Nhung X. Nguyen

The retinal nerve fiber layer in normal eyes.

The retinal nerve fiber layer is different in normal and glaucomatous eyes. The authors used red-free photographs to examine the retinal nerve fiber layer in 234 normal eyes. The retinal nerve fiber layer was most visible in the inferior temporal arcade, followed by the superior temporal arcade, then by the temporal macular area, and finally the nasal area. This distribution was significantly (P less than 0.0001) correlated to (1) the configuration of the neuroretinal rim, which was significantly broadest at the inferior disc pole followed by the superior one, (2) the juxtapapillary caliber of the retinal vessels, which were significantly wider in the inferior temporal arcade than in the superior temporal arcade, and (3) the location of the foveola 0.53 +/- 0.34 mm inferior to the middle point of the vertical optic disc axis. The retinal nerve fiber layer decreased with age. No correlation occurred with sex or right or left eye. No localized retinal nerve fiber layer defects were seen. These features of the normal retinal nerve fiber layer are important for diagnosis of retinal nerve fiber layer changes secondary to optic nerve damage in the diseased eye.

Quantitative assessment of aqueous flare and aqueous ‘cells’ in pseudoexfoliation syndrome

Abstract. We used the laser flare‐cell meter to measure aqueous flare and aqueous ‘cells’ in 38 eyes of 38 patients with pseudoexfoliation, in 36 normal control eyes of 36 subjects, and in 19 eyes of 19 patients with chronic open‐angle glaucoma unrelated to pseudoexfoliation. In pseudoexfoliation eyes, both aqueous flare (0.61 ± 0.55 mg/ml human albumin equivalent) and aqueous ‘cells’ (mean 10.70, range 0–50.6 cells/0.075 mm3) were significantly higher than in the normal control group (flare 0.15 ± 0.06 mg/ml, ‘cells’ 0.43, range 0–2, P< 0.0001) and in the glaucoma group without pseudoexfoliation (flare 0.19 ± 0.08 mg/ml, ‘cells’ 0.80, range 0–2.4, P< 0.0001 and P< 0.005). No significant difference could be found between the flare and cell counts of normal eyes and glaucoma eyes without pseudoexfoliation (P> 0.09, P> 0.05) and between PSX eyes with (18 eyes) and without (20 eyes) open‐angle glaucoma (P> 0.99, P> 0.4). Our findings indicate that the blood‐aqueous barrier is impaired in eyes with pseudoexfoliation, and that the laser flare‐cell meter may be a useful tool to quantify these changes. These alterations of the blood‐aqueous barrier need to be considered in medical therapy and intraocular surgery.

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.

Aqueous flare in retinitis pigmentosa.

Abstract · 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-ocur barriers. This appears to be associated with CME and with autosomal dominant RP.

