CAKE (magazine) stands for Cataract, Anterior Segment, Kudos and Enlightenment, but let’s be honest – the first thing that comes to mind whenever someone mentions ‘cake’ is the kind that we usually get for dessert. As it turns out, CAKE and cake may have more in common than meets the eye. Cake recipes – just like anterior segment surgeries – are complex and precise, following set guidelines and requiring specific ingredients and measurements.
For us at the magazine, this delicious similarity is just icing on our proverbial cake. Below, experts from across Asia-Pacific weigh in on the new ingredients and updated baking procedures that are heating up today’s anterior segment surgery recipes.
Fresh Ingredients in DED Treatment
Conveniently enough, eyes and cake do have one thing in common: No one likes either of them dry. However, resolving the issue of dryness is much simpler with CAKE.
Often described as a vicious cycle, dry eye disease (DED) generally involves three key mechanisms: tear film instability or deficiency, hyperosmolarity, and inflammation. While global prevalence rates vary by study, most agree that people of Asian descent experience higher rates of the disease. In fact, the TFOS DEWS II study1 reported a global prevalence ranging from 5% to 50%, finding that “Asian ethnicity was mostly a consistent risk factor”.
Dr. Louis Tong, senior consultant, Cornea and External Eye Disease Service at Singapore National Eye Centre (SNEC), specializes in the ocular surface. He offers dry eye clinics twice weekly, and notes that there’s generally about 20 to 30 patients visiting each clinic.
For patients suffering from DED, the disease can have quite an impact on their quality of life. Psychological and physical discomfort aside, there is also an economic burden caused by both medical costs and a loss of work productivity. And when many are suffering from DED, this impact can extend into the community.
Treatment is key – however, there is currently no standardized guideline (or foolproof recipe) to reduce signs and symptoms of DED. For many, including Dr. Tong, treatment for DED begins with artificial tears. However, for moderate to severe cases, additional therapy might be required.
Fortunately, now there are additional treatment options to help those patients. For example, to reduce inflammation, topical cyclosporine, diquafosol and lifitegrast eyedrops have shown beneficial results in reducing signs and symptoms of DED.
Dr. Tong also mentioned autologous platelet-rich plasma (PRP) treatment, which a recent study found to be effective as monotherapy to reduce signs and symptoms in patients with moderate to severe DED.2 During the 2017 study, 368 patients underwent monotherapy treatment with autologous PRP. After six weeks, the investigators found that DED symptoms improved in 322 (87.5%) cases. In addition, 280 (76.1%) patients had a decrease in corneal fluorescein staining (CFS), and 106 (28.8%) patients’ best corrected visual acuity (BCVA) improved at least one line.
According to Dr. Tong, another ingredient to watch are scleral contact lenses (SCL). A prospective, interventional case series from 2016 found SCL treatment to have a positive impact on tear osmolarity van Bijsterveld score, as well as improvements in the patients’ BCVA, DED symptoms, and overall quality of life.3
With more and varied treatment options, comes more potential for relief for DED patients. Depending on whether the case is mild or severe, or if it’s associated with other conditions (like graft versus host disease), it is up to physicians to determine which components to include in the treatment of each patient… or bake the perfect cake.
Refractive Surgery’s Better Batter
Just as different cake recipes vary, so do treatment options and strategies in refractive surgery. CAKE-appointed baker Dr. Jodhbir Mehta, head of Cornea External Disease and senior consultant in the Refractive Service at SNEC, chimes in on some of the fresh ingredients that are spicing up refractive surgery.
One is topography-guided cross linking, which – according to a 2016 study – can decrease spherical refractive errors and increase visual acuity.4 In this open-label, randomized clinical trial, investigators assessed the refractive improvements and the corneal endothelial safety of an individualized topography-guided regimen for corneal crosslinking in progressive keratoconus in 50 eyes of 37 patients. In the end, they found that “individualized topography-based crosslinking treatment centered on the ectatic cone has the potential to improve the corneal shape in keratoconus with decreased spherical refractive errors and improved visual acuity, without damage to the corneal endothelium.”
Dr. Mehta is optimistic about this procedure: “While I don’t personally have experience with it, I think it has some potential and should be watched,” he said.
Another refractive recipe that’s causing quite a stir is small incision lenticule extraction – or SMILE as it’s commonly known. “There’s a lot of development with SMILE,” said Dr. Mehta.
