Biomedical subjects

N X Nguyen

Publications and source records attributed to N X Nguyen.

At least 37 records · Page 2Linked to original sources

PubMed2000

[Blood-aqueous barrier after phacoemulsification with posterior chamber lens implantation; foldable acrylate lens vs PMMA lens-- a clinical study on 46 eyes].

BACKGROUND: Cataract surgery leads to a more or less pronounced postoperative inflammation due to breakdown of the blood-aqueous barrier. This alteration of the blood-aqueous barrier can be reduced by minimally invasive surgery. The purpose of this study was to quantify the early course of the postoperative alteration of the blood-aqueous barrier following phacoemulsification with implantation of conventional PMMA posterior chamber lens (IOL) in comparison with foldable acrylic lens implantation. PATIENTS AND METHODS: Forty-six eyes of 46 patients (age 63 +/- 8.8 years) without preexisting deficiences of the blood-aqueous-barrier or previous intraocular surgeries were divided into two groups: group 1 (24 patients): phacoemulsification with one-piece-PMMA-IOL implantation (6.5 mm corneoscleral tunnel incision); group 2 (22 patients): phacoemulsification with foldable acrylic-IOL implantation (3.5 mm incision, 15 patients with corneoscleral tunnel and 7 patients with clear cornea incision). All surgical procedures were performed by one surgeon. The postoperative treatment was standardized. Alteration of the blood-aqueous barrier was quantified by the laser flare-cell meter (Kowa, FC-1000) preoperatively and on the first and the second day after surgery. RESULTS: Preoperative aqueous flare values (photon counts/ms) were comparable in both groups (6.7 +/- 2.7 versus 5.6 +/- 2.7 respectively, p = 0.1). On day 1, aqueous flare in group 1 (9.7 +/- 2.9) was not statistically significantly higher than in group 2 (9.2 +/- 2.2, p = 0.2) and remained relatively constant on day 2 after surgery (9.3 +/- 3.3), whereas the aqueous flare values in group 2 decreased statistically significant (6.7 +/- 2.3, p = 0.01). Postoperatively, there was no statistically significant difference of aqueous flare values between eyes with corneoscleral tunnel incision and eyes with clear corneal incision (p = 0.7) in group 2. CONCLUSIONS: Our study shows that phacoemulsification with foldable IOL implantation leads to a mild and short-lasting alteration of the blood-aqueous barrier. Thus, implantation of foldable IOL may be useful in eyes especially with preexisting alteration of the blood-aqueous-barrier.

Acrylates↗

PubMed2000

[Frequency and risk factors of intraocular pressure increase after penetrating keratoplasty].

PURPOSE: The aim of this study was to evaluate the incidence, risk factors and management of glaucoma following penetrating keratoplasty (PK) and to check for possible correlations with the indication for PK. PATIENTS AND METHODS: 534 eyes of 483 patients (age 54.7 +/- 19.8 years), that had undergone PK from 1989 to 1999 were retrospectively analyzed. The mean follow-up was 2.7 +/- 1.8 years. According to the type of surgical procedure patients were classified in 5 groups: group 1) PK only (n = 291); group 2) PK combined with extracapsular cataract extraction and intraocular lens (IOL) implantation (n = 124); group 3) PK combined with secundary IOL-implantation or IOL-change (n = 32); group 4) PK only after previous cataract surgery (n = 55) and group 5) Cataract surgery after PK (n = 32). The trephination was performed from the epithelial side in donor and recipient either by nonmechanical trephination with the 193 nm excimer laser (n = 444) or mechanical trephination (n = 90). An iridotomy was performed routinely during PK. The postoperative treatment with topical steroids was standardized. RESULTS: Preoperatively, glaucoma was diagnosed in 3.2% for all patients with groups 3 und 4 showing a significantly larger number of glaucomatous eyes (15.6% and 18.9%). Most of the mild early intraocular pressure elevations in group 1 (3.4%) and group 2 (3.0%) were controlled after 6 months (0.5% and 1.1%). Groups 3 and 4 showed most frequently increased intraocular pressure and/or antiglaucomatous treatment (21.4% and 18.7%) six weeks postoperatively. Patients in all groups showed no higher prevalence of persistent glaucoma from six months postoperatively than preoperatively throughout the follow-up period. Again groups 3 and 4 presented the largest number of persistent glaucoma. In most eyes the IOP was controlled by topical antiglaucomatous treatment. Serious forms seen in 2 patients with anterior synechiae caused by anterior chamber lens required several filtering surgeries or pars plicata diathermy, respectively. One patient with pseudoexfoliation syndrome required laser trabeculoplasty. The so-called "Urrets-Zavalia syndrome" was seen in none of the patients. CONCLUSION: The development of increased intraocular pressure after PK varied with the indication for keratoplasty. Postkeratoplasty glaucoma seems to be strongly associated with preexisting anterior synechiae and/or simultaneous anterior chamber lens implant removal. Intraoperative iridotomy can prevent the development of acute angle closure glaucoma after keratoplasty.

