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Original Study

Role of Preoperative Nd:YAG Laser Anterior Capsulotomy in Mature Intumescent Cataracts

Porwal, Amit Champalal DO; Jethani, Jitendra N. MS, DNB; Porwal, Kavita A. MS, DNB; Shrishrimal, Meghna DOMS§; Shah, Parthvi R. DO, DNB

Author Information
Asia-Pacific Journal of Ophthalmology: September-October 2021 - Volume 10 - Issue 5 - p 473-477
doi: 10.1097/APO.0000000000000386
  • Open

Abstract

INTRODUCTION

Cataract surgery is one of the most efficient and safest surgical interventions, but it is dependent on the surgeon's skill and experience especially in difficult cases like intumescent cataracts. Surgery in intumescent cataracts poses a challenge in many ways, as the anterior chamber is shallow. Extension of the capsulorhexis to the periphery and occurrence of the Argentinian flag sign is high due to high intralenticular pressure.1 The Argentinian flag sign occurs in intumescent cataracts due to the hyperhydration of the lens fibers. These hydrated lens fibers create anterior and posterior pressures within the capsule separated by an equatorial cortex that has yet to be liquified and thus is still in contact with the capsule. During capsulotomy when the anterior intralenticular pressure dissipates into the anterior chamber, a difference in pressure caused by the remaining posterior intralenticular pressure causes the lens to be displaced anteriorly placing strain on the capsule and thus leading to its tear.2

Incidence of the Argentinian flag sign ranges from 3.85% to 28.3%.3,4,5,6,11 Gimbel and Willerscheidt4 first described capsulorhexis in 1987 as a central, circular, and curvilinear opening in the anterior capsule. An intact capsulorhexis is very crucial in achieving an uneventful cataract surgery as it offers good stability and centration of intra ocular lens (IOL) and prevents extension of radial tears. Several approaches are described in the literature to achieve a central circular capsulorhexis in intumescent cataracts and to avoid the extension of capsulorhexis towards the periphery such as use of trypan blue dye, 2 stage capsulorhexis, aspiration of fluid cortex by a 30-gauge needle, capsulorhexis using microcapsulorhexis forceps, high molecular weight ocular viscoelastic devices (OVDs) such as Healon 5 and Healon GV, and femto-assisted capsulorhexis.7

Here, we describe a simple preoperative procedure to decrease the intralenticular pressure and to deepen the anterior chamber by doing preoperative Nd:YAG laser anterior capsulotomy.

