血视神经屏障与血脑屏障的比较研究

目的 观察血视神经屏障与血脑屏障之间的差异。 方法 SD雄性大鼠20只，分别取视神经的筛板前区、筛板区、筛板后区、眶内段、管内段、颅内段和大脑皮层，用电子显微镜观察各部位微血管内皮细胞的超微结构；用免疫组织化学的方法检测转铁蛋白受体(OX-26)和金属蛋白酶诱导因子(OX-47)的表达及微血管周围纤维蛋白原外渗情况。 结果 电子显微镜显示视神经各段和大脑皮层微血管内皮细胞均为紧密连接，但筛板前区质膜囊泡较大脑皮层多(P＜0.05)；而筛板区、筛板后区、眶内段、管内段和颅内段质膜囊泡与大脑皮层比较无显著差异(P＞0.05）。免疫组织化学显示筛板前区微血管内皮细胞OX-26和OX-47表达阴性，微血管周围有微量纤给蛋白原外渗；而筛板区、筛板后区、眶内段 、管内段、颅内段和大脑皮层微血管内皮细胞OX-26和OX-47阳性表达，微血管周围未见纤维蛋白原。 结论 筛板前区微血管内皮细胞在超微结构、标记物表达及通透性方面与大脑皮层存在差异，因而不具有血脑屏障特性，而筛板区、筛板后区、眶内段、管内段和颅内段与大脑皮层存在相似的特性，故具有血脑屏障特性。 （中华眼底病杂志，2006，22：390-393）     

The blood flow in post-laminar optic nerve in monkeys was dependent on intraocular pressure level

The effects of artificial elevation of intraocular pressure on the blood flow in the 1mm post-laminar portion of the optic nerve was evaluated in 9 monkeys (Macaca fuscata). The intraocular pressure of one eye was elevated while the fellow eye served as control. The intraocular pressure of the control was maintained at 15 mmHg. We used the hydrogen clearance method in quantitating the blood flow. Anesthesia was maintained with injection of pentobarbital sodium into the femoral vein. In each experiment, the intraocular pressure was raised from 15 mmHg to 30, 50 or 70 mmHg in a stepwise fashion. At the intraocular pressure level of 15 mmHg, the blood flow measured 120.0 +/- 19.4 ml/min/100g (mean +/- standard deviation). The blood flow decreased linearly along with the rise of intraocular pressure up to 70 mmHg. The blood flow at 70 mmHg was 37% of the initial value. At each level of raised intraocular pressure, the blood flow remained constant for at least 60 minutes. The decreased blood flow promptly returned to the initial level when the raised intraocular pressure was restored to the initial value of 15 mmHg. We concluded from the above findings that the blood flow in the immediate post-laminar portion of the optic nerve is dependent on the level of intraocular pressure up to 70 mmHg.     

视网膜母细胞瘤眼球摘除术后病理与预后分析

目的　分析视网膜母细胞瘤（ｒｅｔｉｎｏｂｌａｓｔｏｍａ,Ｒｂ）侵犯眼球部位与患者预后之间的关系,为病情的预测和治疗提供依据。方法　回顾性分析２００３年１月至２０１１年２月于中山大学中山眼科中心行眼球摘除术的单眼Ｒｂ患者。记录术后肿瘤侵犯的部位、治疗情况和生存情况并评估患者的５ａ生存率（５ｙｅａｒｐｒｏｂａｂｉｌｉｔｙｅｖｅｎｔ-ｆｒｅｅｓｕｒｖｉｖａｌ,５-ＰＥＦＳ）。随访以患者死亡或至２０１２年２月截止,随访时间为（４６．３±２９．２）个月。结果　共有２０２例２０２眼患者纳入研究,其中筛板及筛板前侵犯所占比例最大（４０．６％）,５-ＰＥＦＳ也最高（９６．１％）;筛板后视神经侵犯和视神经断端侵犯者５-ＰＥＦＳ分别是８２．５％和４０．０％,三者比较差异有显著统计学意义（Ｐ＜０．０１）。筛板后视神经侵犯接受治疗的患者５-ＰＥＦＳ（９１．６％）有高于未治疗者（６６．７％）的趋势（Ｐ＝０．０９）;视神经断端侵犯者接受治疗与未治疗的５-ＰＥＦＳ分别是５０．０％和０（Ｐ＜０．０１）,单纯脉络膜侵犯患者５-ＰＥＦＳ是９３．８％,巩膜侵犯患者接受和未接受辅助化疗的５-ＰＥＦＳ分别是５７．１％ 和７７．８％（Ｐ＞０．０５）。２例眼眶侵犯患者均死亡,４例患者眼球摘除术后眼眶复发,从眼球摘除术到眼眶复发的时间是５～１５个月,平均为９．８个月。结论　Ｒｂ眼球摘除术后病理检查对患者预后的预测和辅助治疗有指导意义;眼球摘除术后２ａ,尤其１ａ内是Ｒｂ复发的高发期,这期间所有患者需要密切随诊。     