Adult↗

PubMed2000

[Regression analysis of corneal endothelium after nonmechanical penetrating keratoplasty].

PURPOSE: The corneal endothelial cell density is a crucial parameter for the pump function and the transparency of grafts after penetrating keratoplasty (PK). The purpose of this study was to assess corneal endothelial cell density with different regression models after nonmechanical penetrating keratoplasty and to check for differences between diagnoses and two different storage methods. PATIENTS AND METHODS: Two-hundred ninety-six eyes (195 keratoconus, 101 Fuchs' dystrophies, 148 each with short-term preserved and organ-cultured donor corneas) of 268 patients were included in this prospective study. Donor and recipient trephination was performed using nonmechanical trephination technique with the excimer laser 193 nm along metal aperture masks from the epithelial side. The time course of the endothelial cell density (specular microscope EM 1100, TOMEY, Erlangen) after PK was assessed. Endothelial cell density was first analyzed in a cross sectional manner at the 3, 6, 12, 18 and 24 months follow-up and, secondly in a longitudinal manner with linear, polynomial and exponential regression models in the sense of minimizing the residuum (distance between observed and predicted endothelial cell count). The mean donor postmortem time was 10.3 +/- 6.8 hours for short-term-preserved and 19.6 +/- 9.5 hours for organ-cultured corneas (p < 0.0001). The storage time was 63 +/- 49 and 19 +/- 7 days (p < 0.0001), respectively. RESULTS: In a cross section, overall mean endothelial cell density decreased from 2145 +/- 599 cells/mm2 at the 3 months to 1751 +/- 605 cells/mm2 at 2 years follow-up (p > 0.05). Cell density did not differ significantly between different diagnoses or storage methods at any postoperative stage. In a longitudinal section, the linear regression model estimated an annual decrease of 214 cells/mm2. In a polynomial model the decrease expressed by a tangent to the regression line at 24 months was 175 cells/mm2. The exponential regression model yielded a relative decrease of 9.5% annually. The so-called residuum as a measure for the validity of the regression model was maximal in the linear and minimal in the exponential estimate. With keratoconus and short-term preserved donor material the endothelial cell loss was less in the regression analysis. CONCLUSION: During the first two years after nonmechanical trephination in PK, a non-significant decrease in endothelial cell density was observed. The exponential regression model seems to be predestinated for analysis of the time course of corneal endothelium in a longitudinal manner. The annual cell loss ranged around 9.5% without significant differences between diagnoses and storage methods.

Adolescent↗

PubMed2000

[Laser tyndallometry and monitoring of treatment in 20 children with juvenile uveitis].

BACKGROUND: Treatment of children with juvenile uveitis requires adequate control of inflammation while minimizing systemic or ocular side effects. The study was performed to evaluate the potential use of the laser flare-cell meter in monitoring and adjustment of therapy in juvenile uveitis. PATIENTS AND METHODS: Retrospectively, we monitored 20 children (11 girls and 9 boys) with an age range from 3 to 15 years presenting with juvenile iridocyclitis (10/20), intermediate (5/20) or posterior (5/20) uveitis. During the follow-up period (median 25.2 months, range: 2 to 83 months) multiple clinical controls were performed. We recorded clinical data, present therapy, and measurements using the laser flare-cell meter (Kowa FC-1000). RESULTS: Laser flare-cell meter measurements were easily obtained and highly reliable even in these young patients. During follow-up, 36 recurrences of intraocular inflammation were detected in 19 eyes. Relapses of inflammation as well as a response to treatment were seen at an early stage. Semiquantitative observations of cells and aqueous flare in the anterior chamber, or visual acuity of patients were less reliable in predicting recurrences. CONCLUSIONS: Laser tyndallometry offers a reliable, examiner-independent method to assess intraocular inflammation in children with juvenile uveitis and to adjust the necessary treatment.

