Blue light-filter intraocular lenses in vitrectomy combined with cataract surgery: results of a randomized controlled clinical trial

Blue Light Exposure: Ocular Hazards and Prevention-A Narrative Review

INTRODUCTION

Exposure to blue light has seriously increased in our environment since the arrival of light emitting diodes (LEDs) and, in recent years, the proliferation of digital devices rich in blue light. This raises some questions about its potential deleterious effects on eye health. The aim of this narrative review is to provide an update on the ocular effects of blue light and to discuss the efficiency of methods of protection and prevention against potential blue light-induced ocular injury.

METHODS

The search of relevant English articles was conducted in PubMed, Medline, and Google Scholar databases until December 2022.

RESULTS

Blue light exposure provokes photochemical reactions in most eye tissues, in particular the cornea, the lens, and the retina. In vitro and in vivo studies have shown that certain exposures to blue light (depending on the wavelength or intensity) can cause temporary or permanent damage to some structures of the eye, especially the retina. However, currently, there is no evidence that screen use and LEDs in normal use are deleterious to the human retina. Regarding protection, there is currently no evidence of a beneficial effect of blue blocking lenses for the prevention of eye diseases, in particular age-related macular degeneration (AMD). In humans, macular pigments (composed of lutein and zeaxanthin) represent a natural protection by filtering blue light, and can be increased through increased intake from foods or food supplements. These nutrients are associated with lower risk for AMD and cataract. Antioxidants such as vitamins C, E, or zinc might also contribute to the prevention of photochemical ocular damage by preventing oxidative stress.

CONCLUSION

Currently, there is no evidence that LEDs in normal use at domestic intensity levels or in screen devices are retinotoxic to the human eye. However, the potential toxicity of long-term cumulative exposure and the dose-response effect are currently unknown.

Effect of Blue Light-Filtering Intraocular Lenses on Age-Related Macular Degeneration: A Nationwide Cohort Study With 10-Year Follow-up

PURPOSE

To determine the incidence rate of age-related macular degeneration (AMD) after cataract surgery and compare the relative incidence of AMD in pseudophakes with blue light-filtering intraocular lenses (BF-IOLs) and non-BF-IOLs.

DESIGN

A nationwide cohort study conducted using the Taiwan National Health Insurance Research Database.

METHODS

We enrolled 186,591 patients who underwent cataract surgery in both eyes between 2008 and 2013 and monitored them from the index date (the date of first cataract surgery) until AMD, death, loss to follow-up, or December 31, 2017, whichever occurred first. Propensity score matching (PSM) was used to balance the baseline characteristics between the BF-IOL and non-BF-IOL groups.

RESULTS

BF-IOLs were implanted in 21,126 patients (11.3%) and non-BF-IOLs were implanted in 165,465 patients (88.7%). Patients in the BF-IOL group tended to be younger, with fewer men, different cataract surgery years, higher income, more nonmanual workers, more patients from urban and suburban areas, and fewer chronic diseases compared with the non-BF-IOL group. With a mean follow-up period of 6.1 years (range, 1-10 years) after cataract surgery, 12,533 and 1655 patients developed non-exudative AMD and exudative AMD, respectively. The incidence rate of non-exudative AMD and exudative AMD (per 1000 person-years) was 9.95 and 1.22 for the BF-IOL group and 11.13 and 1.44 for the non-BF-IOL group, respectively. After PSM, no statistical difference in the incidence rate of nonexudative AMD (hazards ratio, 0.95; 95% CI, 0.88-1.03) and exudative AMD (hazard ratio, 0.96; 95% CI, 0.77-1.18) was observed between the BF-IOL and non-BF-IOL groups.

CONCLUSIONS

In Taiwan, the incidence rate of AMD after cataract surgery was 11.59 per 1000 person-years. The use of a BF-IOL for up to 10 years had no apparent advantage over a non-BF-IOL in the incidence of AMD.

Safety and effectiveness of an iris hook assisted phacoemulsification in vitrectomized eyes

AIM

To introduce a simple iris hook assisted phacoemulsification (PE) procedure and evaluate the safety and efficacy of it in completely vitrectomized eyes.

