正常眼用噻吗心安后肾上腺素对其房水生成的影响

本文以荧光光度计测定肾上腺素对滴用噻吗心安之正常眼的房水形成的急性作用。肾上腺素对某些人是一种有效的降眼压药物,已用为青光眼的局部治疗。近来发现肾上腺素在正常眼的最初作用是增加房水生成和排出,因排出作用大于生成,结果眼压降低。噻吗心安是一种β-肾上腺素能阻滞剂,现用于治疗慢性开角型青光眼。局部用药使房水生成减少而引起快速及长时间的眼压降低。人眼的肾上腺素能系统与眼压的复杂关系还不完全清楚。由于肾上腺素是α和β受体的联合兴奋剂,促进房水生成增加;噻吗心安是β受体     

α_2-肾上腺素能受体激动剂的研究进展

α2-肾上腺素能受体激动剂是一类较新的降眼压药物，目前氨可乐定已不仅用于预防和治疗激光术后（小梁成形术、虹膜切除术或囊膜切除术）的眼压升高，也用于青光眼患者的长期药物治疗。Bri－monidine对α2-受体有高度选择性，降眼压效果显著持久，全身和局部副作用少，并且具有神经保护作用，这些优点使其成为新的有效的抗青光眼药物之一。     

重视长期局部应用抗青光眼药物对眼表组织的损伤

长期应用抗青光眼药物能引起结膜慢性炎症、浅层点状角膜炎及干眼症等眼表疾病。病理研究发现该类患者结膜杯状细胞数量减少、眼表上皮鳞状化生及角膜上皮细胞凋亡。已有证据表明滴眼液中的防腐剂苯扎氯胺有毒性作用,是眼表组织损伤的重要原因。药物性眼表损伤患者临床表现无特异性,症状轻微,病变发生滞后,常与眼表疾病共存或混淆,可严重影响患者的生活质量和青光眼的治疗。因此,要十分重视长期局部应用抗青光眼药物对眼表组织的损伤问题,选用降眼压效果好、作用时间长的抗青光眼药物,必要时使用联合固定配方制剂,减少药物使用的种类和次数。对需要使用多种药物才能达到靶眼压或出现眼表组织损伤的患者,应及时采取手术或激光等其他治疗措施。注意对眼表组织损伤的预防及共存眼表疾病的治疗。研制无防腐剂或含有新型防腐剂的抗青光眼药物,改进或研制长效药物和药物赋形剂是今后新型抗青光眼药物剂型发展的方向。     

抗青光眼新药brimonidine的研究及应用进展

α2 肾上腺素能受体促效剂brimonidine(BMN) ,是一种较新型的降眼压药物。近年来的研究结果表明 ,BMN对α2 受体有高度选择性 ,降眼压效果确实而持久 ,全身和局部副作用小 ,不引起视神经的缺血性病变 ,具有神经保护作用。是一类安全有效的抗青光眼药物 ,尤其适用于对 β 阻滞剂禁忌的患者。     

局部肾素-血管紧张素系统在体外培养牛眼小梁细胞的表达

青光眼的主要危险因素是病理性的眼压增高.目前,房水的生成研究正在不断进展,而眼压是否存在调节、如何调节,至今机制不明,这给临床上青光眼的诊断和治疗带来了困惑.目前临床上常用的降眼压药物如8肾上腺素能受体阻滞剂噻吗心安、α1肾上腺素能受体兴奋剂、α2肾上腺素能受体兴奋剂可乐定等血管活性物质,均可通过局部肾素-血管紧张素系统引起血压显著变化.由此表明肾素-血管紧张素系统有可能通过自分泌方式参与眼压调节.``     

固定制剂拉坦噻吗滴眼液降眼压效果的短期临床观察

前列腺素类滴眼液的出现为药物治疗青光眼提供了新的途径,其降眼压机制主要是通过增加葡萄膜巩膜房水引流,而不减少房水生成。噻吗洛尔眼液是一种非选择性的β-肾上腺素能受体阻滞剂,其降眼压作用原理是降低眼房水的形成能     

α2—肾上腺素能受体激动剂的研究进展

α２－肾上腺素能受体激动剂是一类较新的降眼压药物，目前氨可乐定已不仅用于预防和治疗激光术后（小梁成形术，虹膜切除术或囊膜切除术）的眼压升高，也用于青光眼患者的长期药物治疗，Ｂｒｉｍｏｎｉｄｉｎｅ对α２－受体有高度选择性，降眼压效果显著持久，全身和局部副作用少，并用具有神经保护作用，这些优点使其成为新的有效的抗青光眼药物之一。     

青光眼治疗新策略

局部使用降眼压药物是目前治疗青光眼的主要方法,复合制剂指把2种或2种以上的药物放在一个滴眼瓶里,它增强了降眼压作用,减少了副反应,能提高患者的依从性.目前,已在临床上使用的复合制剂主要有胆碱能激动剂与肾上腺素能激动剂复合制剂、β-受体阻滞剂与胆碱能激动剂复合制剂、局部碳酸酐酶抑制剂β-受体阻滞剂复合制剂、前列腺素类药物与β-受体阻滞剂复合制剂和α2受体激动剂与β-受体阻滞剂复合制剂.大多数复合制剂都含有β-受体阻滞剂,随着前列腺素类药物逐渐取代β-受体阻滞剂成为一线用药,含前列腺素类药物的复合制剂可能成为未来的发展趋势和青光眼治疗的新策略.尽管如此,复合制剂也存在自身的缺点,并非适用于所有的患者.因此,临床医生应该根据个体化用药原则,为患者制定出合理的用药方案.     

