C. Hirn

Retinal nerve fiber layer birefringence evaluated with polarization sensitive spectral domain OCT and scanning laser polarimetry: a comparison.

A polarization-sensitive spectral domain optical coherence tomography (PS-SD-OCT) system is used to measure phase retardation and birefringence of the human retinal nerve fiber layer (RNFL) in vivo. The instrument records three parameters simultaneously: intensity, phase retardation and optic-axis orientation. 3D data sets are recorded in the optic nerve-head area of a healthy and a glaucomatous eye, and the results are presented in various ways: En-face phase-retardation maps of the RNFL are generated from the recorded 3D data and results are compared with scanning laser polarimetry (SLP). The depth information provided by OCT is used to segment the RNFL in the intensity image and measure the RNFL thickness. From the retardation and thickness data, 2D birefringence maps of the RNFL are derived. Circumpapillary plots of RNFL retardation and thickness obtained by PS-SD-OCT are quantitatively compared with those obtained by SLP.

Analysis of the Origin of Atypical Scanning Laser Polarimetry Patterns by Polarization-Sensitive Optical Coherence Tomography

PURPOSE To analyze the physical origin of atypical scanning laser polarimetry (SLP) patterns. To compare polarization-sensitive optical coherence tomography (PS-OCT) scans to SLP images. To present a method to obtain pseudo-SLP images by PS-OCT that are free of atypical artifacts. METHODS Forty-one eyes of healthy subjects, subjects with suspected glaucoma, and patients with glaucoma were imaged by SLP (GDx VCC) and a prototype spectral domain PS-OCT system. The PS-OCT system acquires three-dimensional (3D) datasets of intensity, retardation, and optic axis orientation simultaneously within 3 seconds. B-scans of intensity and retardation and en face maps of retinal nerve fiber layer (RNFL) retardation were derived from the 3D PS-OCT datasets. Results were compared with those obtained by SLP. RESULTS Twenty-two eyes showed atypical retardation patterns, and 19 eyes showed normal patterns. From the 22 atypical eyes, 15 showed atypical patterns in both imaging modalities, five were atypical only in SLP images, and two were atypical only in PS-OCT images. In most (15 of 22) atypical cases, an increased penetration of the probing beam into the birefringent sclera was identified as the source of atypical patterns. In such cases, the artifacts could be eliminated in PS-OCT images by depth segmentation and exclusion of scleral signals. CONCLUSIONS PS-OCT provides deeper insight into the contribution of different fundus layers to SLP images. Increased light penetration into the sclera can distort SLP retardation patterns of the RNFL.

Kombinierte Katarakt- und Glaukomoperation: Phakotrabekulotomie versus Phakotrabekulektomie

ZusammenfassungHintergrundBei Patienten mit Glaukom und Katarakt bieten kombinierte Operationstechniken die Aussicht auf bessere Drucksenkung und Absetzen antiglaukomatöser Medikation mit dem Nachteil langsamerer Rehabilitation und häufigerer postoperativer Komplikationen im Vergleich zu Clear-Cornea-Kataraktchirurgie.MethodeRetrospektive Analyse zweier konsekutiver Fallserien mit kombinierter Katarakt- und Glaukomoperation bei primärem Offenwinkelglaukom oder Pseudoexfoliationsglaukom. In Gruppe 1 (69 Augen) wurde nach der Kataraktoperation und Linsenimplantation eine Trabekulotomie durchgeführt. In Gruppe 2 (60 Augen) wurde eine Phakotrabekulektomie mit Mitomycin C (MMC) durchgeführt. Das MMC wurde ca. 8 Minuten präoperativ in einer Dosis von 2,5 μg oder 5 μg subkonjunktival injiziert. Intraokularer Druck (IOD) und Therapiebedarf nach 1 und 2 Tagen, 1 und 2 Wochen und 1, 3, 6 und 12 Monaten sowie Erfolgs- und Komplikationsraten wurden verglichen.ResultateDer mittlere IOD in Gruppe 1 und 2 betrug 14,3 bis 15,4 bzw. 12,4 bis 13,7 mm Hg. Der Gruppenvergleich war nach 1 und 2 Wochen und 3 Monaten statistisch signifikant (p < 0,05). Der Therapiebedarf unterschied sich nach dem ersten Monat im weiteren Verlauf nicht signifikant. In der Kaplan-Meier-Analyse waren die Erfolgsraten mit Kriterium IOD < 21 mm Hg nicht signifikant unterschiedlich. Mit Kriterium IOD < 18 mm Hg ohne Therapie betrugen die Erfolgsraten nach einem Jahr 63% in Gruppe 1 und 83% in Gruppe 2 (p = 0,0159). In Gruppe 1 entwickelte sich statistisch signifikant häufiger ein Hyphäma (26% vs. 7%; p = 0,005), in Gruppe 2 hingegen postoperative Hypotonie (35% vs. 9%; p < 0,001).DiskussionDie Phakotrabekulektomie mit MMC erzielte tendenziell niedrigere IOD-Werte sowie signifikant bessere Erfolgsraten für Druckwerte < 18 mm Hg ohne Therapie, allerdings mit häufigeren potentiell bedrohlichen Komplikationen und Sekundärinterventionen. Für die Mehrzahl der Patienten mit Katarakt und Glaukom scheint die Phakotrabekulotomie aufgrund meist ausreichender Drucksenkung fast ohne relevante Komplikationen die bessere Option zu sein.AbstractBackgroundThe frequent coincidence of cataract and glaucoma arises the decision to perform either combined surgery or clear cornea cataract surgery. The perspective of a better pressure regulation and reduced medication after combined surgery must be weighed against a slower rehabilitation and higher risk of postoperative complications.MethodRetrospective analysis of two consecutive case series of combined cataract and glaucoma surgery including patients with primary open angle glaucoma or pseudoexfoliative glaucoma. In 69 eyes of group 1 we performed a phacotrabeculotomy. In 60 eyes of group 2 we performed a phacotrabeculectomy with intraoperative Mitomycin C (MMC). 2.5 μg or 5 μg MMC were injected subconjunctivally 8 minutes preoperatively. Intraocular pressure (IOP) and antiglaucomatous medication were compared 1 and 2 days, 1 and 2 weeks, 1, 3, 6, and 12 months postoperatively. Furthermore we compared success and complication rates.ResultsThe mean IOPs of groups 1 and 2 were 14.3 to 15.4 and 12.4 to 13.7 mm Hg. This difference was statistically significant after 1 and 2 weeks and 3 months (p < 0.05). Mean medication did not differ between groups after the first month. Kaplan-Meier analysis yielded similar success rates for the criterion IOP < 21 mm Hg. The criterion IOP < 18 mm Hg without therapy resulted in success rates of 63% in group 1 and 83% in group 2 (p = 0.0159). Group 1 developed a statistically significantly higher frequency of hyphema (26% vs. 7%; p = 0,005), whereas group 2 had a significantly higher frequency of hypotony (35% vs. 9%; p < 0,001).DiscussionPhacotrabeculectomy with MMC resulted in slightly lower IOP values and significantly better success rates for IOP < 18 mm Hg without therapy. This might be advantageous for patients with a low target pressure. On the other hand a higher rate of potentially sight-threatening complications and secondary interventions had to be accepted. For the majority of patients phacotrabeculotomy appears to be the better choice resulting in sufficient IOP regulation almost in absence of relevant complications.