Purpose
To describe the use of the neodymium–yttrium-aluminum-garnet (Nd:YAG) laser to lyse residual cortex after phacoemulsification cataract surgery and report the complications and outcomes of treatment.
Design
Interventional, retrospective case series.
Methods
Consecutive patients who underwent Nd:YAG laser treatment for residual cortex at the Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan were identified by review of laser logs from 2005 to 2011. The medical records were reviewed, and the course and complications of treatment were recorded. The main outcome measures were improvement in subjective vision and corrected distance visual acuity.
Results
Eighteen eyes of 18 patients, mean age 66 ± 11 years, were included. Eight eyes (44%) had intraoperative posterior capsule rupture. Before treatment with the Nd:YAG laser, all patients had subjective visual complaints, with 6 patients reporting counting fingers or worse visual acuity. Eleven patients (61%) were successfully treated with 1 session of cortical lysis, while 5 patients underwent 2 and 2 patients underwent 3 or more treatments. Five patients (28%) had elevated intraocular pressure (IOP) within 1 day of treatment, and 1 patient developed cystoid macular edema. All patients had resolution of subjective visual symptoms, and at final follow-up corrected distance acuity was 20/25 or better in 13 patients (72%).
Conclusions
The Nd:YAG laser can be used to lyse residual cortex after uncomplicated cataract surgery or cases with intraoperative posterior capsular rupture, and results in an improvement in subjective and corrected distance visual acuity. Elevated IOP is a common complication.
The neodymium–yttrium-aluminum-garnet (Nd:YAG) laser is employed most commonly to perform capsulotomy for treatment of visually significant posterior capsular opacity. Its use has also been described for a wide variety of anterior segment conditions, including creation of an iridotomy, anterior vitreolysis, anterior capsule relaxing incisions, and anterior capsulotomy in white intumescent cataracts, among others.
Lens cortex can be retained after both complicated and uncomplicated phacoemulsification cataract surgery. Authors have suggested that hydrated opaque cortical material can be liquefied with the Nd:YAG laser, but to our knowledge no authors have reported a case series on the use of the Nd:YAG laser to lyse residual cortex after cataract surgery. The objectives of this study were to describe the use of the Nd:YAG laser for laser lysis of residual cortex after cataract surgery, and to report clinical outcomes and complications.
Methods
A retrospective review was performed of the medical records of patients who had undergone treatment with the Nd:YAG laser for lysis of residual cortex after cataract surgery. Consecutive patients were identified by review of the Nd:YAG laser log from September 1, 2005 through October 31, 2011, seeking procedures listed as cortical lysis. Best-corrected distance visual acuity (CDVA) at each visit, course and complications after phacoemulsification cataract surgery, Nd:YAG treatment parameters, and postoperative course and complications after cortex lysis (including intraocular pressure [IOP], presence of macular edema by clinical examination, retinal detachment, intraocular lens damage, or intraocular lens movement) were recorded.
In all patients, 1 drop of apraclonidine 1% was administered 10 minutes before treatment. Topical proparacaine 0.5% was used to anesthetize the eye and an Abraham capsulotomy lens coupled with hydroxypropyl methylcellulose 2.5% was placed. The YC-1600 Nd:YAG laser (NIDEK Inc, Fremont, California, USA) was fired directly at the retained cortex, titrating the energy to the lowest amount necessary to induce liquefaction. The mean energy used during Nd:YAG lysis was determined by taking the mean of the highest and lowest value recorded in a given treatment session. The total energy was estimated by multiplying the mean calculated energy by the total number of pulses in a treatment session. Statistical analysis was done using Excel 2010 (Microsoft, Redmond, Washington, USA). Continuous variables were compared with the Student t test and categorical variables were compared with a Fisher exact test, with a P value <.05 considered significant.
Results
Eighteen eyes of 18 patients were included, with 6 men and 12 women. Mean age was 66 ± 11 years. Preoperative, intraoperative, and postoperative day 1 data after phacoemulsification cataract surgery are shown in Table 1 . Ten eyes (56%) had a routine intraoperative course while 8 eyes (44%) had an intraoperative posterior capsular rupture, with 3 requiring a limited anterior vitrectomy. One patient underwent subsequent pars plana vitrectomy for retained nuclear fragments. A posterior chamber intraocular lens was placed in the capsular bag in 9 eyes and in the ciliary sulcus in 9 eyes. On the first postoperative day after cataract surgery, residual cortex was visualized in 9 of 16 eyes (56%; 2 eyes unknown) including in the central visual axis in 2 eyes.
