Top 10 Trends in Anterior Segment for Fall 2019

Ah, Paris. The city of love, fabulous food and wine, and haute couture. As the city gears up for the much-anticipated Paris Fashion Week in September, so do we at CAKE Magazine for our first-ever Top 10 list of anterior segment trends. While fashion might not be top-of-mind for many physicians – we haven’t necessarily seen any ophthalmologists strutting down a catwalk (yet!) – trends backed by research and data certainly are. That’s because these new(er) procedures, instruments and innovations have one end goal: improving patient outcomes.

To learn what’s ‘hot’ (and also what’s ‘not’), we spoke with some of the most stylish ophthalmologists lighting up the anterior segment. Below, they reveal their opinions on what’s trending in refractive, glaucoma, and cataract surgery.

1 SMILE is Looking Dapper

According to Prof. Dr. Gerd Auffarth, chairman of the Department of Ophthalmology at the University of Heidelberg, Germany, a lot of changing trends can be seen in refractive surgery today. “Treating myopia, especially in younger patients, has become the standard in ophthalmology,” he said. 

For treating myopia, LASIK has ruled the refractive runway for quite a while. However, a new contender is causing quite a stir: SMILE or small incision lenticule extraction. SMILE is designed to treat refractive errors like myopia, hyperopia, presbyopia and astigmatism. And while LASIK uses an excimer laser to create a flap, SMILE uses the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) to create a corneal lenticule, which is then extracted through a small incision. 

Data shows SMILE has similar efficacy and safety to LASIK, with potential advantages in biomechanical stability and postoperative outcomes. So, this begs the question: Is SMILE the new ‘black’?

According to Dr. Gaurav Luthra, director of cataract & refractive surgery at Drishti Eye Institute, Dehradun, India, SMILE is currently the trend in refractive surgery. “With better understanding of the key strengths and the limitations of the procedure, and the confidence of numbers – with more than two million SMILE procedures performed worldwide – there is better acceptance of the procedure by refractive surgeons.”

“There is now some competition between the SMILE procedure and classical Femto LASIK,” said Prof. Auffarth. “SMILE gets a lot of attention especially at international meetings – however, Femto LASIK is still performed in higher numbers than SMILE.”

A 2016 study¹ by Shen Z. et al., compared results from SMILE with Femto LASIK (FS-LASIK) for treating myopia in 1,076 eyes. At 6 months post-op, there were no significant differences between the two groups with regard to the following: a loss of one or more lines in the best corrected spectacle visual acuity (BSCVA); uncorrected visual acuity (UCVA) of 20/20 or better; logMAR UCVA; postoperative refractive spherical equivalent or postoperative refraction within ±1.0 D of the target refraction. However, they did find that the FS-LASIK group suffered more severely from dry eye symptoms and lower corneal sensitivity at 6 months.

The authors concluded that “both FS-LASIK and SMILE are safe, effective and predictable surgical options for treating myopia. However, dry eye symptoms and loss of corneal sensitivity may occur less frequently after SMILE than after FS-LASIK”.

“With visual results of SMILE appearing at least on par, if not better than LASIK, the benefits of a flapless procedure including better corneal biomechanics (and lesser risk of ectasia) and minimizing flap complications will be too appealing to any surgeon, and ultimately the patient, to ignore,” said Dr. Luthra. “Moreover, with pure astigmatic corrections becoming commercially available and good outcomes reported in ongoing hypermetropia SMILE trials, the indications continue to expand.”

2 Hot On Its Heels: Topography-Guided Refractive Surgery

Dr. George Beiko, a cataract, anterior segment and refractive surgeon practicing in St. Catharines, Ontario, Canada, says: “My impression is that corneal lenticule directed and corneal surface procedures involving topography guided approaches seem to be the trends in refractive surgery.”  