METHODS

Fifty-two eyes of 52 patients were selected in this prospective study done from May 2018 to September 2018. Institutional Review Board (IRB)/Ethics Committee approval was obtained. The research followed the tenets of the Declaration of Helsinki and informed consent was obtained from the subjects after an explanation of the nature and possible consequences of the study. Patients with any other ocular pathology such as lens-induced glaucoma, uveitis, hypermature cataracts with areas of capsular calcification/fibrosis, cataracts with zonular weakness, trauma, and synechial angle closure were excluded from the study. All the patients with a mature cataract with shallow anterior chamber that opens on indentation during gonioscopy were included in the study. Preoperative ocular evaluation was comprised of demographic details, visual acuity, slit-lamp examination, intraocular pressure (IOP) measurement, gonioscopy, anterior chamber depth (ACD) measurement, fundus evaluation of the fellow eye, B scan of the eye to be operated upon, and IOL power calculation. Every patient underwent a thorough systemic evaluation by a physician to rule out any systemic ailments such as diabetes, hypertension, asthma, or cardiac morbidities. All the patients were counseled regarding the nature of their cataracts and the need for an additional intervention. An informed consent was obtained for preoperative Nd:YAG laser anterior capsulotomy and the cataract surgery thereafter. A thorough slit-lamp examination was done (Haag Streit Model BM 900 LED) and ACD was assessed using Van Hericks grading. IOP was recorded with Goldmann applanation tonometer (GAT) with AT 900 slit-lamp-mounted GAT followed by gonioscopy. An indirect gonioscopy was done with a Volk four-mirror gonioprism. Pupils were then dilated using combination of Tropicamide 0.8% and Phenylephrine 5.0%. Postdilation IOP was measured by Goldman Applanation Tonometer and ACD was measured by anterior segment optical coherence tomography (ASOCT) (Carl Zeiss Visante OCT 1000). The measurement was taken from the center of the anterior lens capsule (highest convexity) to the back of the cornea (perpendicularly above the center). IOL power was calculated manually with Biomedix A scan machine model named Ecorule with 10 axial length readings and IOL power was calculated using SRK-T formula. B-Scan (Alcon-Ultrascan) was done in all patients. An APPA YAG Laser machine of model 307 was used for the study with the wavelength of 1064 nm and a frequency of 2.5 Hz. Preoperative Nd:YAG laser anterior laser capsulotomy was performed in all eyes with laser beam targeted in the center of the pupil on the anterior capsule with the beam defocused slightly anteriorly. A single shot of 1.2 mJ was fired without the use of Abraham capsulotomy lens. A gush of the liquified cortex was noted. After Nd:YAG laser, a slit-lamp examination was done to see whether the oozing of the cortical matter has ceased and then the post-YAG IOP was measured using GAT and ACD was measured using ASOCT. All the preoperative evaluation was done by a single glaucoma consultant. A single reading of pre- and post-Yag IOP and ACD was taken. Patient was taken up for surgery within 10 minutes of laser after giving a peribulbar block. A manual small incision cataract surgery was performed in all patients by a single surgeon with an experience of more than 20 years. A sclerocorneal tunnel of 6.5 mm and a side port of 0.9 mm was made. The cortical matter leaked into the anterior chamber was then aspirated using a Simcoe canula and then the anterior capsule was stained with trypan blue dye under air bubble. A cruciate opening was noted on the capsule with everted edges (Fig. 1). As all the surgeries were performed in a community setup, no high molecular weight OVD but a low molecular weight OVD hydroxy propyl methyl cellulose was used. The capsulorhexis was done with Utratas capsulorhexis forceps taking one of the flaps of the opening created by laser. The nucleus was then prolapsed in the anterior chamber and delivered using a wire Vectis. Cortical cleanup was done using Simcoes cannula, and IOL was implanted. The ease of performing a complete central circular capsulorhexis with hydroxypropyl methylcellulose was noted. Postoperative findings such as inflammation and corneal edema were noted. This technique was novel to our institute and was studied in detail so that it can be inculcated in the routine protocols of the institute for managing intumescent white cataracts.

FIGURE 1
FIGURE 1:
Cruciate opening in anterior capsule stained with trypan blue.

RESULTS

The mean age of patients was 57.6 ± 5.2 years. The mean ACD was 1.66 ± 0.28 mm pre-YAG laser and 1.9 ± 0.3 mm post-YAG laser. There was a mean increase in ACD by 0.24 ± 0.1 mm (Fig. 2). This was statistically significant as it clearly showed that the intervention had increased the ACD. Mean IOP recorded was 13.5 ± 2.3 mm Hg pre-YAG laser and 11.9 ± 1.9 mm Hg post-YAG laser. A mean decrease in IOP by 1.38 ± 1.32 mm Hg postlaser (Fig. 3) suggests that the reduction in lens thickness and intralenticular pressure has affected the dynamics of the iris lens diaphragm and has affected the IOP too. On two tail t test, the change in ACD and IOP change was significant (P < 0.05). (Figs. 4 and 5) No intraoperative complications were noted. There was an extension of capsulorhexis in 1 eye nearing the end of the capsulorhexis formation with Utratas forceps (1.92%) (Fig. 6). It was observed that there was no need for repeated insertion of instruments and viscoelastic and the capsulorhexis could be performed in a single go due to the reduction in the intralenticular pressure. As there was a decrease in the number of surgical maneuvers, the surgical time reduced significantly. The surgeon hence experienced a good sense of control and safety while performing high-risk cataract surgery. Postoperatively, none of the patients had fibrinous membrane or anterior chamber reaction of +3 to +4. All the patients were discharged with topical antibiotic steroid combination with a frequency of 6 times per day.

FIGURE 2
FIGURE 2:
The mean anterior chamber depth increases after doing YAG. ACD indicates anterior chamber depth.
FIGURE 3
FIGURE 3:
The mean IOP decreases post-YAG. IOP indicates intraocular pressure.
FIGURE 4
FIGURE 4:
Pre-YAG anterior segment OCT. OCT indicates optical coherence tomography.
FIGURE 5
FIGURE 5:
Post-YAG anterior segment OCT. OCT indicates optical coherence tomography.
FIGURE 6
FIGURE 6:
Percentage of intraoperative complications.