Adolescent↗

PubMed1999

Quantification of aqueous flare after phacoemulsification with intraocular lens implantation in eyes with pseudoexfoliation syndrome.

BACKGROUND: Impairment of the blood-aqueous barrier is a frequent finding in eyes with pseudoexfoliation syndrome (PEX). OBJECTIVE: To perform noninvasive quantification of aqueous flare using the laser flare-cell meter to analyze blood-aqueous barrier breakdown following phacoemulsification with intraocular lens implantation in eyes with and without PEX. METHODS: After other conditions that might account for impairment of the blood-aqueous barrier were excluded, 11 eyes with PEX and 11 eyes with senile cataract without PEX were included in the study. Aqueous flare was quantitatively determined using a laser flare-cell meter preoperatively as well as 1, 3, and 5 days postoperatively. Phacoemulsification with posterior chamber intraocular lens implantation was performed by one surgeon. RESULTS: On the first postoperative day, flare values (calculated as mean+/-SD photon counts per millisecond) in eyes with PEX were higher (42.2+/-21.3) than in eyes without PEX (30.6+/-15.1) (P>.05). On days 3 and 5, postoperative flare values decreased slowly in eyes with PEX (23.9+/-7.4 and 21.2+/-5.7 photon counts per millisecond, respectively) and were significantly higher than in eyes without PEX (14.8+/-5.4 and 10.5+/-1.4 photon counts per millisecond, respectively) (P<.05). CONCLUSIONS: Breakdown of the blood-aqueous barrier is significantly more extensive in eyes with PEX and may be an important risk factor for early postoperative complications. The altered response to surgery should be considered in eyes with PEX.

Aged↗

PubMed1999

Quantification of blood-aqueous barrier breakdown after photorefractive keratectomy for myopia.

BACKGROUND: Photorefractive keratectomy (PRK) using the excimer laser is a well-established surgical technique for correction of mild to moderate myopic refraction errors in case of spectacle or contact lens incompatibility. As it is still uncertain whether this procedure causes intraocular inflammatory changes, it was the purpose of this study to quantify breakdown of the blood-aqueous barrier following PRK and to look for possible correlations with clinical parameters. PATIENTS AND METHODS: Aqueous flare was quantified using the laser flare-cell meter after medical pupil dilation preoperatively and on days 1, 3 and 7 as well as 1 month and 3 months following PRK with a 193-nm excimer laser (MEL 60, Aesculap-Meditec) in 37 eyes of 22 patients. The preoperative spherical equivalents were -4.4 +/- 3.1 D (range -1.5 to -8.0 D). Pre-, intra- and postoperative treatment was standardized. RESULTS: Preoperatively, aqueous flare values were 3.9 +/- 0.8 photon counts/ms and showed no significant correlation with the spherical equivalent (p > 0.1). Postoperatively, aqueous flare rise was very small with flare values not significantly higher than preoperative values. All postoperative flare values were below the normal limit (< 8.0 photon counts/ms). Flare was highest on day 3 after PRK surgery. There was no statistically significant correlation between aqueous flare and depth of stromal ablation. The number of aqueous "cells" did not increase following PRK at any postoperative follow-up examination. CONCLUSION: Our results indicate that PRK in mild to moderate myopia does not cause a significant breakdown of the blood-aqueous barrier.

Adult↗

PubMed1999

Underestimation of intraocular lens power for cataract surgery after myopic photorefractive keratectomy.

