Serum albumin enters the posterior chamber of the eye permeating the blood-aqueous barrier

In order to check the entrance site of serum albumin into the aqueous humor, rabbits were injected intravenously either with Evans blue (which reacts very quickly with albumin) or horseradish peroxidase. The Evans blue-albumin complex (Eb-a) was traced to the posterior chamber as early as I min after injection by examining frozen half eyes. The Eb-a was localized in frozen sections by fluorescence microscopy in the stroma of the ciliary and iridial processes, as well as in the lumen of all blood vessels from 1 to 60 min after injection even at doses as low as 3 mg/kg. The peroxidase activity was also localized on these same structures from 8 min to 4.5 h. Neither tracer was visualized in the iris stroma outside the lumen of blood vessels. This was also true for experiments with Eb (75 mg/kg) in which the blood-aqueous barrier was disrupted. The concentration (m/v) of Evans blue and the peroxidase activity in the aqueous humor of the anterior chamber were estimated by spectrophotometry. The morphological integrity of the blood-aqueous barrier was demonstrated by electron microscopy in all peroxidase-injected rabbits. Considering that (a) the Eb-a appeared first in the posterior chamber, (b) there was a high concentration of tracers in the stroma of the ciliary and iridial processes, (c) neither tracer was visualized in the iris stroma, (d) there was no evidence of disruption of the blood-aqueous barrier, and (e) the concentration of both tracers in the aqueous humor kept increasing up to 4 h after injection, it was assumed that serum macromolecules entered first the posterior chamber and subsequently migrated to the anterior chamber. Most likely they passed in between the cells of the inner layer of the ciliary epithelium, the site of the so-called blood-aqueous barrier. No evidence was found indicating migration of macromolecules from the stroma of the processes directly to the anterior chamber via the iris root.     

超声乳化白内障吸除术对血-房水屏障功能的影响

目的　观察小切口超声乳化白内障吸除人工晶状体植入术及相关因素对血 房水屏障功能的影响。方法　使用激光蛋白细胞检测仪对 60例 (64只眼 )白内障患者超声乳化白内障吸除人工晶状体植入术前、后的房水蛋白浓度进行定量检测 ,记录并比较闪光值。术后随访时间为 3个月。结果　超声乳化白内障吸除人工晶状体植入术前 ,术后 1d、1周、1个月及 3个月术眼房水的平均闪光值分别为 (6 94± 0 3 4 )、(2 6 2 7± 1 3 7)、(13 96± 1 0 5)、(9 0 7± 0 43 )及 (7 16± 0 2 7)光粒子数 /ms ,其中术后 1d、1周及 1个月高于术前 ,且差异均有显著意义 (P <0 0 5) ;术后 3个月与术前比较 ,差异无显著意义 (P >0 0 5)。术后早期术眼房水蛋白浓度与患者年龄呈正相关 (r =0 40 0 ,P =0 0 0 1) ,与患者的性别和眼别均无相关。术中虹膜脱出者术后 1d和 1周血 房水屏障功能破坏严重。结论　超声乳化白内障吸除人工晶状体植入术在术后短期内影响术眼的血 房水屏障功能 ;激光蛋白细胞检测仪可动态评价超声乳化白内障吸除术对血 房水屏障功能的影响。 (中华眼科杂志 ,2 0 0 4,40 :2 6 2 9)     

Integrity of the blood-aqueous barrier in hyperuricemia

Neither the origin nor the role of high levels of uric acid, found in the aqueous humor of some human glaucomatous eyes, is known. A model of hyperuricemia in the rat was evaluated for its contribution to urate levels in the aqueous humor. Epinephrine-induced hyperuricemia in male rats was shown to increase mean serum urate levels from 1.2 mg/dL to 6.7 mg/dL. Female rats were shown to have a lower uric acid baseline and a lower absolute hyperuricemic level than males. The mean aqueous-humor urate levels were increased from 0.06 mg/dL to 0.33 mg/dL for male rats. In our studies, the blood-aqueous barrier effectively prevented equilibration between the systemic and ocular compartments. The increased aqueous-humor uric acid levels in glaucoma may arise from intraocular mechanisms.     

