Blood-aqueous Barrier Research Articles

Ascorbic acid concentration in rabbit vitreous measured by microdialysis with HPLC-electrochemical detection before and after vitreous surgery

Microdialysis with high performance liquid chromatography and electrochemical detection (HPLC–ECD) was used to measure ascorbic acid (AA) concentrations in rabbit vitreous before and after vitrectomy. A cellulose microdialysis probe was implanted in the vitreous humor, and after stabilization, AA measurements were made daily over a 10 day period. The effect of removing two-thirds of the vitreous by vitrectomy was examined. The effect of triamcinolone acetonide (TA) was evaluated in four groups of rabbits: Group 1, sub-tenon TA (20 mg) alone; Group 2, intravitreous TA (4 mg) alone; Group 3, sub-tenon TA (20 mg) after vitrectomy, and Group 4, intravitreous TA (4 mg) after vitrectomy. The results showed that the AA concentration after vitrectomy was significantly lower from days 2 to10 with a maximum reduction of 49.5% ( P<0.005) on day 7. No significant changes in the AA level was observed in Groups 1 and 2, a mild recovery of AA concentration reduction after vitrectomy was detected in Group 3. The highest recovery of the AA concentration reduction was observed in Group 4. The attenuating effect of TA treatment on the reduction of AA in the vitreous after vitrectomy was significant. This attenuating effect of the TA may be due to prevention of the disruption of the blood-aqueous barrier by its anti-inflammatory action.

Pilocarpine's effects on the blood-aqueous barrier of the human eye as assessed by high-resolution, contrast magnetic resonance imaging

The purpose of this research was to reassess the effects of topical pilocarpine on the integrity of the blood-aqueous barrier, using high resolution, magnetic resonance imaging, and the standard intravenous contrast agent gadolinium dimeglumine. It has long been known that topical pilocarpine gives rise to an increase in protein levels in the anterior chamber of the eye. This protein scatters light and is referred to clinically as ‘flare’. Prior studies concluded that pilocarpine-induced flare resulted from disruption of the blood-aqueous barrier. These studies relied upon indirect methods that precluded direct visualization of the posterior chamber of the eye. Five normal, human volunteers (age 22–40) received a single drop of 3% pilocarpine in one eye, following baseline measurements of pupil size and anterior chamber ‘flare’. These measurements were repeated every 15 min for 45 min. The subject was then positioned in the magnet and the eye that received pilocarpine was taped closed and covered with a 3 in.-diameter receive-only surface coil. The open contralateral eye focused on a target to maintain fixation of the imaged eye. A baseline image of the eye was obtained and the contrast agent was administered intravenously. A series of additional images was obtained during the following 60 min to track the movement of contrast material from the bloodstream into the tissues and compartments of the eye. Percent enhancement was calculated from selected regions of interest in the images, including the ciliary body, and the anterior and posterior chambers. Within the 45 min after administration of pilocarpine, pupil size in mm decreased from (mean± s.d.) 5.7±1.5 to 2.5±0.5 ( p=0.0106). During this period, average flare/ s.d. (photons msec −1) increased from 3.7±1.1 to 12.5±4.7 ( p=0.0151). In all cases, MRI images showed rapid enhancement of the ciliary body, followed by a progressive increase in signal in the anterior chamber but not the posterior chamber. These studies confirm that topical pilocarpine gives rise to ‘flare’ in the anterior chamber. But the lack of enhancement in the posterior chamber strongly suggests that the presence of this added protein in the anterior chamber is not the result of increased permeability of the blood-aqueous barrier of the ciliary body. These studies also introduce the novel concept that not all clinically observed flare is the result of blood-aqueous barrier compromise.