METHODS

A single centre study which included 65 previously completely vitrectomized eyes of 62 patients who underwent cataract surgery. Patients were randomly divided into 3 groups. Patients received PE, and intraocular lens (IOL) implantation with the assistance of iris hook (Synergeties™) as group A (25 eyes); patients who received PE assisted with a 25G pars plana irrigation as group B (20 eyes), and patients who received PE performed without the help of any instrument as group C (20 eyes). Main outcome measures were surgery duration, Ultrasound (U/S) total time, endothelial cell density (ECD), cumulative dissipated energy (CDE) and complications of the procedures.

RESULTS

With the help of iris hook, the patients in group A had the lowest ECD loss rate (0.07±0.03, 0.09±0.03, and 0.10±0.03, P<0.05), shortest CDE (12.2±4.1, 15.8±6.0, and 16.0±6.0, P<0.05) and U/S total time (36.6±13.0s, 46.3±16.4s, and 47.6±16.1s, P<0.05), and minimal incidence of complications. The longest surgery duration was in group B (19.4±1.6min) and maximum complications rate in group C (20% miosis, 10% posterior capsular tears, 5% zonular dialysis, 5% cystoid macular edema). While best-corrected visual acuity (BCVA), intraocular pressure (IOP) and ECD did not show a significant difference among the three groups.

CONCLUSION

Without prolonged surgery duration, the iris hook assistant method can minimize heat generation during surgery and incidence of complications, which transfer the challenged PE in vitrectomized eyes into a regular surgery. It does not need any change in the hydrodynamic parameters and in the bag PE technique, easy to operate even for junior surgeons.

The Effect of Blue-Light Filtering Intraocular Lenses on the Development and Progression of Neovascular Age-Related Macular Degeneration

PURPOSE

To assess the effect of blue-light filtering (BLF) intraocular lenses (IOLs) on the prevention of neovascular age-related macular degeneration (nAMD) after cataract surgery.

DESIGN

Cohort study.

PARTICIPANTS

Patients who underwent uneventful cataract surgery between 2007 and 2018 at the Ophthalmology Unit of Kymenlaakso Central Hospital, Kotka, Finland.

METHODS

Subsequent nAMD rates were compared between patients who received BLF IOLs and those who received non-BLF IOLs. Kaplan-Meier and Cox regression analyses for the overall risk of nAMD developing were assessed. Best-corrected visual acuity (BCVA), foveal thickness, treatment interval, and total number of intravitreal injections were secondary outcomes. A separate analysis was performed on patients with pre-existing nAMD to assess the effect of BLF IOLs on nAMD progression. A single eye of each patient was included.

MAIN OUTCOME MEASURE

Neovascular age-related macular degeneration-free survival.

RESULTS

Included were 11 397 eyes of 11 397 patients with a mean age of 75.4 ± 8.3 years (62.5% women). The BLF IOL was used in 5425 eyes (47.6%), and the non-BLF IOL was used in 5972 eyes (52.4%). During follow-up (BLF IOL group, 55.2 ± 34.1 months; non-BLF IOL group, 50.5 ± 30.1 months; P < 0.001), 164 cases of new-onset nAMD were recorded (BLF group, n = 88; non-BLF group, n = 76). The nAMD-free survival was similar between the groups (P = 0.465, log-rank test). In a Cox regression analysis controlling for age, gender, and a documented diagnosis of macular degeneration, the use of a BLF IOL was not predictive of nAMD development (hazard ratio [HR], 1.075; 95% confidence interval [CI], 0.79-1.47; P = 0.652). In nAMD patients, secondary clinical outcomes at 1 year were comparable for BCVA (0.57 ± 0.4 logarithm of the minimum angle of resolution vs. 0.45 ± 0.4 logarithm of the minimum angle of resolution; P = 0.136), foveal thickness (285 ± 109 μm vs. 299 ± 103μm; P = 0.527), number of anti-vascular endothelial growth factor injections (6.5 ± 2.5 vs. 6.2 ± 2.7; P = 0.548), and treatment interval (7.5 ± 2.4 weeks vs. 8.1 ± 2.4 weeks; P = 0.271) for BLF and non-BLF IOLs, respectively. Similarly to patients in whom nAMD developed after the surgery, among patients with nAMD before surgery (BLF, n = 71; non-BLF, n = 74), the clinical outcomes again were comparable (all P > 0.05).

