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  5. FP570 : Decoding Intumescent cataracts using Intraoperative OCT: The MACPoD Classification

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Dr. Sanket Bhatnagar, B16754, Dr. Rohit Shetty, Dr. Aishwarya, Dr. Mathew Kurian

Retrospective Analysis of Intra-operative Optical Coherence Tomography in Mature Cataracts and a New Classification System for its Management

The tremendous success of cataract surgery has given rise to expectation of perfect outcomes in every case. ref Intumescentmature cataracts are a challenge to the operating surgeon due to the risk of rhexis extension, potentially weak zonules and risks associated with nucleus management. Ref Securing a round and regular capsulorhexis in such cases improves the outcome of the surgery 1,2

Femtosecond laser assisted cataract surgery (FLACS) has been an innovation in cataract surgery. ref Ocular coherence tomography (OCT) directed micro-pulsed shots in the infra-red range of light have been shown to be precise and reproducible in delivering the laser to the tissue resulting in better predictability in the creation of a capsulorrhexis3,4  However despite the optimum use of such a technology, capsular tags and rhexis tears are seen especially in intumescent mature cataracts.5-7

Imaging the anterior segment before cataract surgery using anterior segment OCT may help in identifying and preventing certain intra-operative complications.8,9 OCT integrated in the operating microscope and the FLACS platforms has brought the advantages of anterior segment OCT to operating table.

In this paper we suggest an OCT based morphological classification system for intumescent mature cataracts. This classification predicts the mechanism of an incomplete rhexis and modifications in the planning of the capsulotomy based on this classification.

 Materials and methods:

This interventional cross sectional study recruited patients after informed consent. Institutional ethical review board clearance was obtained and the tenets of the Helsinki Declaration were followed. For the purpose of this study an intumescent mature cataract was defined as a white cataract with a domed anterior capsule indicative of raised intra-lenticular pressure with or without fluid clefts detected on slit lamp examination

30 eyes of 30 patients with intumescent mature cataracts as diagnosed on slit lamp biomicroscopy were operated using the RESCAN™ 700 (Carl   Zeiss   Meditec,   Oberkochen,  Germany), a microscope integrated SD-OCT system that includes a heads-up display system and an external video display panel with foot pedal control of the OCT scanner. The system is based on the Lumera 700 platform. The OCT has an axial resolution of 5µ in the tissue and transverse resolution of 15µ. Anterior segment imaging can be achieved with the standard microscope viewing system. For posterior segment imaging, the RESIGHT lens system or a contact lens can be utilized. It gives a cube at the area of interest on the right end of the screen and the point of interested can be changed with X, Y and Z axis adjustments. It also includes image stabilization for better quality scans.10

Cube scans (4 x 4 mm) were done for all the cases. The OCT images were acquired in horizontal and vertical orientations in the form of a continuous video feed. Bi-planar clear corneal incision of 2.2mm using a microkeratome, and uni-planar sideports at 7 and 12 o’clock were made. Trypan blue was used to stain the capsule. The anterior chamber was filled with a high viscosity ophthalmic viscosurgical device (OVD) to flatten the domed anterior capsule and the capsulorhexis was performed using micro-rhexis forceps through the side post after attempting to release the raised intralenticular pressure when possible. All the complications like Argentinian flag sign and rhexis run-off were managed successfully using the standard techniques1,2,11In all cases uneventful nucleus management by phacoemulsification was followed by implantation of a single piece hydrophobic intraocular lens (IOL) within the capsular bag. Except for the intraoperative OCT the pre and post-operative care of these patients followed the standard operating protocols of the institution.

Retrospectively, the videos were critically reviewed to look for risk factors which lead to the aforementioned complications during capsulorhexis and whether the morphology of an intumescent mature cataract on OCT could be used to predict the risk of intraoperative rhexis challenges during cataract surgery and FLACS in particular.

Subsequently, 20 eyes with intumescent mature cataracts and undergoing FLACS using the Alcon LenSx platform were assessed. LenSx uses a diode pumped solid state mode-locked laser source to produce the femtosecond micro pulses of 1030nm wavelength with beam monitoring systems for laser delivery. The LenSx has an integrated Spectral Domain Optical coherence tomography (SD-OCT) system which uses infrared laser beam derived 2 and 3 dimensional computerized reconstructions of the ocular structures. The patient interface consists of sterile disposable silicon Softfit® contact lens which is attached to the focusing objective. The bed height is raised and the interface is lowered until the PI touches the cornea. After ensuring appropriate docking determined by the absence of corneal folds, loose conjunctiva and air bubbles, suction was activated. Enface video and the cross-sectional circle and line OCT scan images were used to refine the incision and capsulorhexis. Clear corneal 2.2mm incision and limbus centred 4.8 mm diameter capsulotomy were performed. The ablation proceeds postero-anteriorly in the counter-clockwise direction. The customizable parameters of the capsulotomy are the diameter and Delta up and down which can be adjusted between 250 µ to 400 µ.