| Patient | Cataract Preoperative | Intraoperative | Postoperative Day 1 | |||
|---|---|---|---|---|---|---|
| Ocular Comorbidities | CDVA | Complications | Lens Placement | CDVA | Cortex Seen? | |
| 1 | Sjogren, KCN, epiretinal membrane | 20/100 | PC tear with AVx | Sulcus | 20/50 | No |
| 2 | None | 20/40 | None | Capsular bag | 20/25 | Yes |
| 3 | Incontinenta pigmenti | 20/50 | None | Capsular bag | 20/25 −2 | Yes |
| 4 | Glaucoma suspect | 20/50 −1 | PC tear | Sulcus | 20/100 −1 | No |
| 5 | None | 20/30 +2 | None | Capsular bag | 20/15 −3 | No |
| 6 | ABMD, ocular hypertension | 20/25 +2 | None | Capsular bag | 20/30 | Yes |
| 7 | None | 20/60 | None | Capsular bag | 20/30 +1 | No |
| 8 | s/p PPV | Unknown | PC tear | Sulcus | Unknown | Unknown |
| 9 | None | 20/50 −2 | PC tear | Sulcus | 20/40 +2 | Yes |
| 10 | s/p PPV; fungal endophthalmitis, Fuchs | 20/400 | Simultaneous DSAEK; rebubble ×2 | Capsular bag | HM @ 2 ft | Yes |
| 11 | Pseudoexfoliation syndrome | 20/50 | PC tear with AVx | Sulcus | 20/200 | No |
| 12 | Early dry AMD | 20/30 +2 | Floppy iris, anterior capsular tear | Sulcus | CF @ 2 ft | Yes |
| 13 | None | 20/125 | None | Capsular bag | 20/20 −1 | No |
| 14 | None | 20/25 | PC tear with AVx | Sulcus | 20/50 | Yes |
| 15 | Pterygium | 20/40 | None | Capsular bag | 20/20 −1 | Yes |
| 16 | None | 20/100 | None | Capsular bag | 20/15 −2 | Yes |
| 17 | s/p PPV; optic neuritis | 20/80 −1 | PC tear | Sulcus | 20/200 | No |
| 18 | PDR s/p PRP; h/o CSME s/p focal | Unknown | PC tear with retained nuclear fragments | Sulcus | Unknown | Unknown |
Table 2 contains CDVA prior to Nd:YAG laser lysis of retained cortical material, complications following laser lysis of cortex, and CDVA at follow-up. Prior to Nd:YAG laser lysis, all patients had subjective visual complaints, judged to be attributable to cortical material in the pupillary axis. Cortex was present centrally, and was posterior to the intraocular lens in 13 of 18 patients (72%). CDVA was 20/50 or better in 7 eyes, 20/60 to 20/200 in 5 eyes, and counting fingers or worse in 6 eyes.
| Patient | Location of Cortex | CDVA Prior to Lysis | Complications | CDVA After Laser Lysis | Time to CDVA After Lysis (days) |
|---|---|---|---|---|---|
| 1 | Central, posterior to IOL | 20/70 | None | 20/40 | 129 |
| 2 | Central and temporal, posterior to IOL | CF | IOP 66 mm Hg | 20/20 | 12 |
| 3 | Central, posterior to IOL | 1/200 | None | 20/20 | 77 |
| 4 | Temporal, posterior to IOL | 20/25 +2 | None | 20/20 | 47 |
| 5 | Central, posterior to IOL | 20/70 −1 | None | 20/20 +2 | 6 |
| 6 | Central, posterior to IOL | HM | None | 20/20 | 31 |
| 7 | Central, posterior to IOL | CF | None | 20/30 | 152 |
| 8 | Nasal and paracentral, posterior to IOL | 20/20 −3 | None | 20/20 | 40 |
| 9 | Central, posterior to IOL | 20/60 −1 | None | 20/20 | 19 |
| 10 | Central, posterior to IOL | 20/1000 | None | 20/500 | 28 |
| 11 | Central, posterior to IOL | CF | IOP 65 mm Hg | 20/25 +3 | 3 |
| 12 | Superior and paracentral, posterior to IOL | 20/50 | None | 20/25 +2 | 46 |
| 13 | Central, posterior to IOL | 20/25 −2 | None | 20/20 | 14 |
| 14 | Inferotemporal, posterior to IOL | 20/30 | IOP 67 mm Hg | 20/15 | 28 |
| 15 | Temporal, anterior to IOL; central, posterior to IOL | 20/80 | None | 20/20 −2 | 7 |
| 16 | Temporal, anterior to IOL | 20/25 +1 | IOP 54 mm Hg | 20/20 | 2 |
| 17 | Temporal and central, posterior to IOL | 20/200 | Cystoid macular edema | 20/125 | 40 |
| 18 | Central, posterior to IOL | 20/30 −1 | IOP 48 mm Hg | 20/30 +1 | 30 |
Eleven of 18 patients (61%) were treated with 1 session, 5 patients underwent 2 sessions, 1 patient underwent 3 sessions, and 1 patient required 4 sessions, resulting in a total of 28 treatment sessions of Nd:YAG laser lysis across all patients. The first Nd:YAG treatment was performed a mean of 338 ± 1204 days after cataract surgery, with a range from 6 days to 15 years. Excluding 1 outlier who underwent treatment 15 years after cataract surgery (possibly subsequent to minor ocular trauma dislodging retained cortical material), Nd:YAG lysis was first performed a mean of 54 ± 44 days after cataract surgery. The median time between cataract surgery and first lysis of cortex was 38 days. Across all Nd:YAG treatment sessions (n = 28), mean pulse energy was 1.7 ± 0.5 milijoule (mJ), with mean of 88 ± 37 pulses, and mean total energy of 159 ± 114 mJ. Prednisolone acetate 1% drops were used after 15 of 28 treatments (54%), with a range of administration from every 2 hours to once daily. Fourteen of 18 eyes underwent at least partial posterior capsular opening during a session of cortical lysis. Two patients underwent subsequent Nd:YAG capsulotomy in a separate session without complication.
