred in all eyes that received PTK centrally. Mild to moderate corneal haze appeared in these corneas during the first few months after surgery. Some patients avoided the need for keratoplasty. No significant complications occurred after PTK except recurrence of granular deposits in one case of granular dystrophy. We think that PTK with the 193-nanometer excimer laser is indicated in the treatment of some superficial corneal disorders.

Adult↗
PubMedDate not supplied

Clinical experience of two-step photorefractive keratectomy in 19 eyes with high myopia.

The maximum myopic correction with one-step ablation in excimer laser photorefractive keratectomy (PRK) using the ExciMed UV200 LA 193-nanometer excimer laser (Summit Technology, Inc, Waltham, Mass,) is only up to 6.00 D because of a fixed computer program. We performed a simultaneous two-step PRK procedure for nearly full correction on 19 eyes of 19 patients with myopia ranging from -8.00 to -13.50 D. We clinically evaluated the results of this modified technique at 6 months, or more, after surgery. In the two-step PRK procedure, we attempted in the first-step of a maximum correction of -6.00 D (including up to -7.50 D) with 4.5-millimeter ablation zone. The second step was performed immediately thereafter to correct the remaining myopia with a 5.0-millimeter diameter ablation. Mean preoperative manifest refraction was -9.77, D and mean postoperative manifest refraction was -1.09 D at 6 months after two-step PRK. Uncorrected visual acuity of 20/40 or better was achieved in 74% of 19 eyes (two were amblyopic eyes). Corneal subepithelial haze was trace or +1 in all cases at 3 months, but faded out after 3 months. Transient intraocular pressure elevation occurred in one case. No other significant complications developed. Long-term follow up will be required to evaluate the results of two-step PRK.

Adult↗
PubMedDate not supplied

Rotational autokeratoplasty in advanced lipid keratopathy.

1. Autokeratoplasty (AKP) has many advantages, such as having no immune reaction, providing easy postoperative care in younger patients, having susceptibility to amblyopia without delay, and demonstrating no vascularization of the autograft. 2. AKP does have its disadvantages, including limitations of patient selection and a high rate of postoperative astigmatism, anterior synechia, and glaucoma. 3. The largest problem inhibiting the widespread use of AKP is the limitations of patient selection.

Adult↗