The presence of capsular tags and incomplete capsulotomy were correlated with the OCT based morphology. Modifications of Delta up-down are suggested based on these observations to enhance completeness of capsulotomy.

Results:

Based on our retrospective video analysis of the footage obtained from intra-operative OCT of intumescent mature cataract the features that were studied were the presence and position of fluid clefts and the curvature of the anterior surface of the lens.

The pre-operative morphological features showed many variations with respect to location of fluid clefts. The location of clefts correlated with the magnitude of flattening of anterior lens curvature seen upon injection of OVD. We propose the following variants of mature intumescent cataracts based on the type and location of fluid clefts seen on Intraoperative OCT:

  1. Minimal or absent fluid clefts with a flat anterior capsule
  2. Anterior fluid clefts with a domed anterior capsule
  3. Central fluid clefts with a domed anterior capsule
  4. Posterior fluid clefts with a domed anterior capsule
  5. Diffuse fluid clefts with a domed anterior capsule

In the 20 eyes undergoing FLACS the integrated OCT on the femto platform showed

a.) Number and percentage of each

b.) Association of leaked fluid in each type

c.) Number and percentage of free floating capsulotomies

d.) Number and percentage of incomplete rhexis: Subclassify into tags and larger incomplete and correlate to fluid leakage and fluid position

Discussion:

A complete capsulorhexis is an important step in enhancing the safety and efficacy of modern cataract surgery.Intumescent mature cataracts are notorious for the Argentinian Flag sign and rhexis run-off. Several methods have been described to create a proper rhexis in the presence of raised intralenticular pressure such as performing the CCC in air, decompressing the swollen lens with a needle, aspirating the liquefied cortex from the eye staining the capsule to improve visualization,5 and performing a 2-stage CCC12. Other techniques have been described to manage the run off once it has happened 2,11,13  The importance in classifying intumescent mature cataracts is that it prepares the surgeon for different intraoperative challenges associated with different steps of surgery.

The anterior capsulotomy is created by scanning a cylindrical shell extending from a position in the lens volume through the capsule and into the anterior chamber. The cylindrical scan pattern penetrates the capsule in a circular shape. Tags and bridges may occur as a result of minimal torsional movements of the eye which can occur despite the limbal conjunctival suction of the patient interface. Micro- movements cause straying of the laser spots and result in tags.  Delta up-down adjustment is an excursion limit of laser which is essential for complete resection of capsule. A commonly used limit of 250-400µ is usually sufficient for regular cataracts. However, in intumescent mature cataracts a rigidly fixed limit may yield inconsistent outcomes due to the changes in capsular location and the leak of opaque cortical fluid in anterior chamber.

Basti et al14 used slit lamp bio microscopy based classification by observing the intra lenticular pressure manifested by the curvature of anterior lens capsule, colour of the nucleus and status of the cortex.  They divided them into 8 categories based on each morphological feature.

Brazitikos et al15  also classified mature cataracts based on A- Scan echography and slit lamp bio- microscopy features into three groups. They also studied the complication rates in each category with rhexis extension being most common in intumescent cataracts.

Our observation is that the presence and location of fluid clefts in the intumescent cataract as seen on OCT can predict the intra-operative behaviour of the capsule during capsulorrhexis.

When there are minimal fluid clefts, the intralenticular pressure is not very high and there is minimal convex curvature of the ALC. There is minimal movement on initial puncture of the ALC and the media tends to remain clear as there is minimal fluidic cortical matter to leak out of the punctured capsular bag. There is a relatively low risk of rhexis extension and such cataracts do not warrant any modifications during conventional rhexis and no adjustments are required to the delta up-down feature during femto assisted capsulotomy either.

Raised intra-lenticular pressure as indicated by a convex, domed ALC is seen in all other morphological forms of intumescent mature cataracts that we have described. This is associated with a high possibility of movement of the ALC flap upon initiating capsulotomy.

In cataracts with fluid clefts located anteriorly and centrally, use of a high viscosity OVD to pressurise the anterior chamber would redistribute the intralenticular fluid resulting in a flatter anterior capsule profile. The initiation of the rhexis causes egress of cortical fluid, releases the raised intra-lenticular pressure and causes the ALC flap to settle down. When performing manual capsulorhexis in such cataracts the risk of rhexis extension is minimised once the cortical fluid leaks out as adequate intralenticular decompression occurs. Filling the anterior chamber with appropriate high viscosity OVD would perform the dual function of clearing the liquefied cortex from the anterior chamber thus improving visibility for subsequent steps as well as increase the anterior chamber pressure to greater than the intralenticular pressure to minimise further risk of rhexis extension.

In FLACS if the delta adjustment does not take the downward movement of the ALC into account it may cause an incomplete capsulotomy. Increasing the delta down is recommended to compensate for the ALC movement and ensure adequate spot delivery to the capsule. However despite this adjustment there may be an incomplete femto capsulotomy as the presence of the opaque liquefied cortex in the anterior chamber results in poor penetrance of Femtosecond energy.  This morphologic type is most likely to be associated with FLACS capsulotomy complications.

