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Role of anterior segment optical coherence tomography for safer management of mature white cataracts

Dhami, Abhinav MS*; Dhami, Abhijit Singh MBBS; Singh, Hardeep BSc; Dhami, Gobinder Singh MD, MBBS

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Journal of Cataract & Refractive Surgery: April 2019 - Volume 45 - Issue 4 - p 480-484
doi: 10.1016/j.jcrs.2018.11.009
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Abstract

Despite the availability of advances such as laser-assisted capsulotomy, performing a safe continuous curvilinear capsulorhexis (CCC) still poses a challenge in mature and intumescent cataracts. It is a constant challenge and struggle for ophthalmologic surgeons to achieve a CCC without any inadvertent capsular complications in such cases, regardless of their level of experience in the modern era, despite the advances in phacoemulsification.1,2 The major problems are decreased visibility, the absence of the red reflex after the anterior capsule of the lens is perforated in intumescent cataracts, and the sudden outflow of liquid cortex that blocks the surgeon’s vision, thus causing uncontrollable extension of the initial opening, which is called the Argentinian flag sign.1,2 It can lead to more serious complications, such as zonular rupture or rupture of the posterior capsule, vitreous loss, nucleus drop, and posterior displacement of an intraocular lens (IOL).2,3 The incidence of an incomplete capsulorhexis associated with white cataract surgery was 28.3% in a study by Chakrabarti et al.4 Various methods have been described to improve and facilitate an easy capsulorhexis, which include the use of trypan blue, puncture of the anterior capsule with positive pressure in the anterior chamber, a two-stage capsulorhexis,5 an insulin needle–assisted capsular perforation and fluid removal,2 and recently, femtosecond laser–assisted capsulorhexis.1 Despite this, the possibility of developing an Argentinian flag sign continues to occur.

Herein, we describe a new method of using anterior segment optical coherence tomography (AS-OCT) to analyze the presence or absence of fluid pockets under the anterior capsule and its surgical management.

Patients and methods

In this prospective interventional study, patients with intumescent and mature white cataracts were scheduled for elective unilateral standard phacoemulsification and IOL implantation by two surgeons (G.S.D., A.D.), during the period of October 2017 to April 2018, in a private ophthalmic hospital in the northern part of India. After providing an explanation of the risks and a guarded visual prognosis, written informed consent forms for the surgery were obtained from all the patients.

The exclusion criteria included a history of coexisting ocular disease (eg, uncontrolled glaucoma or ocular tumors), corneal opacities and retinal pathology, if detected on B-scan ultrasound (eg, proliferative diabetic retinopathy or retinal detachment). The patients were divided in two groups. Group 1 (n = 15) included all the patients who showed the presence of subcapsular fluid on AS-OCT, whereas Group 2 (n = 15) included all the patients without the presence of any subcapsular fluid pockets on AS-OCT.

Technique

A wide angle-to-angle imaging scan was used on spectral-domain OCT (Cirrus HD-OCT, Carl Zeiss Meditec AG) for analyzing the presence or absence of fluid pockets in mature/intumescent cataracts, which generate a wide field, with a speckle-reduced raster scan of anterior chamber depth of 2.9 mm. The scan uses 20 B-scans, 15.5 mm in length, each composed of 1024 A-scans and is horizontally oriented (Figure 1, a). The scan is adjustable from −89 degrees to 90 degrees. The 2.9 mm scan depth is achieved by allowing the source and mirror images to overlap using an anterior chamber external lens.

Figure 1
Figure 1:
a: Wide angle-to-angle scan for anterior segment optical coherence tomography showing anterior fluid pockets (red arrow and blue arrow). b: Side-port entry being made. c: Introduction of a 30-gauge needle perforating the anterior capsule. d: Needle-assisted fluid drainage showing clearance of the subcapsular fluid.

AS-OCT was performed preoperatively in all patients (n = 30) with mature/intumescent cataracts, and the presence or absence of fluid pockets under the anterior capsule was analyzed and the depth of fluid pocket from the anterior capsule to the first hyperreflective back-shadow of the nucleus was measured (Figure 1, a). Topical moxifloxacin 0.3% eyedrops were used every 2 hours before the surgery.

Preoperatively, full asepsis was maintained, and preoperative cleaning of the conjunctival sac was done with povidone–iodine 5% antiseptic and topical anesthesia using tetracaine hydrochloride 1.0%, and then pupil dilation was performed. The temporal site was used for performing routine cataract surgery.

Next, 0.8 mm incision side ports were made using a microvitreoretinal knife at 4 o’clock and 11 o’clock, depending on whether it was the right eye or the left eye being operated (Figure 1, b). Anterior capsule staining using trypan blue 0.1% was performed under air. A dispersive ophthalmic viscosurgical device (OVD) was injected through one of the side ports to remove the air bubble and dye from the anterior chamber. The OVD was injected in an amount sufficient to pressurize the chamber properly. A temporal self-sealing clear corneal incision was made using a 2.8 mm steel blade.

