Achieving ‘super vision’ with corneal surgery
Main symposium speakers discuss definitions, metrics, and surgical techniques. Cheryl Guttman Krader reports
Cornea-based techniques for vision correction are being highlighted during the ESCRS Congress Sunday morning main symposium. The session is titled “20/20 in 2020: Cornea” and is chaired by Béatrice Cochener-Lamard MD, PhD, and Vikentia Katsanevaki MD, PhD.
Dr Cochener-Lamard noted that the evocation of 2020 lent itself nicely to craft a title using a word play on “20/20 visual acuity” for a programme reviewing past and forthcoming advances in cornea-based approaches to refractive surgery.
“Refractive surgery was born with the application of incisional corneal surgery and then advanced and expanded with the introduction of procedures using the micron precision excimer laser followed by intrastromal strategies and most recently by femtosecond laser lenticule extraction,” said Dr Cochener-Lamard, Professor and Chair of Ophthalmology, University Hospital of Brest, France.
“Over the years we have seen patient outcomes benefit because of technological advances in energy delivery that improve treatment profiles and imaging techniques for centration optimisation, pupillary shift correction, cyclotorsion compensation for astigmatic treatments, and laser guidance, including by topography or aberrometry.”
Aberrometry ushered in a new era in laser vision correction. Introducing the language of optical aberrations and treatment targeting more than mere spherocylindrical correction, it also focused attention on evaluating vision quality as a performance, said Dr Cochener. “Rather than simply correcting a refractive error and providing 20/20 visual acuity, we now expect that patients will maintain optimal visual performance in all living conditions, day and night. This defines ‘Super vison’ that is the topic for the first presentation in our session by Jesper Hjortdal MD, PhD, Aarhus, Denmark, who will emphasise that vision be measured both objectively and qualitatively.”
The refinement of surgical precision has required the parallel development of strategies for measuring visual acuity, as well as tools to quantify vision quality. Thus, Nino Hirnschall MD, PhD, Vienna, Austria, will discuss modern techniques for refractive evaluation, with particular reference to recent automated measurement platforms. He will also describe the different scales of visual acuity and the optimal conditions for assessment, including distances and recommended lighting.
“Objective measurements of vision quality” is the topic for a talk given by the renowned expert in optics, Pablo Artal PhD, Murcia, Spain. Dr Artal will demonstrate how optical aberrations impact visual performance and discuss ways to measuring and modulate them.
In a presentation titled “From guided ablation to small lenticule extraction”, Liem Trinh MD, Paris, France, will review the literature on topographically-guided LASIK and SMILE, the femtosecond laser-based technique of lenticule extraction.
Dr Cochener-Lamard observed that understanding of the link between the geometric profile of the cornea (ie, asphericity) and treatment-induced optical aberrations (eg, spherical aberration and coma) gave rise to topographically-guided and wavefront-guided treatments, respectively, which aim to optimise the quality of vision.
“In particular, these techniques targeted improved visual performance under mesopic conditions by preserving preoperative asphericity and not increasing or even decreasing preoperative optical aberrations. They also led to presbyLASIK that accentuated corneal prolaticity for a gain in depth of field.”
Discussing SMILE, Dr Trinh will review its theoretical advantages compared with LASIK along with its outcomes and limitations.
“Whereas refractive correction by lenticule extraction is currently available using a single manufacturer’s femtosecond laser platform, the technique is currently being developed by competitor companies, which indicates a definite interest in this approach,” Dr Cochener-Lamard said.
Still in an early stage of development, intrastromal implantation of a lenticule to remodel the cornea is being evaluated as a method of correcting hyperopia or even presbyopia with placement of a lenticule featuring an aspheric profile. Numerous studies are also being undertaken using intrastromal lenticule implantation as a means to reinforce a keratoconic cornea. Mario Nubile MD, PhD, Pescara, Italy, a pioneer in this area, will provide an inventory of current investigations in his talk titled “New perspectives of intrastromal implantations”.
Dr Cochener-Lamard said that in creating an agenda for the symposium, issues emerging for patients after keratorefractive surgery could not be ignored. In the final presentation of the session, Thomas Kohnen MD, PhD, Frankfurt, Germany, will describe reprocessing, remote adjustments, corneal enhancement and cataract management after corneal refractive surgery. Dr Kohnen will demonstrate the complementary nature of corneal and intraocular strategies and present data from studies investigating the ability to achieve the expected result.
Dr Kohnen said: “There is not one correct strategy for restoring spectacle independence after previous corneal surgery. Rather, there is a wide range of surgical options. and intraocular lenses should be available, which, if completed with precise anamnesis, preoperative examination and calculation, take into account the individual needs of the patient and lead to a high level of postoperative patient satisfaction and spectacle independence.”
Dr Cochener-Lamard observed that innovation is also reflected in the virtual format of the symposium and in the entire 38th Congress of the ESCRS.
“The ESCRS Congress has been adapted to the requirements created by the COVID-19 health crisis that has turned the planet upside down and given rise to a virtual world of communication and education, which will surely last forever,” Dr Cochener-Lamard said. “This symposium, like the whole event, will be a hybrid meeting made up of the speakers and an online audience of delegates who can ‘chat’ with each expert for an optimal interactivity not previously offered.”