Zwei Jahre Erfahrung mit der akkommodativen Hinterkammerlinse 1 CU

ZusammenfassungNachdem die optische Rehabilitation von Patienten mit Katarakt dank moderner mikrochirurgischer Techniken und der Entwicklung von faltbaren Hinterkammerlinsen (HKL) heute hervorragend ist, stellt die Therapie der Presbyopie nunmehr eine der großen ungelösten Fragen der Ophthalmologie dar. In den letzten Jahren wurde, basierend auf Konzepten von K.H. Hanna, mit Hilfe von Finite Elemente Computersimulationstechniken die akkommodative Hinterkammerlinse 1 CU entwickelt. Diese soll die verbliebenen Kontraktionskräfte des Ziliarmuskels in eine anteriore Bewegung der Kunstlinsenoptik im Auge umwandeln (Optik-Shift-Prinzip). Nach der Erstimplantation im Juni 2000 haben wir die 1 CU inzwischen bei über 90 Patienten implantiert. Die bisherigen Erfahrungen und Studien zeigen eine gute und sichere Implantierbarkeit, gute Zentrierung, fehlende kunstlinsenspezifische Komplikationen und guten Fernvisus. Im Vergleich zu Kontrollgruppen konnte bei Patienten mit der 1-CU-HKL ein signifikant besserer fernkorrigierter Nahvisus, eine größere Akkommodationsamplitude sowie mit dem IOL-Master (Zeiss) eine signifikant größere anterior-posteriore Bewegung der Kunstlinsenoptik nach medikamentöser Stimulation bzw. Lähmung des Ziliarmuskels nachgewiesen werden. Diese Ergebnisse können als Bestätigung des Konzeptes des Optic-Shift-Prinzips der 1-CU-HKL interpretiert werden. Insgesamt erscheint das Konzept akkommodativer Kunstlinsen attraktiv und zukunftsträchtig. Weitere Studien hinsichtlich Langzeitverträglichkeit und Akkommodationsleistung, vor allem randomisierte maskierte multizentrische Studien, sind erforderlich und in Vorbereitung.AbstractAfter marked improvement of optical rehabilitation of cataract patients during the last decades due to small incision surgery and foldable intraocular lenses (IOL), presbyopia is now one of the great unsolved questions in ophthalmology. During recent years a new accommodative IOL, the 1CU lens, has been developed based on the concepts of K.D. Hanna and on finite element computer simulation models. The 1CU IOL is designed to transform contracting forces of the ciliary muscle into anterior movement of the IOL optic (optic-shift concept). After the first implantation of a 1CU IOL in Erlangen in June 2000, we have now successfully implanted the 1CU IOL in over 90 patients. Our experiences and the results of several clinical studies indicate good and safe implantability, good centration, no IOL-specific complications, and good distance visual acuity. In comparison to control groups with conventional IOL, patients with the 1CU enjoyed significantly better distance-corrected near visual acuity, a larger accommodative range, and increased anterior and posterior axial movement of the lens optic after medical stimulation or inhibition of the ciliary muscle. We interpret our results as confirmation of the optic-shift concept of the 1CU IOL. Overall, the concept of accommodative IOL appears attractive and may have a great potential in the future. Additional studies including randomized blind multicenter evaluation of the 1CU IOL are necessary to further evaluate long-term and accommodative results.

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.

Optic disc morphometry in simple optic nerve atrophy

Abstract. This study was undertaken to evaluate the optic disc changes in eyes with non‐glaucomatous optic nerve damage. The intra‐ and parapapillary region was evaluated morphometrically in 106 eyes of 56 patients with simple optic nerve atrophy (SONA) and in 107 normal eyes of 57 subjects. Colour stereo optic disc diapositives were used. Only one randomly chosen eye per subject and patient was taken for statistical analysis. Characteristics of SONA were: decreased visibility of the parapapillary retinal nerve fibers, diminished retinal vessel diameter, and area with pallor larger than area with cupping. Size and form of the optic disc, neuroretinal rim, peripapillary scleral ring, and zone Alpha and Beta of the parapillary chorioretinal atrophy were not significantly different. Also, distinctness of a tesselated fundus, frequency of optic disc haemorrhages and frequency of bared circumlinear or bared cilioretinal vessels did not differ significantly. These morphologic features are helpful in the diagnosis and differential diagnosis of SONA.

New Glaucoma Classification Method based on Standard Heidelberg Retina Tomograph Parameters by Bagging Classification Trees

PURPOSE In this article we propose and evaluate nonparametric tree classifiers that can handle non-normal data and a large number of possible predictors using the full set of standard Heidelberg Retina Tomograph measurements for classifying glaucoma. METHODS The classifiers were trained and tested using standard Heidelberg Retina Tomograph parameters from examinations of 98 subjects with glaucoma and 98 normal subjects of the Erlangen Glaucoma Registry. All patients and control subjects were evaluated by 15 degrees -optic disc stereographs, Heidelberg Retina Tomograph measurements, standard computerized white-in-white perimetry, and 24-hour-intraocular pressure profiles. The subjects were matched by age and sex. Standard classification trees as well as bagged classification trees were used. The classification outcome of the trees was compared with the classification by two published linear discriminant functions based on Heidelberg Retina Tomograph variables with respect to their cross-validated misclassification error. RESULTS The bagged classification tree had the lowest misclassification error estimate of 14.8% with a sensitivity of 81.6% at a specificity of 88.8%. The cross-validated error rates of the two linear discriminant function procedures were 20.4% (sensitivity 82.6%, specificity 76.7%) and 20.6% (sensitivity 81.4%, specificity 77.3%) for our set of observations. Bagged classification trees were able to reduce the misclassification error of glaucoma classification. CONCLUSIONS Bagged classification trees promise to be a new and efficient approach for glaucoma classification using morphometric 2- and 3-dimensional data derived from the Heidelberg Retina Tomograph, taking into account all given variables.