Microangioarchitecture of optic papilla

Two hundred postmortem normal human eyes of 100 cases were studied by four methods to investigate the microangioarchitecture of the optic papilla. The following results have been obtained. The Zinn's circle is important to the blood supply of the optic papilla. It gives off tributaries to the papillar prelaminar and laminar layers and pial vessel network at the retrolaminar portion. The blood supply of the prelaminar layer comes directly from the branches of the short posterior ciliary arteries and Zinn's circle, while the choroidal vessels contribute only a few branches to this area. The above two results are not consistent with Hayreh's idea. Between the central retinal artery system and short posterior ciliary artery system, there are anastomoses at the pial vessel network and in the optic nerve at the retrolaminar portion, but none is found, obviously, in the intraocular portion of the optic nerve. The microangioarchitecture of the optic papilla is accommodated to the nerve in which it resides. The most superficial vessels are radiating, those in the prelaminar and laminar layers are lamellar, and those in the retrolaminar portion are an interwoven network. The caliber of the capillary at the prelaminar and laminar layers is the narrowest, therefore, an ischemic change easily takes place right here.     

Optic nerve invasion of uveal melanoma: clinical characteristics and metastatic pattern

PURPOSE: To determine the frequency of optic nerve invasion in uveal melanoma, to identify clinical factors associated with optic nerve invasion, and to analyze the metastatic pattern and the association with survival. METHODS: All iris, ciliary body, and choroidal melanomas (N = 2758) examined between 1942 and 2001 at the Eye Pathology Institute, University of Copenhagen, Denmark, and the Institute of Pathology, Aarhus University Hospital, Aarhus, Denmark, were reviewed. Cases with optic nerve invasion were identified and subdivided into prelaminar or laminar invasion and postlaminar invasion. Clinical characteristics were compared with those from 85 cases randomly drawn from all ciliary body and choroidal melanomas without optic nerve invasion from the same period. Survival data were obtained by the Kaplan-Meier method, and the Mantel-Cox log-rank test was used to test differences in survival among the three patient groups. RESULTS: Optic nerve invasion was found in 157 uveal melanomas (5.7%; 95% confidence interval [CI], 4.8%-6.6%). Frequency varied during the observation period between 5% and 7%. Only choroidal and ciliary body melanomas were found to invade the optic nerve. Eighty-five (54%) were confined to the prelaminar or laminar part, and 72 (46%) were confined to the postlaminar part. Increased intraocular pressure (IOP) and juxtapapillary location were associated with prelaminar or laminar invasion and postlaminar invasion. Age older than 70 years, reduced vision to light perception or worse, nonvisible fundus, and large (>15 mm) tumor size were associated with postlaminar spread. In univariate analysis, patients with postlaminar invasion had significantly higher all-cause and melanoma-related mortality than the other patients. CONCLUSIONS: Optic nerve invasion in uveal melanoma is found in 1 in 20 patients. Visible juxtapapillary melanoma or loss of light perception should make the clinician suspicious of melanoma with optic nerve invasion, and special awareness of postlaminar spread should be addressed when increased IOP is present independently of decreased visual acuity and tumor location.     

Does the blood-brain barrier play a role in Glaucoma?

The optic nerve head, although part of the central nervous system, lacks classical blood-brain barrier properties. The tissue of Elschnig does not totally separate the optic nerve head from fenestrated peripapillary choriocapillaries. The microvessels in the prelaminar region of the optic nerve head have less effective barriers than those in the laminar or retrolaminar regions. In glaucoma, the blood-brain barrier in the optic nerve head may even be weaker. Incomplete blood-brain barrier renders circulating molecules, such as endothelin-1 (ET-1), direct access to smooth vascular muscle cells and pericytes both in the prelaminar part of the optic nerve head and to adjacent retinal tissue. This potentially leads to some vasoconstriction as observed in the peri-papillary retinal vessel in glaucoma patients. In extreme situations, this may provoke retinal vein occlusion. The direct access of these molecules also influences the barrier function. If, simultaneously, ET-1 reduces endothelial tight-junctions and matrix-metalloproteinase (MMP)-9 degrades the basement membrane, not only macromolecules but even red blood cells may cross the blood-brain barrier and lead to what is clinically observed as optic disk hemorrhages.     