Spontaneous Corneal Hem- and Lymphangiogenesis in Mice with Destrin-Mutation Depend on VEGFR3 Signaling

Lymphangiogenesis, the formation of new lymphatic vessels, is important for tumor metastasis and induction of immunity to peripheral antigens including organ transplants. We herein describe a novel mouse model of spontaneous, secondary lymphangiogenesis in the normally avascular cornea. corn1 mice, which suffer from a deletion in the gene encoding the cytoskeletal protein destrin, develop hemangiogenesis as well as spontaneous outgrowth of LYVE-1+++/CD31+ lymphatic vessels into the cornea starting at age 4 weeks. Corneal lymphangiogenesis is delayed in onset, is less intense, and regresses earlier compared with hemangiogenesis. Moreover, the lymphangiogenesis is preceded only by a mild recruitment of CD45+ inflammatory cells into the cornea. In contrast to mice with inflammation-induced hem- and lymphangiogenesis, corn1 mice do not develop breakdown of the blood-aqueous barrier. Finally, in this novel mouse model, a blocking anti-VEGFR3 antibody significantly inhibited not only lymph- but also hemangiogenesis. In summary, destrin deletion has differential effects on spontaneous hem- and lymphangiogenesis in the normally avascular cornea and represents a novel mouse model to study the mechanisms of lymphangiogenesis and to test the antihem- and antilymphangiogenic properties of known or new antiangiogenic agents.

Capsular Phimosis Following Phacotrabeculectomy

Three cases of severe capsular phimosis following augmented phacotrabeculectomy complicated by intense postoperative fibrinous uveitis are described. The marked inflammation was possibly related to the combined procedure itself, the excessive intraoperative manipulation to stretch the pupil, and the compromised blood-aqueous barrier after prolonged use of pilocarpine. The combination of fibrinous uveitis and the small size of capsulorhexis attained through a stretched pupil are possible risk factors for developing severe capsular phimosis in the absence of zonular weakness or preoperative uveitis. For patients with similar risk factors, two separate surgical procedures should be considered. Alternatively, a larger capsulorhexis or radial relieving incisions should be attempted during phacotrabeculectomy to prevent this complication, which could jeopardize the outcome of otherwise successful surgery.

Changes of blood-aqueous barrier after phacoemulsification in patients with previous glaucoma filtering surgery

To evaluate the effect of trabeculectomy and/or phacoemulsification surgery on blood-aqueous barrier function. Phacoemulsification with implantation of intraocular lens was performed on 46 cataract eyes of 40 glaucoma patients following previous trabeculectomy (group 1), and 64 cataract eyes of 60 patients (group 2). The aqueous flare and cells were examined preoperatively and on days 1, 7, 30, 90 postoperatively using a laser flare-cell meter (LFCM). The mean aqueous flare values were (15.12 +/- 2.87), (40.24 +/- 3.75), (24.33 +/- 3.38), (21.18 +/- 1.77), (16.51 +/- 1.70) photon counts/ms in group 1 preoperatively and on days 1, 7, 30, 90 after surgery (P < 0.05) respectively; and were (6.94 +/- 2.34), (26.27 +/- 10.21), (13.96 +/- 6.44), (9.07 +/- 2.67), (7.16 +/- 1.89) photon counts/ms in group 2 (P < 0.05) respectively. Trabeculectomy can breakdown blood-aqueous barrier permanently while phacoemulsification damage the blood-aqueous barrier transiently. Phacoemulsification combined with a previous trabeculectomy can enhance this damage.

Blood-Aqueous Barrier Changes After the Use of Prostaglandin Analogues in Patients With Pseudophakia and Aphakia

To investigate the effects of prostaglandin analogues on the blood-aqueous barrier and to evaluate the occurrence of cystoid macular edema in aphakic or pseudophakic patients with glaucoma. In this randomized, masked-observer, 6-month clinical trial, patients with primary open-angle, pseudophakic, or aphakic glaucoma were treated once daily with bimatoprost (n = 16), latanoprost (n = 15), or travoprost (n = 17) or twice daily with unoprostone (n = 16) or lubricant drops (control group) (n = 16). Blood-aqueous barrier status, which was assessed using a laser flare meter; intraocular pressure; the occurrence of angiographic cystoid macular edema; and conjunctival hyperemia were evaluated. Mean flare values were significantly higher in the bimatoprost, latanoprost, and travoprost groups throughout follow-up (P < .02). Four latanoprost-treated eyes, 1 bimatoprost-treated eye, and 1 travoprost-treated eye developed cystoid macular edema; all cases resolved after discontinuation of the prostaglandin analogue and treatment with topical diclofenac sodium. Mean intraocular pressure reductions after 6 months were higher for the latanoprost (26%), bimatoprost (28%), and travoprost (29%) groups than for the control (3%) and unoprostone (14%) groups (P< .05). Bimatoprost induced significantly higher hyperemia scores than latanoprost, unoprostone, and placebo (P< .01). Bimatoprost, latanoprost, and travoprost use may lead to disruption of the blood-aqueous barrier in patients with pseudophakia and aphakia.

