The impact of posterior vitreous adhesion on ischaemia in eyes with retinal vein occlusion.

PURPOSE: To evaluate whether posterior vitreous adhesion (PVA) contributes to retinal ischaemia in eyes suffering from central (CRVO) or branch retinal vein occlusion (BRVO). METHODS: Retrospective patient chart analysis of eyes with CRVO/BRVO receiving pars-plana vitrectomy (ppV). Prior to surgery fluorescence angiography was conducted to classify RVO as ischaemic or not. RESULTS: Sixty eyes were included, thereof 36 (60%)/24 (40%) with CRVO/BRVO. In the CRVO group, 17 (47%)/19 (53%) eyes were classified as ischaemic/non-ischaemic. Respective results for BRVO-affected eyes were 16 (67%)/8 (33%). PVA/posterior vitreous detachment (PVD) was found in 33 (92%)/3 (8%) eyes with CRVO and in 23 (96%)/1 (4%) patients suffering from BRVO. Value differences of PVA/PVD between ischaemic- and non-ischaemic-typed RVO failed statistical significance for both, CRVO (p = 0.095) and BRVO (p = 1.0). CONCLUSIONS: Posterior vitreous adhesion had no impact on retinal ischaemia in this investigation. As an attached posterior vitreous cortex acts as a scaffold and thus significantly increases neovascularization (NV) development in ischaemic-typed RVO, a prospective study evaluating the effect of enzymatic vitreolysis is indicated.

Intracameral concentrations of the fibrinolytic system components in patients with age-related macular degeneration.

PURPOSE: To detect the intracameral concentrations and activities of plasminogen and other components of the fibrinolytic system, and to investigate whether those concentrations and activities are higher in patients with age-related macular degeneration (AMD) in comparison to healthy controls. METHODS: Prospective case series of 93 patients scheduled for standard phacoemulsification. RESULTS: Mean plasminogen activity in patients with non-exsudative AMD (n = 24) revealed to be 0.06%N, in patients with exudative AMD (n = 7) 0.03%N and in healthy controls (n = 43) 0.02%N (p = 0.38, ANOVA). Plasminogen activator inhibitor I (PAI-1) was detected in neither group. Alpha2-antiplasmin activity was 1.61 U/ml in the non-exudative AMD group (n = 27), 0 U/ml in the exudative AMD group (n = 7) and 0.54 U/ml in the control group (n = 48) (p = 0.1, ANOVA). Concentrations of plasmin-a2-antiplasmin complex (PAP) were detected at levels of 17.91 ng/ml in the non-exudative AMD group (n = 11), of 16.6 ng/ml in the exudative AMD group (n = 5), and of 17.43 ng/ml in the control group (n = 14) (p = 0.92, ANOVA). CONCLUSIONS: Plasminogen is present with a very low activity in aqueous humor. There are no significant differences in aqueous humor concentrations or activities of plasminogen and other components of the fibrinolytic system between patients with non-exudative AMD, exudative AMD, and healthy controls. Further studies should investigate vitreous samples instead of aqueous humor samples. A careful and accurate workup of obtained intraocular fluids is needed to detect the low concentrations and activities of the parameters analyzed.

Evaluation of a posterior vitreous detachment: a comparison of biomicroscopy, B-scan ultrasonography and optical coherence tomography to surgical findings with chromodissection.

