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.

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.

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.

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.

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