This Issue of Acta

This Issue of Acta

Quantification of Blood-Aqueous Barrier Breakdown after Phacoemulsification in Fuchs’ Heterochromic Uveitis

Purpose: To quantify the breakdown of the blood-aqueous barrier (BAB) following phacoemulsification with posterior chamber lens implantation in eyes with Fuchs’ heterochromic uveitis (FHU). Patients and Methods: In this retrospective study, 19 eyes of 19 patients with FHU (mean age 38 ± 14 years) and 35 eyes of 35 patients with senile cataracts (mean age 63 ± 9 years) underwent phacoemulsification with one-piece PMMA posterior chamber lens implantation. Aqueous flare was quantified using the laser flare-cell meter (LFCM, Kowa FC-1000) following medical pupillary dilation preoperatively and 1, 3, and 5 days, then 1 and 6 weeks and 6 months postoperatively. Results: Mean preoperative aqueous flare (in photon counts per millisecond) in FHU vs. controls was 11.7 ± 3.5 vs. 5.8 ± 1.7. Following cataract surgery, mean aqueous flare increased to 27.8 ± 4.4 vs. 16.0 ± 4.5 on day 1, decreased to 23.6 ± 4.0 vs. 11.8 ± 3.5 on day 3, and to 18.0 ± 3.0 vs. 9.5 ± 1.7 on day 5. In FHU eyes, it was 13.9 ± 2.7 after 1 week, and had returned to preoperative levels after 6 weeks (10.9 ± 2.5) and remained stable for up to 6 months (mean 10.3 ± 2.2). Pre- and postoperatively, aqueous flare values were 2–3 times higher in FHU eyes than in control eyes with senile cataract (p = 0.01). No postoperative complications such as fibrin formation, synechiae, macrophages on the intraocular lens optic or endophthalmitis were observed in any of the patients. Conclusions: BAB breakdown following phacoemulsification with posterior chamber lens implantation is relatively mild in eyes with FHU and the BAB appears to be fully reestablished to preoperative levels 6 weeks postoperatively, explaining the usually good outcome of cataract surgery in this condition.

Ocular Irritation Following Frequent Applications of Cyclosporinea

ABSTRACTPurpose. Previous studies have shown that repetitive administrations of Cyclosporine A (CsA) eye drops to the rabbit eye caused a long-lasting miosis, accompanied by conjunctival hyperemia, anterior humor flare, and fibrin formation in the anterior chamber. The aim of the present study was to clarify the mechanism of these findings. Methods. One drop of 0.1% CsA eye drops was applied once or six times every 30 minutes for 2.5 hours. The eyes were examined by slit-lamp microscope, and IOP and anterior humor flare were measured prior to the studies and at 0, 1, 3, 6, 12, and 24 hours after administration of CsA or vehicle. While anterior chamber aqueous flare was increasing, aqueous humor and anterior segment of the eye were taken and analyzed. The entry of plasma proteins into the aqueous humor was studied by using Evans blue dye. Result. Conjunctival hyperemia, anterior humor flare and IOP rise miosis and fibrin formation in the anterior chamber were shown after six CsA administration ipsilaterally during 1–12 hours after the final administration. All of these observations were inhibited by pretreatment of indomethacin. While miosis was appearing, Evans blue dye penetrated the nonpigmented layer of the ciliary epithelium and the iris vessels. Calcitonin gene-related peptide (CGRP) was detected (184.1 ± 84.6 pg/mL), and CsA levels (891.6 ± 153.0 ng/mL) in anterior uvea exceeded the trough level. Conclusions. These results suggest that CsA can cause disruption of the blood-aqueous barrier with leaking from vessels in the ciliary processes and the iris, which are probably secondary effects of the irritation response releasing CGRP.