准分子激光原位角膜磨镶术对血-房水屏障功能的影响

目的 :评价准分子激光原位角膜磨镶术 (LASIK)对血 房水屏障功能的影响。方法 :对河南省眼科研究所行LASIK手术的 2 0例 (38眼 )屈光不正患者在手术前 1d及手术后 1d、1w分别行激光闪辉 /细胞光度仪 (KowaFC 2 0 0 0 )检查 ,测定房水闪辉光度值和细胞数 ,观察其数值变化 ,以判断LASIK手术对血 房水屏障功能的影响。结果 :手术前及手术后 1d、1w的房水闪辉光度值分别为 (3.5 3± 1.33)ph/ms、(4 .17± 1.2 4 )ph/ms和 (3.6 2± 1.34)ph/ms,细胞数分别为 (0 .31± 0 .6 1)个 /mm3 、(0 .2 4± 0 .34)个 /mm3 和 (0 .2 2± 0 .5 4 )个 /mm3 ,手术前后差异均无显著性 ,P >0 .0 5。结论 :LASIK手术安全可靠 ,对血 房水屏障无明显影响。     

Molecular sieve effect of the blood-aqueous barrier.

The concentration of seven plasma proteins (orosomucoid, albumin, transferrin, IgG, IgA, IgM and α₂-macroglobulin) was determined in parallel in serum and aqueous humour of 19 patients with assumedly normal aqueous humour and 48 patients with mildly increased total aqueous protein levels. IgM and α₂-macroglobulin were not detectable in any of the aqueous humour samples. For the other proteins the concentration in aqueous humour varied with their molecular size and concentration in the serum, and this relationship was used to evaluate the pore size of the blood-aqueous barrier, for which a pore radius of about 104 Å is proposed.     

眼挫伤的血—房水屏障改变

目的 探讨外伤性葡萄膜炎与血－房水屏障破坏的关系。方法 新西兰兔１８只,以自由落体打击力制备双眼重型闭合性眼球挫伤模型;以＾１３１Ｉ为示踪剂进行房水免疫学测定。并与正常兔眼作对照。结论 兔眼钝伤后可致较严重的血－房水屏障破坏。伤后１周为快速修复期,４周时完全修复。     

Study of the blood-aqueous barrier in choroidal melanoma.

AIMS--Aqueous flare was used to determine the frequency and amount of blood-aqueous barrier breakdown and correlate it with tumour variables. METHODS--Aqueous flare was analysed prospectively by laser flare photometry in 139 consecutive patients seen in the oncology unit for choroidal melanoma. Both eyes of patients were examined with a laser flare cell meter in a standard fashion. RESULTS--Mean flare difference between healthy and tumour eyes was 3.01 (SD 2.5) photons per millisecond (ph/ms) in 32 cases of small melanomas (p < 0.0001), 10.74 (13.9) ph/ms in 92 cases of medium and large melanomas (p < 0.0001), and 19.23 (11.8) ph/ms in 15 cases of very large melanomas (p < 0.0001). This mean differential flare was significantly higher in medium and large than in small melanomas (p < 0.002) and in very large melanomas than in medium and large melanomas (p < 0.028). A difference of > or = 7 ph/ms between affected and healthy eyes was noted in 70 of 139 melanomas (50.4%). It was found in 3/32 small melanomas (9.4%), in 53/92 medium and large melanomas (57.6%), and in 14/15 very large melanomas (93.3%). CONCLUSION--Multiple linear regression analysis showed that flare was most strongly correlated with tumour volume (r = 0.43; p < 0.0001) and tumour height (r = 0.41; p < 0.0008).     