All these methods indirectly point to the reduction of the intralenticular pressure for which no direct evidence or technique to measure it is available.

DISCUSSION

In third world countries, the incidence of white cataracts is fairly high and accessibility to expensive infrastructures such as femto and Zepto laser is difficult. Most of these patients cannot afford to pay for their surgery and are enrolled for free surgery under National Program for Control of Blindness by District Blindness Control Society. In these situations, where there is nonavailability of high molecular weight OVDs, the creation of a stable manual capsulorhexis is of utmost importance to deliver results. Despite all studies and efforts to minimize intraoperative complications in intumescent cataract, the complication that might take place within seconds of puncturing of the anterior capsule is that the high intralenticular pressure expands the initial capsule incision in an uncontrolled way with the development of the Argentinean flag sign.1 It is important to understand that all cataracts that are mature or white may not be truly intumescent cataracts. There is no way to know that a particular lens would behave in a way that it would end up into the Argentinean flag sign in a community setup where intraoperative optical coherence tomography to know the lens thickness is usually not available or possible. Gimble and Willerscheidt4 suggested that a small continous curvilinear capsulorhexis (CCC) could help to know and tackle a high intralenticular pressure. The lens thickness and clinical examination may give a clue in some cases. Karim et al8 described a lens decompression technique by aspirating liquified cortex with a 25G/30G needle. When a needle is inserted the opening created is a horizontal slit that has chances of extending, whereas in our study the opening created by laser is a cruciate opening that has lesser chances of extending.

In a study by Gavris et al9 on 70 eyes with intumescent cataract, capsulorhexis skidding frequency was 11.43%, and in 1 case (1.43%) a posterior capsule rupture occurred.

Figueiredo et al2 put forth the concept of 2 pressurized intralenticular compartments—anterior and posterior—and postulated that it is the posterior intralenticular pressure between the nucleus and posterior capsule of the lens, rather than the vitreous pressure, which pushes the nucleus upward and can lead to capsulorrhexis extension even after the use of preoperative mannitol or aspiration of intralenticular fluid from the anterior compartment post-YAG. This might explain the mechanism of extension of the capsulorhexis in 1 eye of our study.

Gimbel and Willerscheidt4 originally suggested the two-stage CCC approach with a small capsulorhexis or a multipuncture of the anterior capsule before capsulotomy. After emulsification of the nucleus, the small CCC was enlarged to the desired diameter. With this technique, CCC was achieved in 57 eyes (95%) in a study by Chan et al,10 but Hausmann et al11 reported a 28.3% incidence of incomplete capsulorhexis, with a very low success rate in white cataracts with a liquified cortex (68%) compared to those with a solid cortex. Newton Kara-Junior et al12 compared the results of the 1-stage versus the 2-stage capsulorhexis in intumescent white cataracts and found anterior capsule tears in 23.07% of the cases in which the 1-stage capsulorhexis was performed (11 cases) and no ruptures of the anterior capsule were evidenced in which capsulorhexis was done in 2 stages (13 cases). Coelho et al13 reported that preoperative Nd:YAG laser anterior capsulotomy represents a safe and easy option for white intumescent cataracts after conducting a study in 11 eyes. They believed that the use of a single central disruptive pulse of energy may maintain an equal distribution of vector forces, preventing uncontrolled splitting of the anterior capsule to the periphery. We believe that when the Nd:YAG laser is done preoperatively and in the presence of an intact anterior chamber, the IOP would help in keeping a balance such that the intralenticular pressure would be regulated as per the pressure inside the eye in the anterior chamber and the posterior chamber. The IOP thus would prevent an inadvertent tear and would also guarantee the escape of the fluid from the lens that would therefore collapse and the intralenticular pressure would reduce. This, in turn, would be of great help to the surgeon and would enhance his peace of mind as the surgeon now knows that it is safe to start the rhexis as the pressure of the lens has already been balanced. The presence of a cortex or fluid that escaped from the lens in the anterior chamber after Nd:YAG laser anterior capsulotomy cases also proves the basic assumption of increased intralenticular pressure than actual in vivo anterior chamber pressure. We could further believe that intralenticular pressure would create force that is a possible risk for anterior capsule splitting or the Argentinian flag sign.13

