The marvel of minimally invasive glaucoma surgeries (MIGS)—and the reason we push them earlier in the disease course—is their safety and predictable postoperative recovery. In the past, we had fewer options, most of which were more invasive.

As a result, we had to delay surgery for years while patients suffered the discomfort, inconvenience and expense of multiple medications, until finally those medications were no longer enough and surgery was unavoidable. Now we can skip years of suffering and better manage glaucoma by making MIGS part of the treatment equation.

Nowhere is the divergence between traditional surgeries and more modern procedures more apparent than in subconjunctival surgery. Historically, we were hesitant to go into the subconjunctival pathway with trabeculectomy or tube shunt because of the often slow and variable nature of visual recovery and the complex postoperative management. Instead, we waited until glaucoma progressed and the target pressure was aggressively low, often near the 10–12 mm Hg range.

Thankfully, with the options available today, we no longer need to wait so long to perform subconjunctival surgery for patients who need it, and with this earlier intervention we have a better chance of achieving target IOPs because they are not so aggressively low.

Visual recovery and conventional pathway MIGS

With conventional pathway MIGS, such as stenting (iStent; Glaukos, Hydrus; Ivantis), viscodilating (iTrack; Nova Eye Medical, OMNI; Sight Sciences), stripping (Kahook Dual Blade goniotomy; New World Medical), cutting/GATT (OMNI) and others, visual recovery is generally not a major concern. Pressurising the eye intraoperatively usually prevents intraoperative and postoperative hyphaema, although if this does still occur, it usually clears up in a short period of time.

The mechanisms that make visual recovery so seamless for conventional pathway MIGS are also the reason they are not always the best option: the episcleral venous pressure is a floor we cannot cross, so it is hard to reach target pressures below the low to mid-teens. This floor, however, also means we do not get hypotony or flat chambers, which are often the cause of postoperative vision issues.

Unfortunately, some of our patients need those lower target pressures. We also do not know where the resistance to outflow is located in our glaucoma patients; in some, the distal channels are also collapsed or atrophied. In these cases, we are not able to achieve the IOP control we need through the conventional outflow system. Therefore, we need to turn to a subconjunctival procedure to bypass the conventional pathway.

Vision after trabeculectomy or tube shunt surgery

The most common causes of postoperative visual acuity changes are hypotony, choroidals, maculopathy and ocular surface problems. With trabeculectomy and tube shunt, all these problems are possible, so it is difficult to gauge how long visual recovery will take with each patient.

Depending on how flat the chamber becomes and the position of the iris lens diaphragm complex, a return to baseline vision may take 1 week to 1 month or even longer. A non-valve tube might open up in a month and a half or even earlier when the suture dissolves, and that sudden change in IOP can cause a sudden shift in chamber depth and thus a change in vision. In addition, postoperative drops can prolong recovery by destabilising the ocular surface.

Patients who endure weeks or months of recovery are generally not happy with their vision. IOP can be unstable, so they require multiple clinic visits, and they often call the clinic with questions about vision problems and irritation from eye drop medications. The recovery process may still be going on when it is time for the patient to schedule surgery on the fellow eye, which can make them reluctant to do so.

As an experienced glaucoma specialist, I still marvel at the high potential for variability of each step for a trabeculectomy. I use various techniques to manage outcomes by controlling the size, thickness and shape of the flap; titrating the flow by suture placement and tension; and trying to aggressively bring down the IOP yet prevent chambers from flattening postoperatively.

It takes time to build that comfort and skill set, and not all patients have access to surgeons who have completed 1,000-plus trabeculectomy procedures.

 For these and a variety of additional reasons, a less invasive and more predictable subconjunctival procedure is needed to allow access for more patients than traditional surgeries.

A postoperative look at a Xen eye at 1 day, 1 week and 1 month. (

When we want to reach a lower pressure, avoid being beholden to conventional pathways where levels and locations of resistance can be uncertain and follow a more predictable visual recovery than we achieve with traditional subconjunctival procedures, subconjunctival MIGS can deliver the benefits with few limitations. The Xen Gel Stent (Allergan) uses the same bypass mechanism as trabeculectomy, but the only outflow created is a 45-μm lumen, rather than a larger, less consistent hole in the sclera with a variable flap.

With less structural deformation of the sclera, there is less chance of flat chambers postoperatively. Even if numerical hypotony occurs, the chambers do not flatten quite as much because they retain greater structural integrity. There is less concern that deformation of the eye will shift the iris lens diaphragm and cause a myopic shift or, in a pseudophakic patient, move or de-centre a toric lens.

Based on the approval trial, Xen has demonstrated a high safety profile with rare complications.

 The less invasive nature of the device means that the eye remains stable, with less inflammation in the anterior chamber and conjunctiva, often because there is no peripheral iridotomy. In addition, if implanting from an external approach, intraoperative flattening of the anterior chamber is rare.