Luminal characteristics of central retinal vessels in the anterior optic nerve of the young human

PURPOSE: To study the luminal characteristics of the central retinal vessels of young humans where the vessels pass through the anterior optic nerve. METHODS: Serial sections of nine central retinal arteries (CRAs) and 13 central retinal veins (CRVs) from 12 eyes of 12 young donors (aged 20-29 years) without known ocular disease or anatomic malformation were examined by image analysis to determine their luminal dimensional differences right at, anterior to, and posterior to the lamina cribrosa. RESULTS: The average values of the mean area of the CRAs in the prelaminar, laminar, and retrolaminar portions were 16.5 x 10(3) microm2, 17.2 x 10(3) microm2, and 15.2 x 10(3) microm2, and mean perimetric lengths were 541 microm, 528 microm, and 492 microm, respectively. Differences were detected in perimetric length and theoretical luminal area between the laminar and retrolaminar portions, but not the prelaminar and laminar portions. The average values of the mean area of the CRVs in the prelaminar, laminar, and retrolaminar portions were 24.6 x 10(3) microm2, 13.3 x 10(3) microm2, and 7.8 x 10(3) microm2, and mean perimetric lengths were 689 microm, 544 microm, and 411 microm, respectively. There were marked differences between the prelaminar and laminar values and between the laminar and retrolaminar values in terms of the perimetric lengths and theoretical luminal areas. CONCLUSIONS: The results suggest that the resistance of blood flow in CRAs decreases when the blood enters the eye. The gradual constriction of CRVs from the prelaminar to the retrolaminar portion may act as a throttle mechanism in controlling the outflow of the blood and in maintaining the patency of the retinal venules and capillaries.     

Association of magnetic resonance imaging of anterior optic pathway with glaucomatous visual field damage and optic disc cupping

PURPOSE: To investigate the association of magnetic resonance imaging (MRI) of anterior optic pathway with glaucomatous visual field damage and optic disc cupping. SUBJECTS AND METHODS: Twenty-three healthy volunteers (controls) and 31 glaucoma patients (14 with primary open angle glaucoma and 17 with normal tension glaucoma) were enrolled. All the participants showed no abnormal signs in their intracranial space and optic tract causing optic nerve atrophy and visual field defect, as confirmed by MRI. Multislice T1-weighted spin-echo imaging was performed in the sagittal plane followed by the coronal plane. MRI enabled the evaluation of the diameter of the optic nerve located in the retro-bulb space and the height of the optic chiasm in an observer-masked fashion. The MRI data were compared with the mean deviation (MD) score of the full threshold static visual field test and the optic cup-disc ratio (C/D ratio). RESULTS: The optic nerve diameter was significantly smaller in glaucoma patients (2.25 +/- 0.33 mm) than in controls (2.47 +/- 0.24 mm) and the height of the optic chiasm was significantly shorter in glaucoma patients (2.12 +/- 0.37 mm) than in controls (2.77 +/- 0.36 mm). The optic nerve diameter showed significant correlation with MD score (r = 0.547, P = 0.001) and C/D ratio (r = 0.407, P = 0.009). These correlations are similar to that between MD score and C/D ratio (r = 0.490, P = 0.001). The height of the optic chiasm showed significant correlation with MD score (r = 0.503, P = 0.01) and low correlation with C/D ratio (r = 0.339, P = 0.113). CONCLUSION: Glaucoma affects the anterior visual pathway anterogradely at least up to the optic chiasm, and these morphologic changes in the anterior visual pathway are correlated with glaucomatous optic nerve damage. MRI of the anterior visual pathway may be a good tool for evaluating glaucomatous damage objectively.     

Angiographically normal central retinal artery following the total resection of an optic nerve glioma

Although the central retinal artery and its collateral circulation, especially within the anterior optic nerve, have been extensively studied, there continues to be controversy regarding the existence and significance of anastomoses between the central retinal artery and ciliary circulation. We present the case of a 16-year-old boy who underwent total resection of an optic nerve glioma beginning proximally at the chiasm and ending distally flush with the globe. After resection, heavy bipolar cautery was applied. Postoperatively, normal central retinal artery circulation was documented angiographically, suggesting that, at least in some cases, significant anastomoses can develop between the central retinal artery and ciliary circulation in the laminar and prelaminar areas.     

