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What Drives Drug Delivery Strategies in Ophthalmology?
What Drives Drug Delivery Strategies
in Ophthalmology? by Olawale Salami
Drug delivery technologies are often designed to improve the pharmacological and therapeutic properties of already approved drugs. While they offer an obvious way of tackling high unmet needs, like treatment burden reduction or creating lifecycle management solutions for existing products, these strategies are still not widely adopted by many companies, but instead looked upon opportunistically.
Are we there yet?
During a panel discussion at the OIS Retina Innovation Showcase — held on September 10, 2020 — Dr. Sharon Bakalash, founder and CEO at SB Strategic Development Consultants, an expert in drug delivery technologies, along with other expert panelists in the field, shared her thoughts on accelerating the most promising innovations in the field of ocular drug delivery. Dr. Bakalash noted: “Historically, pharmaceutical companies have shown some unwillingness to acquire or invest in drug delivery technology companies”.
What are the possible reasons for this? The panelists shared their thoughts.
Dr. Joshua Horvath, Ph.D., director, device and packaging development, Genentech: “We don’t always have the skill sets in pharma companies to evaluate these technologies, specifically in ophthalmology, where we’ve seen many failures in drug delivery technologies — mostly at the preclinical level. While we might have the money to invest, we don’t have the workforce needed to thoroughly review these ideas. So we need our partners to do some of that legwork upfront.”
Dr. Casey C. Kopczynski, Ph.D., chief scientific officer and co-founder Aerie Pharmaceuticals: “I think the reason for this is that for drug delivery technologies, there must be some form of relatively advanced proof-of-concept and a lead that demonstrates the power of the technology — that should at least be clinic ready. I think platform technologies, in general, are more difficult to value because you are trying to agree with a potential partner on the value of a product that perhaps hasn’t been fully contemplated yet.”
Dr. Jim Cunningham, executive director of drug delivery and pharmaceutical development, Allergan: “I think the addition of novel delivery technologies to new molecules adds time, costs and risks. But the added risk is justified in areas like eye care when we’re focused on local delivery and where outcomes in real-world use are limited by poor compliance.”
Dr. Reza Haque, MD, Ph.D., senior vice president and global head of ophthalmology innovation, Santen: “One of the critical challenges we have today in developing new drug delivery solutions is improving
our understanding of these drugs’ kinetics.”
Roadblocks ahead
Dr. Bakalash stated that drug-device combinations’ commercialization has always been seen as a challenge for many big companies. The panelists discussed this extensively, drawing from their wealth of pharma industry experience.
According to Dr. Horvath: “Regarding plans to bring these combinations to market, it’s not enough to have a drug that works with these combination products. The user can make or break the product. Therefore, having these products in the hands of an ophthalmologist as early as possible in the development process can save many troubles later.”
Dr. Kopczynski said: “The potential for commercialization depends on whether the delivery system is combined with an approved or new drug. For an approved drug, therefore, the question is, how well does the pair have to work for the patients to pay a premium for that technology? These questions have huge implications on pricing.”
Dr. Cunningham noted: “Demonstrating differentiation and value in a realworld setting is vital. One of the unique challenges with combination products is that these are traditionally distinct worlds, and a combination product is more than the sum of its constituent parts. Integration is critical throughout the entire development and commercialization life cycle, and the earlier this is done, the better. Ultimately, it depends on the need. In certain areas with high unmet patient need, it can be worth taking the risk of combining a new molecule with a new drug delivery system.”
Next stop: The age of gene therapy for ocular diseases
Eyevensys, a French biotech company with dreams the size of a 747, has developed a superb way to deliver gene therapy for the treatment of eye diseases — the EYS606 non-viral gene therapy. According to Prof. Francine Behar Cohen, the CEO of Eyevensys: “Using an innovative technique that allows the expression of any therapeutic protein inside the eye through a nonviral method, this minimally invasive procedure has excellent potential for improved safety, patient compliance, and clinical outcomes.” Impressive preclinical results have led to ongoing phase 1/2 trials that aim to evaluate this technology’s proof-of-concept in patients.