Corticosteroids inhibit VEGF-induced vascular leakage in a rabbit model of blood–retinal and blood–aqueous barrier breakdown

Purpose Recent clinical studies show that a single intravitreal injection of the corticosteroid triamcinolone acetonide (TAA) may reduce edematous retinal swelling and improve visual acuity in patients with diabetic macular edema (DME). In addition, clinical and experimental studies strongly suggest that blood–retinal barrier breakdown in diabetes is induced by vascular endothelial growth factor (VEGF). These results suggest that corticosteroids may modulate VEGF-mediated responses in vivo. To test this hypothesis directly, the current study evaluated the effects of TAA and dexamethasone (DEX) in a newly developed rabbit model of VEGF-induced blood–retinal barrier and blood–aqueous (iris) barrier breakdown. Methods VEGF 165 or vehicle was injected intravitreally in female Dutch Belt rabbits, and scanning ocular fluorophotometry was used to non-invasively measure fluorescein leakage from retinal and iris vasculature. VEGF-induced retinal vasculopathy was further assessed with fundus imaging, fluorescein angiography, and ocular coherence tomography. For pharmacologic studies, rabbits were treated with either DEX (2 mg kg −1 daily, s.c.), TAA (2 or 4 mg, intravitreal), indomethacin (20 mg kg −1 daily, s.c.), or vehicle (s.c. or intravitreal). Human umbilical vein endothelial cells (HUVEC) were loaded with the fluorescent Ca 2+ indicator dye fluo-4 and treated with dexamethasone (0·1–10 μ m) or vehicle for either 2 or 24 hr prior to stimulation with 10 ng ml −1 VEGF 165. Results VEGF injected intravitreally induced a time and dose-dependent breakdown of the blood–retinal and blood–aqueous barriers. Maximal vascular leakage was measured at 48 hr after intravitreal injection with a dose of 500 ng VEGF. Other effects of VEGF included prominent retinal vasodilation, vessel tortuousity, fluorescein leakage from retinal vessels, and inner retinal edema. These VEGF-mediated responses are transient and approach baseline by 1 week. VEGF-induced blood–retinal and blood–aqueous barrier breakdown was completely blocked by the corticosteroid DEX administered systemically for 3 days. In contrast, the non-steroidal anti-inflammatory drug, indomethacin, had no effect. In a separate study with VEGF injected intravitreally at six different time points over 5 months, a single intravitreal 2 mg dose of TAA completely blocked VEGF-induced retinal and iris leakage for 45 days. VEGF/VEGF receptor-2-mediated Ca 2+ mobilization in endothelial cells was not affected by 2 or 24 hr pretreatment with dexamethasone. Conclusion These results indicate that one mechanism by which corticosteroids block blood–ocular barrier breakdown and edema is via their modulation of signaling or effector proteins downstream of the VEGF receptor.

Anti-inflammatory effects of topical ocular MAXIDEX ® administration to rabbits following vitrectomy or lensectomy