The distributions of mitochondria and sodium channels reflect the specific energy requirements and conduction properties of the human optic nerve head

AIM: To study the normal distributions of mitochondria and voltage gated Na+ channels in the human optic nerve head in order to gain insight into the potential mechanisms of optic nerve dysfunction seen in the inherited optic neuropathies. METHODS: Five fresh frozen human optic nerves were studied. Longitudinally orientated, serial cryosections of optic nerve head were cut for mitochondrial enzyme histochemistry and immunolabelling for cytochrome c oxidase (COX) subunits and voltage gated Na+ channel subtypes (Na(v) 1.1, 1.2, 1.3, and 1.6). RESULTS: A high density of voltage gated Na+ channels (subtypes Na(v) 1.1, 1.3, and 1.6) in the unmyelinated, prelaminar, and laminar optic nerve was found. This distribution co-localised both with areas of high COX activity and strong immunolabelling for COX subunits I and IV. CONCLUSIONS: Increased numbers of mitochondria in the prelaminar optic nerve have previously been interpreted as indicating a mechanical hold up of axoplasmic flow at the lamina cribrosa. These results suggest that this increased mitochondrial density serves the higher energy requirements for electrical conduction in unmyelinated axons in the prelaminar and laminar optic nerve and is not a reflection of any mechanical restriction. This could explain why optic neuropathies typically occur in primary inherited mitochondrial diseases such as Leber's hereditary optic neuropathy, myoclonic epilepsy with ragged red fibres (MERRF), and Leigh's syndrome. Secondary mitochondrial dysfunction has also been reported in dominant optic atrophy, Friedreich's ataxia, tobacco alcohol amblyopia, Cuban epidemic optic neuropathy, and chloramphenicol optic neuropathy. These diseases are rare but these findings challenge the traditional theories of optic nerve structure and function and may suggest an alternative approach to the study of commoner optic neuropathies such as glaucoma.     

Blood flow and glucose consumption in the optic nerve, retina and brain: effects of high intraocular pressure

Glucose consumption and regional blood flow were determined using the [14C]-2-deoxyglucose (2-DG) method and microspheres in the optic nerve, the retina and different parts of the brain in monkeys. The relationship between the 2-DG accumulation and blood flow in the optic nerve head region was similar to that in grey matter of the brain under pentobarbital anaesthesia as well as under urethan anaesthesia. Pentobarbital anaesthesia resulted in lower values for blood flow and glucose metabolism in most regions. In the optic nerve the highest values were observed in the distal part; there was a fall in blood flow and metabolism along the nerve. There was a corresponding increase in myelin content. Artificial increments in intraocular pressure resulting in a perfusion pressure (mean arterial pressure minus intraocular pressure) of 40 cm H2O had no appreciable effect on the 2-DG accumulation. At a perfusion pressure of 20 cm H2O 2-DG accumulation in the retina and prelaminar part of the optic nerve was markedly increased indicating partial ischemia resulting in anaerobic glycolysis. At intraocular pressures higher than the systolic arterial blood pressure there was still some accumulation of 2-DG in the intraocular tissues, but no blood flow, which indicates that glucose could diffuse into the eye through the sclera. Behind the lamina cribrosa there was no indication of a reduction in blood flow or a metabolic disturbance. The results indicate that the blood flow and metabolism of the retina and prelaminar part of the optic nerve is disturbed only at very high intraocular pressures, and that even at extreme pressures there is no disturbance behind the lamina cribrosa in acute experiments. The 2-DG method will be useful in further studies on the nutritional status of the optic nerve head since it can detect abnormal glycolysis even in very discrete regions due to its high spatial resolution.     

The role of fluorescein angiography in the interpretation of optic nerve head diseases

In normal individuals fluorescein angiography of the optic nerve head has some peculiar signs. Three early phases can be distinguished, they include: 1) retrolaminar and laminar filling, 2) prelaminar filling, 3) superficial capillary filling. A late staining is also part of the fluorescein angiography of a normal disc. Many optic nerve disturbances show changes of the above mentioned angiographic signs. The Authors discuss the fluorescein angiographic pattern of 1) anterior ischemic optic neuropathy, 2) central retinal vein occlusion, 3) papilledema and 4) drusen.     

