Manish Mahabir, Senior Resident, All India Institute of Medical Sciences.
Q. What should be our approach to cataract surgery in posterior polar cataracts?
José Güell
Director of Cornea and Refractive Surgery Department, Instituto Microcirugía Ocular (IMO), Barcelona, Spain
A. Posterior polar cataracts remain a significant challenge for anterior segment surgeons. Although new imaging technologies such as high-definition OCT and UBM may help in preoperatively evaluate the adhesion characteristics between the posterior cortex and the capsule, they still provide a number of surgical surprises (false positives
and negatives). That is why we should follow certain general strategic rules during the surgery.
My recommendations are:
1. Properly size the capsulorhexis diameter either manually of with the FS laser to 4-5mm, in order to have it ready for a possible sulcus implantation with an optic capture through the rhexis.
2. Slowly hydrodeliniate the nucleus, avoiding cortical hydrodissection, because the latter is the classical trigger for “exploiting” the posterior capsule.
3. Emulsify first the nuclear content with low fluidics.
4. Using a slow injection of viscoelastic, try to dissect the posterior cortex from the posterior capsule and, again, proceed with I-A under low fluidics setting.
5. In all cases, you should be ready for anterior vitrectomy because, despite of all preventive manoeuvres, the number of eyes with PC rupture is high.
6. If an anterior vitrectomy should be performed, some surgeons would prefer to do it from the corneo-limbal incisions and others through the pars plana.
The advantage of the latter is that the possibility of increasing the size of the rupture is smaller, as well as there being less chance of leaving strands of vitreous in the anterior segment and thus, in a number of cases we will still consider an “in the bag IOL” implantation (in some cases we might be able to create, from the rupture, a continuous posterior capsulorhexis and then consider to luxate the “in the bag IOL” optic through it).
7. Finally, and especially because it will usually be an intraoperative individual decision, we must have ready and properly calculated our favourite IOLs to be implanted, both in the bag and at the sulcus.
John SM Chang
Director, GHC Refractive Surgery Centre, Hong Kong
A. Preoperative differentiation:
Anterior segment OCT is useful to evaluate a suspected posterior polar cataract (PPC). The posterior capsule (PC) is intact in a pseudo PPC, no defect is seen in the PC, and there is a gap/clear space between the cataractous lens and the PC. In True PPC, there may be a defect seen in the PC. However, if the lens is dense the PC may not be visible.
Surgical technique:
All cases should be treated as a case of PPC, because even if the PC is intact it can be weak. Preventing PC rupture and nucleus drop is the target of performing a PPC extraction, it is important to avoid transmitting pressure and stress to the posterior capsular bag.
After CCC, a hydrodelineation is preferred rather than a hydrodissection. Fluid is injected intralenticularly from the central core of the nucleus to the outside, this technique avoiding fluid being injected into the subcapular plane and keep the cortical shell intact. The nucleus can be separated and floated up with viscoelastic, allowing a phacoemulsification to be performed in the anterior chamber (AC). The nucleus is phacoed first, then hydrodilineation and phaco the cataractous lens layer by layer outward, leaving the PC with possible defect to last. Every step has to be performed slowly and gently. The last remaining cortex with the posterior plaque should be irrigated and aspirated slowly. It is important to maintain a constant pressure in the AC to prevent AC collapse and PC tear.
