Purpose
To assess the role of femtosecond laser technology in the management of severely subluxated cataracts.
Design
Retrospective, interventional case series.
Methods
All eyes with subluxated cataract seen between July 2012 and June 2015 were assessed for suitability for femtosecond laser–assisted cataract surgery, with the use of capsular tension devices. Participants with subluxated cataracts of at least 6 clock hours of zonular weakness were included in the study. Data collected included patient demographics, preoperative and postoperative best-corrected visual acuity (BCVA), nuclear density, extent of zonular weakness, completeness of capsulotomy, and complications. Poor visual outcome was defined as BCVA of worse than 20/40. Main outcome measure was the retention of the capsular bag.
Results
Of the 72 eyes with subluxated cataracts undergoing surgery during the study period, 47 eyes of 47 patients were eligible for analysis. Mean age of the patients was 60.7 years (standard deviation [SD] 13.2 years). The majority were male (32, 68.1%) and Chinese (38, 80.8%). The mean duration of follow-up was 8 months (SD 5.6 months). The main identifiable cause of lens subluxation was trauma (11 eyes). Almost two thirds (30 eyes) had more than 9 clock hours of zonular weakness. Seventy percent of cataracts (33) were nuclear sclerosis grade 3 and above. The capsular bag was preserved in 43 eyes (91.5%). The intraocular lens was stable and centered at the last follow-up in all these 43 eyes. An anterior capsule tear occurred in 6 eyes, all of which had cataracts of nuclear sclerosis grade 3 and above, with posterior extension occurring in 3 eyes. Primary posterior capsule rupture occurred in 1 eye. At 1 month 37 eyes (80.4%) had a BCVA of 20/40 or better. There was significant improvement in BCVA at 1 month (mean of 0.92 logMAR units [SD 0.88] to 0.22 [SD 0.38] [ P < .001, paired samples t test]), which was maintained at 1 year.
Conclusions
Selected cases of severely subluxated cataracts may be managed using femtosecond laser technology to perform the capsulotomy and nuclear fragmentation, with successful preservation of the capsular bag in 90% of eligible cases, especially in eyes with soft cataracts.
A subluxated crystalline lens is arguably one of the most challenging cataracts for the anterior segment surgeon to deal with today. With advances in technology, these can be increasingly managed via phacoemulsification, with preservation of the capsular bag rather than by the conventional intracapsular cataract or pars plana techniques. Preservation of the capsular bag minimizes vitreous loss, allows placement of a posterior chamber intraocular lens (PCIOL), and reduces the risk of complications such as retinal detachment and glaucoma.
Among the many difficulties faced, the creation of an intact capsulorrhexis, which is a crucial component in such cases, is the most difficult step. Any discontinuity of the capsular rim is a contraindication to the placement of a capsular tension ring (CTR), which in turn compromises the placement of a PCIOL. Excessive lens mobility, lens tilt and/or displacement, and the presence of vitreous in the anterior chamber (AC) are factors that may hinder the creation of a complete capsulorrhexis. Furthermore, the process of tearing the anterior capsule may result in further zonular dehiscence. In contrast, the femtosecond laser has an advantage over manual capsulorrhexis of being able to create a complete circular capsulotomy in eyes with zonular dehiscence without compromising the existing zonules, as it does not require any counter-traction from the zonules. Moreover, the femtosecond laser is able to fragment and soften the nucleus, thereby reducing the amount of manipulation required, and hence minimizes stress on the already compromised zonules. In this paper, we review our series of severely subluxated cataracts managed using femtosecond laser–assisted cataract surgery (FLACS).
Methods
In this cohort study, we retrospectively reviewed the case records of all consecutive patients with subluxated crystalline lens with at least 6 clock hours of zonular weakness. They were managed via an anterior approach at the Singapore National Eye Centre from July 2012 to June 2015 by 1 surgeon (S.P.C.) using femtosecond laser technology. Only cases where the anterior capsule could still be adequately imaged by the optical coherence tomography (OCT) imaging system of the laser machine and cases without anterior segment pathology that would prevent penetration of the laser energy were selected for FLACS. FLACS was performed using the Victus femtosecond laser platform (Bausch + Lomb Technolas Perfect Vision GmbH, Munich, Germany) to create the capsulotomy and for nuclear fragmentation. This study was approved by the SingHealth Institutional Review Board and was conducted in accordance with the tenets of the Declaration of Helsinki.