急性高眼压模型兔眼不同眼压状态下视神经轴浆运输的改变

目的 观察急性高眼压模型兔眼不同眼压状态下视神经轴浆运输的改变。方法 成年新西兰大白兔24只,分为眼压20、30、40 mm Hg(1 mm Hg=0.133 kPa)组和眼压为10～15 mm Hg的对照组,每组均为6只兔。采用前房穿刺灌注法联合压力持续监测法建立急性高眼压模型。实验开始时,兔眼玻璃体腔中注射罗丹明异硫氰酸(RITC)标记轴浆运输。持续3h高眼压后,过量麻醉处死兔后取下视神经。荧光显微镜下观察视神经轴浆运输情况的改变。采用德国Leica公司Q500IW图像分析软件对RITC进行灰度定量分析,并对各眼压组平均灰度值和筛板前、筛板区、筛板后350 μm区域灰度值进行统计学分析处理。结果 RITC在视神经中心呈顺行标记染色。不同眼压组轴浆运输情况不同,随着眼压升高,轴浆运输能力减弱,差异有统计学意义(F=159.3,P＜0.05)。筛板前区,各眼压组间灰度值比较,差异无统计学意义(F=0.2545,P＞0.05)。40 mm Hg组灰度值与对照组灰度值比较,在筛板区（t=5.684）和筛板后350 μm区域（t=5.124）差异均有统计学意义(P＜0.05);20、30 mm Hg组灰度值与对照组灰度值比较,差异无统计学意义(t=1.747,P＞0.05)。结论 眼压40 mm Hg持续3h将导致视神经轴浆运输改变,轴浆运输障碍部位以筛板区及以后的区域为主。     

Laminar displacement and prelaminar tissue thickness change after glaucoma surgery imaged with optical coherence tomography

Purpose. To study changes in lamina cribrosa position and prelaminar tissue thickness (PTT) after surgical IOP reduction in glaucoma patients. Methods. Twenty-two patients (mean age, 71.4 years) were imaged with spectral domain optical coherence tomography (SD-OCT; 24 radial B-scans centered on the optic nerve head [ONH]) before trabeculectomy or tube shunt implantation. Follow up images were acquired 1 week, 1 month, 3 months, and 6 months postsurgery. Bruch's membrane opening (BMO), the internal limiting membrane (ILM) and the anterior laminar surface (ALS) were segmented in each radial scan with custom software. Surfaces were fitted to the ILM and ALS with the extracted three-dimesional coordinates. PTT was the distance between the ILM and ALS, perpendicular to a BMO reference plane. Serial postsurgical laminar displacement (LD), relative to the BMO reference plane, and changes in PTT were measured. Positive values indicated anterior LD. Results. Mean (SD) presurgery IOP was 18.1 (6.5) mm Hg, and reduced by 4.7 (5.5), 2.4 (7.7), 7.0 (6.2), and 6.8 (7.5) mm Hg at 1 week, 1 month, 3 months, and 6 months postsurgery, respectively. At the four postsurgery time points, there was significant anterior LD (1.8 [9.5], -1.1 [8.9], 8.8 [20.2], and 17.9 [25.8] μm) and PTT increase (1.7 [13.3], 2.4 [11.9], 17.4 [13.7], and 13.9 [18.6] μm). LD was greater in ONHs with larger BMO area (P = 0.01) and deeper ALS (P = 0.04); however, PTT was not associated with any of the tested independent variables. Conclusions. Both anterior LD and thickening of prelaminar tissue occur after surgical IOP reduction in patients with glaucoma.     