Since flow occurs through a single point around 5 mm posterior to the limbus, rather than in multiple directions closer to the limbus as in a trabeculectomy, the bleb forms more posteriorly and often with a lower profile, resulting in a quieter bleb and shorter-duration corticosteroid use after surgery. With fewer corticosteroids and thus fewer topical preservatives, the ocular surface tends to experience less disruption and resulting postoperative vision fluctuation. Xen has also been shown to cause less endothelial cell loss than trabeculectomy, which could be an issue as patients get older and have other corneal risk factors.

Although postoperative bleb needling is sometimes needed, my postoperative bleb needling rates have dropped significantly (now less than 10%) with changes in technique, intraoperative confirmation of a freely mobile stent and use of an intraoperative needling if resistance is found. If needling is required, it is a different type of intervention than a trabeculectomy needling. We do not see a sudden drop in IOP, so there is less change in chamber depth that could affect visual recovery.

In the end, Xen reaches similarly low pressures as traditional subconjunctival surgeries, with a predictable postoperative course, resulting in fewer visits (1 week and 1 month) and calls to my practice.

 In my experience, visual acuity is often similar to baseline on postoperative Day 1, and if not, it usually reaches baseline by the 1-week visit. Patients are happy and show no reluctance to undergo surgery on the second eye — all because their postoperative course is rather benign and visual acuity is maintained.

Owing to the high safety profile and rapid visual recovery, I have now offered this device to patients who are refractory to drops despite their level of glaucoma severity. For instance, a patient with mild or moderate open-angle glaucoma who is taking four classes of medication, has a history of a previous MIGS, has stable IOP and visual folds but is not compliant with drops would not typically have been a subconjunctival bypass candidate in the past, but this patient is now a perfect candidate for a Xen.

Welcome to the interventional glaucoma mindset.

Dr Singh is President of The Eye Centers of Racine and Kenosha, Wisconsin, United States. He is a consultant to Alcon, Allergan, Bausch + Lomb, Ellex, Glaukos, Iantech, New World Medical, Omeros, Shire and Zeiss.

1. Francis BA, Hong B, Winarko J, et al. Vision loss and recovery after trabeculectomy: risk and associated risk factors. 

2. Birchall W, Bedggood A, Wells AP. Do scleral flap dimensions influence reliability of intraocular pressure control in experimental trabeculectomy? Eye (Lond). 2007;21:402- 407.

Reitsamer H, Vera V, Ruben S, et al. Three-year effectiveness and safety of the Xen gel stent as a solo procedure or in combination with phacoemulsification in open-angle glaucoma: a multicentre study. 

Olgun A, Duzgun E, Yildiz AM, et al. Xen Gel Stent versus trabeculectomy: short-term effects on corneal endothelial cells. 

Marcos Parra MT, Salinas López JA, López Grau NS, et al. Xen implant device versus trabeculectomy, either alone or in combination with phacoemulsification, in open-angle glaucoma patients. 

Articles

A gel stent allows for less invasive subconjunctival procedures and an easier recovery course than traditional forms of minimally invasive glaucoma surgery.

Achieving more predictable visual recovery following glaucoma surgery

The National Centre for Children’s Vision and Eye Health at Prevent Blindness has debuted the Children’s Vision Equity Alliance (CVEA).

For more than a decade, the National Centre for Children’s Vision and Eye Health at Prevent Blindness (NCCVEH) has worked to provide access to vision and eye care services to children across the country.

Working with other stakeholders, the NCCVEH has established the CVEA to bring together experts from eye health, education and public health groups. With these connections, it will work to advance equity in children’s vision and eye health through education, access, policies, and partnerships.

According to the recent report from the NCCVEH, “Children’s Vision and Eye Health: A Snapshot of Current National Issues 2nd Edition,” children experiencing health and socioeconomic inequities have lower rates of vision testing, experience disparities in visual impairment, and have reduced access to care.

Moreover, Latino and Black/African-American children are two to three times more likely to have unmet vision needs. Without early detection and treatment, uncorrected vision disorders can impair child development, interfere with learning, and even lead to permanent vision loss.

In an effort to address these challenges to vision care, the CVEA has set some initial goals, including to:

Foster education about the role of vision in the learning, health, and development of children in the target population of underserved communities of colour (specifically Black/African-American, Indigenous and Latinx communities), beginning with a social media campaign to educate targeted populations.

Advocate for policies and practices to support equitable access to vision care for children.

Develop partnerships to support healthy vision and eye health equity for children.

Continue to attract leaders from the fields of ophthalmology, optometry, public health, school nursing, early childhood care and education, medical care, and parent education and engagement who work toward health equity.

According to Jeff Todd, president and CEO of Prevent Blindness, since the organization’s founding in 1908, Prevent Blindness has worked to ensure all children have the eye care access they deserve to enjoy healthy vision across their lifetimes.