Topography-guided laser refractive surgery corrects vision by altering the surface of the eye. The procedure has been found to be uniquely effective in eyes with corneal irregularities or in highly aberrated corneas, where wavefront aberrometry is often not possible.^2-3

Holland S. et al., published a review³ of topography-guided ablations in normal corneas and highly aberrated corneas and found that “topography-guided laser ablation is increasingly used with good efficacy and safety outcomes in highly aberrated corneas with irregular astigmatism.” These include eyes with refractive surgery complications including post-LASIK ectasia, decentered ablation, small optical zones, asymmetrical astigmatism, and postradial keratectomy astigmatism. “Topography-guided laser refractive surgery is proving to be effective and well-tolerated in the visual rehabilitation of highly aberrated eyes, with increasing predictability based on the recent research,” Holland concluded.

“The expected future trend in refractive surgery procedures is likely to see a growth in SMILE procedures, phakic lenses with photorefractive keratectomy (PRK) and advanced surface ablation (ASA) holding fort, and LASIK numbers gradually declining, to remain limited to customized treatments not possible yet with SMILE,” added Dr. Luthra.

3 RLE is All the Rage

Another trend noted by Dr. Beiko and Prof. Auffarth is the refractive lens exchange (RLE), which rides the wave between refractive and cataract surgery. The procedure is identical to cataract surgery, except rather than a cloudy lens, a clear lens is replaced to correct presbyopia.

“It seems that lens-based refractive surgery is also on the rise,” said Dr. Beiko. In fact, improved outcomes in cataract surgery have organically led to the use of lens surgery as a refractive modality. It offers distinct advantages over corneal refractive surgery in selected cases, while simultaneously eliminating the need for cataract surgery in the future. 

According to Alio et al., RLE is an elective intraocular surgery that needs to be minimally invasive and performed with precision and high accuracy. The authors said: “The indication of this surgery is the presence of high refractive error in the absence of cataract and requires an approach with the risk–benefit ratio in mind depending on the age, refractive condition and pre-operative condition,” adding that in general, RLE should be performed only in presbyopic eyes and the main challenge involved is to reach emmetropia.⁴ 

Prof. Auffarth has also taken notice of RLE, including presbyopic clear lens extraction, up to premium lens application in cataract patients. “The more sophisticated the implant, the more advanced and the more comprehensive the preoperative evaluation should be, as well as having high standards for the intraoperative procedures.”

On the flip side, Dr. Beiko provided a word of caution regarding these procedures: “Surgical intervention for presbyopia with clear lens extraction needs to be critically reviewed. Long-term follow-up of uncomplicated lens extraction reveals optical quality to be inferior to the native lens, retinal detachment rates and in-the-bag lens dislocation both increase with time, opacification of intraocular lens optic may be an issue with some materials, and with only partial resolution of the presbyopia – all to be of grave concern.”

4 The Sophistication of   Astigmatism Management

Cataract surgery is one of the most common procedures to treat preventable blindness around the world. So, what is trending in cataract today? According to Dr. Beiko, management of astigmatism is a very hot topic, specifically as it applies to the posterior corneal surface. 

More than 50% of patients undergoing cataract surgery have corneal astigmatism ≥0.75D, which may significantly limit visual outcomes if left uncorrected. Generally, with astigmatism, the main consideration is related to the anterior cornea. However, it’s been revealed that the posterior surface exhibits more toricity than the anterior surface – and ignoring posterior corneal astigmatism (PCA) could be a significant factor with regard to postoperative refractive astigmatism after toric intraocular lens (IOL) implantation.⁵

“Our understanding of the role of the posterior corneal surface is extensive, but our ability to measure it directly is limited,” explained Dr. Beiko. “Devices recently made available which measure the total keratometry and incorporate the Barrett formulas, which have been developed for this measurement, have been very effective in my hands.” 

The Barrett formula uses the Universal II formula to predict the required spherical equivalent IOL power; and the calculator derives the posterior corneal curvature based on a theoretical model proposed to explain the behavior of the posterior cornea.5 These lens power calculations, based on predicted, rather than measured posterior corneal curvature have yielded the best results thus far.⁶

“More surgeons now rely on these newer formulas, including Barrett and Hill-RBF methods, for more predictable outcomes,” said Dr. Luthra.

A 2019 study⁶ by Skrzypecki et al. compared refractive predictions of the Barrett Toric Calculator, based on IOL Master 700 biometry (Carl Zeiss Meditec), with and without measurements of posterior corneal curvature. The authors found that astigmatism prediction errors, with and without measured posterior corneal curvature, were similar. “The updated Barrett Toric Calculator is the first formula to provide non-inferior and reliable predictions based on measurement of posterior corneal curvature,” the authors concluded. 