抗青光眼新药brimonidine的研究及应用进展

α２－肾上腺素能受体促效剂ｂｒｉｍｏｎｉｄｉｎｅ（ＢＭＮ）,是一种较新型的降眼压药物。是一类安全有效的抗青光眼药物,尤其适用于对β－阻滞剂禁忌的患者。     

《眼科》杂志2014年“健康眼压与健康眼表”研究专题征文活动通知

青光眼是首位不可逆性致盲眼病，青光眼患者需要终生接受降眼压治疗，降眼压药物治疗是治疗青光眼的重要手段。目前青光眼药物种类繁多，由于药物保存、预防污染等方面的考虑，多数抗青光眼药物均含有不同类型及浓度的防腐剂。因此对于长期使用降眼压药物与眼表健康的关系值得关注及研究。     

Electrophysiological determination of the refractive state of the eye of the opossum

The refractive state of the eye of the South American opossum Didelphis marsupialis aurita was investigated with electrophysiological techniques. Using adult specimens, trapped from the wild, averaged cortical evoked responses were recorded from the region of projection of the central visual field. Stimuli consisted of a phase reversal of a square wave grating generated on a CRO screen, with luminance of 2.4 cd/m2 and contrast 0.84. The refractive state of the eye was altered by means of trial lenses and the amplitude of the cortical responses thus obtained compared to those obtained with no lens (control values). Refraction "tuning curves" were determined for each animal. The average refractive state was found to be -2.27 D indicating that this species when raised in its habitat shows, at low ambient luminosity, some degree of myopia. Determination of the Contrast Sensitivity Function indicate that induced ametropias lead to a reduction of the cut-off value of the spatial frequency and a loss of contrast sensitivity.     

Influence of exercise on the structure of the anterior chamber of the eye

Purpose

To measure changes in anterior chamber structure before and after exercise in healthy individuals using anterior segment optical coherence tomography (ASOCT).

Methods

Thirty‐two healthy young individuals performed jogging for 20 min. Eye blinking rate was recorded during rest and exercise. The anterior chamber angle (ACA), angle opening distance at 500 μm from the scleral spur (AOD500), trabecular‐iris space area at 500 μm from the scleral spur (TISA500), iris concavity (IC), iris concavity ratio (CR), iris thickness at 750 μm from the scleral spur (IT750), anterior chamber depth (ACD), anterior chamber width (ACW), pupil diameter (PD), intraocular pressure (IOP), blood pressure (BP) and heart rate (HR) were recorded before and after exercise. Anterior chamber angle (ACA), AOD500, TISA500, IC, IT750, ACD, ACW and PD were measured with ASOCT.

Results

Compared with rest, the blinking rate during exercise did not change significantly (13.04 ± 5.80 versus 13.52 ± 5.87 blinks/min, p = 0.645). The average IOP (15.4 ± 2.4 versus 12.4 ± 2.1 mmHg), ACA (35.96 ± 11.35 versus 40.25 ± 12.64 degrees), AOD500 (0.800 ± 0.348 versus 0.942 ± 0.387 mm), TISA500 (0.308 ± 0.155 versus 0.374 ± 0.193 mm²), IC (?0.078 ± 0.148 versus ?0.153 ± 0.159 mm) and CR (?0.027 ± 0.050 versus ?0.054 ± 0.056) changed significantly (all p < 0.001), while the average IT750 (0.463 ± 0.084 versus 0.465 ± 0.086 mm; p = 0.492), ACD (3.171 ± 0.229 versus 3.175 ± 0.238 mm; p = 0.543) and ACW (11.768 ± 0.377 versus 11.755 ± 0.378 mm; p = 0.122) showed no significant change after exercise.

Conclusion

The blinking rate did not change significantly during exercise, while ACA, AOD500 and TISA500 increased after exercise. Exercise also induced or increased IC. These changes in anterior chamber structure were only associated with exercise, but not with the postexercise change in PD or IOP.     

Determination of the location of the fovea on the fundus

PURPOSE: To evaluate whether the distance between optic nerve head and fovea in healthy eyes determined by scanning laser ophthalmoscope may facilitate estimation of the location of the fovea relative to the optic disc in patients with macular disease. METHODS: The angular distance was measured, in horizontal and vertical directions, between the center of the optic nerve head and the fovea in 104 eyes of 104 healthy probands. For additional evaluation of intraindividual variation in 70 of these persons the contralateral eye was measured as well. RESULTS: The distance between the optic disc and the fovea differed vertically more than horizontally (-1.5 +/- 0.9 degrees [-3.65 to +0.65 degrees ] vs. 15.5 +/- 1.1 degrees [13.0-17.9 degrees ]). There was a mean angle between the fovea and the center of the optic disc versus the horizon of -5.6 +/- 3.3 degrees. The intraindividual difference between right and left eyes was markedly lower, with average angles being 0.2 +/- 1.3 degrees vertically and 0.0 +/- 1.1 degrees horizontally. CONCLUSIONS: The distance between the optic nerve head and the fovea does not allow for a meaningful determination of the location of the fovea in eyes in which morphologic changes have occurred. The angle of rotation of the fovea relatively to the center of the optic nerve head is relatively stable. Therefore, the size of a central scotoma can be determined by movement of the blind spot according to the change of the preferred retinal locus (PRL). In addition, the knowledge of the location of the fovea enables determination of the position in the contralateral eye of the same patient.