“Through the new Children’s Vision Equity Alliance, coordinated by our National Centre for Children’s Vision and Eye Health at Prevent Blindness, we are working collaboratively with leaders, stakeholders and advocates to make sure we evolve and grow to effectively and strategically respond to the needs of families in underserved populations and communities,” he said in a statement.

For more information about The Children’s Vision Equity Alliance or children’s vision health topics, please visit their 

 or contact Donna Fishman at 800-331-2020 or 

The Children’s Vision Equity Alliance was created to improve access in children’s vision and eye health, working to advance equity in children’s vision and eye health through education, policies and partnerships.

Children’s Vision Equity Alliance formed by Prevent Blindness’s National Centre for Children’s Vision and Eye Health

At the 2021 American Academy of Ophthalmology annual meeting, Dr Mohamed Abou Shousha, founder, president and CEO of Heru; spoke with the 

team about Heru and their new diagnostic platform, re:Vive 2.0. The new device now monitors color vision, contrast sensitivity and dark adaptation.

 My name is Mohamed Abou Shousha. I'm the CEO and founder of Heru. I'm also a practicing ophthalmologist from Bascom Palmer Eye Institute.

Heru was born out of necessity from Bascom Palmer, where we see 300,000 patients every year. And we know all the gaps in vision care. And we created Heru to address those gaps.

Heru is a wearable platform that is AI powered. It has many verticals to it: health and wellness eye exams, diagnostic eye exams, home monitoring and chronic disease management. And we close the loop by providing vision augmentations to patients to allow them to live their best lives.

I'm very excited to announce that we have launched Heru re:Vive 2.0, which is our FDA-registered diagnostic platform. It provides six diagnostic tests, five CPT codes in one wearable device. We provide suprathreshold visual field testing, full threshold visual field testing, Ishihara, D-15, contrast sensitivity and dark adaptation—and that's all in one device.

The status quo are devices, each one of them that would take a room, a separate room, a technician, a workflow, and it's about like $30–50,000. We replace all those by one wearable device.

Our science is solid. We have shown equivalency to the standard of care. So for the patient, this means better access to vision care, better vision care, better experience and ultimately better health for the patient.

The American Academy of Ophthalmology (AAO) annual meeting was held November 12 to 15 at the Ernest N. Morial Convention Centre in New Orleans, Louisiana. The event included Subspecialty Days and a virtual component for remote participation.

Videos

Dr Mohamed Abou Shousha discusses Heru’s wearable AI-powered diagnostic devices at AAO 2021.

Addressing gaps in vision care with a wearable diagnostic platform

The expectations of my patients have changed in recent years, with more now asking for independence from spectacles at all distances. However, I was not satisfied with the outcomes offered by multifocal, trifocal or traditional IOLs (with or without capsular tension rings).

Now, with the introduction of the next-generation RayOne EMV monofocal IOL (Rayner), I am able to offer many patients excellent vision at both intermediate and far distance, which satisfies much of their daily needs. The new IOL received a CE mark in June 2020.

The lens is designed to provide superior intermediate vision compared with standard monofocal IOLs and is the first and only IOL designed to enhance patient outcomes in a monovision setting; it can provide, on average, up to 2.25 D depth of focus when used with a 1.0 D offset. It is non-diffractive and dysphotopsia-free, with no zonal demarcation on the surface, and is designed to induce positive spherical aberration across a controlled aspheric surface.

There are no specific indications based on an individual’s profession, and patient selection typically depends on surgeon preference. In practice, surgeons prefer—and it is recommended that—the closest negative to zero is targeted for the dominant eye with approximately 0.75–1.0 D offset in the non-dominant eye. With the extended depth of vision provided by this lens, the dominant eye is more forgiving of post-operative myopic shift than with aberration-free aspheric IOLs.

Figure 1. Simple OVD injection into IOL cartridge.

In a first-in-eye series, patients who were implanted with this lens and followed for 1 month after surgery reported a high degree of satisfaction with refractive outcomes; 70% reported spectacle independence at distance, intermediate and near vision. No halo, glare, starbursts or haze were observed.

In addition, all patients were dysphotopsia free, and none reported trouble negotiating steps, stairs or kerbs due to changes in depth perception. Overall, no depth perception or contrast sensitivity issues were reported.

Surgeons participating in the study also responded with a great degree of satisfaction. They uniformly reported smooth lens transition with the preloaded injector (Figure 1), fine IOL control during insertion (Figure 2) and excellent stability and centration of the IOL in the capsular bag. All the participating surgeons reported reaching their targeted subjective refractive outcome.

Figure 2. Handy IOL implantation through the preloaded injector. 

No intraoperative or postoperative adverse effects were reported. One practice participating in the series administered a spectacle independence and visual functioning questionnaire to patients receiving the lens. All respondents reported no difficulty in reading medicine bottles, participating in sports, watching television or driving during the day or night.

The lens is compatible with a smartphone app that is associated with it and free-of-charge to Rayner customers. The app is a unique telehealth solution for collecting patient-reported outcomes data for the first 3 years after cataract surgery.

