Fortschritte der Ophthalmologie : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft最新文献

The early diagnosis of glaucoma relies on the detection of manifest damage in present-day clinical practice. The reason for such damage in glaucoma may be seen in the breakdown of the autoregulation of the circulation in the optic nerve head. This autoregulation can be assessed by the pressure tolerance test devised by ourselves which may detect glaucoma before manifest damage can occur. We demonstrate a standardized method in which the test procedure is controlled by a computer. In particular, the time course of the examination which is of crucial importance is exactly defined. The method is no more difficult to apply than automatic perimetry. We describe six examinations in seven subjects each. The results are analyzed by the estimation of variance components. The intraocular pressure shows an intraclass correlation of 0.41 and the critical pressure an intraclass correlation of 0.27. The intraindividual variability of critical pressure is mainly due to the widely known variability of intraocular pressure. The autoregulation behavior shows a very good constancy, which makes the test clinically useful in the differential diagnosis of glaucoma.

With a new technique the impedance of 89 normal and 7 severely damaged corneas was determined in vivo to look into the correlation between impedance and corneal cell damage. We found highly significant differences in impedance between normal and pathologically altered corneas. At 500 Hz frequency the impedance of normal corneas was 53.6 kOhm while the impedance of burned corneas only averaged 8.0 kOhm. There seems to be a correlation between the degree of pathological alteration of the corneal tissue and impedance as measured with this technique. The electrode head used allows fast, reproducible measurement of corneal impedance without any strain on the patient. Further studies must elucidate whether the method can be used as an early indicator of corneal damage before the onset of macroscopic change.

Posterior capsule opacification is a common postoperative complication after extracapsular cataract extraction and lens implantation. If the patient's visual acuity is reduced markedly, a capsulotomy with a Nd-YAG laser may become necessary. Various attempts have been made with the aim of developing an injectable solution capable of damaging the epithelial cells of the capsule bag irreversibly and thereby avoiding posterior capsule opacification. This solution should be applied for a short time during the operation. In tissue culture we tested the influence of two injectable solutions [lens epithelial necrosis factor (LENF)] and aqua bidest. on cellular growth. Balanced salt solution served as control. We used human epithelial carcinoma cells, type HEp-2. The results were evaluated by vital staining (ethidium bromide and acridin orange), hemotoxylin staining, autoradiography and measurement of protein and DNA synthesis. The results showed that LENF is capable of damaging 100% of the epithelial cells irreversibly if it is applied for 20 s or longer. The influence of each of these solutions was tested on 20 human capsular flaps, which were excised during the operation. The flaps were immersed for 30 s in the different solutions. Vital staining of these flaps led to the following results: LENF causes a 100% cell damage of all epithelial cells of the capsular flaps. No vital cells remained. On the other hand Aqua bidest. cannot guarantee 100% cell damage of the capsular flap epithelia. Sixty percent of the capsular flaps treated with aqua bidest, showed differing amounts of remaining vital cells.

In the course of 1 year we investigated 32 patients suffering from retrobulbar neuritis, using photographs of the retinal nerve fiber layer (RNFL). All photographs revealed defects of the RNFL in the area of the papillomacular bundle. These observations were compared with photographs of eyes not affected by any ophthalmological diseases. No loss of retinal nerve fiber bundles was found in any of these cases. One remarkable finding of this study was that 90% of the patients with retrobulbar neuritis also had defects in the RNFL of the contralateral eye.

Delayed resorption of pooled subretinal fluid has been reported to cause impaired visual acuity due to involvement of the macula in up to 10% of all case. In our series of 60 eyes treated consecutively with pneumatic retinopexy for retinal detachment, 9 eyes experienced delayed absorption of subretinal fluid. Only 6 eyes showed the phenomenon of pooled, localized subretinal fluid without peripheral extension to the ora serrata. The time for complete absorption of these circumscribed subretinal bullae ranged from 8 to 52 weeks (mean 22.7 weeks). Impaired visual acuity could not be detected in any of these cases. This may be due to the location of these bullae, which never involved the macula. Therefore, we do not consider the occurrence of this phenomenon to be a reason not to carry out pneumatic retinopexy.