We conducted a series of surgical studies ( n=155) to find out the possible utility of the Dutch Belted rabbits as an ocular test model. Following either vitrectomy ( n=59) or lensectomy ( n=96) studies using either BSS ® or BSS ® Plus, we characterized the corresponding magnitude and duration of inflammatory response of selected endpoints over a one-week period. Preoperative Dutch Belted rabbits served as controls for baseline determination ( n=27). Inflammatory endpoints included clinical inflammation, blood aqueous barrier (BAB) changes measured by particle-scatter and fluorophotometry, corneal edema, and prostaglandin-E 2 (PGE 2). Topical ocular 0·1% dexamethasone (MAXIDEX ®) served as a positive treatment group. We compared the inflammatory features (treated and untreated) to determine significance. Using either irrigating solution, the endpoints ( n=101) were shown increased in both models. While the clinical scores were similar following both types of surgery (ns; p=0·51), the lensectomy study caused a more marked effect on corneal edema ( p=0·0004) and PGE 2 production ( p=0·002) compared with the vitrectomy study. After the lensectomy procedure, BSS Plus ® ( n=52) compared with BSS ® ( n=24) showed a significant improvement ( p=0·004) of clinical score during the recovery phase. Further improvement was gained over BSS Plus ® ( n=52) using MAXIDEX ® treatment. Topical MAXIDEX ® (lensectomy, n=20/group; vitrectomy, n=12/group) reduced clinical score ( p<0·001), decreased BAB breakdown to fluorescein ( p<0·01), lessened particle flare ( p<0·05), inhibited aqueous PGE 2 levels ( p<0·001), and reduced corneal edema ( p=0·01) in the lensectomy group. The use of the rabbit model offers a convenient test to identify therapeutic agents that could lessen ocular complications after these common ocular surgeries.

Heparin in the intraocular irrigating solution in pediatric cataract surgery

Purpose: To investigate the antiinflammatory effects of adding heparin sodium to the irrigating solution to prevent fibrinoid reaction and related long-term complications after pediatric cataract surgery. Setting: Department of Ophthalmology, Inönü University, Turgut Özal Medical Center, Malatya, Turkey. Methods: Thirty eyes of 18 children who had cataract or other ocular surgery were included in the study. Bilateral cataract surgery was performed in 20 eyes of 10 children and bilateral secondary intraocular lens (IOL) implantation in 4 eyes of 2 children (Group 1). Four eyes of 4 children had unilateral cataract surgery and 2 eyes of 2 children with previous perforating eye injury had synechiotomy and pupilloplasty (Group 2). Heparin sodium was added to the irrigating solution during surgery in 12 left eyes of children with bilateral surgery (Group 1a) and in all eyes in Group 2. Heparin sodium was not added during surgery in 12 right eyes of children having bilateral surgery (Group 1b, control). Early and late postoperative intraocular reactions were recorded and compared. Results: In Group 1a (heparin added), 6 eyes had less fibrinoid reaction and fewer related complications such as posterior synechias, pupil irregularity, and intraocular lens (IOL) decentration than the fellow right eyes. No eye in Group 1a having primary cataract surgery had hyphema or intraocular bleeding. Hyphema occurred on the first postoperative day in 1 eye in Group 1a that had secondary IOL implantation. Conclusions: Adding heparin sodium to the irrigating solution decreased postoperative inflammatory and fibrinoid reactions and related complications such as synechias, pupil irregularity, and IOL decentration in pediatric cataract surgery. However, the use of heparin during surgery can be risky in eyes with a defective blood–aqueous barrier such as after previous ocular surgery.

Prostaglandin Analogs and Blood-Aqueous Barrier Integrity: A Flare Cell Meter Study

Purpose: To study, with an objective method, inflammation of the anterior segment of the glaucomatous eye after treatment with latanoprost, travoprost and bimatoprost. Materials and Methods: Sixty patients with chronic open-angle glaucoma aged between 38 and 76 years (mean 64.0 ± 12.2) were randomly assigned to latanoprost 0.005, travoprost 0.004 and bimatoprost 0.03%. The study period lasted 6 months. Intraocular pressure (IOP) was measured every 2 weeks. We studied the intraocular inflammation before and after 3 and 6 months of therapy with an instrument composed of a He-Ne laser beam system, a photomultiplier mounted on a slitlamp microscope and a computer. This flare meter allows objective determination of the flare and the number of cells in the aqueous of the anterior chamber. Results: At the baseline, IOP was 26.4 ± 3.6 mm Hg. After 3 months of treatment, mean IOP in the latanoprost group was 17.9 ± 0.3 mm Hg (p < 0.001) with a mean cellularity of 12.638 ± 3.284 photons/ms (p < 0.001). The travoprost group had an IOP of 17.2 ± 0.3 mm Hg (p < 0.001) with a cellularity of 9.719 ± 1.927 photons/ms (0.001). Finally, IOP in the bimatoprost group was 17.6 ± 0.5 mm Hg (p < 0.001) with a cellularity of 6.138 ± 1.475 photons/ms (p < 0.032). After 6 months of treatment, IOP in the latanoprost group was 18.1 ± 0.3 (p < 0.001), in the travoprost group 17.3 ± 0.3 (p < 0.001) and in the bimatoprost group 17.7 ± 0.5 mm Hg (p < 0.001), whereas cellularity was 11.838 ± 3.218 (p < 0.001), 8.950 ± 3.692 (p < 0.001) and 7.617 ± 2.603 photons/ms (p < 0.001), respectively. After 3 months, the travoprost (p < 0.013) and the bimatoprost groups (p < 0.001) had less flare compared with the latanoprost group and this remained so even at 6 months. When we compared the travoprost group with the bimatoprost group, we found significantly less flare at 3 months in the bimatoprost group (p < 0.001) but not at 6 months (p < 0.246). Conclusions: The flare meter analysis shows that the eyes treated with bimatoprost and travoprost have a less significantly broken blood-aqueous barrier and their anterior chamber is also significantly less inflamed.