It is hoped that with this unique data-collection tool, we will be able to better evaluate clinical outcomes over time. Additional clinical studies are also planned to further contribute to the weight of evidence with this innovative technology.

Functional intermediate vision means that patients can read their mobile phone, use a computer, shop and enjoy a meal without the use of glasses. With the appropriate light, they can also read at near distance with the binocular use of both eyes, which is an important feature of this monofocal option.

I think that this lens will be an attractive option as many patients are asking for presbyopia correction and the previously available multifocal IOLs have not been able to achieve excellent vision results. This is sometimes because preoperative patient consultations have not fully identified the patient’s expected outcomes, especially with respect to the need for a period of postoperative adaptation with most multifocal IOLs.

For this reason, the new lens may be attractive for many clinics in Italy, as it will likely meet many patients’ expectations in terms of glasses independence and does not involve a period of adaptation after surgery. We have based the cost to patients on the price of the IOL and do not impose a premium charge for the implantation procedure itself.

I also explain to the patients of mine who are good candidates and considering the new lens that without the features that this particular lens provides, they will continue to replace glasses every few years for the rest of their lives, which of course will add up to considerable costs over time.

Although my clinic is still in its initial phase of experience with this lens, my patients and I have been very happy with the outcomes we have seen, including greater spectacle independence with few reports of visual disturbances. Additional data from the patient-reported outcomes database and further clinical studies will allow us to increase our degree of confidence in this new option in the monofocal setting.

With the ability to provide quality of vision for sports, socialising, computer use and other daily activities, the outcomes already seen in initial experience will likely translate to a better quality of life as well.

Dr Buratto is the director of the Centro Ambrosiano Oftalmico - Camo S.p.A. (Ophthalmic Microsurgery Centre) in Milan, Italy. He has no relevant financial disclosures.

Patients desire spectacle independence at all distances. Early experience with a recently launched IOL suggests that it can satisfy their demands for extended depth of vision.

New IOL offers patients greater spectacle independence over wider range

Study reports that optic nerve pallor is prevalent in ZIKA virus patients

Dr Denise Freitas reported that the ocular findings in infants with congenital Zika virus syndrome were similar among the affected infants and occurred frequently. The most prevalent of the findings was optic nerve pallor.

Presbyopia-correcting drops provide hope for frustrated patients

Dr Cathleen McCabe describes how VUITY, the first and only FDA-approved eye drop to treat age-related blurry near vision, provides opportunities for patients looking for spectacle independence.

Mitomycin C associated with increase in corneal haze after corneal crosslinking

Dr Shady Awwad pointed out that the application of mitomycin C after corneal crosslinking does not prevent development of corneal haze after the procedure and instead contributes to development of more corneal haze.

Study of bimatoprost implant reports IOP reduction for 2 years or more

Dr Felipe Medeiros noted that a phase 3 clinical extension study of the bimatoprost implant found that patients’ IOP was lowered and stayed low with no additional treatment or changes in their visual fields.

Though rare, ocular surface tumours often prove deadly

Nathan Hall pointed out that an epidemiologic analysis of malignant ocular surface tumours found significant differences in geographic prevalence rates in the United States.

Study proves intra-arterial tissue plasminogen activator beneficial for treatment of central retinal artery occlusion

Intra-arterial tPA treatment could provide benefits for patients with central retinal artery occlusion.

Universal face masking reduces endophthalmitis incidence during anti-VEGF injections

Dr Sunir J. Garg speaks on the influence of COVID-19 universal face masking on the risk of endophthalmitis following intravitreal anti-VEGF injections.

Dosing variability with pre-filled syringes of aflibercept presents risk of overdose

Dr Roger A. Goldberg noted that small misalignments in the plunger can lead to possible overdosing.

Plasma metabolomic profiles could predict AMD progression

Dr Ines Lains explained that the mechanisms of AMD progression currently remain poorly understood and the tools to predict and halt progression are limited.

Drug delivery to retina via port delivery system is efficient for patients with wet AMD

In a poster presented at the American Academy of Ophthalmology 2021 annual meeting in New Orleans, Dr Mark Wieland noted that the port delivery system with ranibizumab provides drug delivery over an extended period.

Central subfield thickness changes linked to worse visual outcomes in DMO

Dr Ajay Kuriyan discusses his poster at AAO, "Fluctuations in central subfield thickness associated with worse visual outcomes in patients with diabetic macular oedema in clinical trial setting."

DMO treatment: Brolucizumab proves noninferior to aflibercept, requires fewer injections

Dr Dilsher Dhoot reported the results of the KESTREL and KITE in which brolucizumab was compared with aflibercept for treating diabetic macular oedema.

DMO: Study finds faricimab provides sustained retinal stability

Dr Veeral Sheth presented research that found faricimab, a bispecific monoclonal antibody, provided sustained retinal stability in patients with diabetic macular oedema (DMO) compared with other retinal treatments.