Although no patient had an elevated IOP requiring treatment prior to laser lysis, 5 of 13 patients (28%) had a significant rise in IOP following a treatment session. IOP was routinely checked in all patients 1 hour after completion of Nd:YAG cortical lysis, with 1 patient having an elevation (48 mm Hg) requiring treatment. Four other patients had symptomatically elevated IOP within 1 day of treatment. These 4 patients, evaluated on an emergent basis, had IOP at presentation from 54 to 67 mm Hg. Management consisted of maximally tolerated ocular hypotensive drops including a beta-adrenergic antagonist, an alpha-2 adrenergic agonist, and a carbonic anhydrase inhibitor, as well as an oral carbonic anhydrase inhibitor. One patient required oral glycerin. Intraocular pressure was lowered to an acceptable level in 4 patients, who were discharged. One patient’s IOP was refractory to medical treatment and the patient underwent emergent anterior chamber paracentesis at the slit lamp. Intraocular pressure was immediately lowered to 8 mm Hg. All patients with a rise in intraocular pressure were examined the following day and found to have an acceptable IOP. By the next clinic visit, all ocular hypotensive medicines were discontinued. Two patients who had an IOP increase during their first session of Nd:YAG cortical lysis underwent a second session without a rise in IOP.
All patients had resolution of subjective visual symptoms and improvement in CDVA after Nd:YAG lysis of retained cortical material ( Table 2 , mean follow-up 40 ± 42 days after last session of laser lysis, range 2–152 days). Mean CDVA improved significantly (logarithm of minimal angle of resolution [logMAR] 0.90 ± 0.84 vs 0.15 ± 0.37, P = .001). Five patients had limited postoperative visual potential, and in all other patients (n = 13, 72%) CDVA was 20/25 or better. Patients maintained follow-up for 723 ± 604 days (range 14 days to 5.4 years). One patient, with a history of optic neuritis and pars plana vitrectomy for an epiretinal membrane and macular edema, developed chronic cystoid macular edema (CME). At final follow-up nearly 3 years after laser cortical lysis, the macular edema had resolved but CDVA was limited to 20/125. In a patient with a prior history of fungal endophthalmitis who underwent simultaneous phacoemulsification cataract surgery and endothelial keratoplasty, CDVA at final follow-up was 20/500, limited by a dense recurrent epiretinal membrane. One patient had CDVA of 20/40 secondary to keratoconus, another had CDVA of 20/30 secondary to high myopia with astigmatism, and another with a history of retained nuclear fragments had CDVA of 20/30. No patients experienced retinal detachment, intraocular lens damage, or intraocular lens movement, or required intraocular surgery for cortex removal, after Nd:YAG cortical lysis.
Table 3 compares eyes that experienced an IOP rise after Nd:YAG cortical lysis to those that did not. Patients who experienced an elevated IOP were significantly younger (57.0 ± 17.2 vs 69.2 ± 6.6 years, P = .04), but did not have a different rate of intraoperative posterior capsular rupture, IOL placement in the sulcus, or location of cortex. There was no statistically significant difference in the total energy used (226 ± 233 mJ vs 145 ± 70 mJ respectively, P = .15), the use of topical corticosteroids, or the creation of a posterior capsular opening between those treatment sessions that led to an IOP increase and those that did not.