OBJECTIVE: To assess the validity of corneal power measurement and standard intraocular lens power (IOLP) calculation after photorefractive keratectomy (PRK). DESIGN: Nonrandomized, prospective, cross-sectional, clinical study. PARTICIPANTS: A total of 31 eyes of 21 females and 10 males with a mean age at the time of surgery of 32.3 +/- 6.6 years (range, 24.4-49.5 years). INTERVENTION: Subjective refractometry, standard keratometry, TMS-1 corneal topography analysis, and pachymetry were performed before and 15.8 +/- 10.4 months after PRK for myopia (n = 24, -1 .5 to -8.0 diopters [D], mean -5.4 +/- 1.9 D) or myopic astigmatism (n = 7, sphere -2.0 to -7.5 D, mean -4.4 +/- 1.9 D; cylinder -1.0 to -3.0 D, mean -1.9 +/- 0.7 D). The IOLP calculations were done using two different formulas (SRK/T and HAIGIS). MAIN OUTCOME MEASURES: Keratometric power (K) and topographic simulated keratometric power (TOPO) as measured (Kmeas, TOPOmeas) and as calculated according to the change of power of the anterior corneal surface or according to the spherical equivalent change after PRK (Kcalc, TOPOcalc), IOLP for emmetropia, and postoperative ametropia for calculated corneal powers were assessed in a model. RESULTS: After PRK, mean Kmeas and TOPOmeas were significantly greater (0.4-1.4 D, maximum 3.3 D) than mean KRcalc and TOPOcalc (P < 0.0001). On average, the relative flattening of the cornea after PRK was underestimated by 14% to 30% (maximum, 83%) depending on the method of calculation. The mean theoretical IOLP after PRK ranged from + 17.4 D (SRK/T, TOPOmeas) to +20.9 D (HAIGIS, Kcalc) depending on the calculation method for corneal power and IOLP calculation formula used. For both formulas, IOLP values using keratometric readings were significantly higher (>1 D) than IOLP values using topographic readings (P < 0.0001). The theoretically induced mean refractive error after cataract surgery ranged from +0.4 to +1.4 (maximum, +3.1) D. Corneal power overestimation and IOLP underestimation correlated significantly with the spherical equivalent change after PRK (P = 0.001) and the intended ablation depth during PRK (P = 0.004). CONCLUSIONS: To avoid underestimation of IOLP and hyperopia after cataract surgery following PRK, measured corneal power values must be corrected. The calculation method using spherical equivalent change of refraction at the corneal plane seems to be the most appropriate method. In comparison with this method, direct power measurements underestimate corneal flattening after PRK by 24% on average. Use of conventional topography analysis seems to increase the risk of error. However, because this study is retrospective and theoretical, there is still a need for a large prospective investigation to validate the authors' findings.

Adult↗

PubMed1999

[Transplant endothelium and measuring corneal thickness after non-high-risk keratoplasty with briefly or long-term preserved corneal donor tissue].

PURPOSE: The corneal endothelial cell density is essential for the pump function and the transparency of grafts after penetrating keratoplasty (PK). The purpose of this study was to assess corneal endothelial cell density after non-high-risk PK and to check for possible correlations with storage parameters of the donor corneas using two different storage methods. PATIENTS AND METHODS: Endothelial cell density (specular microscope EM 1100, TOMEY, Erlangen) and central corneal thickness (ultrasonic pachymetry SP-2000, TOMEY, Erlangen) were assessed 6 weeks, 3, 6, 9 months and one year postoperatively in 168 non-high-risk PKs. Short-term-preserved donor corneas were used in 89 patients, whereas in 79 patients organ-cultured corneas were used. The donor trephination was performed from the epithelial side using an artificial anterior chamber. The postoperative treatment with topical steroids was standardized. The mean donor post-mortem time was 9.6 +/- 8.0 hours for short-term-preserved and 17.6 +/- 10.5 hours for organ-cultured corneas (p < 0.0001). The storage time was 71 +/- 49 and 380 +/- 167 hours (p < 0.0001), respectively. RESULTS: Endothelial cell density did not differ significantly between the two storage methods (p > 0.05). At 6 weeks postoperatively, the mean endothelial cell density was 2042 +/- 675 cells/mm2 for short-term-preserved corneas and 1972 +/- 522 cells/mm2 for organ-cultured corneas (p = 0.7). Endothelial cell density did not decrease significantly (p > 0.05) within the observation period of 12 months in both groups (after 12 months: 1868 +/- 957 cells/mm2 and 1638 +/- 643 cells/mm2, respectively). The mean corneal thickness was 542 +/- 50 microns for short-term-preserved and 541 +/- 55 microns for organ-cultured corneas and remainded unchanged during the follow-up of 12 months (542 +/- 42 microns and 521 +/- 43 microns, respectively). Neither the group of short-term-preserved corneas nor organ-cultured corneas showed a significant correlation between endothelial cell density or central cornea thickness with post-mortem time or with storage time of the donor corneas at any postoperative stage (p > 0.1). CONCLUSION: During the first year after PK, only a small decrease in endothelial cell density was observed in comparison with the 6-weeks finding. The storage method does not seem to affect the short-term changes of endothelial cell density. Further long-term studies are necessary to assess the clinical relevance of these observations.

