Abstract
Purpose
To assess the short and long-term changes in Visual Field (VF) Mean Deviation (MD), Visual Field Index (VFI), and intraocular pressure (IOP) after femtosecond laser-assisted cataract surgery (FLACS) in glaucomatous eyes.
Materials and methods
Interventional, prospective case series. Patients with glaucoma, who required cataract surgery were included. All patients underwent a complete ophthalmologic assessment and Visual Fields. FLACS was performed in all patients by a single experienced surgeon. IOP was measured during surgery immediately before and after pretreatment suction docking. Changes from baseline in VF MD and VFI, IOP, visual acuity (VA), and number of glaucoma medications were evaluated up to one-year follow-up.
Results
Fourteen eyes of 11 patients were included. Eighty-five percent were female, with a mean age of 74.2 ± 7.9 years. Nine (64.3%) and 5 (35.7%) were diagnosed with primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG), respectively. We found a slight IOP reduction after the docking phase during FLACS in both glaucoma subtype groups. No significant changes in visual field mean deviation (MD) and visual field index (VFI) were found from baseline to 12 months after surgery in both groups. A significant reduction in IOP values was found in all cases from baseline up to one year follow up. No significant changes were observed in BCVA and number of topical glaucoma medications after one year in both groups.
Conclusion
In our patients, there was an IOP reduction immediately after suction docking FLACS pretreatment. Mean IOP at final follow-up showed a reduction from baseline. There was no change in VF MD and VFI from baseline to final one-year follow-up. FLACS appears to be well tolerated in early and moderate glaucoma and appears to be a safe tool for glaucoma patients undergoing cataract surgery. Similar results to traditional surgery can be obtained with the advantages of femtosecond laser precision.
1
Introduction
Glaucoma is the leading cause of irreversible blindness worldwide. A high percentage of glaucoma patients have preexisting cataracts; also, glaucoma medications, lasers and surgical procedures are known to be cataractogenic, so a large number of these patients will require cataract extraction, glaucoma surgery, or a combined procedure over time.
The first Femtosecond Laser-Assisted Cataract Surgery (FLACS) was performed in 2008 and since its introduction its use has become widespread as a safe tool with benefits such as decreasing loss of endothelial cells, a well-centered and predictable capsulorrhexis, better intraocular lens (IOL) position, and less phacoemulsification energy and time requirements, among others. , ,
The use of FLACS in glaucoma is an encouraging prospect, but very few studies on the safety of this technology on glaucoma patients are available. Glaucoma patients can have several characteristics that make cataract surgery more challenging: ocular surface disease, presence of filtering blebs, narrower anterior chambers, fragile zonules, small or poorly dilating pupils, and unpredictable behavior of the anterior capsule, among others. Another aspect of these patients is that many of them will require glaucoma surgery or have had it, which adds to the complexity of cataract surgery, either alone or in combination.
During FLACS, the eye is stabilized by a suction docking system. The application of vacuum for a docking system was studied for laser in situ keratomileusis (LASIK) and it has been suggested, that it transiently increases IOP to more than 90 mmHg in non-glaucomatous eyes. , An ex vivo study suggested that femtosecond liquid docking systems create a minimal IOP rise, which was also reported in other studies of FLACS in eyes with no history of glaucoma or ocular hypertension, where only a transient mild IOP increase was shown. , Recent FLACS studies comparing healthy and glaucomatous eyes show that both glaucomatous and non-glaucomatous eyes presented an initial IOP spike on the first day after surgery, followed by a sustained IOP reduction, that was greater and persisted longer in eyes with glaucoma. ,
The superiority of FLACS compared to manual phacoemulsification cannot be determined with the evidence available today. Considering the characteristics of glaucoma patients, and the added risk of IOP rising during the docking procedure in these eyes with an additional vulnerability to IOP changes, we find it is important to assess the short and long-term outcomes of FLACS in patients with glaucoma.
In the present study, we report the short and long-term changes of intraocular pressure (IOP) after FLACS in glaucomatous eyes and their postoperative evolution regarding visual field (VF) mean deviation (MD) and visual field index (VFI), IOP, Best-Corrected Visual Acuity (BCVA), and number of glaucoma medications, with a one-year follow-up.
2
Patients and methods
An interventional prospective case series study was conducted in the Glaucoma Department of Asociación Para Evitar la Ceguera en México (APEC), a tertiary care ophthalmology center. The study was approved by the Institutional Review Board and the Ethics Committee of the hospital and followed the guidelines of the Helsinki Declaration.
Patients with a glaucoma diagnosis who required cataract surgery were consecutively recruited. Inclusion criteria included diagnosis of primary or secondary open or angle-closure glaucoma and vision impairing cataract (BCVA < 20/40). Patients with history of previous ophthalmological surgery of any kind, corneal or conjunctival alterations (severe ocular surface disease, allergic conjunctivitis, chronic scarring conjunctivitis, keratoconus) VA Hand Movement (HM) or worse, brunescent cataracts, eyes with phacodonesis, pupils that dilated less than 6.5mm, patients that could not comply with follow up appointments, or that refused to sign an informed consent to participate, were excluded from the study.