Elevated homocysteine levels in aqueous humor of patients with pseudoexfoliation glaucoma

Purpose To determine total homocysteine levels in aqueous humor of pseudoexfoliation open-angle glaucoma patients. Design Case-control study. Methods Total homocysteine levels were measured by enzyme-linked immunosorbent assay in aqueous humor and plasma of 29 patients with pseudoexfoliation glaucoma and 31 control patients with cataract. Patients with factors affecting homocysteine levels were excluded. Results We observed significantly elevated (twofold) homocysteine levels in the aqueous humor of the glaucoma patients ( Z = −5.11, P < .0001). Additionally, the calculated ratio (plasma:aqueous humor) was significantly lower in these patients ( Z = −3.57, P < .001), and aqueous homocysteine was significantly correlated with their respective elevated plasma levels ( r = .42, P = .02). Conclusions Because homocysteine induces vascular injury and alterations of extracellular matrix, high aqueous homocysteine may trigger the abnormal matrix accumulation characteristic. It may reflect the proposed impairment of the blood-aqueous barrier of pseudoexfoliation open-angle glaucoma and be involved in its pathogenesis.

Increased aqueous flare intensity in eyes with liquefied after-cataract

Purpose: To describe aqueous flare intensity in eyes with white liquefied after-cataract. Setting: Department of Ophthalmology, Toyama Medical and Pharmaceutical University, Toyama, Japan. Methods: Seven patients with unilateral liquefied after-cataract and another 10 unaffected patients with an intraocular lens (IOL) were examined. The eyes were divided into 3 groups. The first group was composed of 7 eyes with liquefied after-cataract. The second group included the fellow eyes of the patients with unilateral liquefied after-cataract; 4 had an IOL, and 3 had cataract. The third group included 10 additional eyes without liquefied after-cataract. All patients underwent cataract operations consisting of phacoemulsification/aspiration with continuous curvilinear capsulorhexis and acrylic IOL implantation in the capsular bag. Aqueous flare was measured using a laser flare–cell meter. Results: The mean ± SD of aqueous flare intensity was significantly higher in the first group (11.8 ± 1.8 photon counts/msec) than in the second group (6.4 ± 0.8 photon counts/msec) and in the third group (6.3 ± 0.7 photon counts/msec). Conclusion: It is possible that liquefaction of after-cataract and disruption of the blood–aqueous barrier may be related.

