Long-term clinical outcomes after femtosecond laser-assisted cataract surgery: results from a multicenter prospective comparative cohort study

Session Details

Session Title: Presented Poster Session 04: Femto Laser 1

Session Date/Time: Saturday 13/09/2014 | 15:00-17:00

Paper Time: 15:00

Venue: Pod 1 (Poster Village)

First Author: : B.Vote AUSTRALIA

Co Author(s): :    S. Ewe   R. Abell   P. Allen   N. Kerr   A. Howie   P. Davies

Abstract Details

Purpose:

To investigate the clinical efficacy of Catalys Precision Laser (Optimedica, Sunnyvale, CA) femtosecond laser-assisted cataract surgery (LCS) when compared to phacoemulsification cataract surgery (PCS). Despite emerging short-term benefits, it remains unclear whether LCS results in superior visual and refractive outcomes over conventional PCS in the long term. The aim of this study was to assess the long-term post-operative clinical outcomes in a comparative cohort of eyes undergoing LCS versus PCS at two surgical centres.

Setting:

Two ambulatory day surgery operating theatres

Methods:

A total of 1,310 patients were included in this prospective comparative cohort study (LCS vs. PCS) of two surgeons from two clinical centres. Patients with previous ocular surgery or trauma, active ocular disease or ocular comorbidities (e.g. keratoconus, macular disease, amblyopia, significant corneal astigmatism), poorly dilating pupils, or known zonular weakness were excluded from the study. Patients with no contraindications to LCS were offered Femtosecond laser pretreatment to their cataract surgery at an out-of-pocket cost. LCS contraindications included age < 22 years, extensive corneal scarring, corneal ring inlays, past glaucoma filtration surgery or incisional refractive surgery (e.g. radial keratotomy). Based on this clinico-socioeconomic cohort selection, patients undergoing LCS had anterior capsulotomy, lens fragmentation +/- automated corneal incisions performed by Catalys femtosecond laser pretreatment followed by cataract extraction and IOL insertion; whilst PCS was performed using manual incisions, capsulorhexis, and standard phacoemulsification and IOL insertion. Scheimpflug imaging with the Pentacam was used to objectively assess cataract grade using the Pentacam Nuclear Staging (PNS) All patients underwent extensive pre- and post-operative (6 months) assessments, including slit lamp examination, Goldmann tonometry, OCT, corneal topography, corneal pachymetry, specular microscopy, keratometry and subjective refraction plus BCVA assessment by a masked examiner.

Results:

A total of 1310 eyes were included, 698 eyes underwent LCS, whilst 612 eyes underwent PCS. There were no baseline differences between cohorts, specifically no difference in pre-operative objective cataract grade (PNS grade 2.89). However, significantly more LCS patients underwent toric IOL insertion than PCS patients. Intraoperatively, mean effective phacoemulsification time was reduced by 85% in the LCS group (P < 0.0001) when compared to the PCS group. Two-thirds of eyes in the LCS group had zero effective phacoemulsification time. Mean post-operative BCVA was slightly better in the LCS group (96.37% vs 93.55% achieving 6/12 or better p = 0.07), There was no statistical difference between groups for eyes achieving BCVA of 6/9 or better. Eyes achieving mean absolute error within 0.5 and 1.0 Diopters of target refraction was similar between the two groups (82% LCS vs 78% PCS +/-0.5D NS; 96.1% vs 93.1% +/-1D NS). There was a much higher rate of Posterior Capsule Opacification (PCO) occurrence in the LCS group (62% vs 41%, P < 0.0001), with 50% of each group undergoing YAG laser capsulotomy (30.9% vs 21.4%, p<0.01). Central macular thickness, by OCT was increased in both groups at six months, but did not differ significantly.

Conclusions:

We have previously published the first prospective comparative cohort study between femtosecond LCS and PCS. This recent study, an extension of our previous comparative cohorts, analyses the long-term clinical outcomes of over one thousand patients who have undergone cataract surgery at our two centres. The study showed only a slight improvement in mean absolute error (MAE) and BCVA after LCS, with a significant reduction in phacoemulsification energy. Whilst there were no baseline differences between cohorts, there was a significant operative difference with more patients in the LCS cohort receiving TORIC IOLs than in the PCS cohort. This alone might be enough to account for the small difference between groups. The results are also confounded by the higher post-operative incidence of PCO in the LCS cohort, although the threshold for YAG laser capsulotomy was similar in both groups at 50% of those identified with PCO. Femtosecond laser-assisted cataract surgery may result in slightly superior visual and refractive outcomes in some patients (~3% NS), but in our cohorts was also associated with a 50% increase in PCO development. Our previously published cost-effectiveness modelling identified femtosecond laser pretreatment did not meet accepted thresholds for cost-effective health interventions (ICER ~92,000AUD cost/QALY). This modeling worked on an assumption of 5% improvement in visual outcomes along with 50% reduction in key complications including PCO. This current large comparative cohort study suggests our cost-effectiveness modelling is even less favourable for LCS (i.e. LCS is even less cost-effective than predicted). At current cost to patients and utilizing real comparative cohort data (rather than hypothetical) femtosecond laser pretreatment does not represent a cost-effective addition to conventional phacoemulsification (~$3500 AUD cost/QALY for PCS) Well-matched randomized control trials with large numbers and long follow up are needed to better ascertain the visual benefits (if any) of femtosecond laser pretreatment.

Financial Interest:

NONE