What exactly is EYS606? According to Prof Cohen: “Eyevensys’ EYS606 is a technology made of three components: first, a plasmid DNA with a proprietary plasmid backbone that allows the incorporation of any gene encoding any therapeutic protein; second, a device applied on the eye surface under topical anesthesia; and third, an electrical pulse generator. Once injected, the ciliary muscle becomes a biofactory that secretes any therapeutic protein into the vitreous and posterior segment. Direct administration of plasmid into the ciliary muscle is carried out using a proprietary electrotransfection method. We have a robust pipeline covering several indications, including wet and dry AMD, geographic atrophy, retinal vein occlusion, diabetic macular edema and glaucoma.”
– Prof. Francine Behar Cohen
Extended delivery: Time to drop the bottle
Dr. Mark Blumenkranz, CEO, and his colleagues at Kedalion (California, USA), addressed age-old challenges of drug delivery to the anterior chamber.
According to Dr. Blumenkranz: “Up to 25% of eye drop bottles, even those with preservatives, are contaminated, and up to a third of patients who think they have good technique miss the eye under observational studies. Unfortunately, up to half of all patients stop using eye drops within one year of starting. We believe that Kedalion’s AcuStream provides the best solution for these issues.”
AcuStream is a novel, preservative-free, horizontal delivery system applicable to various topical pharmaceuticals in different indications. What makes AcuStream such a unique product? It has a multidose, preservative-free capability that delivers microdoses at less than 20% of an average eye drop volume, with exact proprietary aiming technology, including suspensions. More importantly, it is low cost, creating exciting commercial incentives. Multidose preservative-free delivery improves patient outcomes and eliminates preservative-related side effects.
“AcuStream technology was challenged in multiple independent laboratory studies. It showed no bacteria in the drug reservoir and comparable topical performance to paired preserved dropper bottle,” Dr. Blumenkranz added. Furthermore, smart connectivity allows patients and physicians to monitor dosing and compliance metrics and is a useful tool for compliance monitoring in clinical trials.
“The results of our prospective, randomized, double-masked clinical trial in patients with symptomatic presbyopia showed that Kedalion’s leading dose significantly outperformed other dose groups, with two-thirds of patients achieving 3 lines of near vision gains. Kedalion will use series B funding to meet several key
– Dr. Mark Blumenkranz
milestones,” shared Dr. Blumenkranz.
Kedalion also has a differentiated presbyopia candidate in its lead program, and the company is on track toward its next phase 3 study and NDA submission.
A better ride: Painless keratoconus treatment?
– Dr. Damon Smith
TALLC pharmaceuticals is developing a new generation of anti-inflammatory, analgesic drugs delivered by SmartCelle technology to address unmet patient needs. In his presentation, Dr. Damon Smith, CEO of TALLC, explained: “Our lead indication is keratoconus, an orphan disease, usually first seen in teenagers, that causes a progressive thinning, weakness, and eventually, bulging of the cornea and vision distortion.”
He added: “Current treatment options for keratoconus, such as corneal transplant or cross-linking surgery, do not address patient needs. Corneal cross-linking surgery is incredibly painful and unbearable in many of our patients. This is why many patients delay early treatment because of fear of surgery,” explained Dr. Smith.
“Therefore, if we could treat the pain effectively and believe that more patients with keratoconus will have surgical treatment earlier, outcomes would be better. Unfortunately, we cannot do this well today since opioids have a huge risk of addiction, topical non-steroidal anti-inflammatory drugs (NSAIDs) delay wound healing and increase infection risk, and steroids don’t act fast enough, delaying healing and increasing intraocular pressure (IOP).”
So what is TALLC’s solution for adequate pain control during keratoconus surgery?
“We developed a new drug called TA-A001, which acts by stimulating human CB2 receptors which are found throughout the body and extensively on immune cells, where they have a vital role in controlling inflammation. TA-A001 binds more tightly to CB2 receptors than any other receptors found in the body and is 10 times more effective than NSAIDs in pain control models. It has a rapid onset of action and produces long-lasting effects after a single administration,” said Dr. Smith. “We deliver TA-A001 using our proprietary SmartCelle technology. These are 30nm micelles which promote deep penetration of the cornea, allowing TA-A001 to combat surgical pain and inflammation more effectively,” he added.