President John Saharek on the ImprimisRx pipeline, details 3 products

ImprimisRx President John Saharek shares an update on a few of the company's latest products during AAO 2021.

A brief overview of the plethora of findings presented at the 2021 American Academy of Ophthalmology meeting held November 12-15 in New Orleans, LA.

Review of findings presented at the American Academy of Ophthalmology annual meeting

The port delivery system with ranibizumab (Susvimo, Roche/Genentech), an ocular implant approved recently to treat wet age-related macular degeneration, provides drug delivery over an extended period. The implant provides a dose of 100 mg/ml that is released over 6 months. The implant was approved based on the results of the Archway phase 3 study in which the results of the implant were compared with the results achieved with injections of ranibizumab alone.

Retina specialists Drs Mark Wieland and Jay Stewart looked at the implant’s release and refill-exchange efficiency in vitro and reported that “about 70% of the ranibizumab 100 mg/mL was released from the implant over 6 months; levels were unmeasurable after 450 days.”

Dr Weiland discussed their findings during a presentation at the American Academy of Ophthalmology 2021 annual meeting in New Orleans.

Specifically, the mean respective active release rates at 6 months, expressed as µg/day, were 3.95, 3.99, 3.85, and 4.00 at the initial filling of the implant and at the first, second, and third refill/exchanges, they reported.

They also found that during refilling of the implant, about 98% of the previous implant contents were replaced with fresh drug in one 100 mg/mL refill.

The investigators concluded that the PDS continuously and reproducibly delivers ranibizumab over a period of months while maintaining its potency.

's Sheryl Stevenson speaks with Dr Sunir J. Garg, co-director of retina research at the Wills Eye Hospital in Baltimore, Maryland, United States, on the highlights of his presentation at the 2021 annual American Academy of Ophthalmology (AAO) meeting regarding the impact of COVID-19 universal face masking on the risk of endophthalmitis following intravitreal anti-vascular endothelial growth factor (VEGF) injections.

The American Academy of Ophthalmology (AAO) annual meeting was held November 12 to 15 at the Ernest N. Morial Convention Centre in New Orleans, Louisiana, United States. The event included Subspecialty Days and a virtual component for remote participation.

Cheryl Guttman Krader is a contributor to Dermatology Times, Ophthalmology Times, and Urology Times.

As cases of diabetes increase worldwide, the disease is accompanied by a precipitous increase in its most common complication, diabetic retinopathy (DR). At the same time, the aging population is growing, which is significant considering that the risk of developing DR increases the longer individuals live with diabetes and that the consequences of DR are unique in older patients.

In a recently published article, Dr Ashay D. Bhatwadekar and colleagues reviewed these issues to increase awareness and identify the best strategies for patient care.

“Understanding age-related retinal changes that increase vulnerability to DR in older individuals and age-related therapeutic challenges is essential for optimizing treatment of DR within the senior population,” said Dr Bhatwadekar, an associate professor of ophthalmology at the Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, in Indianapolis.

“Proper treatment of DR in [senior patients] could reduce the overall burden of diabetes.”

The authors pointed out that the retinal structure is altered with age in several ways. Macular blood flow decreases by 20% on average and the retina becomes thinner, with the change in thickness especially affecting the inner nuclear layer. In addition, the response of the microglia to injury slows, Müller cells become more susceptible to oxidative stress and the extent of lipofuscin accumulation in retinal pigment epithelial cells increases.

“The changes in blood flow that occur with aging may worsen ocular perfusion abnormalities in diabetes, and proliferation of microglia in the outer retina can contribute to proinflammatory responses,” Dr Bhatwadekar said.

There are also age-related metabolic changes affecting the retina that are relevant for the development of DR. Disease-specific pathophysiologic mechanisms, such as accumulation of advanced glycation end products and the polyol pathway that contribute to oxidative stress, take advantage of the aging retina’s vulnerability that is associated with a defunct antioxidant defence system.

In addition, the effects of the VEGF pathway, which promotes angiogenesis, vascular permeability, and inflammation, could be augmented in the eyes of elderly individuals by the presence of a decreased retinal blood flow, Dr Bhatwadekar explained.

Other DR pathogenic pathways that may be exacerbated by aging-related alterations relate to protein kinase C activation and hexosamine.

Clinical studies of DR in aging individuals highlight the heightened concerns in senior patients. Not only does the prevalence of DR increase with age, but available evidence points to associations with depression and cognitive decline.

The article reviews current treatments for DR and diabetic macular oedema, including a discussion of their mechanisms and role in clinical care. In addition, summary information is presented about emerging treatments that are being investigated in both preclinical and clinical trials. These include aldose reductase inhibitors that work by inhibiting the polyol pathway, a treatment that increases expression of sirtuin 1, protein kinase C inhibition and gene therapy to introduce VEGF genes. In addition, there is interest in sodium-glucose cotransporter 2 inhibition and angiopoietin-2 inhibition.