In our experimental study on 53 rabbits we compared the amount of corneal endothelial damage caused by radial keratotomy (RK) referred to (1) the number of incisions (4, 8, or 16), (2) the postoperative interval (0 h, 48 h) and (3) the direction of the incision [centripetal (cp), centrifugal (cf)]. The endothelial damage was quantified by means of the Janus green photometry technique. Morphological changes were evaluated by scanning electron microscopy (SEM). Depending on the group examined, we found endothelial damage extending over 3-7% of an analysed surface of 64 mm2. One perforation caused endothelial damage of up to 17% of the surface examined. Increasing the number of incisions from 4 to 8 or 16 resulted in a statistically significant increase in the amount of endothelial damage (4.2%, 5.1%, 5.8%; P less than 0.05). At 0 h it was significantly higher than after 48 h (5.5%, 4.6%; P less than 0.05). The direction of the incision had no statistically significant influence in our study (zp: 5.2%, zf: 4.9%). The morphological changes in the rabbit corneal endothelium examined directly after the RK procedure were ruptures in the cell membranes, loss of cells, and posterior corneal protrusions beneath the incisions. After 48 h, we found fewer damaged cells and no denuded Descemet's membranes, but larger polymorphy of the cells and a numerical increase in the microvilli of the cells surrounding the damaged cells. Our results support the crucial argument against RK: the alteration and destabilization of healthy corneal tissue up to the endothelium.

The results of local application of monoclonal antibodies (mAb) in rabbit eyes are presented. To improve intraocular access of the high-molecular-weight protein it was entrapped in large (0.2 microns) unilamellar, negatively charged liposomes. Concentrations of the free or encapsulated drug were measured by ELISA in different eye compartments following repetitive drop administration or single subconjunctival injection. Although mAb became measurable in specimens of conjunctiva and cornea, it was not detectable (less than 0.5 ng/ml) in aqueous humor, lens or the vitreous body. In contrast, concentrations of the liposome-encapsulated drug were measurable as little as 30 min after topical application in the aqueous humor.

A series of 52 patients, aged 60-85 and suffering from chronic obstruction of the nasolacrimal duct with no other complication of the lacrimal mechanism or of the eyelids (e.g. ectropium), were treated by means of silicon tube intubation instead of dacryocystorhinotomy. The tubes remained in place for 10-12 months and the patients were observed a 3-year postoperative period. In 37 cases (71%) the nasolacrimal duct remained patient after 3 years. In 7 cases, although the drainage was not opened, the patients ceased to show evidence of secretion of mucus or pus. We consider that intubation of the nasolacrimal duct is an alternative to dacryocystorhinotomy, but only if the patient knows that the tubes are to remain in place for a lengthy period of time. This does not disturb a cooperative patient since the tubes are essential and do not create any irritation. Furthermore, tears are partially eliminated around them and, thus, improvement of the symptoms is apparent from the first day onward.

A histopathological study was conducted on four cases in which a diffuse iris melanoma presented with glaucoma. Drainage surgery was performed on three eyes for medically non-responsive raised intraocular pressure, and all cases eventually (within 2-7 years) required enucleation for secondary glaucoma. In the iridectomy specimens the tumour melanocytes were small, uniform in size and spindle shaped, while in the enucleation specimens the tumour cells were epitheliod and pleomorphic. The dedifferentiated tumour in the enucleated eyes spread extensively within the anterior chamber and anterior uvea. In three cases there was evidence of intrascleral spread. However, none of the patients has died from metastatic disease in the follow-up period of 2-6 years since enucleation.

Sulfur hexafluoride (SF6) is used for internal tamponade during retinal detachment surgery. It is usually injected into the eye by a plastic syringe either with a sharp needle or by using the infusion system during pars plana vitrectomy. Although several suggestions exist for the appropriate application of intraocular SF6 and other perfluocarbons, a sudden postoperative rise in tension or hypotonia has been observed repeatedly. We simulated the preparation and application of mixtures of sulfur hexafluoride and air and analyzed possible mistakes. SF6 was quantitatively analyzed by infrared spectroscopy. SF6 does not rapidly diffuse out of capped plastic syringes made of polypropylene, as commonly employed in the Federal Republic of Germany. SF6 and air mix completely during aspiration. If the volume of microporefilters or tubes being used for preparation and instillation of mixtures of SF6 and air is ignored, this may result in a 20% deviation in SF6 concentration. Silicone tubes, which are widely used for the influsion during pars plana vitrectomy, are not recommended for the application of SF6. SF6 and fluorcarbones diffuse through silicone tubes and absorb and desorbe in the tube. Infusion lines made of polyethylene or polyvinylchloride, e.g. butterflies, should be preferred.