Subluxated cataract surgery – part 3 progressive subluxation and dangling subluxation
Everything you ever wanted to know about subluxated cataract surgery – Part 3. Dr Soosan Jacob reports
Supracapsular glued IOL – A: Phacoemulsification and cortex aspiration; B: Haptics of a three-piece IOL are sequentially exteriorised over an intact capsular bag and anterior hyaloid face; C and D: Well-centred, stable IOL
In-the-bag intraocular lens (IOL) with sutured scleral fixation of a segment or ring or the glued capsular hook technique is an option for subluxated cataract.
However, in progressive zonulopathy secondary to pseudoexfoliation, high myopia, aniridia, Marfan’s syndrome etc, a two- or three-point fixation is preferable to avoid late subluxation of the unsupported side. Lensectomy with vitrectomy and anterior chamber (AC) IOL, iris or glued scleral fixated IOL, provides long-term fixation but loss of posterior capsule, disturbance of anterior hyaloid face and vitreous can increase the risk of posterior segment complications.
The supracapsular glued IOL technique has advantages of retaining an intact posterior capsule and hyaloid face; avoiding vitreous disturbance; decreasing the incidence of posterior segment complications such as retinal detachment and cystoid macular oedema; maintaining bicamerality of the eye while providing stable long-term fixation of the IOL.
SUPRACAPSULAR GLUED IOL:
Phacoemulsification is started after making two partial thickness lamellar flaps 180 degrees apart. Capsular hooks engage the rhexis and support the bag during phacoemulsification. An AC maintainer is used to allow slow infusion into the eye when required, to prevent shallowing of the AC and extension of dialysis while removing phaco and irrigation/aspiration probes.
Good but gentle cortical cleaving hydrodissection allows complete cortex aspiration. After cortex removal, glued IOL implantation is done above the intact capsular bag. Two ab-interno sclerotomies are created under the scleral flaps with a bent 23-gauge needle. The sclerotomies are made without entering the vitreous cavity by going ab-interno via the AC in a supracapsular plane parallel to the iris to come out under the scleral flap.
Loosening the capsular hooks to allow the bag to fall slightly backwards and ballooning the iris upwards by injecting a cohesive viscoelastic under the iris in the quadrant of the scleral flap creates space to help pass the needle easily. After again expanding the retroiridal space with viscoelastic, the haptics of a three-piece foldable IOL are sequentially externalised above the anterior capsule using end-gripping microforceps introduced through the sclerotomies.
The use of high molecular weight viscoelastic allows these manoeuvres to be performed easily. Intra-scleral haptic tuck is then utilised for stabilizing the glued IOL as conventionally done and scleral flaps and conjunctiva are closed with fibrin glue. Retention of the capsulo-zonular barrier maintains complete bicamerality of the eye, separating posterior chamber from vitreous cavity, thus leading to lesser endophthalmodonesis and pseudophacodenesis, especially important in eyes already predisposed to a higher incidence of retinal complications.
Postoperative phimosis, if it occurs, can be prevented/ tackled in a more controlled manner with relaxing cuts on the anterior capsule, either at the time of surgery or postoperatively with the YAG laser.
These are difficult to stabilise for performing phacoemulsification, and trying to do so often results in prolonged and complicated surgery, with eventual loss of any remaining area of zonular support as well. Therefore, a better option in such cases is to extract the cataract with bag and perform AC IOL, iris-fixated or sutured/sutureless glued scleral fixated IOL.
LENSECTOMY WITH VITRECTOMY
WITH IOL FIXATION:
This may be performed in soft cataracts where the vitrectomy probe is used in aspiration mode. Though the commonly performed technique is to use the vitrectomy probe to cut and aspirate the crystalline lens from end to end, care needs to be taken to avoid lens fragment drop as well as accidental vitreous aspiration.
In my opinion, an ideal and better way to prevent lens material drop into the vitreous is to create a small opening in the capsular bag using the vitrector in cutting mode, followed by peeling and aspirating all the soft lens material through this opening with the vitrector in suction mode.
This prevents fragment drop, admixture of vitreous with lens material and inadvertent aspiration of vitreous. After removal of all the soft lens material in this manner, the empty capsular bag is removed using vitrector in cutting mode. The visual axis is cleared and an anterior vitrectomy is performed followed by IOL implantation using the surgeon’s preferred choice. The glued IOL scaffold technique (described below) can also be used for these soft, dangling cataracts.
INTRACAPSULAR CATARACT EXTRACTION AND SECONDARY IOL FIXATION:
This is done in cataracts with nuclear sclerosis which a vitrectomy probe will not be able to remove. Glued IOL flaps and sclerotomies are created. Posterior assisted levitation is performed through the sclerotomy to bring the dangling cataract up into the AC. An anterior vitrectomy is then done through the sclerotomy.
With nuclear sclerosis of grade 1 to 2, a glued IOL scaffold technique can then be used to position a glued IOL behind the iris. Here, the haptics of a three-piece IOL are carefully exteriorised sequentially under the nucleus as a glued IOL, and the haptics are tucked into intra-scleral Scharioth tunnels. If required, intracameral miochol may be used to constrict the pupil. The phaco probe is then used to emulsify the nucleus.
The constricted pupil, together with the glued IOL scaffold, prevents any fragment falling into the vitreous. For higher grades of nuclear sclerosis, after bringing the nucleus into the AC, a corneoscleral incision is made and the cataract is removed in toto using a vectis. In all cases where vitrectomy is done, preservative free intravitreal triamcinolone acetonide should be used to identify and remove any vitreous in the AC.