CONCLUSIONS

In a large cohort of patients who underwent cataract surgery, the use of a BLF IOL resulted in no apparent advantage over a non-BLF IOL in the incidence of nAMD or its progression, nor in clinical variables related to nAMD severity.

Blue-light filtering intraocular lenses (IOLs) for protecting macular health

BACKGROUND

An intraocular lens (IOL) is a synthetic lens that is surgically implanted within the eye following removal of the crystalline lens, during cataract surgery. While all modern IOLs attenuate the transmission of ultra-violet (UV) light, some IOLs, called blue-blocking or blue-light filtering IOLs, also reduce short-wavelength visible light transmission. The rationale for blue-light filtering IOLs derives primarily from cell culture and animal studies, which suggest that short-wavelength visible light can induce retinal photoxicity. Blue-light filtering IOLs have been suggested to impart retinal protection and potentially prevent the development and progression of age-related macular degeneration (AMD). We sought to investigate the evidence relating to these suggested benefits of blue-light filtering IOLs, and to consider any potential adverse effects.

OBJECTIVES

To assess the effects of blue-light filtering IOLs compared with non-blue-light filtering IOLs, with respect to providing protection to macular health and function.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 9); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the ICTRP. The date of the search was 25 October 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), involving adult participants undergoing cataract extraction, where a blue-light filtering IOL was compared with an equivalent non-blue-light filtering IOL.

DATA COLLECTION AND ANALYSIS

The prespecified primary outcome was the change in distance best-corrected visual acuity (BCVA), as a continuous outcome, between baseline and 12 months of follow-up. Prespecified secondary outcomes included postoperative contrast sensitivity, colour discrimination, macular pigment optical density (MPOD), proportion of eyes with a pathological finding at the macula (including, but not limited to the development or progression of AMD, or both), daytime alertness, reaction time and patient satisfaction. We evaluated findings related to ocular and systemic adverse effects.Two review authors independently screened abstracts and full-text articles, extracted data from eligible RCTs and judged the risk of bias using the Cochrane tool. We reached a consensus on any disagreements by discussion. Where appropriate, we pooled data relating to outcomes and used random-effects or fixed-effect models for the meta-analyses. We summarised the overall certainty of the evidence using GRADE.

MAIN RESULTS

We included 51 RCTs from 17 different countries, although most studies either did not report relevant outcomes, or provided data in a format that could not be extracted. Together, the included studies considered the outcomes of IOL implantation in over 5000 eyes. The number of participants ranged from 13 to 300, and the follow-up period ranged from one month to five years. Only two of the studies had a trial registry record and no studies referred to a published protocol. We did not judge any of the studies to have a low risk of bias in all seven domains. We judged approximately two-thirds of the studies to have a high risk of bias in domains relating to 'blinding of participants and personnel' (performance bias) and 'blinding of outcome assessment' (detection bias).We found with moderate certainty, that distance BCVA with a blue-light filtering IOL, at six to 18 months postoperatively, and measured in logMAR, was not clearly different to distance BCVA with a non-blue-light filtering IOL (mean difference (MD) -0.01 logMAR, 95% confidence interval (CI) -0.03 to 0.02, P = 0.48; 2 studies, 131 eyes).There was very low-certainty evidence relating to any potential inter-intervention difference for the proportion of eyes that developed late-stage AMD at three years of follow-up, or any stage of AMD at one year of follow-up, as data derived from one trial and two trials respectively, and there were no events in either IOL intervention group, for either outcome. There was very low-certainty evidence for the outcome for the proportion of participants who lost 15 or more letters of distance BCVA at six months of follow-up; two trials that considered a total of 63 eyes reported no events, in either IOL intervention group.There were no relevant, combinable data available for outcomes relating to the effect on contrast sensitivity at six months, the proportion of eyes with a measurable loss of colour discrimination from baseline at six months, or the proportion of participants with adverse events with a probable causal link with the study interventions after six months.We were unable to draw reliable conclusions on the relative equivalence or superiority of blue-light filtering IOLs versus non-blue-light filtering IOLs in relation to longer-term effects on macular health. We were also not able to determine with any certainty whether blue-light filtering IOLs have any significant effects on MPOD, contrast sensitivity, colour discrimination, daytime alertness, reaction time or patient satisfaction, relative to non-blue-light filtering IOLs.