Effect of intraocular lens fixation on the blood-aqueous barrier

We used slit-lamp fluorophotometry to evaluate the influence of various intraocular lens fixation sites on the blood-aqueous barrier in 106 eyes. After an average follow-up period of 1.1 years, eyes with anterior chamber lenses with closed or rectangular loops had a significantly higher concentration of fluorescein than did eyes with other types of implants (P less than .1 to P less than .001). In eyes with posterior chamber lenses, those with ciliary sulcus fixation had a significantly higher concentration of fluorescein than did those with intracapsular fixation (P less than .02). Compared with aphakic eyes without implants, eyes with any implant other than posterior chamber lenses with intracapsular fixation had significantly higher fluorescein concentrations (P less than .02 to P less than .001). These results indicated that the flexibility and the intraocular location of the lens loops are significant factors in securing the integrity of the blood-aqueous barrier of pseudophakic eyes. Posterior chamber lenses with intracapsular fixation caused the least trauma to the blood-aqueous barrier.     

Experimental brucei trypanosomiasis: Immunosuppression of the blood-aqueous barrier

Experimental Trypanosoma brucei infection induces intense protein leakage into the anterior chamber of cats' and dogs' eyes, with a cyclitis-like symptomatology, preceded by hypersensitivity of conjunctiva and respiratory mucosae, together with lacrimation, and facial oedema. The pherogram of the aqueous humor is the replica of the serum pherogram at the end-stage of the disease, and is identical to that of secondary aqueous. Absence of any significant changes in serum proteins and immunoglobulins, and the poor cellular reaction at tissue level point towards immune unresponsiveness subsequent to experimental protozoal infection. Light microscopy reveals, at the level of the ciliary processes two kinds of cystic formation, the walls of which are formed by ciliary epithelium. One type contains amorphous material next to trypanosomes, macrophages and plasmocyte-like cells; the second type contains also fibrillar structures possibly collagen. Ultramicroscopy suggests these cystic formations to be enlarged ciliary channels. The fenestrated capillary wall showed no changes, either after withdrawal of aqueous, or after toxic parasite-action; the presence of large protein molecules and trypanosomes in the anterior chamber is due to damage to the ciliary epithelium.     

Recovery of the blood-aqueous barrier after cataract surgery.

Following extracapsular cataract and posterior chamber implant surgery the sequential recovery of the blood-aqueous barrier was measured by anterior segment fluorophotometry. Postoperatively 49 (69.0%) out of 71 eyes (71 patients) had recovered at a uniform rate, re-establishing a normal blood-aqueous barrier by the end of the three-month study. In these eyes recovery of the blood-aqueous barrier was unaffected by the use of preoperative indomethacin, the surgeon, the type of section, or the type of fixation of the implant. In eyes recovering normally after cataract surgery the rate of recovery of the blood-aqueous barrier can be expressed by a in the equation a = (y-b)/x, in which y is the logarithm of the anterior chamber fluorescence, x is the time after surgery, and b is a constant for each patient which is the anterior chamber fluorescence measured immediately after surgery. This normal rate of recovery provides a baseline from which to assess surgical technique or postoperative medication.     

Disruption of the blood-aqueous barrier following paracentesis in the rabbit

The concentrations of protein and prostaglandin are greatly elevated in aqueous humour secondary to anterior chamber paracentesis in the rabbit. A transient increase of intraocular tension which follows paracentesis is mediated by prostaglandin and the breakdown in the blood-aqueous barrier is at least partly mediated by this autacoid. Using a fluorescein angiographic technique the bulk of the plasmoid aqueous was shown to enter the anterior chamber through the pupil and not from the surface of the iris. Furthermore, the capillary beds of the ciliary processes, but not of the iris, took up intravenously-injected colloidal carbon indicating that the ciliary vessels became excessively permeable. The present evidence indicates that the site of disruption of the blood-aqueous barrier occurs within the ciliary processes and not in the iris.