Trans-corneal delivery to the aqueous humor trabecular meshwork and iris also generates an opportunity for glaucoma and uveitis treatments.
“Topical administration to get to the back of the eye is the holy grail, but we believe that TA-A001 delivered by SmartCelle has the potential to reach the back of the eye and treat retinal diseases,” said Dr. Smith.
TA-A001 has a unique mechanism of action, with superior efficacy, compared to any available analgesic on the market today. The topical installation makes it convenient to administer on the day before surgery and up to three days post-surgery. It does not affect wound healing or intraocular pressure and helps promote effective pain management.
Further, CB2 receptors are found both in the cornea, the trabecular meshwork of the uvea and in the retina, where inflammation is shown to be an issue with AMD. The ability to bind to CB2 receptors in the retina can have significant value for treating these diseases, perhaps without the need for intraocular injections.
Editor’s Note:
The OIS Drug Delivery Innovation Showcase was held on November 5, 2020. Reporting for this story took place during the event.
Updates from APOTS 2020
Overcoming Challenges Faced by Ophthalmologists by Hazlin Hassan
At the Asia Pacific Ophthalmic Trauma Society (APOTS) virtual conference held in September 2020, eye surgeons from around the region discussed ways to handle some of the most common challenges faced by ophthalmologists today, including traumatic hyphema, persistent hypotony, and corneal transplantation in the time of COVID-19, among others.
Management of traumatic hyphema
Post-injury accumulation of blood in the anterior chamber — or hyphema — can be one of the most challenging clinical problems faced by ophthalmologists. It is usually painful, and if left untreated, can cause permanent vision problems.
“It is important to do a proper work-up and take the patient’s detailed history, including the mechanism of injury and time of injury, with the time of visual loss, if any,” said Dr. Shams Noman, senior consultant and head of glaucoma from the Chittagong Eye Infirmary and Training Complex, Bangladesh.
The most common cause of a hyphema is blunt trauma. It can also sometimes be caused by strenuous health issues, such as whooping cough or asthma. Blood dyscrasia — such as aplastic anemia, leukemia and hemophilia — are also some of the causes of a hyphema, as well as intraocular tumors, such as retinoblastoma and iris melanoma.
Rarely, a hyphema occurs as a consequence of medical problems that can affect the eye, such as juvenile xanthogranuloma. It may be secondary to ocular surgery or laser, and some medications with anticoagulant properties (aspirin, non-steroidal antiinflammatory drugs or NSAIDs, warfarin, or clopidogrel) may also cause hyphema.
According to Dr. Noman, the principles of management include quick absorption of blood, prevention of complications, and avoidance of recurrence. “Any anticoagulation medication should be discontinued and activities should be limited. The patient should rest in a semi-upright posture, including while sleeping,” he advised. Medical treatments include sedation or complete bed rest with limited activities, cycloplegics, atropine 1% E/D, anti-inflammatories such as steroids, mild NSAIDs, as well as ocular hypotensive agents, and treatment of the cause.
Noted complications include obstruction of the trabecular meshwork with associated intraocular pressure (IOP) elevation, peripheral anterior synechiae (PAS), posterior synechiae, corneal blood staining, rebleeding, pupillary block, and amblyopia in pediatric patients.
As for the challenges that ophthalmologists face? One — in children, it’s not always possible to get them to rest. Another challenge is that associated bleeding disorders or intake of blood thinners also come with risks. Therefore, a cardiologist’s opinion should be sought before stopping blood thinners. And if rebleeding occurs, the rates and severity of complications increase and visual prognosis is reduced from 75% to 65%.
During APOTS 2020, experts build bridges to help ophthalmologists manage challenging cases.
In cases of raised IOP, anti-glaucoma medication can be given. Meanwhile, systemic antifibrinolytic agents reduce the incidence of rebleeding after traumatic hyphema. Therefore, antifibrinolytic agents, such as aminocaproic acid and tranexamic acid, prevent the activation of plasminogen. Dr. Noman noted that tranexamic acid is 8 to 10 times more potent than aminocaproic acid. Additional challenges during intervention include hypotony and ruptured globe.