AUTHORS' CONCLUSIONS

This systematic review shows with moderate certainty that there is no clinically meaningful difference in short-term BCVA with the two types of IOLs. Further, based upon available data, these findings suggest that there is no clinically meaningful difference in short-term contrast sensitivity with the two interventions, although there was a low level of certainty for this outcome due to a small number of included studies and their inherent risk of bias. Based upon current, best-available research evidence, it is unclear whether blue-light filtering IOLs preserve macular health or alter risks associated with the development and progression of AMD, or both. Further research is required to fully understand the effects of blue-light filtering IOLs for providing protection to macular health and function.

Influence of yellow filters on straylight measurements

PURPOSE

To determine whether the yellow filters often used for glare reduction influence retinal straylight measured in healthy eyes.

SETTING

Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium.

DESIGN

Prospective case series.

METHODS

For each eye, the spherical equivalent (SE) was determined using an autorefractometer, followed by 5 straylight measurements taken with the compensation-comparison method. The first measurement was taken with a colorless plano lens placed in front of the eye, followed by 4 other measurements with yellow filters with cutoff wavelengths at 450 nm, 511 nm, 527 nm, and 550 nm. Ametropic volunteers were corrected using an additional lens in all measurements. Age, sex, and eye color were listed. In addition to the basic measurements, base- and age-corrected and base-, age-, and SE-corrected values were calculated.

RESULTS

The data from 56 right eyes of 56 healthy volunteers aged 28.7 years ± 10.3 (SD) were assessed. The straylight of the 4 yellow filters was significantly higher than that of the plano lens (P < .001, analysis of variance [ANOVA]). The straylight also increased with higher cutoff frequencies, albeit insignificantly (P > .05, ANOVA). No significant difference was found between sexes (P = .909) or between eye colors (P > .05).

CONCLUSIONS

The use of yellow filters increased retinal straylight by a small but significant amount compared with the use of unfiltered light. This suggests that the visual comfort often experienced while wearing these filters is not associated with reduced straylight.

Blue-Light Filtering Spectacle Lenses: Optical and Clinical Performances

PURPOSES

To evaluate the optical performance of blue-light filtering spectacle lenses and investigate whether a reduction in blue light transmission affects visual performance and sleep quality.

METHODS

Experiment 1: The relative changes in phototoxicity, scotopic sensitivity, and melatonin suppression of five blue-light filtering plano spectacle lenses were calculated based on their spectral transmittances measured by a spectrophotometer. Experiment 2: A pseudo-randomized controlled study was conducted to evaluate the clinical performance of two blue-light filtering spectacle lenses (BF: blue-filtering anti-reflection coating; BT: brown-tinted) with a regular clear lens (AR) serving as a control. A total of eighty computer users were recruited from two age cohorts (young adults: 18-30 yrs, middle-aged adults: 40-55 yrs). Contrast sensitivity under standard and glare conditions, and colour discrimination were measured using standard clinical tests. After one month of lens wear, subjective ratings of lens performance were collected by questionnaire.

RESULTS

All tested blue-light filtering spectacle lenses theoretically reduced the calculated phototoxicity by 10.6% to 23.6%. Although use of the blue-light filters also decreased scotopic sensitivity by 2.4% to 9.6%, and melatonin suppression by 5.8% to 15.0%, over 70% of the participants could not detect these optical changes. Our clinical tests revealed no significant decrease in contrast sensitivity either with (95% confidence intervals [CI]: AR-BT [-0.05, 0.05]; AR-BF [-0.05, 0.06]; BT-BF [-0.06, 0.06]) or without glare (95% CI: AR-BT [-0.01, 0.03]; AR-BF [-0.01, 0.03]; BT-BF [-0.02, 0.02]) and colour discrimination (95% CI: AR-BT [-9.07, 1.02]; AR-BF [-7.06, 4.46]; BT-BF [-3.12, 8.57]).

CONCLUSION

Blue-light filtering spectacle lenses can partially filter high-energy short-wavelength light without substantially degrading visual performance and sleep quality. These lenses may serve as a supplementary option for protecting the retina from potential blue-light hazard.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02821403.

