White cataract phacoemulsification - Part 2

A: A small size rhexis is initiated; B: It is then spiraled out in a controlled manner to achieve the desired size; C: A horizontal chop technique is used; D: Last fragments are emulsified in a more anterior plane     After rhexis, the next challenging step in white cataract is nucleus removal. The approach to nucleus management depends on the type of white cataract. MEMBRANOUS (CONGENITAL OR TRAUMATIC) WHITE CATARACT: A membranous cataract has partial/complete resorption of cortex, and a flattened membranous capsule consisting of the collapsed capsular leaflets is seen. In cases with partial resorption of cortex, rhexis and other usual steps are done followed by intraocular lens (IOL) implantation within the bag. In congenital cases, a primary posterior capsulorhexis and vitrectomy may also be done. If the cortex is completely resorbed, management aims at opening the visual axis. Depending on the nature of the membrane, a rhexis is created or a vitrector is used to cut the membrane in as round and regular a manner as possible. The IOL may then be placed in the sulcus with membrane capture of the optic as described by Gimbel. With inadequate/unstable capsular support, a scleral or iris-fixated IOL may be done depending on surgeon preference. My personal preference here is to perform a glued IOL. TRAUMATIC WHITE CATARACT: A white cataract may be seen after penetrating or blunt trauma. If surgery is done soon after trauma, depending on the patient’s age, the cataract may be composed either of only soft, flocculent lens material or it may have an endonucleus. In the former case, it 
is sufficient to use an irrigation/aspiration (I/A) probe to aspirate 
the soft lens matter. However, in the presence of an endonucleus, special manoeuvres are adopted for nuclear disassembly. In all cases, the possibility of an associated posterior capsular rupture and weak zonules should be kept in mind. Hydro manoeuvres should not be done or should be done very gently, to prevent a nucleus drop in case of a pre-existing capsular rent. All manoeuvres should be performed gently. Other associated ocular comorbidity such as corneoscleral tear, scarred visual axis, difficult visualisation, soft eye, iris or vitreous loss, subluxation, secondary glaucoma, macular pathology, retinal detachment etc should be kept in mind while planning management. Blunt trauma classically presents as a rosette-shaped cataract with the possibility of coexisting zonulodialysis. SENILE WHITE CATARACT: These can be seen as mature hard white cataracts or hyper-mature white leaking Morgagnian cataracts. MATURE HARD WHITE CATARACT: The entire cortex is opacified and there is very little epinucleus. The nucleus of the white cataract is large, but generally brittle and more amenable to phacoemulsification than hard, brown, leathery cataracts. Care needs to be taken to decrease total phaco time, power and energy used and to keep the corneal endothelium and the posterior capsule safe. Standard nuclear disassembly techniques may be used. Vertical chop works well for these cataracts. If horizontal chop is being used, the chopper should be slid very carefully under the rhexis margin, avoiding damage to the capsulo-zonular complex. HYPER-MATURE WHITE LEAKING MORGAGNIAN CATARACT: A leaking Morgagnian has liquefied cortex and a small brown nucleus settled downwards in a bag of milky fluid. As described in Part 1 of this two-part series on white cataracts (EuroTimes Volume 22, Issue 5, May 2017), the milky fluid is aspirated before performing rhexis. After rhexis, the nucleus is vertically chopped into multiple small fragments which are then removed one by one at or just below the iris plane. The posterior capsule is thin, fragile and floppy, the zonules may be weak, and these together with lack of sufficient epinucleus significantly increase the risk of inadvertent posterior capsular rupture during a sudden post-occlusion surge. Therefore, once the bag is no more held distended by the bulk of nucleus, phaco settings are decreased and the last fragments emulsified in a more anterior plane. Implanting a capsular tension ring helps stabilise loose zonules and makes the posterior capsule less floppy. Very small nuclei are mobile and more difficult to embed. These may be viscoprolapsed out of the bag and emulsified at iris plane using lower vacuum parameters. Gas forced infusion or an air pump attached to the bottle allows increased irrigation, which helps maintain a well formed anterior chamber, holds the iris and IOL backwards and prevents surge, all of which help emulsify the nucleus at a more posterior plane and also helps surgery proceed faster and safer. For smaller sized nuclei, Om Parkash et al have described a variation of the scaffold technique, wherein the IOL is injected into the bag after bringing the nucleus into the anterior chamber. The IOL then acts as a scaffold holding the posterior capsule back while the nucleus is fragmented safely at iris plane. In all cases where more phaco energy is likely to be used in the anterior chamber, the endothelium should be adequately protected with dispersive viscoelastic. NUCLEUS REMOVAL WITH AN INCOMPLETE/TORN RHEXIS: The capsule is handled as described in Part 1 of this series. This is followed by slow-motion phaco with low bottle height and low machine parameters. Hydrodissection should be avoided. If possible, the nucleus is gently brought out of the capsular bag and emulsified in a supracapsular plane. If the nucleus is too large to be brought out in toto, it is carefully chopped making sure no vertical or horizontal forces are exerted on the capsule to avoid a wraparound tear in the capsular bag. Once the nucleus is removed, gentle irrigation is generally sufficient to remove any liquefied cortex present in the fornices of the bag. IRRIGATION/ASPIRATION (I/A): I/A is generally not required in these mature or hyper-mature cataracts and simple irrigation with a cannula often suffices. I/A is done with care for any residual cortical wisps using very low vacuum, since the capsular bag is floppy and zonules weak. Capsule polishing mode is generally enough to remove stubborn cortical wisps. IOL IMPLANTATION: Capsular bag is distended well with viscoelastic and IOL injected, directed towards the capsular fornix to avoid haptics snagging on the floppy posterior capsule. In case of incomplete rhexis, a three-piece IOL may be injected.   Dr Soosan Jacob is Director and Chief of Dr Agarwal’s Refractive and Cornea Foundation at Dr Agarwal’s Eye Hospital, Chennai, India dr_soosanj@hotmail.com