To best face these challenges, timely intervention is needed and a systemic history should be excluded. It’s critical to never stop blood thinners without an internist’s opinion, and tranexamic acid may prevent rebleeding and glaucoma.
Last but not least, Dr. Noman concluded: “Take care of the cornea.”
Persistent hypotony after blunt trauma
Hypotony is an intraocular pressure (IOP) of 5mmHg or less. Low IOP can adversely impact the eye in many ways, including corneal decompensation, accelerated cataract formation, maculopathy and discomfort. “We have to first make sure there is no open globe injury because occult defects can be missed, especially in situations where the mechanisms of the injury are not well-established, or in patients who are difficult to examine — especially in young children,” advised Dr. Victor Koh, consultant ophthalmologist, from the Department of Ophthalmology at National University Hospital, Singapore.
Some common causes include cyclodialysis, ciliochoroidal detachment, ciliary body injury, retinal detachment and anterior proliferative retinopathy. Causes of cyclodialysis include trauma or iatrogenic injury after anterior segment surgery. Meanwhile, complications can range from hypotony maculopathy or edema, choroidal effusion and cataract.
Gonioscopy is one of the imaging modalities to diagnose and localize a cyclodialysis cleft, but it can be difficult due to corneal opacity, hyphema, chronic hypotony after globe trauma, or the cleft may be obscured by peripheral anterior synechiae.
Therefore, high-frequency ultrasound biomicroscopy (UBM) is Dr. Koh’s preferred choice. “It allows me to plan the surgery much better, including the diagnosis of the condition, as well as the extent of the cleft.” The aim of the treatment is to normalize IOP in the long-term and prevent complications.
For small cyclodialysis clefts, observation or the use of topical cycloplegic agents is the preferred treatment. “But in my experience, there is limited success with conservative management. My preferred approach to repairing this cleft is through direct suture cyclopexy,” shared Dr. Koh. Other repair techniques include: argon laser photocoagulation, capsular tension segment technique, cryotherapy, scleral buckling and vitrectomy with gas tamponade.
“Direct surgical cyclopexy is an effective treatment for large cyclodialysis clefts with good IOP control and visual outcomes postoperatively,” he added.
Dr. Koh closed his presentation by emphasizing that a cyclodialysis cleft is an important cause of traumatic hypotony, and that UBM is the current gold standard imaging modality in the localization of cyclodialysis clefts.
Prosthetics in ophthalmic trauma patients
According to Ms. Suriya Abu Waled, senior ocular prosthetic specialist from the Department of Ophthalmology, National University Hospital, Singapore, the most important role of an ocularist is to handle patients with mechanical trauma, such as phthisical eyes, post-enucleation or evisceration that requires ocular prostheses, chemical or burn injuries, and Stevens-Johnson Syndrome — a rare serious disorder of the skin and mucous membranes. “It is not just cosmetic, it is also physical and structural, psychological and economic rehabilitation,” noted Ms. Waled.
One case presented by Ms. Waled was a 17-year-old patient who suffered a globe rupture with the loss of intraocular tissue, phthisis bulbi and entropion. Treatment entailed emergency right globe rupture repair and right lower lid epiblepharon correction with tarsal strip. Meanwhile, post-surgery options included observation and an ocular prosthesis.
To conclude, post-enucleation socket syndrome with superior sulcus deformities, mild to moderate ptosis, and enophthalmos may be corrected with modifications to the prosthesis. Reducing the superior aspect, adding acrylic on the anterior corneal area, reducing the anterior-inferior surface, and adding acrylic on the posteroinferior surface produced satisfactory results.
For those who have lost one or both of their eyes, prosthetics can give hope and confidence to patients.
Preparing corneal tissue donors in emergency cases
Corneal transplantation, also known as corneal grafting, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue.
Corneas can be injured by central abrasions; foreign bodies; burns from chemical, thermal and radiation sources; perforations by saws, grinders and metal objects; among others.
As the COVID-19 pandemic continues, developments in the understanding of the SARS-CoV-2 virus and the screening of donors has allowed for the continued provision of safe corneal tissue.