Data were collected on patient demographics; presenting best-corrected visual acuity (BCVA); intraocular pressure (IOP); density of the nucleus, which was graded according to the Lens Opacity Classification System III (LOCS III) ; surgical technique; extent of zonule weakness; postoperative BCVA; and complications including posterior capsule rupture, cystoid macular edema, endophthalmitis, retinal detachment, and intraocular lens decentration. The nuclear fragmentation pattern and size and completeness of the capsulotomy were also documented. Poor visual outcome was defined as postoperative BCVA of worse than 20/40.
The extent of zonulysis was assessed by the surgeon based on the extent of displacement of the lens intraoperatively. A single-point fixation was chosen (either a CTR [Morcher GmBH, Stuttgart, Germany] with a capsular tension segment [CTS; Ahmed capsular tension segment; Morcher GmbH] or modified capsular tension ring [Cionni 1L; Morcher GmBH]) if there were 6 to <9 clock hours of zonulysis; and a 2-point fixation was chosen (Cionni 1L CTR plus CTS or Cionni 2L CTR [Morcher GmBH] or CTR plus 2 CTS) if there were 9–12 clock hours of zonulysis. A 10/0 double-armed polypropylene suture (Prolene; Ethicon, Somerville, New Jersey, USA) with STC-6 spatulated needles was used to fixate the eyelet of the capsular tension device (CTD) to the sclera.
Surgical Technique
The centration of the capsulotomy was based on the anatomic center of the nucleus, which was identified by the surgeon, with the patient supine, using the operating microscope attached to the Victus, and confirmed with the inbuilt dynamic OCT of the Victus femtosecond laser platform. The size of the capsulotomy was determined by the size of the pupil as well as the extent of decentration of the nucleus. The default size was 5 mm, but this was reduced so as to avoid damage to the lens equator as well as the iris in cases with severe decentration of the nucleus. The capsulotomy treatment band had to be manually adjusted to accommodate any lens tilt in the earlier cases. However, with subsequent improvement in the software the femtosecond laser was able to automatically detect and treat a tilted lens. The nuclear fragmentation pattern depended on the density of the nucleus, with a hybrid pattern of 2 concentric circles and 4 radial cuts (spider pattern fragmentation) being used for eyes with nuclear sclerosis (NS) of less than 4 and 8 radial cuts (16 segments, pizza pattern fragmentation) being used for denser cataracts of NS grades 4 or greater. The laser energy used for the capsulotomy was increased if there was vitreous in the anterior chamber, and/or if there was a dense fibrotic capsule. Similarly the laser energy for nuclear fragmentation was titrated according to the density of the nucleus, with 7.0 μJ being used for cataracts of NS 5 or less and 9.0 μJ for NS 6.