Transvitreal optic neurotomy for nonarteritic anterior ischemic optic neuropathy

PURPOSE: To evaluate the role of transvitreal optic neurotomy in the treatment of nonarteritic anterior ischemic optic neuropathy, a scleral outlet compartment syndrome, in which neurovascular compression at the prelaminar and laminar regions of the optic nerve head may play a major role. METHODS: Seven eyes of seven selected patients with severe vision loss (<20/800) from nonarteritic anterior ischemic optic neuropathy underwent transvitreal nasal radial optic neurotomy. The study was not masked and not randomized. Visual acuity and visual fields, when possible, were measured, and fluorescein angiography was performed preoperatively and postoperatively. RESULTS: Four male and three female patients had a mean age of 52.4 years; five had bilateral disease. The mean follow-up was 13 +/- 7 weeks. Mean preoperative visual acuity was 20/2400; mean postoperative visual acuity was 20/250, with an average of 10 lines of improvement. Six of seven patients showed visual improvement. One patient had peripapillary choroidal neovascularization. In two patients with sufficient visual acuity, preoperative visual fields could be obtained; these patients showed significant improvement in postoperative perimetry. Five patients had some loss of vision, which made it impossible to obtain preoperative visual fields. CONCLUSION: Relaxation of the scleral ring of the prelaminar and laminar regions of the optic nerve head reduces constriction and may prevent necrosis of salvageable but underperfused nerve fibers. Despite improvement of visual acuity in our patients, transvitreal optic neurotomy should be considered experimental, requiring a randomized clinical trial.     

Axonal transport and cytoskeletal changes in the laminar regions after elevated intraocular pressure

PURPOSE: To investigate the axonal cytoskeleton changes occurring in the prelaminar region, lamina cribrosa, and postlaminar region of the porcine optic nerve after an acute increase in intraocular pressure (IOP) and whether this corresponds with axonal transport abnormalities. METHODS: Six white Landrace pigs were used. The left eye IOP was elevated to 40 to 45 mm Hg for 6 hours, and the right eye IOP was maintained between 10 and 15 mm Hg. Rhodamine-beta-isothiocyanate (RITC) was injected into the vitreous of each eye at the beginning of the experiment, to study axonal transport. After euthanasia, optic nerves were removed and prepared for axonal transport and cytoskeleton studies. Antibodies to phosphorylated neurofilament heavy (NFHp), phosphorylation-independent neurofilament heavy (NFH), neurofilament light (NFL), neurofilament medium (NFM), microtubule, and microtubule-associated protein (MAP) were used to study the axonal cytoskeleton. Montages of confocal microscopy images were quantitatively analyzed to investigate simultaneous changes in optic nerve axonal transport and cytoskeletal proteins in the high-IOP and control eyes. RESULTS: Axonal transport of RITC was reduced in the prelaminar, lamina cribrosa, and proximal 400 mum of the postlaminar optic nerve regions in the high-IOP eye. NFHp, NFM, and NFH were significantly reduced in the prelaminar, lamina cribrosa, and proximal postlaminar regions in the high-IOP eye. No differences in NFL, MAP, and tubulin staining were detected. CONCLUSIONS: Elevated IOP induced both axonal transport and cytoskeleton changes in the optic nerve head. Changes to the cytoskeleton may contribute to the axonal transport abnormalities that occur in elevated IOP.     

Pathogenesis of optic disc edema in raised intracranial pressure

Optic disc edema in raised intracranial pressure was first described in 1853. Ever since, there has been a plethora of controversial hypotheses to explain its pathogenesis. I have explored the subject comprehensively by doing basic, experimental and clinical studies. My objective was to investigate the fundamentals of the subject, to test the validity of the previous theories, and finally, based on all these studies, to find a logical explanation for the pathogenesis. My studies included the following issues pertinent to the pathogenesis of optic disc edema in raised intracranial pressure: the anatomy and blood supply of the optic nerve, the roles of the sheath of the optic nerve, of the centripetal flow of fluids along the optic nerve, of compression of the central retinal vein, and of acute intracranial hypertension and its associated effects. I found that, contrary to some previous claims, an acute rise of intracranial pressure was not quickly followed by production of optic disc edema. Then, in rhesus monkeys, I produced experimentally chronic intracranial hypertension by slowly increasing in size space-occupying lesions, in different parts of the brain. Those produced raised cerebrospinal fluid pressure (CSFP) and optic disc edema, identical to those seen in patients with elevated CSFP. Having achieved that, I investigated various aspects of optic disc edema by ophthalmoscopy, stereoscopic color fundus photography and fluorescein fundus angiography, and light microscopic, electron microscopic, horseradish peroxidase and axoplasmic transport studies, and evaluated the effect of opening the sheath of the optic nerve on the optic disc edema. This latter study showed that opening the sheath resulted in resolution of optic disc edema on the side of the sheath fenestration, in spite of high intracranial CSFP, proving that a rise of CSFP in the sheath was the essential pre-requisite for the development of optic disc edema. I also investigated optic disc edema with raised CSFP in patients, by evaluating optic disc and fundus changes by stereoscopic fundus photography and fluorescein fundus angiography.Based on the combined information from all the studies discussed above, it is clear that the pathogenesis of optic disc edema in raised intracranial pressure is a mechanical phenomenon. It is primarily due to a rise of CSFP in the optic nerve sheath, which produces axoplasmic flow stasis in the optic nerve fibers in the surface nerve fiber layer and prelaminar region of the optic nerve head. Axoplasmic flow stasis then results in swelling of the nerve fibers, and consequently of the optic disc. Swelling of the nerve fibers and of the optic disc secondarily compresses the fine, low-pressure venules in that region, resulting in venous stasis and fluid leakage; that leads to the accumulation of extracellular fluid. Contrary to the previous theories, the various vascular changes seen in optic disc edema are secondary and not primary. Thus, optic disc edema in raised CSFP is due to a combination of swollen nerve fibers and the accumulation of extracellular fluid.My studies also provided information about the pathogeneses of visual disturbances in raised intracranial pressure.     