Adult↗

PubMed1999

[Development of visual acuity in the early phase after photorefractive keratectomy in myopia].

BACKGROUND: Photorefractive keratectomy (PRK) using the excimer laser is an accepted surgical technique for correction of myopic refraction errors in case of spectacle or contact lens incompatibility. The purpose of this study was to assess the development of uncorrected (UVA) and best-corrected visual acuity (CVA) in the early course following PRK. PATIENTS AND METHODS: 48 eyes of 29 patients that underwent myopic photorefractive keratectomy using 193 nm excimer laser (MEL 60, Aesculap-Meditec) were included in this study. The mean preoperative spherical equivalent was -5.3 +/- 2.4 diopters (D) (range -1.75 to -9.5 D). Pre-, intra- and postoperative treatment was standardized. The median time interval to complete epithelial closure was 2 days. According to their spherical equivalent, patients were divided in two groups: group 1 with myopia < or = 6 D (n = 28), group 2 with myopia more than 6 D (n = 20). Examination of UVA and CVA were performed preoperatively and on days 3, 7 as well as 1 month, 3 and 6 months postoperatively. RESULTS: On day 3 after surgery UVA was 0.43 +/- 0.21 for group 1 with myopia < or = 6 D, and 0.36 +/- 0.14 for group 2 with myopia more than 6 D. The UVA was stable after 3 months (0.92 +/- 0.29 and 0.66 +/- 0.20, respectively), the CVA was stable after 1 month (1.04 +/- 0.18 and 0.86 +/- 0.19, respectively). After surgery, the UVA increased by +0.73 +/- 0.25, whereas the CVA increased by +0.05 +/- 0.10 for the whole group. The difference comparing pre- and postoperative UVA was significantly higher in group 1 (0.81 +/- 0.22) than in group 2 (0.60 +/- 0.26) (p = 0.002). However, postoperative CVA values were not significantly different from preoperative values in both groups after 6 months (p = 0.3). CONCLUSION: Useful uncorrected visual acuity is normally achieved at day 3 after PRK in eyes with mild to moderate myopia. With higher degrees of myopia the uncorrected visual acuity does increase slower towards a lower level. One of the reasons for this phenomenon might be a significant regression of the refractive effects during the first half year after surgery.

Adult↗

PubMed1999

Tumor growth of a choroidal malignant melanoma and aqueous flare. Report of a case.

We report the use of the laser flare-cell meter (LFCM) in monitoring blood-ocular barrier breakdown induced by a choroidal malignant melanoma in an 88-year-old white male, who refused enucleation or radiation treatment. During a follow-up of 16 months, aqueous flare values measured with the LFCM increased from 12.8 to 26.5 photon counts/ms with continuous tumor growth from a height of 7.9 to 18 mm. Our finding of increasing flare values with tumor growth appears to confirm the observation that aqueous flare is influenced by the size of uveal malignant melanomas. Quantification of aqueous flare with the LFCM may be helpful in the follow-up of eyes with intraocular tumors.

Aged↗

PubMed1999

Quantification of blood--aqueous barrier breakdown after trabeculectomy: pseudoexfoliation versus primary open-angle glaucoma.