Depending upon the presence of fluid pockets, the technique was modified as described by Figueiredo et al.2 by using a 30-gauge needle and entering directly through the limbus. The central anterior capsule (Figure 1, c) was perforated with minimal movements, and active suction of fluid was performed from the mid-equator region until the nucleus was clearly appreciated (Figure 1, d). The same nick was then used to guide a capsulorhexis with the help the Utrata forceps, thus minimizing the risk for the Argentinian flag sign. Hydrodissection was avoided in these cases because typically in such cases, the nucleus tends to be small and mobile. Phacoemulsification was performed using a direct chop technique with segmentation of the nucleus in multiple small quadrants for easy emulsification. Irrigation and aspiration of the cortical matter was done using a coaxial J-shaped cannula. Next, the anterior chamber was refilled with a cohesive OVD for insertion of the IOL into the bag. Before the OVD was removed from the anterior chamber and capsular bag, the main clear corneal incision and side port were sealed using stromal hydration. Intracameral preservative-free moxifloxacin 0.5% was injected in the anterior chamber at the end of surgery in all patients. The eye was patched for overnight if the surgery was performed under local anesthesia or for 2 hours if performed under topical anesthesia.

If no fluid was noted on AS-OCT in a white cataract, then capsulorhexis was performed using Utrata forceps directly; the rest of the technique was same as described above. (Figure 2, a to d)

Figure 2
Figure 2:
a: Wide angle-to-angle scan for anterior segment optical coherence tomography with no fluid pockets. b to d: Completion of capsulorhexis using Utrata forceps and no underlying fluid.

Statistical Analysis

Descriptive statistics were computed for continuous variables and frequency distribution was constructed for qualitative variables. All statistical analyses were performed using SPSS software (version 14.0, SPSS, Inc.). A P value less than 0.05 was considered statistically significant.

Results

The study comprised 30 eyes of 30 patients. There were 14 men (46.6%) and 16 women (53.4%). There was an equal distribution of right and left eyes, 15 (50.0%) each. Table 1 shows the median, mean, and range characteristics of the study patients.

Table 1
Table 1:
Demographics of the 30 study patients.

Of the 30 eyes, 29 (96.6%) eyes underwent monofocal IOL implantation, whereas 1 (3.4%) eye underwent a multifocal IOL implantation. The vision in the operated eyes ranged from light perception (12 patients [40.0%]) to close-to-face hand movement (16 patients [53.3%]).

The characteristic finding of the presence of a subcapsular fluid pocket (Group 1) was noted in 15 eyes (50.0%) and the absence of a fluid pocket (Group 2) in 15 eyes (50.0%) with the white mature cataracts. The mean, median, and range of the fluid pocket height—the fluid height in the subcapsular space above the nucleus—were 0.31, 0.22, 0.09 to 0.73, respectively. In Group 1 (n = 15), complete CCC was achieved in 13 eyes (86.7%) (P = .001) and capsular complications occurred in 2 eyes (13.3%). One case was attributable to the radial extension of the capsule while performing capsulorhexis because of the inadvertent movement of the patient, and the second case had a posterior capsule rupture (PCR) attributable to the radial extension while performing a horizontal nucleus chop. The overall surgical success rate of complete CCC of 87% was achieved in Group 1. In Group 2 (n = 15), eyes with the absence of fluid on AS-OCT, 13 (86.7%) eyes had a complete CCC (P = .001). The number of capsular complications encountered during surgery in Group 2 were 2 (13.3%), each attributable to the occurrence of PCR while performing phacoemulsification. Although the 15 eyes in Group 2 showed no fluid on AS-OCT preoperatively, 1 eye showed fluid release when the capsulorhexis was being performed intraoperatively, with no inadvertent complications.

The mean nuclear density in Group 1 and Group 2 were 1.567 pixel intensity units (PIU) ± 0.43 (SD) and 1.199 ± 0.18 PIU, respectively. In a comparison of the mean values, the mean nuclear density in Group 1 was significantly higher than in Group 2 (P = .005) (Table 2). The correlation of nuclear density with age and axial length showed a weak relationship with insignificant P values of 0.46 and 0.997, respectively (Table 3).

Table 2
Table 2:
Correlation of the cataract nuclear density as measured on AS-OCT in the presence of subcapsular fluid or absence of subcapsular fluid, showing a significant correlation with a P value of .005 in the presence of fluid.
Table 3
Table 3:
Correlation between age and axial length with nuclear density.

Discussion

There are 2 types of senile white cataracts (pearly white cataract and Morgagnian cataract) that can be differentiated by slitlamp evaluation. The first category presents as a homogeneous white surface, whereas the second shows a different shade of white on the anterior surface.1–3 Pearly white cataracts are the early stage of senile white cataracts and they might have either no liquid cortex (liquid-free pearly white cataract) or a small amount of liquid (fluid-filled pearly white cataract), which can be noted on AS-OCT.2

A characteristic common to both fluid-free and fluid-filled pearly white cataracts is an enormous nucleus, which fills the entire capsular bag, and the accumulation of fluid in the anterior and posterior subcapsular spaces, increasing the curvatures of the capsules. This forward and backward arching is attributable to the presence of subcapsular fluid, thus exerting a strong tension on the capsules on the equator. When the anterior capsule of these intumescent cataracts is perforated for performing capsulorhexis, before we depressure the intralenticular compartment, we usually encounter the Argentinian flag sign.2,4,5