According to Mr. Eros Rosikin, a corneal transplant coordinator from Indonesia, donors are screened for history of disease, COVID-19 symptoms, and any direct contact with COVID-19 patients. “If there is any suspicion that the donor may have COVID-19, their cornea cannot be taken,” he said.
There have been no reported cases of transmission of SARS-CoV-2, MERSCoV, or any other coronavirus via transplantation of ocular tissue. Current medical standards of the Eye Bank Association of America (EBAA) require the use of a double povidone-iodine donor prep. Povidone-iodine has documented in-vitro viricidal activity against coronaviruses. Before the procedure for the excision of the donor cornea, informed consent must be taken. The procedure only takes 10 minutes, does not leave blemishes or bleeding, and must maintain the quality of the cornea — which should be taken less than six hours postmortem. The cornea can then be stored for up to 14 days in OptisolGS.
INDUSTRY UPDATE Editor’s Note:
The Asia Pacific Ophthalmic Trauma Society (APOTS) Virtual Conference was held from September 3 to 6, 2020. Reporting for this story took place during the event.
ZEISS Launches Updated IOLMaster 700 Software
ZEISS announces new software for the IOLMaster® 700, with enhanced features and connectivity designed to improve the cataract surgeons’ workflow efficiency and support better outcomes for surgeons and patients. This latest software update includes Central Topography for more insights on corneal shape, empowers doctors to access surgical planning data on their mobile device with EQ Mobile® from ZEISS, and offers Barrett True K with Total Keratometry (TK®) formula.
“ZEISS is dedicated to advancing eye care through the development of new and innovative solutions, like the enhanced software features of the IOLMaster 700,” said Euan Thomson, PhD, President of Ophthalmic Devices and Head of the Digital Business Unit for Carl Zeiss Meditec. “With our comprehensive portfolio of ophthalmic solutions, we will continue to help make the cataract workflow a better experience for both surgeons and patients.”
Cataract surgeons need data insights that enhance their workflow efficiency. Using the Central Topography software feature, surgeons can gain additional information and detect visually relevant asymmetries on central corneal shape with the standard ZEISS IOLMaster 700 measurement. Central Topography, a new feature based on Telecentric 3- zone Keratometry and SWEPT-Source OCT, improves the cataract workflow without needing extra measurements, extra hardware, or extra time — a more intuitive reading without changing the cataract surgeon’s workflow.
When practicing at multiple sites, cataract surgeons need access to approved calculations in real-time. With the latest ZEISS IOLMaster 700 software, doctors can send their biometry data and scleral reference images via ZEISS EQ Mobile to CALLISTO eye® from ZEISS for computer assisted surgery, streamlining the cataract workflow. EQ Mobile, a cloud-based connectivity option, accesses IOL calculation reports on the doctor’s mobile device and allows them to transfer surgical planning data via the cloud to the operating room.
To improve predictions for post-refractive surgery patients, the ZEISS IOLMaster 700 software update features the new Barrett True K with TK formula with up to 12 percent more post-myopic LASIK patients within ±0.5D compared to the classic K calculation formula*. Barrett True K with TK formula uses ZEISS IOLMaster 700 TK without the need for online calculators and manual data input. The cataract workflow doesn’t change.
* Lawless M, et al. Total keratometry in intraocular lens power calculations in eyes with previous laser refractive surgery. Clin Exp Ophthalmol. 2020;48(6):749-756.
Knowledge without Borders
A Q&A with Leading Experts in Ophthalmology
by Olawale Salami
On November 19, 2020, the Alcon Experience Digital Academy organized the ”Ask the Expert” session, where a panel of leading experts in ophthalmology responded to questions from ophthalmologists worldwide. Hot topics included cataract surgery equipment, refractive and vitreoretinal surgery, dry eye and ocular health.