PURPOSE: Impairment of the blood-aqueous barrier in unoperated eyes with pseudoexfoliation syndrome has been demonstrated by fluorescein angiography, fluorophotometry, measurement of aqueous flare, and determination of aqueous protein. We performed noninvasive quantification of aqueous flare using the laser flare-cell meter to compare blood-aqueous barrier breakdown after trabeculectomy in eyes with primary open-angle glaucoma (POAG) and in eyes with pseudoexfoliative glaucoma (PEX). METHODS: Twenty eyes with PEX and 20 eyes with POAG were included in the study. Trabeculectomy was performed by two surgeons according to a standard trabeculectomy technique. Intra- and postoperative treatments were identical in both groups. Aqueous flare was quantitatively determined using the laser flare-cell meter FC-1000 (Kowa, Tokyo, Japan) before and 3, 5, 7, and 9 days after trabeculectomy. Absolute flare and difference between post- and preoperative flare values were statistically analyzed using the Mann-Whitney U-Test for independent samples. RESULTS: Before surgery, aqueous flare values were significantly higher in PEX than in POAG. On days 3, 5, 7 and 9 after surgery, flare values were significantly higher in eyes with PEX than in eyes with POAG. Absolute differences between post- and preoperative flare values also were significantly higher in eyes with PEX, but this was not true for percentage values. CONCLUSION: These results show that substantial blood-aqueous barrier breakdown occurs in eyes with PEX after trabeculectomy. These alterations may contribute to early or late complications of trabeculectomy and indicate the need for close postoperative follow-up evaluation in eyes with PEX.

Aged↗

PubMed1998

Aqueous flare in retinitis pigmentosa.

BACKGROUND: The purpose of this study was to quantify blood-ocular barrier impairment by measuring aqueous flare in retinitis pigmentosa (RP) and to search for clinical correlations. METHODS: Forty-nine patients (94 eyes) with RP and 85 normal controls were examined. Aqueous flare was quantified with the noninvasive laser flare-cell meter (FC-1000, Kowa, Japan). Degrees of cystoid macular edema (CME), vitreous pigment dusting (VPD), intraretinal migration of retinal pigment epithelium, and waxy pallor of the optic nerve head were determined semiquantitatively by biomicroscopy. Data were analyzed using the t-test the Mann-Whitney U-test, the chi-squared test and regression analysis by taking into account the dependency of data from two eyes of the same patients. RESULTS: Aqueous flare (photon counts/ms) was significantly higher in RP (mean 10.11 +/- 3.53) than in normals (3.89 +/- 0.94; P < 0.001). Clinically significant CME was present in 26% of eyes with RP, being significantly more frequent in autosomal dominant RP (11 of 16 eyes, 69%) than in other variants (17%; P < 0.005). Multivariate analysis revealed that CME was most strongly associated with flare values (r = 0.84), P < 0.01), whereas--after adjusting for CME--correlations between aqueous flare and other clinical findings did not reach significance. CONCLUSION: RP eyes show increased aqueous flare values, indicating impairment of blood-occur barriers. This appears to be associated with CME and with autosomal dominant RP.

Adolescent↗

PubMed1998

Quantification of aqueous melanin granules in primary pigment dispersion syndrome.

PURPOSE: Aqueous melanin granules are essential in the pathogenesis of pigment dispersion syndrome and pigmentary glaucoma. We quantified aqueous melanin granules with the laser flare-cell meter in patients with pigment dispersion syndrome, assessed the measurement reproducibility, and correlated the numbers with clinical findings. METHODS: Aqueous melanin granules were counted by means of the cell count mode of the laser flare-cell meter (KOWA FC-1000; Kowa, Tokyo, Japan) in 42 eyes of 21 patients with primary pigment dispersion syndrome under three conditions (undilated pupils, dilated pupils, after exercise). The reproducibility of the measurements was determined with the intraclass correlation coefficient. A control group of 40 age- and sex-matched eyes was also examined after pupillary dilation. The results were correlated with biomicroscopic findings in eyes with pigment dispersion syndrome (retrocorneal Krukenberg spindle, iris transillumination, pigmentation of trabecular meshwork). RESULTS: Numerous aqueous melanin granules were detected in eyes with pigment dispersion syndrome (mean, 2.9 +/- 3.7 granules/0.075 mm3) but only small numbers were counted in normal eyes (0.2 +/- 0.3, P < .001). Medical pupil dilation caused an additional increase of aqueous melanin granules in pigment dispersion syndrome (6.3 +/- 5.3, P < .001), but not undilated exercise (climbing stairs) (2.9 +/- 3.7, P > .5). The reproducibility of the measurements was very high (intraclass coefficient >0.92). The number of melanin granules correlated with the degree of Krukenberg spindle (r = .61, P = .004) and with iris transillumination (r = .69, P = .001). CONCLUSIONS: Quantification of aqueous melanin granules yields reproducible results and shows increased numbers in pigment dispersion syndrome, especially after pupillary dilation. Aqueous melanin granule quantification may be useful for evaluating eyes with pigment dispersion syndrome and for assessing treatment effects.