Following patient transfer to the operating room, a peribulbar block was given. A capsule dye (trypan blue; DORC International BV, Zuidland, The Netherlands) was used in eyes with a dense cataract to improve visualization of the capsular rim. A dispersive ophthalmic viscosurgical device (OVD) was injected to maintain the AC as well as to tamponade the anterior vitreous face and to displace any vitreous in the AC. The OVD cannula was then used to sweep the capsule from its cut edges. If the capsulotomy was found to be incomplete, a capsulorrhexis microforceps (Kawai; ASICO, Westmont, Illinois, USA) was used to complete the capsulotomy. Any vitreous presenting in the AC that could not be displaced readily with the dispersive OVD was removed by dissociated 23 G anterior vitrectomy with the help of a 50% dilution of triamcinolone acetonide 40 mg/mL (Kenalog; Bristol-Myers Squibb Co, Princeton, New Jersey, USA). Minimal or no hydrodissection was performed. Gas bubbles that did not present were not released owing to bag instability. The OVD was also injected into the immediate subcapsular space to create a cleavage plane at the site opposite the main incision and in the subincisional areas. The CTD was then inserted into this plane, prior to phacoemulsification of the nucleus, to support the equator of the bag. Polypropylene iris hooks (DORC International BV, Zuidland, The Netherlands) were used to stabilize the bag and the islet of the CTD. In the early cases, the hooks were used to support the bag directly. However, after an anterior capsule rip occurred during placement of the hooks onto the capsule, the capsular bag was stabilized via the islet of the CTD, with the direction of the hook being reversed so as to face anteriorly. The Nagahara phaco chopper (Inami & Co Ltd, Tokyo, Japan) was used during phacoemulsification to gently free the segmented nuclear pieces from the lens periphery as well as to draw them inward to the phacoemulsification needle tip, so as to avoid having to rotate the nucleus to access the fragments. Following cortical removal the IOL was implanted and the CTD fixated to the sclera using Hoffman pockets. The pupil was miosed, the OVD removed, and wounds were hydrated and checked for integrity, taking care at all stages to maintain a stable AC.
The video recordings of a previous cohort of severely subluxated cataracts managed using a manual technique of capsulorrhexis and conventional phacoemulsification were reviewed (manual group). The time taken for the capsulotomy and nuclear fragmentation was noted and compared with that of the FLACS group.
Outcome Measures and Statistical Analysis
The main outcome measure was retention of the capsular bag. Secondary outcome measures were BCVA at 1 month and 1 year, IOL stability, centration, and perioperative complications. Statistical analysis was performed using SPSS (Ver 13.0; SPSS Inc, Chicago, Illinois, USA).
Results
During the study period, there were 72 eyes with subluxated cataracts that underwent removal via an anterior approach by SPC. All were unilateral cases. Nineteen were successfully managed using manual capsulorrhexis and conventional phacoemulsification for the following reasons: in 8 eyes (42%) the nucleus was too decentered to be imaged by the OCT of the Victus femtosecond laser; 4 eyes (21%) had ACs that were too shallow for femtosecond treatment; 2 (11%) had significant cornea opacity that would hinder the penetration of the laser, and the remaining 5 eyes could not be managed using the femtosecond laser owing to presence of an intumescent cataract, large angle squint, advanced glaucoma, orbital fractures, and cost issues.
Hence 53 cases of subluxated cataracts were managed using FLACS. Of these, 6 cases had less than 6 clock hours of zonular weakness and were excluded from the study; 47 had more than 6 clock hours of zonular weakness and were analyzed. The mean age of the patients was 60.7 years (standard deviation [SD] 13.2 years). The majority of patients were male (32, 68.1%) and Chinese (38, 80.8%) and the mean duration of follow-up was 8 months (SD 5.6 months, range 1–24 months). The cause of lens subluxation included previous ocular trauma in 11 eyes, pseudoexfoliation in 2, and Marfan syndrome in 1 eye. The remaining 33 eyes (70.2%) had no identifiable cause for the lens subluxation. Fourteen of the 47 cases (29.7%) presented with secondary angle closure.
There was almost equal distribution of the density of the cataracts (14 NS grade 2 or less; 16 NS grade 3–4; 17 NS grade 5–6). Thirty eyes (63.8%) had more than 9 clock hours of zonular weakness, of which the majority received 2 CTS with a CTR (13 eyes, 43.3%) and only 7 had a Cionni 2L inserted (23.3%). For the 17 eyes (36.2%) with 6–9 clock hours of zonular weakness, the Cionni 1L was the more commonly used CTD (11 eyes, 35.3%) ( Table 1 ). Thirty eyes (63.8%) had anterior subluxation, 7 (14.9%) had posterior subluxation, and 10 (21.3%) had lateral subluxation. Six eyes (12.7%) required anterior vitrectomy at the outset of surgery, and in 11 eyes (23.4%) anterior vitrectomy was performed during the surgery to clear the vitreous.
| Extent of Zonule Weakness | Capsular Tension Devices | Number (%) |
|---|---|---|
| 6–9 clock hours (17 eyes) | 1 capsular tension segment with capsular tension ring | 6 (35.3) |
| Cionni 1L a | 11 (64.7) | |
| More than 9 clock hours (30 eyes) | None (loss of capsular bag) | 2 (6.7) |
| Cionni 2L a | 7 (23.3) | |
| Cionni 1L a with 1 capsular tension segment | 8 (26.7) | |
| 2 capsular tension segments with capsular tension ring | 13 (43.3) |
a Modified capsular tension rings; Morcher GmBH, Stuttgart, Germany.