According to a 2018 article published in Clinical Ophthalmology, SMILE or “refractive lenticule extraction is becoming the procedure of choice for the management of myopia and myopic astigmatism owing to its precision, biomechanical stability, and better ocular surface.” While SMILE has a steeper learning curve than conventional flap-based procedures, it shares similar safety, efficacy, and predictability as LASIK and is associated with better patient satisfaction.5
In addition, Dr. Mehta shared: “I think over the next few years, we’ll see other players coming into the arena with different machines… and I think that will really ‘spice’ things up.”
The Icing on the Cataract
Flour is to cake as intraocular lenses (IOLs) are to cataract surgery – both are ‘essential ingredients’. According to Dr. Harvey Uy, medical director at Peregrine Eye and Laser Institute in the Philippines, trifocal and extended depth of focus (EDOF) IOLs are rapidly becoming the preferred ingredient for presbyopia correction.
“Over the past five years, we’ve seen a shift in our premium IOL usage from 100% bifocal IOL implantation to more than 80% implantation of trifocal and EDOF IOL,” he shared.
Dr. Uy said there are multiple reasons for this trend. For example, the increasing use of digital devices (like smartphones and tablets) has created a need for optics tailored for intermediate distance viewing. Other reasons include the need for better trifocal optics that minimize multifocal IOL visual disturbances, improved trifocal optical design, and IOL materials that maximize light utilization and visual quality.
“Bifocal IOLs will continue to have a niche market, but our operating room ‘pantries’ will have a growing inventory of trifocal and EDOF IOLs,” said Dr. Uy.
In baking, adding a new ingredient can cause quite a stir. And in ophthalmology – specifically in the quest for perfection in refractive cataract surgery – Dr. Uy said that two ‘not-so-secret’ sauces have been added to the mix: the incorporation of posterior corneal astigmatism (PCA) during IOL calculation and the use of femtosecond lasers for astigmatism correction.
“There is increasing acceptance of PCA measurements for IOL power and position calculations,” said Dr. Uy, explaining that currently, doctors use both 4th generation formulas that account for the effect of PCA (e.g., Barrett and Abulafia-Koch formulas), as well as PCA measurements from biometry devices, like Pentacam (Oculus, Wetzlar, Germany) and IOL Master 700 (Carl Zeiss Meditec Inc., Jena, Germany). “These formulas help minimize postoperative errors of refraction and are very easy to incorporate into daily practice,” he added.
According to Dr. Uy, about one-third of patients have significant astigmatism. To help reduce postoperative astigmatism and improve refractive outcomes, he suggested adding femtosecond laser-assisted cataract surgery (FLACS) topography-guided astigmatism correction.
“We currently use the Streamline IV software on a LENSAR (Orlando, FL, USA) machine,” he explained. “The system allows us to directly import topography data from several topographers, and then calculates incision length and location for arcuate incisions that reduce astigmatism.”
In addition, the software can also create toric IOL alignment marks (either on the cornea or on the anterior capsule) that the surgeon can follow, which eliminates the need for ink-based marking. “In a recent series, we determined that this system consistently allows us to achieve the predicted amount of residual astigmatism using toric IOL calculators – we save time and achieve spectacular results,” added Dr. Uy.
Complex Concoctions (and Sophisticated Soufflés)
Some cakes are simple, while others (like wedding cakes or a chocolate soufflé, for example) are more sophisticated and difficult to master. The same could apply to surgical procedures.
Dr. Mehta detailed one such recipe, which involved the explantation of KAMRA (CorneaGen, Seattle, WA, USA) inlays from three patients. In a case series published in 2018, Dr. Mehta and colleagues reported that patients developed visual symptoms from the inlays three to six years after KAMRA inlay implantation6.
“There are patients who in the past had KARMA inlay insertion under flaps – most of them were performed during clinical trials from 2008 to 2009,” said Dr. Mehta. “Some of these patients have developed a haze around the implants.” All patients reported a decline in distance vision.
“To treat these patients and remove some of the haze, we did a double excimer PTK ablation, treating the flap and the base, after implant removal,” shared Dr. Mehta. According to the paper, “six months following explantation, all patients reported improvement in visual symptoms.”
“So far, the cases we have done have worked well,” he added. “Hopefully, we won’t have too many with such bad haze!”
Dr. Uy also shared his experience with a complicated case: performing FLACS in eyes with small pupils.
“We recently encountered a patient with Fuch’s endothelial dystrophy, a brunescent cataract and 3 mm non-dilating pupil. Our plan was to perform FLACS with use of a pupil expansion device,” said Dr. Uy. In addition to standard PHACO surgical instrumentation, he mentioned that they also employed the Beaver Visitec International I-Ring and a FLACS (LENSAR) laser.