Highlighting the therapy-related challenges occurring in the senior population, the article discusses problems with medication adherence and age-related changes in drug pharmacokinetics and pharmacodynamics.

Anatomic and physiologic changes that occur with aging and the effects of medications that are commonly used by elderly individuals can lead to decreased absorption of orally administered drugs with the potential for reduced efficacy. Thus, the need may arise to consider modifications in the dosing regimen or delivery method.

As noted in the article, an increase in proteases within the vitreous that has been noted with aging suggests there may be age-related pharmacokinetic differences in drugs administered by intravitreal injection. Changes in drug distribution within the eye also may occur, and the potential for age-related differences in systemic distribution, drug metabolism and elimination also needs to be considered when investigating medications administered via an extraocular route.

Older individuals are more prone to medication nonadherence, which should be considered in their use of oral medications and in maintaining follow-up when receiving in-office treatments for diabetic eye disease.

“In the future, it is necessary to consider all of the above factors [when] treating senior patients with DR,” Dr Bhatwadekar said. “Special programs directed toward tailoring and monitoring therapy may provide a better therapeutic outcome for [elderly patients].”

Dr Bhatwadekar is an ad hoc pharmacist at PCA Pharmacy. He reports no other relevant conflicts of interest.

Leley SP, Ciulla TA, Bhatwadekar AD. Diabetic retinopathy in the aging population: A perspective of pathogenesis and treatment. 

. 2021;16:1367-1378. doi:10.2147/CIA.S297494

Confronting issues unique to aging may lead to better outcomes.

Managing senior-specific complications of diabetic eye disease

Dr LaHood is an ophthalmologist specialising in refractive cataract and laser surgery in Adelaide, Australia. His research and teaching focus on the management of astigmatism. He is a consultant to Alcon and Zeiss.

, published in the last month’s edition of 

, looked at patient selection and optimising biometry. In Part 2 of this three-part series, I will provide tips on calculating toric IOL sphere and cylinder power, which can be a great concern to surgeons who use these lenses. I will attempt to simplify the process and explain away certain myths that exist.

There are many toric IOLs on the market. One of the most common questions I am asked is: “What is your go-to lens?” My answer is that all the major brands have good-quality toric lenses that will give you favourable results if you follow the steps I outline.

One of the key considerations is hydrophilic versus hydrophobic designs. Hydrophilic lenses go through a much smaller incision than hydrophobic lenses (1.8 mm) which we know is astigmatically neutral. However, an incision this size requires more specialised equipment, and the hassle-to-benefit ratio favours it being a hassle, in my view.

I advise new surgeons to make their incision size as small as they comfortably can. There is no longer a reason to use a 2.75-mm or even 2.4-mm incision. The sweet spot of incision sizes is 2.2 mm. It provides for a multitude of choices, including hydrophobic lenses.

Hydrophilic lenses have had bad press in the past few years because of fears of opacification, especially if they are exposed to gases inside the eye. In my experience of reviewing these IOLs over many years, I have not seen a single opaque lens, but I accept it does occur on rare occasions.

I think the risks of hydrophilic lens use have been overstated. I avoid them in patients who may undergo procedures with gas in the future, such as an endothelial transplant, but in a standard eye it would not sway my decision.

Certain hydrophilic lenses also have an advantage in terms of ease of rotation. For example, the haptic design of the AT TORBI Toric IOL (Carl Zeiss) is bidirectional and bi-toric, so it can be implanted upside down. This benefits those who are learning because there is no need to worry about the direction of rotation to the targeted axis.

With the standard C-loop haptic design of many toric lenses, if you go slightly past where you intended to place it then you have to bring it back around 180° to get closer to where you want it. Some people call this “the lap of shame” and some call it “the lap of honour.” Either way it can be a frustrating process.

The extra time involved should not be a concern, though. Keep in mind that you are working hard to place it in the right spot for the rest of the patient’s life, so it does not matter if it takes an extra 5 minutes. This is better than having to schedule a second surgery to rotate a misplaced toric IOL.

Another consideration is the cylinder steps that each manufacturer produces. For example, the AcrySOf IQ Toric IOL or Clareon Toric IOL (Alcon) and the Tecnis Toric II (Johnson & Johnson) have 0.75-D steps between most of the cylinder powers, whereas the AT TORBI Toric IOL has a consistent 0.5-D cylinder step.

My colleagues and I recently completed a study evaluating whether the step magnitude made any difference in around 1,000 implanted eyes with two surgeons using 0.5-D steps and two surgeons using 0.75-D steps. We audited our results and found no significant difference between the two in terms of residual refractive error (unpublished data).

This might seem counterintuitive because you would think that smaller steps yield better results. The key is to keep in mind that regardless of whether you are using 0.75-D or 0.5-D steps, you are doing a good job and do not need to change your approach, so do not base your toric choice on the cylinder step magnitude.

In the end, IOL selection will likely come down to familiarity with the platform. There are no features of the major toric IOLs that make me feel that any one is significantly superior to the others.