Intumescent mature cataracts with posterior and diffuse fluid clefts also show convexity of the ALC indicating a high intra-lenticular pressure. A high viscosity OVD in the anterior chamber does not result in a flatter anterior capsule profile as the intralenticular fluid is lying deep or diffusely dispersed within the lens matter and cannot be redistributed. In these cases, there is minimal or no egress of cortical fluid as the liquid material deep within the lens matter is unable to escape. Initiation of the rhexis releases the counter pressure exerted by the anterior capsule and causes the ALC to be pushed toward the endothelium. During manual capsulorhexis, there is high probability of the Argentinian flag sign and rhexis run-off as the underlying deep liquefied cortex attempts to escape resulting in a sustained high intra-lenticular pressure. This morphologic type is most likely to be associated with conventional capsulorhexis complications.

While performing FLACS in intumescent mature cataracts with posterior and diffuse fluid clefts the media remains clear as there is minimal or no fluid cortex released into the anterior chamber and increasing the delta up should ensure adequate completion of capsulotomy.

Intraoperative OCT is necessary to make the initial correlation between the location of the fluid clefts and the intraoperative behaviour of the capsule during capsulorhexis. Pre or intra-operative OCT on any platform should now be adequate to prepare the surgeon to handle the specific challenges posed by the varying morphologies of intumescent mature cataracts.

We expect similar behaviour by the capsule during FLACS irrespective of the platform used. The Victus platform with the OCT scanning during the period of laser firing would be able to confirm our hypothesis related to the movement of the anterior capsule and validate our suggestions related to adjustments in delta excursion.

Conclusion:

AS-OCT is a handy tool to identify the morphological features of intumescent mature cataracts. Knowing the behaviour of the capsule during capsulorhexis can help the surgeon prepare better, when tackling such challenging cases. Modifications in delta excursion based on the morphology of intumescent mature cataracts can refine the outcomes of phacoemulsification and FLACS in such challenging cataracts.

  1. Chan DDN, Ng ACK, Leung CKS, Tse RKK. Continuous curvilinear capsulorhexis in intumescent or hypermature cataract with liquefied cortex. Journal of Cataract & Refractive Surgery. 2003;29(3):431-434.
  2. Figueiredo CG, Figueiredo J, Figueiredo GB. Brazilian technique for prevention of the Argentinean flag sign in white cataract. J Cataract Refract Surg. 2012;38(9):1531-1536.
  3. Kranitz K, Takacs A, Mihaltz K, Kovacs I, Knorz MC, Nagy ZZ. Femtosecond laser capsulotomy and manual continuous curvilinear capsulorrhexis parameters and their effects on intraocular lens centration. Journal of refractive surgery. 2011;27(8):558-563.
  4. Nagy ZZ, Kranitz K, Takacs AI, Mihaltz K, Kovacs I, Knorz MC. Comparison of intraocular lens decentration parameters after femtosecond and manual capsulotomies. Journal of refractive surgery. 2011;27(8):564-569.
  5. Nagy ZZ, Takacs AI, Filkorn T, et al. Complications of femtosecond laser-assisted cataract surgery. J Cataract Refract Surg. 2014;40(1):20-28.
  6. Ostovic M, Klaproth OK, Hengerer FH, Mayer WJ, Kohnen T. Light microscopy and scanning electron microscopy analysis of rigid curved interface femtosecond laser-assisted and manual anterior capsulotomy. J Cataract Refract Surg. 2013;39(10):1587-1592.
  7. Roberts TV, Lawless M, Sutton G, Hodge C. Anterior capsule integrity after femtosecond laser-assisted cataract surgery. J Cataract Refract Surg. 2015;41(5):1109-1110.
  8. Schallhorn JM, Tang M, Li Y, Song JC, Huang D. Optical coherence tomography of clear corneal incisions for cataract surgery. J Cataract Refract Surg. 2008;34(9):1561-1565.
  9. Fukuda S, Kawana K, Yasuno Y, Oshika T. Wound architecture of clear corneal incision with or without stromal hydration observed with 3-dimensional optical coherence tomography. Am J Ophthalmol. 2011;151(3):413-419 e411.
  10. Das S, Kummelil MK, Kharbanda V, et al. Microscope Integrated Intraoperative Spectral Domain Optical Coherence Tomography for Cataract Surgery: Uses and Applications. Curr Eye Res. 2016;41(5):643-652.
  11. Coelho RP, Paula JS, Rosatelli Neto JM, Messias AM. Capsulorhexis rescue after peripheral radial tear-out: quick-pull technique. J Cataract Refract Surg. 2012;38(5):737-738.
  12. Brusini P. Use of air in phacoemulsification of mature cataract. J Cataract Refract Surg.

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