Just like in baking, this cataract procedure also requires several steps.
First, intracameral Shugarcaine, synechiolysis, mechanical stretching and viscodilation were performed. Then, according to Dr. Uy: “If there’s still inadequate pupil dilation, insert the BVA I-Ring via a 2.4 mm clear corneal incision (CCI) into the anterior chamber, then apply to the pupil margins to achieve a dilation of 7 mm.”
The ophthalmic viscosurgical device (OVD) is then removed by irrigation and aspiration and replaced with balanced saline solution (in order to mimic the normal refractive index of the anterior chamber). A safety suture is placed on the CCI.
“At this point, the patient is docked to the FLACS machine and the eye is scanned,” said Dr. Uy. Next, a 5.0 mm pupil centered capsulotomy is planned. “It is important to center the capsulotomy on the pupil instead of the optical axis to create a complete capsulotomy,” he added. After laser anterior capsulotomy and lens fragmentation, the eye is brought back to the operating room. The safety suture is removed and PHACO is performed.
“The lens softening helps lessen ultrasound energy used in these complicated cases,” noted Dr. Uy.
These complicated cases – just like making a soufflé or baking a wedding cake – require precision and skill. And each recipe here needs to be exquisitely executed. From these positive outcomes, to all the emerging and evolving treatment options, the future is certainly looking sweet for both patients and doctors.
[Editor’s note: We know we made you think about cake. A lot. We apologize in advance for any broken diets or waistbands.]Even More New Baked Goods in Cataract
In the next five years, according to Dr. Uy, cataract surgery could consistently achieve outcomes similar to laser refractive surgery. And there are certain “baked goodies” that could help optimize results.
Treats like improved IOLs made from glistening-free material and with advanced optics will be used to maximize light usage and minimize visual disturbances; while trifocal and EDOF optics will provide good vision at all distances.
Multicomponent IOLs with exchangeable optics also look promising: “If there is multifocal optic intolerance or significant refractive error, the optic can be removed and replaced with the optic with the correct dioptric power,” shared Dr. Uy.
An IOL that isn’t positioned properly is like a cake baked at the wrong temperature: no good. Dr. Uy said FLACS lasers could optimize toric placement: “Optimal placement would be based on topography data, which can reduce potential astigmatism from gaps in toric IOL power intervals. Intraoperative surgical guidance can also close the refractive error gaps.”
And with wavefront aberrometry, it is important to provide real time intraoperative guidance for IOL selection and positioning. “Postoperative wavefront aberrometry can also be used to guide touch-ups for remaining astigmatism,” he noted.
In addition, Dr. Uy said advanced biometry devices could use OCT, total corneal measurements, advanced IOL calculation formulas and artificial intelligence to learn from each refractive outcome. There could also be a sweet spot in error correction: “It may be possible for femtosecond lasers to non-invasively change the refractive index of previously implanted IOLs to correct past and future refractive errors. This exciting research work is being carried out,” he concluded.
References
- Stapleton F, Alves M, Bunya VY, et al. TFOS DEWS II Epidemiology Report. Ocul Surf. 2017;15(3):334-365.
- Alio JL, Rodriguez AE, Ferreira-Oliveira R, Wróbel-Dudzi´nska D, Abdelghany AA. Treatment of Dry Eye Disease with Autologous Platelet-Rich Plasma: A Prospective, Interventional, Non-Randomized Study. Ophthalmol Ther. 2017;6(2):285-293.
- La Porta Weber S, Becco de Souza R, Gomes JÁP, Hofling-Lima AL. The Use of the Esclera Scleral Contact Lens in the Treatment of Moderate to Severe Dry Eye Disease. Am J Ophthalmol. 2016;163:167-173.
- Nordström M, Schiller M, Fredriksson A, Behndig A. Refractive improvements and safety with topography-guided corneal crosslinking for keratoconus: 1-year results. Br J Ophthalmol. 2017;101(7):920-925.
- Titiyal JS, Kaur M, Shaikh F, Gagrani M, Brar AS, Rathi A. Small incision lenticule extraction (SMILE) techniques: patient selection and perspectives. Clin Ophthalmol. 2018;12:1685-1699. 6 Ong HS, Chan AS, Yau CW, Mehta JS. Corneal Inlays for Presbyopia Explanted Due to Corneal Haze. J Refract Surg. 2018;34(5):357-360.