Whether you are used to a plate haptic or a C-loop haptic, stick with that selection for your early cases and then feel free to experiment once you have some experience. Eventually you will choose based on the predictability of refractive results but, until that time, I urge you to try all the options and see what suits you best.

There are a lot of third-party and manufacturer toric IOL calculators online. With very basic maths, anyone can calculate what spherical power an eye needs by simply knowing the shape of the front and the length of the eye.

Calculating a toric lens means calculating two lenses – one for each axis. This is still rather simple but people have put a lot of time and effort into refining the process by taking into account the expected lens position, anticipated tilt, posterior corneal astigmatism, etc., so it makes sense to rely on robust, tested calculators. Each of the main lens manufacturers has a calculator, and those such as the Barrett Toric Calculator are also available.

For beginners, I recommend starting out with your lens manufacturer’s calculator. When people are implanting a spherical lens, they will usually look at multiple formulas and decide on which formula suits the eye. With a toric calculator, you do not have this option unless you want to look at multiple calculators.

I have used the Z CALC Online IOL Calculator (Carl Zeiss) website in conjunction with the Goggin nomogram adjusted anterior keratometry (GNAK) when implanting Zeiss toric IOLs and the Barrett Toric Calculator when implanting Alcon toric IOLs and been very happy with both sets of results.

Historically, toric calculators would use the anterior keratometry values and tell you which toric lens would suit a particular eye to give the best refractive outcome. However, we then rediscovered that posterior corneal astigmatism has an impact on the precision of that calculation.

Therefore, different ideas arose for how to incorporate the posterior cornea into the toric IOL calculation. One of these was the Baylor nomogram by Dr Douglas Koch, which makes an adjustment to the cylinder power of the toric IOL. He reported that, depending on the orientation of the anterior corneal astigmatism, you can adjust the cylinder power for that eye up or down.

The other nomogram was from Dr Michael G. Goggin: he adjusted the input instead of the output. He adjusted the keratometry values themselves, and his nomogram is available online at goggintoric.com. I use this calculator because it is the only toric calculator that has prospective published data proving that it is effective.1

Third-party calculators, such as the Alcon Toric IOL Calculator, the Johnson & Johnson Toric Calculator and the Barrett Toric Calculator, incorporate a posterior corneal adjustment that means that nomogram adjustments are not necessary. If you used one of those calculators and also added the Baylor or the GNAK, in principle you would over-adjust for the posterior cornea because you would adjust for it twice. Now, you can simply use one of those calculators mentioned.

What you will find is, when an adjustment is made for the posterior cornea in the calculation of the toric IOL, there is an adjustment made to the power of the cylinder that you are putting in, and you will also notice an adjustment to the axis of implantation. This means that when you take the posterior cornea into consideration as well as the anterior cornea, you are playing with the total corneal power. It is simple vector mathematics that makes sense.

Notably, the steep axis of the total cornea may be quite different from what you have measured on the anterior surface. This will have the biggest impact for a toric lens to treat low-powered oblique astigmatism. A recent study revealed that when you are dealing with an eye with oblique anterior corneal astigmatism, there is no need to adjust the axis of toric IOL implantation from the steep axis of the anterior cornea.2

It can be quite disconcerting to go against the recommendation of online calculators, so I recommend starting with simple with-the-rule or against-the-rule eyes. In some instances, toric IOL calculators can provide various powers with different options.

Some of those options are going to ‘flip the axis’. For example, one cylinder power option will suggest leaving the eye with 0.5 D of astigmatism in the pre-existing axis. Essentially, you underpower the treatment. This could be reasonable, or you could put in the next cylinder magnitude step up and flip the axis of astigmatism but leave that person with only 0.1 D of residual astigmatism.

With glasses, we know that you should not flip the axis, but inside the eye, minimal residual astigmatism regardless of axis is beneficial in terms of visual quality. My advice is to aim for the smallest predicted residual astigmatic error and not to worry at all about flipping the axis of astigmatism.

The other consideration that often arises with targeting minimal residual astigmatism is whether patients should be left with some with-the-rule astigmatism so that they are happy as they age and their cornea changes shape. We know that at a population level, there is more against-the-rule corneal astigmatism in older age and more with-the-rule astigmatism in younger patients. However, we cannot currently predict at an individual level whether an eye will change with time.

I do not personally subscribe to the philosophy of leaving someone with residual with-the-rule astigmatism to ‘future-proof’ their vision. I instead prefer to aim for the best possible unaided visual acuity initially and to deal with any change in the future. This comes down to personal preference.

The final myth that I would like to address when it comes to calculating an appropriate toric IOL cylinder power is that you can ‘depower’ a toric IOL cylinder power by leaving it a few degrees off axis. The idea for this comes from our knowledge that if a toric IOL is not aligned correctly to the steep corneal axis, then it has less optical effect to neutralise astigmatism at that axis. However, the cylinder power does not magically disappear; it is still inside the eye.