Corneal neovascularization after nonmechanical versus mechanical corneal trephination for non-high-risk keratoplasty.

Purpose. To analyze the influence of mechanical versus nonmechanical trephination of donor and host corneas on superficial, peripheral corneal neovascularization occurring after non–high-risk keratoplasty. Methods. Patients of the prospective Erlangen non–high-risk keratoplasty study with standardized corneal photographs taken preoperatively and 1 year later were analyzed (n = 184). Slides of these photographs were projected (magnification ×100) and corneal vessels graded in a standardized semiquantitative fashion into five categories with regard to limbus, sutures, and host-graft junction in each of 12 corneal sectors. Degree (total increase of grades in the 12 sectors) and maximal extent of corneal neovascularization (maximal centripetal extension of blood vessels) were analyzed. In 32 patients mechanical (17%) and in 152 nonmechanical trephination of host and donor tissue was performed (193-nm excimer laser, 83%). Statistical analysis was done using Fishers exact and Mann-Whitney U test. Results. Corneal neovascularization within the first postoperative year was lower in the nonmechanical [73 of 152 (48%)] compared with mechanical trephination group [24 of 32 (75%);p < 0.01; Mann-Whitney U test]. Maximal extent of neovascularization (i.e., vessels reaching the interface or growing beyond) was not yet significantly different between nonmechanical (8%) and mechanical (17%) trephination (p = 0.074). Conclusions. Nonmechanical trephination using the 193-nm excimer laser in non–high-risk keratoplasties might reduce corneal neovascularization occurring within the first postoperative year. This indicates that in the non–high-risk setting, development of postoperative corneal neovascularization may be affected by the trephination technique and subsequent wound-healing response.

Quantification of aqueous melanin granules, intraocular pressure and glaucomatous damage in primary pigment dispersion syndrome☆

OBJECTIVE Aqueous melanin granules may be accurately quantified with the laser flare-cell meter and have been demonstrated to be increased in primary pigment dispersion syndrome (PDS). It was the aim of this study to correlate intraocular pressure, glaucomatous damage of the optic nerve head, and visual field defects with the number of aqueous melanin granules in PDS. DESIGN Cross-sectional study. PARTICIPANTS Thirty-nine eyes of 21 patients with PDS and either ocular hypertension or pigmentary glaucoma. MAIN OUTCOME MEASURES A 24-hour intraocular pressure (IOP) profile, automated perimetry (Octopus G1), and analysis of photostereographs and HRT (Heidelberg Retina Tomograph) images of the optic disc were performed. Aqueous melanin granules were quantified using the cell count mode of the laser flare-cell meter (KOWA FC-1000) with undilated and dilated pupils. Granule counts were correlated with maximum and mean IOP, maximum range (amplitude) of IOP, mean defect of automated perimetry (G1-program), and damage to the optic disc was measured with the HRT. RESULTS The number of aqueous melanin granules showed a strong correlation with maximum IOP in both undilated (r = 0.72, P < 0.001) and dilated eyes (r = 0.5, P = 0.02). A marginal correlation was found with the IOP range (r = 0.43, P = 0.04) and the mean defect of automated perimetry (r = 0.41, P = 0.06) in undilated eyes. The mean IOP and HRT measurements of the optic disc (area, volume of the neuroretinal rim, third moment in contour) showed no statistically significant correlation with the number of aqueous melanin granules (r < 0.4, P > 0.2). CONCLUSIONS A larger number of aqueous melanin granules is strongly associated with high IOP and also with visual field loss, providing additional evidence of the relation between aqueous melanin dispersion and development of pigmentary glaucoma. Quantification of aqueous melanin granules with the laser flare-cell meter might be useful for evaluation of treatment effects, including laser iridotomy, in patients with PDS.