The capsulotomy size in 41 eyes (87.2%) was 5 mm. The capsulotomy size in the remaining 6 eyes (12.8%) ranged from 3 to 4.9 mm. Three capsulotomies were decentered, but the IOL implant could be centered and was stable within the capsular bag. The capsulotomies were complete in all 6 eyes that had vitreous in the AC at presentation. Forty-one capsulotomies (87.2%) were free-floating and 6 (13.0%) were incomplete, resulting in tags and bridges. The energy used for capsulotomy ranged from 7.0 to 7.8 μJ (mean = 7.1 μJ).
Intraoperative Complications
Anterior Capsule Rips
Anterior capsule rips occurred in 6 eyes (12.7%), of which 3 were associated with posterior extension ( Table 2 ). As a result of the anterior capsule rips, a CTD could not be implanted or had to be removed in 4 patients: 1 eye had 6–9 clock hours of zonular weakness and 3 had more than 9 clock hours of zonular weakness.
| Case | Age (y) | Initial VA a | Nuclear Density b | Capsular Tags/Bridges | Extent of Zonule Weakness/CTD | Stage of Anterior Capsule Rip | Posterior Extension | Intraocular Lens Fixation/Postoperative Complications/VA at 1 Year/Remarks |
|---|---|---|---|---|---|---|---|---|
| 1 | 60 | Light perception | 6 | Yes | More than 9 clock hours/None | Insertion of iris hooks (small pupil) | Yes | Iris fixation/None/Hand movement/Pigmentary retinopathy and optic atrophy |
| 2 | 47 | Hand movement | 5 | No | More than 9 clock hours/Cionni 1L c | Insertion of Cionni 1L c | Yes | Intrascleral fixation/None/20/400/Amblyopic eye |
| 3 | 68 | 20/200 | 3 | No | More than 9 clock hours/Cionni 2L c | Insertion of Cionni 2L c | No | In the bag/None/20/30/– |
| 4 | 71 | Hand movement | 6 | No | 6–9 clock hours/None | Phacoemulsification | No | Iris fixation/None/20/70/Previous endogenous endophthalmitis |
| 5 | 65 | Count fingers | 5 | No | More than 9 clock hours/Cionni 1L c and capsule tension segment | Phacoemulsification | Yes | Iris fixation/Cystoid macular edema with epiretinal membrane/20/50/– |
| 6 | 68 | 20/300 | 3 | No | More than 9 clock hours/Cionni 2L c | Phacoemulsification (anteriorly subluxated cataract) | No | In the bag/None/20/25/– |
a Best-corrected visual acuity.
b Lens Opacity Classification System III.
c Modified capsular tension rings; Morcher GmBH, Stuttgart, Germany.
In the first case, the eye had a 4-mm pupil and the rip occurred during insertion of iris hooks to expand the pupil. The capsule had not been stained prior to insertion of the hooks and was not well visualized owing to the bubbles created by the femtosecond laser.
In 2 cases the anterior capsular rip occurred during insertion of the CTD ( Figure ). One eye had an NS 5 cataract and the rip extended posteriorly, resulting in the need for a fibrin glue–assisted intrascleral fixation of an IOL.
Anterior capsule rips occurred during phacoemulsification in 3 cases. Although there was no posterior extension in 1 eye, it was converted to manual cataract removal in view of the NS 6 cataract. Both cases received iris-fixated IOLs. The eye in the last case had an anteriorly displaced capsular bag and the anterior capsule was inadvertently ripped when a Sinskey hook was inserted through the side port during phacoemulsification. The posterior capsule remained intact and the IOL was safely inserted into the bag.