Pseudoexfoliation syndrome: pathological manifestations of relevance to intraocular surgery

Pseudoexfoliation syndrome (PEX) is a common ocular condition often associated with the need for intraocular surgery. Although results of cataract and glaucoma filtering surgery in eyes with PEX in the early stages of the disease may be comparable to those in eyes without PEX, in the later stages morbidity is significantly increased due to periocular surgical complications and the outcome is worse. Surgical and postoperative difficulties are often multifactorial and are directly related to the pathological changes of PEX on intraocular structures. Recent years have seen a large increase in the understanding of the effects of PEX on the various ocular tissues. Although the visible areas of the anterior capsule are most obviously involved, this is only a small part of the picture and of least significance. Biomicroscopically invisible changes of the zonules and their attachments are of greatest consequence. There is also distinct, often active, involvement of almost all tissues of the anterior segment of the eye, many of which have important implications for the anterior segment surgeon including iridopathy, iris vasculopathy (including persistent breakdown of the blood-aqueous barrier and anterior segment hypoxia), ciliary body involvement and keratopathy. Trabecular dysfunction is evident by the deposition of PEX material derived from both in situ and extra-trabecular production as well as protein and melanin deposition. These changes should be kept in mind by all intraocular surgeons as a source of potential difficulties in the perioperative period. Additionally, in light of these changes, patients need to be given realistic expectations regarding the increased risk of complications and more prolonged expected recovery time. In this short review, current reports relating to PEX pathological changes of practical interest to the intraocular surgeon are summarized.

Disorders of the blood-aqueous barrier after phacoemulsification in diabetic patients.

To evaluate the function of the blood-aqueous barrier after phacoemulsification with implantation of a foldable intraocular lens (IOL) in diabetic patients. All patients were enrolled from those scheduled for phacoemulsification with intraocular lens implantation in Zhongshan Ophthalmic Center Guangzhou from March 2002 to June 2002. The classification on diabetic retinopathy (DR) was based on the fundus examination after cataract surgery. The blood-aqueous barrier function was examined using the laser flare cell meter (Kowa FC-2000) preoperatively and on postoperative days 1, 7, 30, and 90 by an independent examiner who was masked to the DR classification. Patients were operated by one experienced surgeon as per standard clinical protocol and were provided the same postoperative medical care. A linear regression and Wilcoxon test were used for the analysis. A total of 112 patients were divided into three groups: patients without diabetic mellitus as normal control (n=56), diabetic patients without diabetic retinopathy (n=2), with nonproliferation diabetic retinopathy (NPDR) (n=37), and diabetic patients with proliferation diabetic retinopathy (PDR) (n=17). All patients were examined and successfully followed up for 3 months after cataract surgery. Aqueous flare mean photon counts in PDR, NPDR, and control eyes were 8.94+/-0.57, 7.03+/-0.27, and 6.94+/-0.34 before surgery and increased to 32.42+/-0.67, 26.07+/-0.83, 26.27+/-1.37 on the first day after surgery (P<0.05), then decreased to 19.86+/-0.78, 14.08+/-0.54 and 13.96+/-1.05 at 7 days after surgery (P<0.05), 13.24+/-0.29, 9.86+/-0.33, and 9.07+/-0.43 at 30 days after surgery (P<0.05); eventually, the counting decreased to 11.25+/-0.31, 7.24+/-0.67, and 7.16+/-0.27 at 90 days after surgery (P<0.05). Linear regression model suggested that other potential variables, such as age, sex, eye (left/right), phaco time, phaco energy, and hypertension were not related to the outcome. For patients without diabetes mellitus and diabetic patients with NPDR, highly statistically significant differences (P<0.05) were found between preoperative flare value and those measured on days 1, 7, and 30 after surgery, but no statistically significant differences (P>0.05) were found between the preoperative flare value and those measured on postoperative days 90. However, patients with PDR still had a higher flare value even on postoperative day 90. The patients with intraoperative iris prolapse had a higher flare value between days 1 and 7 postoperatively. Phacoemulsification with a foldable intraocular lens implantation affects the blood-aqueous barrier more severely in diabetic patients with PDR than patients with NPDR and nondiabetic patients.