According to Dr. Luthra, the increased use of toric IOLs can be attributed to a better understanding of posterior corneal astigmatism, along with better calculators, that incorporate the same. “Most surgeons have lower thresholds for switching to a toric IOL than ever before,” he said, adding that image-guided cataract surgery, like with Zeiss Callisto and the Alcon Verion, has gained popularity with surgeons, especially for toric IOL planning and surgery.

5 OCT in the Spotlight

Dr. Beiko mentioned that another ‘hot’ topic is the integration of intraoperative optical coherence tomography (iOCT) into the microscope, which allows for enhanced visualization of the anterior segment. Intraoperative OCT aids in decision-making in various anterior segment surgeries and has the potential to decrease surgical time as well as postoperative complications.⁷

According to Titiyal et al., iOCT is also useful in assessing the posterior capsule during cataract surgery.⁷ The authors noted: “In cases with posterior polar cataract, it may help detect cases with a true posterior capsular defect, and this may allow the surgeon to exercise extra caution in such cases, thus reducing the incidence of complications.”

6 OCT, Upgraded in Style

In addition to iOCT, the use of OCT for pre- and postoperative patient management has been in style for a while. However, new upgrades are further enhancing its capabilities in anterior segment procedures.

“For premium lens patients, OCT diagnostics for the macula is almost mandatory to rule out epiretinal membranes or other pathologies,” added Prof. Auffarth. “New machines, for example the Oculus Pentacam AXL or Pentacam AXL Wave (Wetzlar, Germany), and similar machines from different other companies, offer the possibility to assemble a lot of parameters on one machine – which is necessary for finding the right lens or excluding the patient due to some pathology.”

“With the availability of reliable high-resolution epithelial thickness mapping on OCT, it has become a valuable tool for better evaluating, planning and following up patients with suspect corneas, as well as candidates for refractive surgery, including monitoring postoperative outcomes and surprises,” explained Dr. Luthra. “Epithelial thickness mapping is likely to become an indispensable aid to the cornea and refractive surgeon with time.” 

Dr. Luthra adds that now, surgeons also increasingly depend upon aberrometry devices like the iTrace to plan premium IOLs, and for dealing with dissatisfied cases. The iTrace (Tracey Technologies, Houston, Texas, USA) is a ray-tracing, wavefront and corneal topography combination device.

7 The ‘Perfect’ Capsulotomy

One of the most important steps to ensure optimal visual outcomes in cataract surgery is the anterior capsulotomy. Recently, femtosecond lasers have allowed surgeons to create a perfectly sized and perfectly circular anterior capsulotomy. However, an increased rate of anterior capsule tears following femtosecond laser has been reported⁸, which remains an important concern.This has led to the development of alternative approaches.

“In regard to femtosecond laser technology in the cataract segment, demand for a perfect circular capsulotomy has become much bigger, and alternative applications have been developed,” shared Prof. Auffarth. “Devices such as CAPSUlaser (Excel-Lens, Livermore, CA, USA) or Zepto (Mynosys Cellular Devices, Fremont, CA, USA) can create a capsulotomy like a femtosecond laser. However, in contrast to femtosecond laser, they cannot perform a fragmentation of the lens and also cannot create corneal incisions.”

The CAPSULaser is a thermal laser, and unlike the femtosecond laser it acts in a continuous manner to create the capsulotomy – plus, it’s small and attaches to the underneath of an operating microscope, which doesn’t interfere with the operating flow. Meanwhile, Zepto is a single-use device which consists of a suction ring containing a wire made of nitinol. The device is pushed into the eye through the phaco wound, then placed on the anterior capsule. Once it has been centered by the surgeon, suction is applied to attach the device to the capsule. A short electric charge is activated to cut the capsule.⁹

8 IOLs: In or Out?

Another trend under speculation are multifocal IOLs – with some opinions in favor, and other not. “Intraocular lenses which increase depth of focus have been disappointing in their outcomes, despite the initial promises,” said Dr. Beiko. So, will they stay or will they go? That is yet to be determined. 

