Managing Corneal Disorders in Cataract and Refractive Patients

by Hazlin Hassan Managing Corneal Disorders in

Cataract and Refractive Patients

For refractive surgery patients, new technologies are available for the detection of corneal disorders, thereby potentially improving outcomes.

This is among the good news that delegates heard at the 37 th Congress of the European Society of Cataract and Refractive Surgeons (ESCRS Paris 2019) during the EuCornea Symposium called ‘Approaches to the Diagnosis and Management of Important Corneal Disorders in the Cataract and Refractive Patient’.

Diagnostic Imaging of the Irregular-Keratoconic Cornea

Prof. Georgios D. Kymionis of JulesGonin Eye Hospital and University of Lausanne, Switzerland, explained that keratoconus – a disorder where the cornea thins into a cone-shape and distorts vision – occurs in one of 2,000 people, with 7% having family history of the disease.

The incidence of keratoconus differs according to geographical location and environmental factors may also contribute to the wide variation in prevalence. Areas with sunshine and hot weather like India and the Middle East have a higher prevalence (2.3%), compared with places with less sunshine such as Finland, Denmark and Russia (0.0003%).

“Thus, ultraviolet light-induced oxidative stress may have a role to play,” said Prof. Kymionis.

Keratoconus impacts the patient’s quality of life. “Vision-related quality of life was worse in keratoconic patients due to low visual acuity,” he explained, adding that using contact lenses to maintain visual acuity (VA) may improve vision-related quality of life. Keratoconic patients also had significantly lower values in social functioning, mental

Diagnostic imaging is the 'cherry on top' for evaluating keratoconus.

health, role difficulties and overall composite scores.

Diagnostic imaging technology is essential for corneal analysis, especially in the early stages of disease. It’s used for screening subclinical keratoconus and evaluating the disease’s progression, preoperative screening of refractive (excluding patients with subclinical keratoconus) and cataract patients – especially in those where a premium intraocular lens (IOL) is used. It’s also important in the evaluation of corneal irregularities in postrefractive surgery patients and in the determination of possible retreatment. Diagnostic imaging technology for corneal analysis includes topography, tomography, corneal thickness maps, epithelial thickness maps, aberrometers and artificial intelligence (AI).

Comparing corneal topography to tomography, Prof. Kymionis said that corneal topography is limited to evaluating the anterior surface of the cornea and has decreased sensitivity and specificity for patients with subclinical keratoconus. On the other hand, corneal tomography measures the elevation maps of both the anterior and posterior corneal surface, lens thickness and opacification, as well as higher order aberrations.

High order aberrations of the anterior and posterior corneal surfaces are good indicators for diagnosing keratoconus and for classifying the stage of the disease, with sensitivity and specificity of 98 and 99%, respectively. “The diagnosis of irregular corneas is complex and depends on many factors. One device by itself is not a good predictor of the condition. Predictive models can be obtained in combination with other indicators,” concluded Prof. Kymionis.

New Technologies for the Detection of Corneal Disorders in Refractive Surgery Patients

According to Prof. Burkhard Dick from the University Eye Hospital Bochum, Germany, new technologies are now available for the early detection of corneal disorders in refractive surgery patients. “Early detection of keratoconus is a serious need. The lack of affordable tools is holding us back,” he explained.

Millions of patients are at risk for keratoconus based on corneal curvature alone, revealed Prof. Dick. There are 309 million patients with >46D corneal curvature or >2D cylinder. Some 90% of these patients live in Asia-Pacific countries, while 60 percent live in India and China. A total of 1.7 million patients are between the ages of 15 and 30-years-old. And while there are 4,000 cornea specialists, around 75% of physicians worldwide do not have topography capability in their offices. This is where the Delphi EyeTopo System – a small, fast and cost-effective smartphone-based topography system at around $1,800 per unit – can help fill the gap. It’s equipped with AI-enhanced, cloud-based analytics and backed by

the entire Nidek Magellan topography library, available to the smartphone and cloud environment.

