The key to resolving iris prolapse is to release the pressure gradient and we have covered this topic many times before. Usually there is fluid trapped behind the nucleus and in front of the posterior capsule, so rocking the nucleus can resolve the iris prolapse in just a second or two. However if the fluid goes through a zonular gap and is now stuck behind the posterior capsule and in front of the anterior hyaloid face, we have a different challenge. This misdirection of aqueous (or balanced salt solution) creates a strong pressure gradient which will push the iris out of the incision. The solution is to remove this fluid and in this video it is done with a pars plana tap. An empty syringe (3cc or 5cc is fine) with a 25 or 27g needle is placed through the pars plana and suction is applied to remove this misdirected fluid. This resolves the gradient, deepens the anterior chamber, and the case can proceed smoothly. This is truly a great video, so much so that I have temporarily suspended our rule of “only HD videos” to show you this technique.
I would recommend doing this with a vitrector rather than a needle. If the axial length of the eye is short…under 22mm…as many of these cases turn out to be you must enter more anterior than usual for a pars plana entry as the pars may end much more anterior and if you enter at say 3.5mm posterior you may go through retina. So please know the axial length, enter as anterior as possible….no more than 3mm posterior to the limbus and angle DOWN with the trocar or vitrector away from the lens so you won’t damage it. Do the vitrectomy with the cutter facing down away from the lens and you only need VERY little to soften the eye. If you keep going you will get a choroidal effusion very quickly. I prefer to give mannitol and wait before I tap even though I do 3 to 4 pars plana vitrectomies a week and am very comfortable with that. I am NOT comfortable doing a blind tap on a tiny little eye where there is tons of posterior pressure and I do that as a last resort.
Due the the possibility of an expulsive hemorrhage potentially responsible for the clinical scenario in this video, prior to performing a PP tap I would have recommended first to examine the retina with an indirect ophthalmoscope or if visulazation was poor to use ultrasound to confirm the absence of a choroidal.
You mentioned to mark the needle so you know how deep to go in. What depth do you generally recommend marking ?
2mm should be plenty