The expert panel was made up of the following ophthalmology experts: Dr. Soon-Phaik Chee, senior consultant for both Cataract and Comprehensive Ophthalmology Service and Ocular Inflammation and Immunology Service at the Singapore National Eye Centre (SNEC); Dr. Stephanie Watson, clinician-scientist at the University of Sydney and Sydney Eye, Sydney Children’s and Prince of Wales Hospitals; Dr. Harvey Uy, medical director at Peregrine Eye and Laser Institute in Makati, Philippines; Dr. Pravin Vaddavalli, head of the Refractive Surgery, Cataract and Contact Lens Service at the LV Prasad Eye Institute in Hyderabad, India; and Dr. Mun Wai Lee, consultant ophthalmologist, vitreoretinal surgeon, and the medical director of Lee Eye Centre in Ipoh, Malaysia.
Question 1: What are the best ways to address dry eye preoperatively in cataract and refractive surgery? — Dr. Stad, Netherlands
Dr. Stephanie Watson: From a practical point of view, patients could present in three possible clinical scenarios: asymptomatic ocular surface disease, symptomatic ocular surface disease discovered postoperatively, and finally, an overt ocular surface disease that requires preoperative treatment.
Next, it is important to remember the issues caused by concurrent dry eye and cataract surgery. Postoperatively, with both cataract and refractive surgery, these include inflammation, toxicity from medications, corneal nerves damage from incisions and increased tear evaporation.
Undiagnosed dry eye can be identified during preoperative screening, and this is best accomplished using questionnaires, including assessing possible risk factors, completed before the consultation in the clinic.
Is dry eye a common preoperative finding in cataract patients? Dry eye is quite a common disorder, and studies have shown that up to 70% of patients have some form of dry eye symptoms, and in some cases, unmasked by cataract surgery.
In eyes with established dry eye disease, screening is not required, and the clinical examination is useful in finding underlying risk factors and grading disease severity. Subsequent investigations are tailored towards the severity. Patient education and reassurance are beneficial, and it is advisable to document dry eye symptoms if they are present preoperatively. Clear communication with the ongoing patient assessment will help allay patients’ fears.
Question 2: What
is the best intraocular lens (IOL) option for a patient with biometry readings of +17D right eye and +14D left eye using the
Barrett formula? — Dr. Akanda,
Bangladesh
Dr. Harvey Uy: The best option for this patient, and any patient, is an IOL that is most satisfactory and best matches the patient’s lifestyle. Therefore, it is essential to discuss patients’ postoperative goals.
Equally important is the posterior segment examination to ensure that a multifocal lens can be used. The Barrett formula is a very accurate and easy formula to use. With pre-existing myopia in this patient, a trifocal lens would be useful to enable the patient to see at different distances, or the patient could be comfortable with a monofocal lens and wearing reading glasses.
With the 3D difference in IOL power, there is a concern for amblyopia in this patient. And in such cases with a history of amblyopia, multifocal lenses may not be feasible.
Question 3: How do you differentiate the Johnson & Johnson TECNIS Synergy, Johnson & Johnson TECNIS +2.75, and Johnson & Johnson TECNIS Symfony in terms of distance visual acuity? — Dr. Quesnel, Canada
Dr. Soon-Phaik Chee: The most crucial factor needed for great distance visual acuity with all these three premium lenses is to achieve the correct refractive target using the most accurate biometry. However, in patients with dense cataract, those with
dry eyes and with advanced posterior subcapsular cataract where optical biometry is challenging, the extended depth of focus (EDoF) lenses (TECNIS Synergy and Symfony [Johnson & Johnson Vision, Florida, USA]) would be the safest lens to use to achieve good distance acuity because they are more forgiving when the refractive target is missed slightly. Therefore, among the three lenses, the EDoF lens is preferred if good distance visual acuity is of primary importance.
Question 4: Concerning the long-term perspective, how safe are laser vision correction treatments compared to spectacles and contacts? During IOP measurements and keratometry measurements, how do we estimate values with laser in-situ keratomileusis (LASIK)corrected eyes? — Dr. Athreya, India
Dr. Pravin Vaddavalli: Concerning the safety of laser vision correction, I decided to get laser vision correction myself. And if I didn’t believe it was safe, I would still be wearing contact lenses or spectacles.
The stability of refractive correction after myopia is relative. And from the perspective of the patient, any change in refractive error could mean that the surgery has resulted in unstable refraction. Long-term studies have shown that stability after 8 to 10 years is excellent after LASIK in low to moderate myopia. However, it tends to be a little less stable for high myopia, mainly due to regression caused by the thickening of the epithelium around the cornea’s central part.