Disorders of the blood-aqueous barrier after phacoemulsification

To determine the status of blood-aqueous barrier after small incision phacoemulsification with implantation of foldable intraocular lens. The blood-aqueous barrier status in 64 eyes of 60 patients who underwent cataract surgery was examined using a laser flare cell meter. The protein level of anterior chamber aqueous humor was evaluated by measurement of the flare value preoperatively and postoperatively. The mean preoperative flare intensity was (6.94 +/- 0.34) photon counts/ms, which increased to (26.27 +/- 1.37), (13.96 +/- 1.05), (9.07 +/- 0.43) and (7.16 +/- 0.27) photon counts/ms on days 1, 7, 30 and 90 after the surgery, respectively. Significantly statistical differences on flare values were found between preoperative data and those on days 1, 7 and 30 after surgery. The blood-aqueous barrier was recovered on day 90 postoperatively. The variables such as age, gender, eye (left/right) had no influence on the flare value. Patients with iris prolapse had a higher flare value at day 1 and day 7 after the surgery. Blood-aqueous barrier after phacoemulsification with implantation of intraocular lens can be measured quantitatively by the laser flare cell meter. The blood-aqueous barrier disorders can be recovered shortly after phacoemulsification.

Changes in HNK-1 epitope and collagen type IX in the aqueous humour of patients with pseudoexfoliation syndrome

Purpose. To investigate alterations in the proteoglycan (PG) and glycosaminoglycan (GAG) content of the aqueous humour in patients with pseudoexfoliation syndrome (PEX). Materials and methods. Aqueous humor samples were obtained during cataract surgery from nineteen patients bearing PEX features and twenty-three age-matched normal controls. Protein and IgG were quantified densitometrically after their electrophoretic separation. Collagen type IX, 3-sulphoglucuronic acid (HNK-1 epitope), biglycan and heparan sulphate proteoglycans were detected in Western and dot blots by using specific monoclonal antibodies (MAbs). The immunochemical analysis was performed in native aqueous humour or after degradation of the glycosaminoglycans with chondroitinases. Results. Degradation of the samples with chondroitinases ABC, AC and B revealed that, in the aqueous humour from PEX eyes, collagen type IX and biglycan had a more dermatan sulphate than did normal eyes. In addition, more HNK-1 epitope was observed in PEX eyes, which after similar enzymatic treatment was found to be located mainly in dermatan sulphate sequences. 3-sulphoglucuronic acid was a constituent of the GAG chains of the collagen type IX. We found that the electrophoretic mobility of the bands of collagen type IX and HNK-1 epitope was exactly the same in the aqueous humour of normal and PEX samples; both migrated as four bands at 120, 113, 92.6 and 56 kDa. The PGs bearing heparan sulphate were found only in normal samples. Other PGs were not detected. Conclusion. Because no significant difference was observed in the concentration of albumin and IgG in PEX and normal samples, the blood-aqueous barrier was probably not significantly compromised in PEX patients with cataract but without open-angle glaucoma. The results support the hypothesis that the pathogenesis of PEX can be linked to disturbed metabolism of GAGs and PGs.

Effect of Disinsertion of Rectus Eye Muscles on Aqueous Humor Composition in Rabbits

To evaluate aqueous humor composition and biochemical analysis in a rabbit model for anterior segment ischemia. Six rabbits underwent bilateral disinsertion of the four rectus eye muscles. One day later, aqueous humor (0.1 to 0.2 mL) was withdrawn from the anterior chamber and the concentrations of electrolytes, glucose, and lactate were determined. Similar assessments were performed in 8 eyes of 4 control rabbits that were not operated on. Sodium and calcium concentrations (mean +/- standard deviation) were significantly higher in the study group than in the control group (142 +/- 2.9 vs 138 +/- 2 mmol/L, P = .002, and 1.4 +/- 0.1 vs 1.3 +/- 0 mmol/L, P = .005, respectively). Potassium concentrations were significantly lower in the study group than in the control group (4.1 +/- 0.5 vs 4.5 +/- 0.1 mmol/L; P = .02). The mean glucose level in the study group was 108.4 mg/dL, which is comparable to the published normal value of 108 mg/dL, and the mean lactate level was 124 mg/dL, which is significantly higher than the published normal value of 78 mg/dL (P = .001). Bilateral disinsertion of the four rectus muscles in rabbits resulted in a breakdown of the blood-aqueous barrier, as reflected and measured by an electrolyte imbalance. These experimental results may be useful in the future in searching for methods of manipulating the ischemic response. There is currently no indication to perform anterior chamber taps in humans for that purpose.