The best optical result you can achieve is when the cylinder of the toric IOL is aligned with the steep axis of the cornea. Rotating it away from this location to depower it and precisely treat the astigmatism on the steep axis will only add residual astigmatism at another axis. This can be proven mathematically and graphically but the technique is still commonly discussed.

My advice is to calculate a toric IOL with the best cylinder power to treat the astigmatism in the eye and to aim to leave it on that steep corneal axis. It may slightly under- or over-treat the corneal astigmatism but it will ultimately give the best achievable refractive outcome with that IOL.

When inputting your data and plans into toric calculators, you will be asked for a surgically induced astigmatism (SIA) prediction. What you are basically doing is telling the calculator, when it is doing the vector maths and taking into consideration the anterior and posterior corneal astigmatism as well as that of the toric IOL, to add a vector of a certain magnitude acting at the axis of your planned incision. This should seem straightforward enough.

If you were to plot the SIA figures from multiple eyes onto a double-angle vector diagram or a centroid plot, you would obtain roughly 0.1 D. Many surgeons would say that is what you should put into the calculator, a 0.1-D flattening effect at your incision. This estimate does work but the problem is that we do not know where that surgically induced astigmatism is going to act in an individual eye.

When we make a cut into a cornea, we simply do not know enough about corneal biomechanics to be able to predict how it will respond. Classical teaching was that if you make a cut at 180°, you will get flattening on that axis and steepening at 90°. If only life were that simple!

Certainly, this is the case for very large incisions, however, for smaller phaco incisions the orientation of the average flattening effect is extremely unpredictable. The centroid value is reasonable since, when you add the vectors of all the SIA values and average them, a 0.1D flattening effect occurs at the axis of the incision; however, if we are going to guess where this effect occurs for an individual eye, I personally would rather estimate zero. This way, even if the flattening effect occurs at 90° to what I had expected, my outcome is no worse off.

I realise that the difference between zero and 0.1 D is tiny but if you understand that this is an estimate for an individual eye based on an extremely variable axis, then I would hope you would also see that zero makes more sense in terms of eliminating unnecessary variables.

So, we have chosen a patient, taken biometry and calculated a toric IOL. The next step is to perform surgery. In the third and final part of this series on getting started with toric IOLs I will discuss what I consider the key points of the surgical and postoperative periods to achieving successful outcomes and how to deal with problems.

1. LaHood BR, Goggin M, Esterman A. Assessing the likely effect of posterior corneal curvature on toric IOL calculation for IOLs of 2.50 D or greater cylinder power. 

2. Ophir SS, LaHood B, Goggin M. Refractive outcome of toric intraocular lens calculation in cases of oblique anterior corneal astigmatism.

This three-part feature discusses tips for success when getting started with toric IOLs. Part 2 tackles calculating toric IOL sphere and cylinder power; though it can seem daunting when treating astigmatism, the process can be simplified with a few key considerations.

Toric IOLs for beginners: Advice on selecting and calculating toric IOL sphere and cylinder power

At the American Academy of Ophthalmology annual meeting, Marc Berger, COO of Verana Health, discussed the VeraQ quality measures dashboard for the IRIS registry report. It is anticipated to launch in 2022.

VeraQ is AI-enhanced health data engine that utilizes the Axon, AQUA and IRIS registries to report on unfiltered healthcare data. Additionally, it enables compliance with Merit-based Incentive Payment System (MIPS), meeting care quality measurements required by the Centres for Medicare and Medicaid Services (CMS). It also helps to identify patients who qualify for a clinical trial.

 Very excited to be here with everyone. In terms of the IRIS registry, I think this is the first year where Verana actually has been ingesting and curating data directly from participating practices.

So we are working end-to-end processing of EHR data, where we're partnering with practices and our technology on our platform, the VeraQ platform, brings in the data, and then organizes in a way which which more effectively processes the data and gives us a better sense of for analysing this information. And in turn, we're able to then provide better insights, more accurate calculations for MIPS specifically, but then they're also use cases that are going to be developed on top of that.

So our use cases are developing particularly around the MIPS calculations and our quality measures. So participating practice will have better and more accurate information, accurate data, be able to run their practices more effectively, and ultimately treat patients with better care.

And that's really the, the keystone of what we're accomplishing over these past two years in our partnership with the AAO. The quality measures database is now being powered by our VeraQ platform. And this platform, like we discussed is more effective from a technological perspective. We've got proprietary algorithms using the data that's provided by participating practices. We're able to provide more accurate and more effective data sets which can then lead to better calculations for MIPS and better-quality reporting, just giving doctors and the administrators as part of these practices, better information within their practices.

Verana Health showcases the VeraQ quality measures dashboard for the IRIS registry report at AAO 2021.

Managing senior-specific complications of diabetic eye disease

Toric IOLs for beginners: Advice on selecting and calculating toric IOL sphere and cylinder power

Verana Health's new quality measures dashboard unveiled at AAO 2021