Efficacy of combined phacoemulsification cataract surgery plus excimer laser trabeculotomy remains stable over 4 years

Session Details

Session Title: Glaucoma II

Session Date/Time: Monday 15/09/2014 | 08:00-10:30

Paper Time: 08:31

Venue: Boulevard F (Level 1)

First Author: : M.Toeteberg-Harms SWITZERLAND

Co Author(s): :    C. Schweier   J. Funk           

Abstract Details

Purpose:

Micro-invasive or minimally invasive glaucoma surgeries (MIGS) have gained significant interest in recent years. They are often combined with phacoemulsification cataract surgery. Accordingly, they have become part of a cataract surgeon’s armamentarium in treating those patients with cataract and a concurrent diagnosis of glaucoma or ocular hypertension. Excimer laser trabeculotomy (ELT) ab interno is one MIGS procedure. In ELT, an excimer laser is used to ablate the trabecular meshwork and inner wall of Schlemm’s canal. These laser channels enhance aqueous humor outflow and lower IOP to a greater degree than that achieved by cataract extraction alone. ELT has been investigated with a follow-up of 2 years or less and has shown promising results. The aim of this study is to investigate whether the IOP-lowering efficacy after combined cataract surgery plus ELT (phaco-ELT) has remained stable in the long term (i.e. up to 4 years).

Setting:

The study has been IRB approved. At a single-center (UniversityHospital Zurich), prospective patients have been recruited. Surgery has been performed by a single-surgeon (J.F.). 66 eyes (37 right, and 29 left eyes) of 58 patients (mean age at surgery was 76.7±9.6y; 44 females and 22 females) have been followed up after phaco-ELT at 1 year (n = 66 eyes; 12.2±0.6 month) and 4 years (n = 39 eyes; 49.0±1.7 month).

Methods:

Patients have been evaluated preoperatively and at 1y and 4y after phaco-ELT. Primary outcome measures are intraocular pressure (IOP), number of anti-glaucoma medications (AGM) used, and Kaplan-Meier-survival. Definition of success is IOP of equal or less than 18 mmHg plus a reduction of 30% from baseline, AGM of equal or less compared to baseline, and no additional incisional or laser surgery (i.e. laser trabeculoplasty or cyclophotocoagulation with the intention to further lower IOP during the follow-up period.) Secondary outcome measures are best-corrected visual acuity (BCVA) and whether complications had developed. Inclusion criteria are a diagnosis of ocular hypertension or manifest glaucoma coupled with an open iridocorneal angle (grade 3 or 4 on the Shaffer scale). Patients with advanced glaucoma (i.e., fixation-threatening visual-field defects), or with an IOP ≥35 mmHg have been excluded. Patients with a history of optic neuropathies other than glaucoma have also been excluded. Data was normally distributed, which has been evaluated by the Kolmogorov-Smirnov and Shapiro-Wilk test.

Results:

Preop BCVA was 0.5±0.4 (logMAR), IOP 19.7±5.2mmHg and the patients used 2.3±1.1 AGM on average. At 1 year post surgery BCVA was 0.2±0.2 (ΔBCVA_preop_1y = +0.3±0.3; P<0.001), IOP 15.3±4.2mmHg (ΔIOP_preop_1y = -4.4±5.8mmHg; P = 0.001; -22.3%), and 1.3±1.3 AGM (ΔAGD_preop_1y = 1.0±1.4; P < 0.001; -43.5%) were used, whereas at 4 years BCVA was 0.2±0.5 (ΔBCVA_preop_4y = +0.2±0.6; P=0.017; ΔBCVA_1y_4y = -0.1±0.5; P=0.176), IOP 15.2±4.1mmHg (ΔIOP_preop_4y = 4.4±6.3mmHg; P<0.001; -22.3%; ΔIOP_1y_4y = 0.7±5.6mmHg; P=0.411), and 1.4±1.3 AGM (ΔAGM_preop_4y = -0.8±1.6; P = 0.003; -34.8%; ΔAGM_1y_4y = -0.1±1.6; P=0.614) were used, respectively. Three patients required subsequent IOP-lowering surgery within the first year and 5 more patients within second to fourth year of follow-up. These cases have been considered treatment failures. Kaplan-Meier survival reveals a success rate of 95.7% at 12 months and 79.8% at 48 months with the given definition of success. In a subgroup analyze of eyes with a preoperative IOP of >21mmHg (mean 25.2±2.8mmHg) the IOP decreased by 8.8±5.2mmHg (ΔIOP_preop_1y; P<0.001; -34.9%) at 1 year and by 9.4±5.5mmHg (ΔIOP_preop_4y; P<0.001; -37.3%) at 4 years compared to baseline. There was no significant change in IOP over time in this subgroup (ΔIOP_1y_4y = 1.4±6.3mmHg; P=0.412).

Conclusions:

ELT can be combined with cataract surgery to lower IOP and reduce medications. The surgery time is prolonged by only a few minutes for the ELT procedure. ELT reduced IOP and lowered AGM significantly. The IOP lowering efficacy of ELT exceeds that of phaco alone as has been previously shown. This effect was particularly pronounced in the subgroup with a preoperative IOP of >21mmHg. The IOP after phaco-ELT remains stable over the entire follow-up of 4 years. Such stability is a major advantage of combined phaco-ELT when compared to phaco alone or to laser trabeculoplasty. The learning curve for ELT is steeper compared to other MIGS procedures. There is no foreign body implantation with ELT, which is a major drawback of some MIGS procedures and has the potential for late extrusion into the eye. For early and mild glaucoma cases with at least a moderate cataract, the combined surgery of excimer laser trabeculotomy and phacoemulsification (phaco-ELT) is an additional procedure for cataract surgeons and glaucoma specialists in their surgical armamentarium, which effectively lowers IOP and reduces medication simultaneously. Phaco-ELT appears as an option to completely avoid, or at least delay trabeculectomy for some years.

Financial Interest:

NONE