Prognostic parameters in pars plana vitrectomy

Based on a period of introduction with the vitrectomy technic the visual acuity results in 143 consecutive cases performed between 1976 and 1980 are related to the anamnestic information, the pre-, per- and post-operative findings. In this introductional period the patients referred had longstanding retinovitreal changes, and, because of lack of prognostic parameters, all patients were offered surgery regardless of the observed pathology. All vitrectomies were carried out with the Klöti macrostripper and diathermy unit, without any additional instrumentation. From the results of these early cases, we have changed our surgical method to a three-port entrance with a separate infusion canula, a separate fiberoptic illumination and an interchange between vitrector, automatic scissors, hook, stilleto, vacuo needle, forceps and intravitreous photocoagulation through a third port. Diabetics should be offered vitrectomy if vitreous haemorrhages last for more than 3 months. Vitrectomy is considered useless or contraindicated in diabetics with lack of light perception or light projection, neovascular glaucoma, extinguished visual evoked potential. Only an improvement in the peripheral vision can be expected in diabetics with macular detachment. In rhegmatogenous detachment cases with intravitreal traction, vitreous operations should be performed only where intraretinal or retroretinal changes do not prevent mobilization or unfolding of the retina. Traumatic vitreoretinal disorders should be operated upon early.