Adult↗

PubMed1998

Blood-aqueous barrier after mechanical or nonmechanical excimer laser trephination in penetrating keratoplasty.

PURPOSE: To analyze whether nonmechanical trephination with an excimer laser influences post-operative blood-aqueous barrier breakdown after penetrating keratoplasty. METHODS: Patients undergoing penetrating keratoplasty for keratoconus or Fuchs dystrophy were prospectively randomly assigned to trephination by either excimer laser or conventional mechanical handheld motorized trephine. All surgery was performed by one surgeon, and preoperative, intraoperative, and postoperative treatment was identical in both groups. Aqueous flare was quantitatively determined postoperatively in a masked fashion by laser flare-cell meter. For statistical analysis, the nonparametric Wilcoxon-Mann-Whitney test was used. RESULTS: A total of 52 eyes of 52 patients were examined (Fuchs dystrophy, 10; keratoconus, 42). During the early postoperative period (days 3 to 9), eyes that had undergone nonmechanical excimer laser trephination (25/52) showed significantly (P < .005) lower flare values than did eyes that had undergone mechanical trephination (27/ 52). In both groups, flare values returned to normal levels by 6 weeks postoperatively. CONCLUSION: Early postoperative blood-aqueous barrier breakdown is less pronounced after penetrating keratoplasty with nonmechanical excimer laser trephination.

Adolescent↗

PubMed1998

[Laser-tyndallometry in eyes with acute retinal necrosis syndrome. Erlanger Laser-tyndallometry study group].

PURPOSE: Acute retinal necrosis syndrome (ARN) is a rapidly progressive viral necrotic retinitis. We used noninvasive measurement of aqueous flare to quantify blood-ocular barrier breakdown in eyes with ARN und to follow the inflammatory activity and treatment effects. PATIENTS AND METHODS: We report on seven patients (5 males und 2 females, age: 16 to 57 years) with ARN that were treated in our institution between 1991 to 1996. Aqueous flare was quantified regularly during treatment using the laser flare-cell meter (Kowa, FC-1000) following pupillary dilation. RESULTS: Aqueous flare was highly significantly increased in eyes with ARN (145.5 +/- 139.7, range 30 to 367 photon counts/ms). Contralateral, unaffected eyes showed normal flare values (3.6 +/- 0.8 photon counts/ms, p < 0.0001; normals: 4.1 +/- 1.1 photon counts/ms). Flare values correlated with inflammatory activity before and during antiviral treatment. In two patients with ARN caused by herpes simplex-virus aqueous flare values were extremely increased (367 and 316 photon counts/ms), and retinal necrosis was rapidly progressive despite antiviral therapy. One patient developed early ARN in his contralateral eye with flare values increasing from 3.5 to 22.0 photon counts/ms, which quickly normalized following antiviral treatment. CONCLUSIONS: Measurement with the laser flare-cell meter allows quantification of blood-ocular barrier breakdown in eyes with ARN und may be useful for monitoring inflammatory activity during treatment.

Adolescent↗

PubMed1998

[Design and preliminary results of the Erlanger non-high-risk penetrating-keratoplasty study].

PURPOSE: The purpose of this prospective study is to examine the non-high-risk penetrating keratoplasty clinically, tyndallometrically and immunological-serologically in order to learn more about the pathogenesis, early symptoms and therapy monitoring of corneal graft rejection. PATIENTS AND METHODS: Since february 1997, patients undergoing non-high-risk-PK have been enrolled in this prospective study. Examinations are done preoperatively and in well-defined postoperative gates (6 weeks, 3 months, 6 months, etc.) and include clinical assessments, corneal topography, laser-tyndallometry, corneal endothelial cell count and corneal pachymetry. Preoperatively as well as at each postoperative examination, 10 ml serum and perioperatively corneoscleral donor tissue are collected and frozen (-80 degrees C) to allow immunological and serological examinations in case of graft rejection later. A relational data base (MS Access) guarantees complete and homognous standardized clinical and serological data. We randomised our patients with respect to duration of topical steroid therapy in standard situations (short-time vs. long-time) as well as for systemic steroid therapy (bolus group vs. tapering group) in case of a graft rejection in 2 treatment groups. RESULTS: Up to March 1998, 99 patients have been enrolled in this prospective study. Our report includes the first consecutive 55 patients (25 female, 30 male, recipient age 56.9 +/- 19.4 years, donor age 57.0 +/- 19.9 years). Up to now (follow-up 2.5 +/- 2.1, maximum of 7.3 months) we did not observe immunologic graft rejections. In one patient a primary graft failure occurred. Laser tyndallometry showed a reduction of blood-aqueous barrier breakdown from 6 weeks postoperatively (9.3 +/- 5.7 photon counts/msec) to 3 months postoperatively (6.8 +/- 3.5 photon counts/msec). CONCLUSION: This prospective randomized clinical and immunological study after non-high-risk-PK is supposed to give more information about pathogenesis, early symptoms and therapy monitoring of graft rejection after elective PK. The concept and design of this study are described. Preliminary data may give significant results in a few years.