There are a very few studies assessing the role of preoperative Nd:YAG laser anterior capsulotomy with a very small sample size and where the ACD is not known. Our study has a comparatively bigger sample size and an ASOCT to measure the pre- and postlaser ACD. We also believe that this was done approach has certain advantages compared to other approaches especially in a developing country where higher end machinery with better phacodynamics are not readily available. It is also clear from our work that preoperative Nd:YAG laser anterior capsulotomy is an easy, useful and reproducible option with the small learning curve. Also, the rate of complication is minimal with this useful technique of reducing or in other words balancing the pressure dynamics between the lens and anterior chamber. In a high workload center, capsulorhexis followed by preoperative Nd:YAG laser anterior capsulotomy saves a lot of time. Preoperative Nd:YAG laser anterior capsulotomy technique reduces the need for repeated entry of instruments in the anterior chamber. A perfect central opening is achieved in a single attempt. Not only the complication rate is the least, but there is a significant increase in the ACD and that in turn increases the ease and comfort of surgery and reduces the surgical time.

Limitations

  • Specular microscopy was not done to evaluate the endothelial cell count.
  • Change in the lens thickness was not assessed.
  • We have no data to compare preoperative Nd:YAG laser anterior capsulotomy in one eye and other techniques described in literature in the opposite eye and can serve as a subject for future research in the institute.

CONCLUSIONS

Preoperative Nd:YAG laser anterior capsulotomy is a safe and effective technique in reducing intralenticular pressure and avoiding intraoperative complications in mature intumescent cataracts. The technique described by us has the advantage of familiarity of the steps of standard small incision cataract surgery while ensuring enhanced safety and consequently better surgical outcomes.

REFERENCES

1. Dhingra D, Balyan M, Malhotra C, et al. A multipronged approach to prevent Argentinian flag sign in intumescent cataracts. Indian J Ophthalmol 2018; 66:1304–1306.
2. Figueiredo CG, Figueiredo J, Figueiredo GB. Brazilian technique for prevention of the Argentinean flag sign in white cataract. J Cataract Refract Surg 2012; 38:1531–1536.
3. Perrone DM. Argentinean flag sign is the most common complication for intumescent cataracts. Ocular Surgery News US Edition Dec 2000.
4. Gimbel HV, Willerscheidt AB. What to do with limited view: the intumescent cataract. J Cataract Refract Surg 1993; 19:657–661.
5. Vajpayee RB, Bansal A, Sharma N, et al. Phacoemulsification of white hypermature cataract. J Cataract Refract Surg 1999; 25:1157–1160.
6. Chakrabarti A, Singh S, Krishnadas R. Phacoemulsification in eyes with white cataract. J Cataract Refract Surg 2000; 26:1041–1047.
7. Gavriş M, Mateescu R, Belicioiu R, et al. Is laser assisted capsulotomy better than standard CCC? Rom J Ophthalmol 2017; 61:18–22.
8. Nabil KM. Lens decompression technique for prevention of intraoperative complications during phacoemulsification of intumescent cataract. Indian J Ophthalmol 2017; 65 (12):1436–1439.
9. Gavris M, Popa D, Caraus C, et al. Facoemulsificarea in cataracta alba, intumescenta. Oftalmologia 2004; 48:81–87.
10. Chan DD, Ng AC, Leung CK, et al. Continuous curvilinear capsulorhexis in intumescent hypermature cataract with liquefied cortex. J Cataract Refract Surg 2003; 29:431–434.
11. Hausmann N, Richard G. Investigations on diathermy for anterior capsulotomy. Invest Ophthalmol Vis Sci 1991; 32:2155–2159.
12. Kara-Junior N, de Santhiago MR, Kawakami A, et al. Mini-rhexis for white intumescent cataracts. Clinics 2009; 64:309–312.
13. Coelho RP, Paula JS, Silva RN, et al. Preoperative Nd:YAG laser anterior capsulotomy in white intumescent cataracts: report of 11 cases. Arq Bras Oftalmol 2009; 72:113–115.
Keywords:

Argentinian flag sign; capsulorhexis; capsulotomy; mature intumescent cataract; Nd:YAG laser

Copyright © 2021 Asia-Pacific Academy of Ophthalmology. Published by Wolters Kluwer Health, Inc. on behalf of the Asia-Pacific Academy of Ophthalmology.