Effect of blue light-filtering intraocular lens on color vision in patients with macular diseases after vitrectomy

To evaluate the color vision of patients with macular diseases after implanting a blue light-filtering intraocular lens (IOL) during vitrectomy. Twenty-seven patients had a blue light-filtering IOL implanted during vitrectomy for macular diseases (macular disease group), and 40 patients without macular disease had the same type of IOL implanted (non-macular disease group). The postoperative best-corrected visual acuity (BCVA) was ≥ 16/20 in all patients. The Farnsworth-Munsell 100-hue test was used to determine total error scores (TES) and mean error scores under photopic and mesopic conditions in both groups. The TES under mesopic conditions was significantly higher than that under photopic conditions in both groups (P < 0.05). However, the TES in the macular disease group was not significantly different from that of the non-macular disease group under both photopic and mesopic conditions. The mean error scores under photopic conditions for hues 11, 14, 16, 17, 18, and 20 (yellowish-red to yellow) were significantly higher in the macular disease group than in the non-macular disease group. The mean error scores for hues 7 and 85 (red) were significantly higher in the non-macular disease group than in the macular disease group. Under mesopic conditions, the mean error scores for hues 30, 60, and 61 were significantly higher in the non-macular disease group than in the macular disease group (P < 0.05). Our results indicate that blue light-filtering IOLs do not alter color discrimination in eyes with macular diseases, and these patients had good postoperative BCVA even under mesopic conditions.

Ultraviolet or blue-filtering intraocular lenses: what is the evidence?

Cataract surgery was revolutionised by the introduction of modern intraocular lenses in the late 1940's. By the late 1960's to 1970's evidence had emerged that short-wavelength light caused phototoxicity at the retina and retinal pigment epithelium. By the early 1980's ultraviolet filters had been incorporated into intraocular lenses. This caused intense controversy, as there was concern that the UV-filtering chromophore might leach out into the eye causing toxicity. With the arrival of blue-filtering intraocular lenses (BFIOLs) in 1990's, a further debate was ignited as to their safety and potential disadvantages. Selecting the optimal performing intraocular lens to obtain the best visual performance with the fewest potential drawbacks has become complex and challenging for cataract surgeons and their patients with the wide choice of lenses available. Choosing a personalised lens to address astigmatism, presbyopia, spherical aberration, chromatic aberration, and potentially to shield the retina from short-wavelength light is now possible. The potential benefits and possible side effects of these different innovations emphasise the importance of assessing the evidence for their clinical utility, allowing the surgeon and the patient to weigh-up the risk benefit ratio and make an informed decision. The BFIOLs were developed to reduce cyanopsia, address chromatic aberration, and improve contrast sensitivity in different lighting conditions, as well as to prevent short-wavelength light reaching the retina thus potentially reducing the risk of developing age-related macular degeneration. Further design development of the BFIOLs was to mimic the natural crystalline lens absorption and transmittance properties in adulthood. Multiple publications have reported on the potential benefits and pitfalls of implanting a blue-filtering lens. The potential disadvantages raised in the literature over the last 25 years since their introduction, regarding compromise of visual function and disruption of the circadian system, have been largely dispelled. The clear benefits of protecting the retina from short-wavelength light make a BFIOLs a sensible choice. The purpose of this article presented at the Cambridge symposium 2015 is to review the literature on this subject.

Internal limiting membrane contrast after staining with indocyanine green and brilliant blue G during macular surgery

PURPOSE

To evaluate the difference in color contrast by performing a color contrast ratio (CR) analysis and resulting visibility of the internal limiting membrane (ILM) when stained with indocyanine green and brilliant blue G (BBG) during macular surgery by performing a color CR analysis.

METHODS

The authors analyzed 40 consecutive cases in which vitrectomy with ILM removal was performed to treat a macular hole or an epiretinal membrane. The surgical procedure was performed in 21 patients (21 eyes) after staining with indocyanine green and in 19 patients (19 eyes) after staining with BBG. The color CRs were estimated based on digital analysis of the red, green, and blue data of the digital images captured, and the CRs obtained with the two dyes were compared.