Genetic testing can also be done to identify patients at risk. Genomic deoxyribonucleic acid (DNA) is extracted from a buccal swab sample, and next generation sequencing (NGS) analysis is carried out using a custom panel, primarily targeting the coding regions of 75 genes identified to be involved in the eye structure and function.

The test screens for over 70 mutations that lead to transforming growth factor beta-induced (TGFBI) corneal dystrophies. This allows for the analysis of a larger number of collected positives and control samples, greater detailed information on individual variant contribution to keratoconus progression, and therapeutic use.

There is a need for technology that is easy to adopt, and AI will further improve diagnosis of the disease. Genetic testing is a new addition to the clinician’s toolbox. Add this to existing optical and scanning methods, and at-risk patients can be identified earlier, perhaps before any changes are detected on current devices. With improved monitoring, doctors can implement preventative treatments. Preoperative evaluation in refractive surgery can help determine the individual’s potential to progress to keratoconus, which can be a deciding factor in procedure selection or against a corneal procedure.

Preventing the Onset and Progression of Keratoconus

Dr. Mario Nubile, MD, PhD, from the University of Chieti Pescara, Chieti, Italy, provided tips on how to prevent the onset or progression of keratoconus.

“Avoid eye rubbing and use topical steroids or cyclosporine eye drops,” he advised, noting that hybrid lenses offer higher satisfaction and visionrelated quality of life, as compared to rigid lenses. Larger diameter contact lenses are associated with decreased lens awareness and enhanced on-eye stability.

On corneal transplants, he said that deep anterior lamellar keratoplasty (DALK), a safe procedure for all levels of keratoconus, is preferred in phakic eyes or in patients with mental disability. It spares the recipient’s endothelium, there is a lower risk of rejection and a higher graft lifespan, and it’s less prone to increases in intraocular pressure (IOP). “Penetrating keratoplasty (PK) to treat advanced keratoconus with endothelial failure has a higher risk of rejection and deep central corneal scarring,” added Dr. Nubile.

Editor’s Note: The 37th Congress of the European Society of Cataract and Refractive Surgeons (ESCRS) took place from September 14 to 18 at Pavilion 7, Paris Expo, Porte de Versailles, Paris, France. Reporting for this story also took place at the ESCRS 2019.

INDUSTRY UPDATE

New Intraocular Lens Injector Announced by Medicel

Switzerland-based med-tech company Medicel, a leading producer of lens injection systems, has announced a new intraocular lens (IOL) injector: Ergojet. The new multi-purpose tool is an evolution of ACCUJECT PRO and promises increased safety and efficiency in ophthalmic surgery. Medicel is the exclusive manufacturer of this patented technology.

Designed with vital input from surgeons, Ergojet was created for an easier, more ergonomic procedure, and comes with bespoke adaptation, readyto-use documentation, and packaging solutions. Additionally, it enables IOL manufacturers to go to market with a reliable, high-end system in the shortest time frame. Two IOL manufacturers launched the preloaded IOL Ergojet at ESCRS Paris 2019.

The pioneering instrument is the first disposable screw injector and is made for single-handed operation of a push injector. This allows for smooth and controlled injection of almost any one-piece IOL, and it can be used in various ophthalmic surgeries, including implanting IOL pressure sensors, capsular tension rings, IOLs and artificial irises. Ergojet can also aid in corneal transplants.

The new instrument retains the benefits and is compatible with ACCUJECT PRO, a platform for preloaded hydrophobic and hydrophilic preloaded systems. It’s designed to lie stable, without unintended rotation between the thumb and index finger, and the gear driven plunger allows surgeons to screw or push with one hand for complete control and easier operation. Ergojet is available as backor top-loaded, with incisions ranging from 1.6 to 3.0mm, depending on the lens and diopter used.

Designed with Switzerland’s famous watch technology in mind, Medicel focused on precision gears – resulting in an almost powerless transmission. This means it doesn’t matter how fast or slow surgeons inject: It follows their direction and turns the operation wheel accordingly. The power felt is only one-quarter of that invested, which makes surgery less risky for patients and surgeons alike.

Worldwide, Medicel injection systems are used in 20% of foldable IOL procedures.