[Pathophysiology of cataract formation after vitrectomy]. / Pathophysiologie der Katarakt-Entwicklung nach Vitrektomie.

Cataract formation is one of the most common complications after vitrectomy and cataract extraction in such cases will have to be performed under more difficult conditions. A knowledge of the different types of cataract, their frequency and causes may help to develop strategies to prevent this complication. In addition to a progressive nuclear opacification, which may occur after any type of vitrectomy, transient feathering of the lens often occurs after intraocular gas tamponade, while permanent subcapsular opacification may occur in silicone oil-filled eyes. Nuclear opacification after vitrectomy morphologically and histologically resembles age-related cataracts, but shows a faster progression: two years after vitrectomy half of the eyes require cataract extraction and there seems to be an age limit: the opacification progresses faster in patients over 50 years old. The main cause for nuclear cataracts most probably is oxidative stress. Oxygen in the avascular lens is provided by diffusion, meaning that the surrounding oxygen content is crucial for the oxygen content within the lens and thus for the formation of reactive oxygen species. In rabbits and also in humans the partial oxygen pressure is highly elevated in the vitreous cavity after vitrectomy and posterior to the lens since the vitreous is lacking as a diffusion barrier for the oxygen. The partial oxygen pressure might be additionally elevated by ventilation with oxygen and a high oxygen pressure in the infusion fluid during surgery. This elevated partial oxygen pressure may lead to increased oxygen stress and thus to lens opacification by oxidation of structural proteins. The key for the prevention of cataract formation therefore seems to be avoidance of oxidative stress, factors that might increase the protective or repair systems are so far not available. Ventilation with oxygen should be minimised as should be the partial oxygen tension in the infusion fluid. New hydrogels as vitreous substitutes might have a beneficial influence on intraocular partial oxygen tension.

[Air embolisation during vitrectomy?]. / Luftembolie bei Vitrektomie?

Life-threatening complications are extremely rare in ophthalmic surgery. If they occur, then mostly because of a pre-existing severe cardiovascular condition of the patient, and only to a much lesser extent because of the operation of the eye itself. One theoretically possible complication is an air embolisation during air tamponade of the vitreous cavity with simultaneously opened choroidal vessels. There are some descriptions of such possible cases of air embolisation in the anaesthesiologic literature. Vitreoretinal surgeons should be aware of the theoretically possible complication of air embolisation during vitrectomy with air tamponade and simultaneously opened choroidal vessels.

[Anaylsis of the surgeon factor in the treatment results of rhegmatogenous retinal detachment in the "scleral buckling versus primary vitrectomy in rhegmatogenous retinal detachment study"]. / Einfluss des Operateurs auf die Operationsergebnisse bei rhegmatogener Ablatio retinae im Rahmen der "Scleral Buckling versus Primary Vitrectomy in Rhegmatogenous Retinal Detachment Study".

BACKGROUND: The effect of the surgeon on the outcome of surgical treatment for rhegmatogenous retinal detachment (RRD) has previously been analysed in a few studies only. In the prospective multicentre SPR study, scleral buckling (SBS) and primary vitrectomy (PV) were compared in RRD with medium complexity in a randomised fashion. In this study, we examined the surgeon factor on the outcome of RRD surgery within the SPR study. MATERIAL AND METHODS: An analysis of the surgeon as a factor on the functional outcome (logMAR visual acuity), primary anatomic success (retinal reattachment central to the aequator without any additional retina-affecting surgery including laser, cryo and macular pucker surgery) and final anatomic success (retinal reattachment one year postoperatively) was carried out. RESULTS: Overall, 416 phakic patients (209 SBS, 207 PV) and 265 pseudophakic patients (133 SB, 132 PV) were recruited by 45 surgeons in 25 centres. In the phakic group, the mean functional outcome of individual surgeons was between 0.2 and 0.74 (mean, 0.41, SD 0.41). This difference reached statistical significance (p = 0.0398). In the pseudophakic subgroup, the mean functional outcome was between 0.09 and 0.64 (mean, 0.42, SD 0.49) without reaching a statistical significance (p = 0.0715). Primary success per surgeon varied between 41.67 % and 90.00 % (mean, 63.16 %) in the phakic subgroup and 33.33- 80.95 % (mean, 61.75 %) in the pseudophakic subgroup. Final anatomic success was achieved in 92.86 - 100.00 % (mean, 97.96 %) in the phakic subgroup and 80.00 - 100.00 % (mean, 95.44 %) in the pseudophakic subgroup. There was no statistically significant correlation between surgeon and anatomic outcomes. CONCLUSION: In the phakic subgroup, a statistically significant correlation between surgeon and functional success could be demonstrated for RRD with medium complexity. This correlation was not interrelated to the surgical method. Functional outcome in pseudophakic patients and anatomic outcomes in both subgroups of phakic and pseudophakic patients showed no statistically significant correlation between surgeon and anatomic success.

[New developments in retinal detachment surgery]. / Neue Entwicklungen in der chirurgischen Therapie der rhegmatogenen Ablatio retinae.

The initial surgery is one of the most important factors influencing the anatomic and functional outcome of retinal detachment surgery. With the continual modifications in vitrectomy techniques, the strategy in primary vitrectomy surgery is also changing. Recent developments are the use of 25- and 23-gauge trocar systems and new surgical techniques without the use of perfluorcarbons or gas or silicone oil tamponade. In addition, heavy silicone oils are now entering routine clinical use, especially for proliferative vitreoretinopathy (PVR) redetachments of the lower fundus periphery. Regarding adjunct pharmacologic therapy, daunorubicin and 5-fluorouracil/low molecular weight heparin have been found to improve the results of patients with PVR or at risk for PVR.

Treatment of central retinal vein occlusion by radial optic neurotomy in 107 cases.

BACKGROUND: To evaluate the potential role of radial optic neurotomy (RON), a new surgical technique has been recently proposed for treating central retinal vein occlusion (CRVO). It is hypothesized that CRVO constitutes a neurovascular compartment syndrome at the site of the lamina cribrosa, which can be alleviated by performing a radial incision at the nasal part of the optic nerve head, relaxing the cribriform plate and the adjacent sclera. METHODS: One hundred and seven patients were treated with RON for CRVO at five collaborating ophthalmologic centers. All patients were evaluated by a standardized protocol. For analysis of the angiographic and fundus findings, reference images were used. Intraoperative and postoperative complications were reviewed. RESULTS: On 55 right and 52 left eyes of 107 patients (55.6% male, 44.4% female) with a median age of 68 years (range 21-91 years), RON was performed. The median follow-up time was 6 months (range 1-24 months). The median preoperative visual acuity (VA) was 0.05 (logMAR 1.3), increasing to a median postoperative VA of 0.08 (logMAR 1.1). Patients with an interval of more than 90 days between RON and onset of CRVO showed no significant change in VA at the 6-month follow-up. Severe peripapillary swelling of the optic nerve head prior to RON resulted in an average increase of 4.2 lines in VA at the 6-month follow-up. Angiographic findings of shunt vessels were seen in 18/30 cases after 12 months and were accompanied by an average improvement of VA of six lines. Visual field tests showed various defects in 86.8% of all cases. In one patient an iatrogenic injury of the central retinal artery occurred (0.9%). CONCLUSION: Despite the potential risk of visual field defects, RON seems to be a quite safe procedure. The majority of patients showed rapid normalization of the morphologic fundus findings, with an improvement in VA uncommon for the natural history of CRVO. No significant change in VA was seen in patients with an interval of more than 90 days between the onset of CRVO and RON. A prospective study is warranted for further investigation.