Successful intraoperative use of AS-OCT has been described for the assessment of clear corneal wound architecture and OCT-guided femtosecond laser–assisted cataract surgery, calculation of IOL power,6 and evaluation of the lens, anterior chamber, and angle structures.1,2 To our knowledge, to date, there are no published studies of using AS-OCT to assess the presence of fluid in white cataracts. At present, the methods for the management of white cataracts is with a plain puncture technique with the use of saline to extract the fluid, performing a 2-step capsulorhexis or needle puncture followed by fluid aspiration, of the use of femtosecond laser–assisted capsulorhexis.1–3

The incidence of complications as reported in literature include incomplete capsulorhexis associated with white cataract surgery (28.3%),3 or failed capsulorhexis (<4%), PCR (<1%), and conversion to extracapsular cataract extraction (<4%).1 The capsular runaway complications in our study in Group 1 were minimal (2 [13.3%]), with the detection of fluid on AS-OCT and simultaneous 30-gauge needle-assisted fluid drainage. These are comparable to capsular complications noted by Conrad-Hengerer et al.,1 wherein the use of femtosecond laser–assisted capsulorhexis revealed 8% of the chances for anterior capsule tears. In our study, the 1 eye in Group 2 in which no fluid was noted preoperatively on AS-OCT evaluation but was observed intraoperatively while performing CCC can be attributed to the limitation of AS-OCT to visualize to a depth of 2.9 mm in the mature cataracts because of their high nuclear density. Centurion et al.7 used the Pentacam (OCULUS Optikgeräte GmbH) for the tomographic evaluation of shape and thickness of mature white cataracts and concluded that the thickness of mature cataracts larger than 5.36 mm along with greater spherical shape of the lens are important risk factors in predicting the Argentinian flag sign7; however, we believe that the presence of intralenticular fluid, as highlighted in our study, has a greater role in predicting the possibility of capsular complications.

The importance of needle drainage for subcapsular fluid arises from the presence of fluid in the anterior and posterior subcapsular space; thus, removal of the fluid decreases the forward and backward pressure, thereby decreasing the risk for Argentinian flag sign.1,2 Localization of fluid using AS-OCT helps in planning the surgical procedure without worrying about capsular complications, and this allows even multifocal IOLs to be planned in mature cataract cases. Only in 1 case, while performing a 30-gauge needle-assisted fluid removal in Group 1, a radial tear occurred on the temporal side because of inadvertent movement by the patient, and IOL implantation was deferred; however, the other 14 cases had a stable IOL implantation intraoperatively, with a surgical success rate of 87%.

The major lacunas in our study are the small sample size and the incapacity of the AS-OCT to achieve better acquisition and localization of the posterior capsular details in the mature cataracts.

In conclusion, our study highlights a new method of using AS-OCT to identify the presence of fluid pockets in mature and intumescent cataracts, thus enabling better planning using needle drainage for fluid aspiration with a 30-gauge needle and henceforth reducing the capsule-related complications that are typically anticipated with mature and intumescent cataracts.

What Was Known

  • To date, the management of white cataracts was being conducted with a plain puncture technique and use of saline to extract the fluid. The other techniques are to perform a 2-step capsulorhexis or a femtosecond laser–assisted capsulorhexis.1

What This Paper Adds

  • The new technique allows the surgeon to better manage subcapsular fluid removal intraoperatively using a 30-gauge needle, thus minimizing the risk for developing radial capsule tears.
  • The anterior segment optical coherence tomography acts as a guide in determining the presence or absence of fluid for a stable and easy removal of subcapsular fluid.

References

1. Conrad-Hengerer I, Hengerer FH, Joachim SC, Schultz T, Dick HB. Femtosecond laser–assisted cataract surgery in intumescent white cataracts. J Cataract Refract Surg. 2014;40:44-50.
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. Assia EI, Apple DJ, Barden A, Tsai JC, Castaneda VE, Hoggatt JS. An experimental study comparing various anterior capsulectomy techniques. Arch Ophthalmol. 1991;109:642-647.
4. Chakrabarti A, Singh S, Krishnadas R. Phacoemulsification in eyes with white cataract. J Cataract Refract Surg. 2000;26:1041-1047.
5. Gimbel HV. Two-stage capsulorhexis for endocapsular phacoemulsification. J Cataract Refract Surg. 1990;16:246-249.
6. Basti S. Different faces of the white cataract: a phaco surgeon’s perspective. Aust N Z J Ophthalmol. 1999;27:53-56.
7. Centurion V, Leal EB, Lacava AC. O exame de imagem do segmento anterior no diagnóstico de certeza da catarata branca intumescente [Image test in the sure diagnosis of intumescent white cataract]. Rev Bras Oftalmol. 2008;67:236-242.

Disclosures

None of the authors has a financial or proprietary interest in any material or method mentioned.

© 2019 by Lippincott Williams & Wilkins, Inc.