Adult↗

PubMed1997

Detection of a common mutation in factor V gene responsible for resistance to activate protein C causing predisposition to thrombosis.

Hereditary predisposition to thrombosis due to activated protein C resistance (APCR) has been attributed to a missense mutation in the factor V gene at nucleotide 1691 (G to A), causing replacement of arginine at codon 506 with glutamine. Using an RFLP-PCR assay to detect this mutation, we measured a prevalence of 3.3% in healthy Caucasians and 1.25% in healthy African-Americans. In addition, we evaluated a total of 90 consecutive specimens submitted to the coagulation laboratory at the Medical College of Virginia for the presence of this mutation. We compared our results for 78 of these specimens with the values measured by a modified partial thromboplastin assay, the COATEST. Twelve of the 90 samples could not be tested using the COATEST because the patients were undergoing anticoagulant therapy. One of the latter 12 specimens was positive by the RFLP-PCR test. Using the genetic test as the definitive assay and the cutoff value established for distinguishing between normal and abnormal results by the COATEST, the COATEST had a sensitivity of 50% and specificity of 93% for the detection of factor V mutation. Analysis of the 90 samples stratified by ethnic groups revealed a frequency of mutation of 13.3% for Caucasians and 6.88% for African-Americans, although with the present sample size, the difference was not statistically significant. Although the COATEST is technically simpler to perform than the genetic test for diagnosing the presence of the factor V mutation, its use for this purpose is limited due to low sensitivity. Thus where this disorder is clinically suspected, submission of the specimen directly for genetic testing by RFLP-PCR or equivalent assay should be considered.

Black People↗

PubMed1997

[Value of blue-on-yellow VEP for early diagnosis in suspected glaucoma. Biostatistical considerations and results].

BACKGROUND: In the Erlangen glaucoma study, the blue-on-yellow VEP was shown to be able to discriminate between controls and manifest glaucoma patients. SCIENTIFIC QUESTIONS AND AIMS: In our investigation, we assessed the validity of the blue-on-yellow VEP for early diagnosis of glaucoma. With this aim, we compared different subgroups of glaucoma suspects. The main issue of the investigation was the biostatistical aspects of early diagnosis of glaucoma. MATERIAL, METHODS AND RESULTS: Within a group of patients who were suspected of having ocular hypertensive glaucoma without visual field loss we compared 109 patients with optic disc damage [preperimetric (PPM) 47 +/- 11 years] and 91 patients without optic disc damage [ocular hypertension (OHT) 45 +/- 10 years]. We evaluated the N 1-amplitude and the peak latency of the blue-on-yellow VEP. The peak latency was significantly longer in the PPM group (first examination: OHT 118 +/- 9.5 ms, PPM 122.0 +/- 10.5 ms; second examination: 119.1 +/- 7.4/121.9 +/- 11.0 ms; third examination: 118.5 +/- 9.1/122.4 +/- 10.9 ms). The amplitude was reduced in the PPM group (P = 0.08). The differences between the two groups only allowed limited individual separation: (sensitivity of 42% for advanced optic disc damage with 80% specificity among OHT patients). CONCLUSIONS: The reduced sensitivity of a diagnostic procedure within a group of glaucoma suspect patients compared with patients with manifest glaucoma might be explained by: (1) possible misclassifications of patients and (2) a smaller degree of loss of visual function in the early stages of the disease.

Adult↗