RESULTS

Color contrast analysis was performed in all 40 eyes, in which the ILM was removed after staining with indocyanine green or BBG, and the CRs were estimated in every eye. The CR (mean ± SD) obtained with indocyanine green and BBG was 4.3 ± 0.3 and 2.4 ± 0.1, respectively. Indocyanine green provided a significantly higher CR than BBG (P = 0.015).

CONCLUSION

Digital color contrast analysis can be used to evaluate the visibility of digital images, and it may be useful when choosing the dye to use for staining the ILM better.

Premium IOLs in Glaucoma

Advanced technology or premium intraocular lenses have been developed to meet the patient expectations of perfect distance and near vision without the need for spectacles. Careful patient selection is critical when implanting these implants. This brief review focusses mainly on multifocal and toric IOLs and their application and limitations in patients with glaucoma.

How to cite this article: Ichhpujani P, Bhartiya S, Sharma A. Premium IOLs in Glaucoma. J Current Glau Prac 2013;7(2): 54-57.

Recent studies provide an updated clinical perspective on blue light-filtering IOLs

Background

Recent reviews of blue light-filtering intraocular lenses (IOLs) have stated their potential risks for scotopic vision and circadian photoentrainment. Some authors have challenged the rationale for retinal photoprotection that these IOLs might provide. Our objective is to address these issues by providing an updated clinical perspective based on the results of the most recent studies.

Methods

This article evaluates the currently available published papers assessing the potential risks and benefits of blue light-filtering IOLs. It summarizes the results of seven clinical and two computational studies on photoreception, and several studies related to retinal photoprotection, all of which were not available in the previous reviews. These results provide a clinical risk/benefit analysis for an updated review for these IOLs.

Results

Most clinical studies comparing IOLs with and without the blue light-filtering feature have found no difference in clinical performance for; visual acuity, contrast sensitivity, color vision, or glare. For blue light-filtering IOLs, three comparative clinical studies have shown improved contrast sensitivity and glare reduction; but one study, while it showed satisfactory overall color perception, demonstrated some compromise in mesopic comparative blue color discrimination. Comparative results of two recent clinical studies have also shown improved performance for simulated driving under glare conditions and reduced glare disability, better heterochromatic contrast threshold, and faster recovery from photostress for blue light-filtering IOLs. Two computational and five clinical studies found no difference in performance between IOLs with or without blue light-filtration for scotopic vision performance and photo entrainment of the circadian rhythm. The rationale for protection of the pseudophakic retina against phototoxicity is discussed with supporting results of the most recent computational, in-vitro, animal, clinical, and epidemiological investigations.

Conclusions

This analysis provides an updated clinical perspective which suggests the selection of blue light-filtering IOLs for patients of any age, but especially for pediatric and presbyopic lens exchange patients with a longer pseudophakic life. Without clinically substantiated potential risks, these patients should experience the benefit of overall better quality of vision, reduced glare disability at least in some conditions, and better protection against retinal phototoxicity and its associated potential risk for AMD.

Electronic supplementary material

The online version of this article (doi:10.1007/s00417-011-1697-6) contains supplementary material, which is available to authorized users.

Cataract surgery after pars plana vitrectomy

PURPOSE OF REVIEW

To review recent studies and advances and their possible implications in the care of patients undergoing cataract surgery after pars plana vitrectomy.

RECENT FINDINGS

Optical biometry has shown to be superior to ultrasound biometry in vitrectomized eyes but still not achieving as good results as it does in nonvitrectomized eyes. Blue light-filter intraocular lenses, with their possible advantage of macular protection, have shown no operative or functional disadvantages in vitrectomized eyes, and thus their routine use can be justified. However, presbyopia-correcting intraocular lenses, at least at their current stage of development, generally, are still not accepted for vitrectomized eyes. Combining cataract surgery with intravitreal injections of bevacizumab or triamcinolone acetonide in patients with macular edema and cataract is advisable to avoid exacerbation of the condition and improve visual outcome. Despite the recent advances, incidences of posterior capsular opacification and retinal detachment are still considerable.

SUMMARY

Understanding ocular anatomical alterations imposed by the previous pars plana vitrectomy surgery and the underlying vitreoretinal disease will allow the surgeon to address the special challenges. Despite that, recent advances in techniques and instrumentation have improved the surgical safety and outcomes, reported complications rates are still relatively high.