Question 5: What is the latest phaco machine from Alcon? Is it the Centurion? — Dr. Suliman, Saudi Arabia
Dr. Mun Wai Lee: The Centurion is the latest machine from Alcon. Today there has been a shift away from gravitybased fluidics to active fluidics, and the Centurion is the first machine to achieve this. It incorporates a proprietary feedback mechanism that maintains stability within the eye so that the input and egress of fluids are accurately balanced. This results in optimal control and a very stable anterior chamber during surgery.
The Centurion is more intuitive when it comes to intraocular pressure (IOP) and allows surgeons to operate at more physiological pressures with optimal control. Changes in the anterior chamber are detected by the active sentry handpiece sensor, which provides rapid feedback to the machine, controlling the input fluid and maintaining excellent stability.
Contributing Doctors
Question 6: How does a surgeon decide when to implant an anterior chamber IOL and choose the correct one? — Dr. Humphry, United Kingdom
Dr. Soon-Phaik Chee: Anterior chamber IOLs are placed in the anterior chamber of phakic eyes and are used to treat myopia or nearsightedness. These are usually flexible, open-looped IOLs, or those with iris claws, which are clipped to the iris.
When using the iris-claw IOLs, which are in the anterior chamber in front of the pupil, sizing is not an issue as these come with standard haptic lengths. However, with the open-looped IOLs, sizing becomes essential. And here, the IOL inventory will be needed to select the most suitable size. The appropriate way to size the IOL is to measure the horizontal white-to-white and add 1mm to the reading. An anterior chamber lens should be avoided in children, patients with uveitis, and glaucoma.
On the best methods, I would suggest that surgeons use methods that attach the haptics of the lens to the sclera rather than the IOL resting on the iris.
Dr. Soon-Phaik Chee, MD, is a professor at the National University of Singapore and Duke-National University of Singapore Graduate Medical School, Singapore. She is a senior consultant for both Cataract and Comprehensive Ophthalmology Service and Ocular Inflammation and Immunology Service at the Singapore National Eye Centre (SNEC). In addition to her clinical commitments, Dr. Chee also serves as group lead member of the Cataract research team at the Singapore Eye Research Institute.
Dr. Lee Mun Wai is a consultant ophthalmologist, vitreoretinal surgeon, and the medical director of Lee Eye Centre, Ipoh, Malaysia. Dr. Lee underwent ophthalmic training in the United Kingdom and Singapore and trained in vitreoretinal surgery at Lions Eye Institute, Western Australia. Active in ophthalmic research, he has published over 20 papers in peerreviewed journals.
Dr. Harvey Uy is a clinical associate professor of ophthalmology at the University of the Philippines and Medical Director at Peregrine Eye and Laser Institute in Makati, Philippines. He has published over 50 peer-reviewed articles and book chapters and serves on the American Journal of Ophthalmology Case Reports editorial board.
Dr. Pravin K. Vaddavalli serves as director of the Tej Kohli Cornea Institute at LV Prasad Eye Institute and is head of the
Refractive Surgery, Cataract and Contact Lens Service at the LV Prasad Eye Institute in Hyderabad, India. He has over 70 publications, peer-reviewed Ophthalmology journals, and over 300 presentations at international and national meetings and has written chapters for mainstream Cornea textbooks.
Dr. Stephanie Watson is a clinician-scientist known for her ground-breaking research in corneal therapies, appointed at the University of Sydney and Sydney Eye, Sydney Children’s and Prince of Wales Hospitals. She has over 106 publications, is often invited to speak internationally, and has raised over $10 million for her research program. She is chair of Ophthalmic Research Institute of Australia, chair-elect to ARVOs Advocacy and Outreach Committee, expert advisor to the $150M Stem Cell Therapies Mission, and editor for the Cochrane Eyes and Vision Group.
Editor’s Note:
The “Ask the Expert” Session organized by Alcon Experience Digital Academy was held on November 19, 2020. Reporting for this story took place during the session.
