A peribulbar anaesthesia is preferred. Smallest possible incision depending on the surgeon’s ease should be used. Phacoemulsification has an edge over manual small incision surgery(MSICS) but care should be taken in more than 1800 subluxation where MSICS may be easier. All the steps are performed keeping in mind the site of subluxation. (Table 3)
Table 3: Dos and Don’ts |
|
1 |
Incisions should be preferably away from area of zonular weakness |
2 |
Use high molecular weight viscoelastic |
3 |
Capsulorrhexis should be initiated in an area remote from the dialysis |
4 |
Capsulorrhexis is more easily performed with forceps than with cystitome & should be made "off-center" in an eye with significant lens subluxation |
5 |
The partial thickness scleral flaps for Cionne’s ring or scleral fixation should be dissected before opening the main wound |
After the initial incision, a high molecular weight viscoelastic is injected over the area of zonular dialysis to temponade the vitreous and maintain a deep non- collapsible anterior chamber. The capsulotomy should be large enough to allow easy manipulation of nucleus and should be started away from the site of subluxation. (Figure 5) A 5.5 -6 mm for phacoemulsification and 6.5 mm for MSICS is usually adequate.
Fig 5: Capsulorhexis is started away from the site of zonular dehiscence.
Which technique of MSICS?
In most of the patients, the nucleus is not very hard and once the nucleus comes in the anterior chamber there is little difficulty in its final delivery. In smaller subluxations, any technique namely Blumenthal`s, microvectis, phacosandwich or phacofracture can be used. In more than 180 degree subluxation or generalized zonular weakness Blumenthal’s technique is not preferred because the fluid through the anterior chamber maintainer(ACM) may further compromise the remaining zonules. Also while using the ACM, the site of insertion at the limbus is changed according to site of dehiscence so that it does not lie over the area of weak zonules. No attempt should be made to perform the capsulorrhexis under fluid through ACM as it becomes difficult to control.
Fish hook technique, where the nucleus is engaged with the hook on its undersurface with the inferior pole still in the capsular bag can be dangerous in cases of inferior zonular dehicense.
Insertion of CTR & MCTR
CTR/MCTR can be inserted into the capsular bag at any point after the capsulorrhexis; however the bulk of the nucleus can make visualization and placement of the CTR
difficult. Also in MSICS, the fixation hook of MCTR obstructs the nuclear delivery out of the bag into the anterior chamber especially the model with double loops.
The CTR is inserted using forceps or a specially designed injector. A ‘fish –tail’ technique can also be used to insert the CTR where both its ends are held with the forceps in a crossed manner to create a central closed loop which is placed adjacent to the area of dehicense in the capsular bag first. This is followed by release of each end at a time and manipulation of the entire device into the bag.( Figure 6)
Fig 6:Fish tail technique of CTR insertion
MCTR needs to be fixed to the sclera using either an ab-externo or an ab interno approach with single or double armed 9,0 prolene suture on CIF-4 needles. The 9,0 prolene is preferred over 10,0 prolene with the recent reports of biodgradation of 10,0 prolene.
Fig 7: Partial thickness scleral flap dissected.
Fig 8: A CIF -4 needle passed 1.5 mm from limbus at the scleral bed to emerge from the main wound.
Fig 9: The 9,0 prolene is tied to the loop on the Cionne’s ring.
The authors prefer an ab –externo approach. A partial thickness scleral flap is dissected at the fixation site. ( Figure 7) The CIF-4 needle is passed 1.5mm posterior to the limbus through the scleral bed to emerge from the main wound and tied to the fixation hook.( Figure 8 & 9) In case of larger subluxation, where double loop device is used, two scleral flaps are prepared 180 degrees apart and prolene is passed as earlier and tied to the other fixation hook. The MCTR is inserted with smooth forceps through the main incision and dialed into the capsular bag.(Figure 10) The Y- hook can be used to "dial" the MCTR until the eyelet is centered adjacent to the partial thickness scleral flap. An anchoring knot is placed adjacent to the exiting 9,0 prolene suture using 10,0 nylon and the prolene is tied to it. The curved needle on 10,0 nylon is then used to take a bite from undersurface of the scleral flap which when pulled covers the mesh of sutures. ( Figure 11 & 12)
Fig10:The Cionne’s ring being inserted
Fig11: The anchoring suture is placed adjacent to the exiting prolene suture
Fig12: A bite is taken from undersurface of the scleral flap
Alternatively, using a double-armed 9,0 prolene suture, two passes are made from each scleral bed, which is tied to the fixation hook and the two prolene ends emerging 1.5 mm apart and posterior to limbus are tied to each other. The knot is then rotated to be buried into the sclera and covered by conjunctiva.