Tumour angiogenesis as a prognostic factor for disease dissemination in retinoblastoma

AIM: To evaluate tumour angiogenesis as a predictor of prognosis in retinoblastoma. METHODS: This was a retrospective, non-randomised comparative clinicopathological study. The histopathology from 24 cases of Reese-Ellsworth (RE) group V unilateral retinoblastoma treated by enucleation alone was reviewed. Group I consisted of five patients (four RE group Vb and one group Va) who developed disseminated disease at a mean of 10.4 months after enucleation. The remaining 19 patients constitute group II (18 RE group Vb and 1 group Va), none of whom had developed metastatic disease with a mean follow up of 54 months. None of the 24 patients had evidence of extraocular disease at enucleation. The surgical specimens from patients with unilateral retinoblastoma treated by enucleation at Hospital do Cancer AC Camargo between January 1992 and December 1995 were identified, reviewed and the clinical data recorded. Two subsequent histological sections were prepared. One stained with haematoxylin and eosin for assessment of choroidal and optic nerve invasion, and the other for immunoreaction with an endothelium specific marker (antibody anti-CD 34). The main outcome measures were choroidal and/or optic nerve invasion and quantification of the tumour's relative vascular area (TRVA) obtained by Chalkley counting. RESULTS: Choroidal invasion was present in three eyes of group I (all massive) and six eyes of group II (two focal and four massive). Optic nerve invasion was found in two eyes of group I (all post-laminar) and four eyes of group II (three prelaminar and one post-laminar). There was no statistical difference regarding choroidal or optic nerve between the two groups. The TRVA was the only independent variable found to predict disease dissemination (p = 0.008 by Cox analysis). A TRVA equal to or greater than 3.9% had 100% sensitivity and 79% specificity in predicting disease dissemination. CONCLUSIONS: Quantification of angiogenesis, through measurement of the TRVA, can help to identify patients with retinoblastoma at high risk for disease dissemination after enucleation.     

老年人视网膜中央血管在前部视神经的解剖特征

目的：观察老年人前部视神经视网膜中央血管的解剖特征。 方法：通过组织连续切片和计算机影像分析，观察60~82岁老年人的18只眼球标本中无解剖变异的视网膜中央动脉(CRA)15条，视网膜中央静脉（CRV）23条在筛板前、筛板区及筛板后的管径变化。 结果：老年人筛板前、筛板区、筛板后CRA平均面积的均值分别为（12.70,17.40,18.00）×10^-3mm^2_;平均周长的均值分别为0.56，0.56，0.57mm，平均周长之间相比无显著差异。CRV平均面积的均值分别为（7.00，5.40，7.90）×10^-3mm²；平均周长的均值分别为0.44，0.38，0.41mm；CRV平均周长筛板前与筛板区相比，筛板区与筛板后相比均有显著差异。 结论：老年人CRA眼球内外管径一致；CRV在筛板区管径最小。 （中华眼底病杂志，1997，13：213-214）
     

光相干断层扫描检测筛板结构的临床应用及新进展

筛板是位于视旁深部,由胶原纤维构成的筛束和穿行有神经、血管及神经胶质细胞的筛孔组成的复杂结构,为视网膜神经节细胞轴突穿出眼球时提供结构和营养支持。眼压引起机械应力的直接作用以及筛板变形和重塑导致轴浆运输、血运障碍,共同导致视网膜神经节细胞轴突损伤进而死亡。因此,筛板被认为是青光眼病变的始发部位。光相干断层扫描技术的发展...