PURPOSE: To find the most reliable and efficient noninvasive technique to clinically detect a posterior vitreous detachment. METHODS: In a prospective study of 30 eyes in 30 patients with macular pucker or macular hole formation, the posterior vitreous cortex was examined 1 day prior to a scheduled vitrectomy. Three independent investigators classified the posterior vitreous cortex of each eye as 'attached' or 'detached' via slit-lamp biomicroscopy (BM), 10-MHz B-scan ultrasonography (I³ Innovative Imaging Inc.), and optical coherence tomography [OCT III Stratus(®) (Carl Zeiss Meditec Inc.) and RTVue-100 OCT (Optovue Corp.)]. These preoperative findings were then compared during a triamcinolone acetonide-assisted vitrectomy 1 day later. RESULTS: Triamcinolone acetonide-assisted vitrectomy showed in 60% a posterior vitreous detachment and in 40% an attached posterior vitreous cortex. Preoperatively conducted B-scan ultrasonography and BM revealed the highest, correct evaluation of the posterior vitreous status. The prediction of the OCT was confirmed intraoperatively in 12.5%. In all other cases, the evaluation by OCT was not possible or was inadequate. CONCLUSION: The prognostic most reliable but investigator-dependent methods to clinically detect whether the posterior vitreous cortex is detached are B-scan ultrasonography and BM. The objective technique of the high-resolution, two-dimensional time-domain OCT allows only in a few cases a clear differentiation of preretinal structures.

Sampling aqueous humor: anterior segment anatomy, anesthetic and surgical technique, and rates of yield.

PURPOSE: To evaluate anterior segment anatomy and anesthetic and surgical techniques with respect to the amount of aqueous humor (AH) that can be sampled out of the anterior chamber (AC) at the beginning of standard cataract removal procedures (phacoemulsification). METHODS: In a prospective survey, volumes of sampled AH from 123 eyes (110 patients) were analyzed in regard to AC anatomy (anterior chamber depth, ACD) and different anesthetic techniques (local and general anesthesia). RESULTS: 107 eyes (87%) were included into our analysis, and 16 eyes (13%) had to be excluded due to failure of AH collection. We found a significant positive association between ACD and obtained AH volume (p=0.007). In general anesthesia, a strong trend to acquire more AH in comparison to local anesthesia was apparent, but statistical significance failed (p=0.167). Different anesthetic techniques seem to have no significant influence on ACD (p=0.169). No training curve for the individual surgeon was obtained. No complications were observed. CONCLUSION: When AH sampling is performed in eyes with a deep AC and when the procedure is performed under general anesthesia, more AH can be aspirated.

The vitreomacular interface in retinal vein occlusion.

PURPOSE: To evaluate the posterior vitreous adhesion status in patients with a history of central or branch retinal vein occlusion and to compare the results with the natural time-course of posterior vitreous detachment in healthy age-related controls. METHODS: A retrospective chart review in terms of the posterior vitreous adhesion status was performed in 132 patients (133 eyes) with a history of a central (CRVO) or branch (BRVO) retinal vein occlusion. All patients underwent vitrectomy. Based on the operation reports, the vitreous adhesion status was classified as attached, partially detached or completely detached. The results were compared to the natural time-course of posterior vitreous detachment development in healthy age-related controls. RESULTS: Eighty-one eyes met the inclusion and exclusion criteria. Fifty-two eyes (64%) had a history of CRVO and 29 eyes (36%) a history of BRVO, respectively. In the CRVO group, the posterior vitreous was attached in 47 eyes (90%) and completely detached in five eyes (10%). In the BRVO group, the posterior vitreous was attached in 27 eyes (93%), partially detached in 1 eye (3%) and completely detached in another eye (3%). A subdivision into age classes and a comparison with healthy age-related controls [data by Weber-Krause & Eckardt (1997) Ophthalmologe, 94, 619-623] showed in patients between 65 and 69 years of age an attached posterior vitreous cortex in 72% in healthy eyes, in 100% in CRVO (p = 0.109) and in 89% in BRVO (p = 0.440), in patients between 70 and 79 years of age an attached posterior vitreous cortex in 56% in healthy eyes, in 86% in CRVO (p = 0.010) and in 100% in BRVO (p = 0.038) and in patients between 80 and 89 years of age an attached posterior vitreous cortex in 43% in healthy eyes, in 100% in CRVO (p = 0.191) and in 67% in BRVO (p = 0.582) (Fisher's exact t-test). CONCLUSION: In patients with a history of CRVO or BRVO, the posterior vitreous cortex stays attached more frequently in all age groups in comparison with the healthy age-related controls.