Evolution of LVC and cataract surgery
Professor Theo Seiler delivers Heritage Lecture at 38th Congress of the ESCRS.
Theo Seiler MD, PhD
The history, development and complex implications of laser vision correction (LVC) both before and after cataract surgery were all addressed in a fascinating 2020 ESCRS Heritage Lecture delivered by Theo Seiler MD, PhD.
In his talk, Prof Seiler discussed the overlap between LVC and cataract surgery, the difficulty of obtaining consistently predictable refractive outcomes now that the first-generation of LVC patients has reached cataract age and the ways in which LVC can successfully improve the outcomes of cataract surgery.
“We are all aware that laser vision correction jeopardises the precision of cataract surgery. But on the other hand, LVC creates a kind of compensation because we can enhance the optical performance postoperatively of the operated eye and increase patient satisfaction,” he said.
The early history of laser vision correction (LVC) was a far cry from the high-tech technological precision that refractive surgeons today take for granted, said Prof Seiler.
“The first PRK surgeries that I performed were quite rudimentary by modern standards. The eye tracking and centration were performed using only my hands and my eyes so you can imagine that safety suffered accordingly, “he said.
Turning to modern cataract surgery, Prof Seiler noted that while significant improvements have been achieved in IOL power calculations due to advances in optical biometry, there is still considerable inaccuracy when it comes to keratometry measurements for post-LVC eyes.
“Studies have shown that despite better preoperative diagnostics that the chance of postoperative refractive surprise is still greater than 20%,” he said.
The primary reason for these refractive surprises is the irregularity of the cornea after previous refractive surgery, noted Prof Seiler.
“The corneal curvature or corneal power is significantly altered by LVC. Prof Seitz was one of the first to publish on this back in 1999 and he figured out if you use standard formulas and algorithms in these eyes you will end up with a postoperative hyperopia of up to +3 or +4 dioptres,” he said.
Almost 20 years after Prof Seitz’s study, modern biometry has still not resolved the problem of IOL power calculations in eyes with previous corneal refractive surgery, said Prof Seiler. He cited a recent study by Koch et al that looked at the accuracy of several of the most popular methods currently used for IOL power calculation including the Haigis-L, the Shammas-PL and the Barrett True-K formulas.
“We see that the accuracy is not significantly better because between only 40% and 70% of the patients postoperatively were within 0.5D of their target refraction. So that still seems to be an unsolved problem,” said Prof Seiler.
Tools such as the ASCRS post-refractive IOL calculator, which incorporate a variety of formulas, may prove helpful in increasing the likelihood of attaining the target postoperative refraction in eyes that have undergone previous PRK, LASIK or RK, he added.
Careful preoperative counselling of the patient can also help in the event of a refractive surprise.
“In Zurich we try to avoid this dilemma and explain to them that the predictability is not as good for post-refractive surgery eyes but that we can compensate for this by performing a laser enhancement treatment using a flap re-lift or we can change the intraocular lens. That is also why we select an IOL type that can be easily exchanged,” he said.
Fine-tuning cataract surgery outcomes
In the final part of his lecture, Prof Seiler discussed how laser vision correction can be used to improve the outcomes of cataract surgery.
Specifically, Prof Seiler said that selective wavefront-guided LASIK may increase the success rate of multifocal and toric IOL implantations.
Prof Seiler cited recent studies (Maurino et al, Ophthalmology 2015;122:700-10; Rodov et al, J Refract Surg 2019; Jul 1;35(7):434-440) that looked at the quality of vision after bilateral multifocal and trifocal IOL implantation.
“Maurino et al. showed that only 77% of patients never wore glasses for any purpose and only 68% said that they were very satisfied with their vision, which is not very impressive. Another study by Rodov et al. found that only 76% of patients would choose the same IOL again,” he said.
Prof Seiler’s own group carried out a prospective study of 213 eyes of 108 patients implanted with a trifocal IOL and found that 56 eyes (26%) were dissatisfied after surgery. The refractive reasons for their dissatisfaction were astigmatism in 63%, myopia in 45%, hyperopia in 20% and higher-order aberrations greater than 0.5 microns in 13%.
After selective wavefront-guided LASIK, there was a significant increase of satisfaction from 2.1 preoperatively to 3.6 postoperatively on a scale of 1 (not satisfied) to 4 (totally satisfied), said Prof Seiler.
“Of the unsatisfied 42 patients, 38 said they would choose the same procedure of trifocal IOL and femto-LASIK again. In total, the satisfaction degree increased from 74% to 96% of the patients due to selective wavefront-guided LASIK. Of the four patients who were dissatisfied, all of them suffered from dry eye. This is why we now do selective wavefront-guided PRK in patients with significant dry eye preoperatively in order to re-establish the tear film faster,” he concluded.
Theo Seiler: c/o firstname.lastname@example.org
To listen to Prof Seiler’s lecture visit https://player.escrs.org/featured/heritage-lecture-2020-cataract-surgery-and-laser-vision-correction-theo-seiler