White cataract phacoemulsification

A,B: Initial puncture on the lens capsule in intumescent white cataract resulting in Argentinian flag sign C: Milky fluid released obstructs visualisation; D: A forceps is better than cystitome to complete rhexis A white cataract may be age related or otherwise. Senile white cataract can be mature intumescent cortical cataract, hypermature cataract or hypermature Morgagnian cataract. A traumatic cataract with broken lens capsule may also present as a white cataract as also membranous traumatic/ congenital cataracts with resorption of lens proteins. Senile white cataracts can be intumescent white with cortex liquefaction, white with large nuclei and less cortex or white with fibrosed anterior capsule (Brzitikos et al). White cataracts are challenging at numerous points of surgery. CHALLENGES WITH RHEXIS A soft eye with a good peribulbar block, pinkie ball application and preoperative intravenous mannitol is important. Tight speculum and bridle suture should be avoided. Lack of red glow and release of milky fluid on creating the initial puncture makes visualisation of the leading edge of rhexis difficult. The anterior capsule may be thin and fragile or fibrosed, both of which further compound difficulty. Increased intra-lenticular pressure makes the anterior capsule convex, increasing the risk of a rhexis run-out. The intra-lenticular pressure in an intumescent white cataract is quite high and the initial nick on the anterior capsule can extend rapidly to both sides resulting in the “Argentinian flag sign” 
- a potentially dangerous situation. The rhexis is done through a partially opened main port or a side port in order to prevent escape of viscoelastic and better maintain a taut anterior chamber (AC). Trypan blue dye injected under a small air bubble is used for staining the capsule to enhance visualisation. A trisoft shell technique may also be used where a viscodispersive ophthalmic viscosurgical device (OVD)(eg. Viscoat) is first injected on the anterior capsule for approximately 25% fill, followed by viscoadaptive OVD (eg. Healon5) under this which pushes the viscodispersive upwards to coat the endothelium. A small amount of Trypan blue is then painted in a back-and-forth manner over the anterior capsule. An endoilluminator also helps improve visualisation. High molecular weight/cohesive OVD is used to increase AC pressure and prevent a radial run-out of the rhexis. For initiating rhexis, an initial puncture into the anterior capsule with the cystitome followed immediately by aspiration of liquefied cortex through the cystitome needle helps rapidly decompress the cataract and decrease intra-lenticular pressure. Gentle rocking of nucleus helps release both anterior and posterior liquefied cortex. The initial cut should not be initiated with forceps as a large cut can be uncontrolled and result in a rapid run-out. Milky fluid released in the AC is aspirated after decompressing the lens. After the initial puncture and aspiration with cystitome, it is easier to continue the rhexis with a microforceps as the liquefied cortex does not offer support to the cystitome tip. A two-step rhexis can be done where an initial small CCC/ mini-rhexis is secondarily enlarged just prior to IOL implantation. OVD is refilled when necessary to keep the anterior capsule flat. The Little rhexis trick is employed in case of outwards extension of rhexis. The capsule flap is unfolded to lie flat. While holding it as close to the root of the tear as possible, it is first pulled backwards in a horizontal plane along the circumference of the completed segment of rhexis and then with the flap held stretched, directed more centrally to initiate the tear. If the rhexis run-out is irretrievable, it may be attempted to be completed by creating a cut on the flap and continuing forwards or by creating a nick on the opposite side and completing it backwards. Alternatively, a can-opener capsulotomy can be done in the incomplete area. All precautions for phacoemulsification with a torn rhexis should be employed. Phacocapsulotomy utilises the phaco tip to simultaneously create an initial anterior capsular puncture and remove some of the lenticular material following which a forceps completes the rhexis. An Argentinian flag sign is seen in intumescent white cataract. Risk factors include diabetes, UV exposure, steroid usage etc. As Trypan blue stiffens and makes the capsule brittle, it has also been proposed as a risk factor. If a split is seen, the AC pressure should be immediately increased with cohesive OVD to prevent a wraparound tear. A perpendicular relaxing cut is made on one of the leaflets which is then joined on the other side as a partial circular tear. A fibrosed and calcified anterior capsule may be seen in some hypermature cataracts, membranous congenital cataracts or as post-traumatic sequelae – the rhexis is started in a normal area and circumnavigated around the affected area to include it. If not possible, microscissors or vitrector may be used in the affected zone in which case, subsequent manoeuvres should be as described for torn rhexis. Femtosecond laser assisted cataract surgery (FLACS) may be utilised for rhexis. Milky fluid released may interfere with subsequent cuts resulting in microadhesions that need to be manually released. A fibrosed capsule needs higher energy levels to be cut. HYDRO PROCEDURES In mature white cataracts that have large nuclei and less cortex, hydrodissection may result in the fluid wave being trapped behind the nucleus. Further injection of fluid can cause fluid to build up within the capsular bag resulting in capsular block syndrome and a capsule blow-out with resultant risk of drop of a large nucleus into the vitreous cavity. This should be avoided by very gentle, multi-quadrant hydrodissection using a low volume of fluid as well as by gently rocking the nucleus to allow fluid trapped behind the nucleus to flow out. A thorough cortical cleaving hydrodissection is not mandated as there are generally very little cortical fibres that are adherent to the capsule and most cortex if present is either in a liquefied form or can be easily washed out. Hydrodelineation need not be attempted as there is generally no epinucleus. In cases of traumatic white cataracts, there should always be the suspicion of a posterior capsular break and hydro manoeuevres may be avoided. Nucleus management will be discussed 
in Part 2 of this series. Dr Soosan Jacob is Director and Chief of Dr Agarwal's Refractive and Cornea Foundation at Dr Agarwal's Eye Hospital, Chennai, India and can be reached at:
dr_soosanj@hotmail.com.