Subgroup analysis of possible risk factors for anterior capsular rip ( Table 3 ) showed that all had occurred in eyes with nucleus density of 3 or more, although this did not reach statistical significance. Age, capsulotomy size, number of fixation points, and amount of laser energy for the capsulotomy used were not significant risk factors.
| No Rip (N = 41) | Rip (N = 6) | P | |
|---|---|---|---|
| Age at surgery (y) | |||
| Median | 61.0 | 66.5 | .39 a |
| Range | 25–88 | 47–71 | |
| More than 9 clock hours of zonule weakness, n (%) | 25 (61.0) | 5 (83.3) | .40 b |
| Nuclear density grade 3 or higher (LOCS III), n (%) | 27 (65.9) | 6 (100) | .16 b |
| Capsulorrhexis size (mm) | |||
| Median | 5.0 | 5.0 | .59 a |
| Range | 3.0–5.0 | 5.0–5.0 | |
| Energy (μJ) | |||
| Median | 7.0 | 7.0 | .64 a |
| Range | 7–7.8 | 7.0–7.0 | |
| New software | 10 (24.4) | 2 (33.3) | .64 b |
a Independent samples Mann-Whitney U test.
Other Intraoperative Complications
Primary posterior capsular rupture occurred in 1 eye during phacoemulsification of the last fragment. However, because the posterior capsule rupture was small, with no resultant vitreous loss, the CTD could still be retained and the IOL was placed in the bag.
One of the incomplete capsulotomies was associated with an off-the-visual-axis inferior partial endothelial keratotomy, which occurred during the femtosecond laser creation of the capsulotomy. The lens was severely tilted and the anterior chamber was extremely shallow. The bandwidth of capsulotomy treatment was manually increased and, unbeknownst to the surgeon, this inadvertently encroached on the cornea.
Postoperative Complications
One of the eyes with anterior capsule rip and posterior extension developed cystoid macular edema at 1 month that was associated with an epiretinal membrane. The BCVA at 1 year was 20/50. None of the other eyes that had an anterior capsule rip or primary posterior capsule rupture had any postoperative complications. Cystoid macular edema at postoperative month 1 was also noted in another eye that did not have any intraoperative complications. The BCVA at last follow-up at 3 months was 20/40.
Retinal detachment occurred in 2 patients postoperatively. One occurred at 2 months after surgery and this patient achieved a BCVA of 20/25 at 6 months following retinal detachment surgery. In the second patient the retinal detachment was noted at the first postoperative week. However, he declined further intervention and was lost to follow-up after 1 month. His visual acuity was count fingers at presentation and 20/400 at his last follow-up.
There were no cases of postoperative endophthalmitis and there were also no cases that had vitreous in the anterior chamber. All 43 eyes that had received a CTD retained a stable and centered intraocular lens at the last follow-up. There were no IOL dislocations.
Visual Outcome
There was a significant improvement in BCVA by postoperative 1 month, from a median of preoperative 0.6 logMAR units (range 0.1–3.0) to 0.1 (range 0.0–3.0) ( P < .001, Wilcoxon signed rank test). In the 19 eyes that had at least 1 year follow-up, there was no difference in the BCVA between postoperative month 1 and 1 year (median [range] = 0.1 [0.0–3.0] logMAR units and 0.20 [0.0–3.0], respectively, P = .42, Wilcoxon signed rank test). Five eyes had a poor visual outcome of BCVA worse than 20/40; 4 of these eyes had an anterior capsule rip, but the poor vision was not related to the rip itself but was a consequence of preexisting pathology ( Table 2 ). The remaining eye with a poor visual outcome presented with glaucomatous optic neuropathy secondary to angle-closure glaucoma. There were no perioperative complications and the IOP was less than 22 mm Hg postoperatively.
Comparison of Manual and Femtosecond Laser–Assisted Cataract Surgery Groups
Comparison of the manual and FLACS groups showed that the time required to perform the capsulorrhexis was greatly reduced by the use of a femtosecond laser, but the anterior capsule rip rate was significantly lower in the manual group ( Table 4 ).