A 2017 paper¹⁰ reported that “the patient’s satisfaction depends on careful and individualized selection based on the preexisting conditions, visual needs and realistic expectations, as well as on the knowledge of the different optical designs and visual performances of the multifocal IOLs, and the proper surgical technique and eventual complications management. The main reasons for patient dissatisfaction following a multifocal intraocular lens implantation are residual ametropia, posterior capsule opacification (PCO), dry eye, IOL decentration, inadequate pupil size, and wavefront abnormalities”.

It’s also suggested that trifocal models are better for those patients who require a good intermediate vision. “Trifocal lenses are gaining increased popularity for managing near vision performance in cataract surgery, but they are far from being the mainstay in daily practice,” said Dr. Beiko.

“Trifocal IOLs, which offer good acuity at near, intermediate and distance, with lesser complaints of glare and haloes, have taken over from the bifocals and to an extent from the extended depth of focus (EDOF) lenses in many practices,” added Dr. Luthra. “Trifocals are likely to gradually replace the bifocal IOLs completely as surgeon confidence grows.”

9 MIGS is a Runway Hit

When topical drops fail to manage intraocular pressure (IOP), and with the complications posed by more invasive surgeries to treat glaucoma, micro-invasive glaucoma surgery (or MIGS) has certainly been ‘in’ lately.

Currently, there are numerous MIGS devices and procedures – and to list them all would require more space than this short runway. Dr. Beiko helped to narrow down the list to one: The ab externo approach and placement of the XEN GEL Implant (Allergan Inc., CA, USA). It decreases IOP by creating a permanent drainage shunt from the anterior chamber to the subconjunctival space through a scleral channel.¹¹

“This technique offers the opportunity for some surgeons to perform it at the slit lamp, negating the necessity of going to the operating theatre,” said Dr. Beiko.  

A 2019 review¹² by Chatzara et al., summarized the current knowledge on XEN implant for the treatment of glaucoma. They found that there was a significant reduction in IOP, as well as in the number of medications needed, both in patients treated with XEN implant alone or combined with cataract surgery. The authors concluded that “XEN implant devices have been developed as a surgical alternative for glaucomatous patients and are expected to play an important role in the management of glaucoma in the future”.

“I believe that devices which increase flow through the trabecular meshwork remain the mainstay of modalities employed surgically to manage glaucoma,” Dr. Beiko concluded.

10 Ocular Fads: Hot or Not?

While fads in fashion can result in embarrassing photos, ‘fads’ in ophthalmology can have more devastating consequences, like permanent ocular damage (sounds fun!). And ironically enough, some of these ocular ‘fads’ can have quite a bit to do with actual fashion – no metaphor needed!

Prof. Auffarth said that one anterior segment procedure that may fall under this category is the elective changing of iris color by femto-laser or other laser applications – or keratopigmentation (KTP).

“In the last three to four years, it came several times up as a lifestyle procedure and there has been some investment in new companies changing a dark or brown iris to a blue one,” he said. 

In 2018, Alio et al., published a study¹³ which reported complications observed in 234 eyes of 204 patients treated with KTP for both therapeutic and cosmetic reasons. Different KTP techniques and three generations of pigments (GP) were used. Of those, 50 eyes of 29 patients suffered complications (12.82%). They found that 49% of patients complained of light sensitivity, then color fading and change in color (19%). 

Neovascularization, visual field limitations and magnetic resonance imaging (MRI) complications constituted 7%, 4% and 2%, respectively. Although light sensitivity remained with the corneal-specific pigments, it gradually disappeared in most of the patients (81.81%) 6 months postoperatively. Organic complications were observed with the previous GP, but resolved with the latest and third GP.

“It seems to be for some patients or some societies or professions as something very important – however, the complications can be quite dangerous. I think this is ‘fad’ in the category of anterior segment,” concluded Prof. Auffarth.

Be sure to catch up with the CAKE team at the European Society of Corneal and Refractive Surgeons (ESCRS) annual meeting in Paris. We will be wearing our finest haute couture while we continue our search for all things ‘hot’ in ophthalmology.

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