Eligible patients underwent a comprehensive ophthalmological examination. Intraocular pressure was taken preoperatively and postoperatively in every visit with Goldmann Applanation Tonometer (GAT). Preoperative glaucoma medications used were registered and classified by class, based in the Terminology and Guidelines for Glaucoma 2nd Edition, Table IX, Monotherapy. Patients performed Humphrey 24–2 white-on-white VF, using the SITA-Standard algorithm with a size III stimulus; MD and VFI were recorded preoperatively, and postoperatively on day 1, month 1, month 3, month 6 and month 12. Changes from baseline in VF were confirmed in at least two consecutive reliable tests. VA was assessed using the Snellen chart preoperatively and in every follow-up visit.
Femtosecond laser (LenSx Laser System, Alcon Laboratories, Inc.) anterior capsulotomy and lens fragmentation were completed in all patients, a contact docking interface was used for 1.5 minutes. All cataract extractions were performed by a single experienced surgeon (R.C.D.). IOP was recorded during surgery using a Schiötz indentation tonometer immediately before and after suction docking, prior administration of a topical anesthetic (tetracaine 0.5g) with the patient in a supine position. Schiotz tonometer calibration was checked before every use, IOP measurements were taken with the 5.5 g weight and the 15 g weight to confirm, and if they did not match the measurements were repeated.
Data regarding IOP, VF MD and VFI, BCVA, and glaucoma medications were collected preoperatively and during the follow-up using a computerized database (Microsoft Excel).
2.1
Statistical analysis
Descriptive statistical analysis was performed using the Stata© software version 15.1 (StataCorp. 2015, Stata Statistical Software: Release 15. College Station, Texas, US: StataCorp LP.) The normal distribution of variables was assessed with Shapiro – Wilk test and p < 0.05 was considered significant. The continuous variables were expressed as means ± standard deviation (SD) or median and interquartile range (IQR). The categorical variables were expressed as number (n) and percentages (%).
3
Results
Fourteen eyes of 11 patients were included. Most of them were female (9, 81.8%) with a mean age of 74.4 ± 8.2 years (range: 57–87 years). Nine (64.3%) and 5 (35.7%) were diagnosed with primary angle-closure glaucoma (PACG) and primary open-angle glaucoma (POAG), respectively. Demographic and baseline clinical characteristics are summarized in Table 1 . No complications were recorded during the surgeries.
| Characteristic | Value |
|---|---|
| Age (years), Mean ± SD (range) a | 74.4 ± 8.2 (57–87) |
| Gender, n (%) a | |
| Female | 9 (81.8) |
| Glaucoma subtype, n (%) | |
| Primary angle closure glaucoma | 9 (64.3) |
| Primary open angle glaucoma | 5 (35.7) |
| Baseline best-corrected visual acuity (LogMAR), Median (IQR) | 0.3 (0.18–0.4) |
| Baseline sphere (D), Mean ± SD | 1.4 ± 1.8 |
| Baseline cylinder (D), Mean ± SD | 0.04 ± 1.26 |
| Baseline intraocular pressure (mmHg), Median (IQR) | 15.5 (14-17) |
| Baseline number of topical glaucoma medications, Median (IQR) | 1 (1-3) |
| Baseline visual field mean deviation (dB), Median (IQR) | −4.5 (−8.24–−3.05) |
| Baseline visual field index (%), Median (IQR) | 93 (84–99) |
Regarding short-term IOP changes, we found a slight reduction in values after the docking phase in both glaucoma subtype groups ( Table 2 ).
| Primary angle closure glaucoma (n = 9 eyes) | Primary open angle glaucoma (n = 5 eyes) | |
|---|---|---|
| Before docking, Median (IQR) | 17.3 (15–19) | 18 (18–19) |
| After docking, Median (IQR) | 16 (12–18) | 16.5 (15-17) |
No clinically significant changes were observed in BCVA and number of topical glaucoma medications from baseline to one year after FLACS in both glaucoma subtype groups.
There were 5 patients that “decreased” their BCVA after surgery at the end of follow-up. They are patients number 3, 4, 8, 10, and 13 shown in Table 4 . These patients developed posterior capsular opacification that decreased their vision after it had initially increased after surgery. At the 12 months follow-up, these patients had not been treated with yag capsulotomy.
Regarding IOP, a significant mean reduction in values was found in all cases at last follow-up ( Table 3 ). Table 4 shows changes from baseline in BCVA, IOP, number of medications, MD, and VFI individually in every patient. In both groups, an increase in IOP at day 1 after FLACS was found; however, IOP values showed a reduction at month 1 that was maintained until the las follow-up at 12 months after the surgery. ( Fig. 1 ).
