Lisa Martén, MD, MPH; David I. Geffen, OD, FAAO; Tracy Schroeder Swartz, OD, MS, FAAO, Dipl ABO; Monica Youcefi, OD; Amanda J. Setto, OD; and Paul J. Dougherty, MD
Refractive surgery is defined as a surgery performed to reduce dependence on glasses and contact lenses and improve uncorrected visual acuity. The first eye surgeries were cataract removals performed in ancient Greece in the 5th century BC.1 The word cataract is derived from a Greek word meaning fall of water.1 The procedure of couching was first described in literature by an Indian surgeon in 800 BC using a curved needle to push the lens into the vitreous cavity.2 This was the only surgery for cataracts performed for many centuries, until a French surgeon named Jacques Daviel (1696–1762) performed the first extracapsular cataract extraction in 1747.3 There were no fine sutures at that time, so patients were not allowed to move after surgery to avoid expulsive hemorrhages. There was an increased risk of mortality due to having to remain immobilized with sandbags for days after surgery. Topical anesthetics such as cocaine were also used more frequently, which allowed a more comfortable surgery.2 During the 1850s, lensectomies started to be performed to reduce myopia, marking the beginning of refractive surgery.
Before the development of intraocular lenses (IOLs), the cataract procedure left patients aphakic, severely farsighted, and visually impaired. During World War II, it was noted injured pilots who had glass and plastic in their eyes had no intraocular inflammatory response. This inspired Dr. Harold Ridley, an English ophthalmologist, to use polymethyl methacrylate to develop IOLs in cataract surgery.4 He performed the first IOL implantation in 1949. Over the next few years, other materials were used to create IOLs and an international symposium on IOLs and implants was held in 1966. The Intraocular Implant Club was formed after this meeting, with Dr. Ridley as the first president.2 Through his innovative work and discoveries, Ridley single-handedly changed the future of eye surgery. With the advent of IOLs, cataract surgery became a refractive procedure.
Cataract surgery continued to evolve with another advancement developed by Charles D. Kelman, known as the father of phacoemulsification.5 With extracapsular surgery, patients had a longer healing process, a hospital stay, a larger incision, sutures, and more risk of complications. Inspired by his dentist’s ultrasound probe, he developed a technique using ultrasonic waves to emulsify the nucleus of the crystalline lens to remove the cataract. The ultrasound technology was combined into a handpiece with the use of irrigation and aspiration to fit through a much smaller incision.2,3
Improvements in A-scan technology to determine axial length and optical formulas to calculate lens power to reduce postoperative refraction have improved visual outcomes. The modern combination of phacoemulsification, foldable IOLs, biometry, lens formulas, and intraoperative measurements have evolved cataract surgery into an ideal refractive procedure. With the ease of an outpatient procedure, predictable visual outcomes, routine postoperative care, and minimal restrictions following surgery, cataract surgery has become the most commonly performed surgical procedure in any specialty.3
CORNEAL REFRACTIVE SURGERY
As lens surgery was being perfected, corneal surgeries were also developing. Astigmatism correction with horizontal incisions on the corneal surface was done in the late 1800s.6 Around the same time, L. J. Lans was developing the beginning theory behind radial keratotomy (RK) in the Netherlands. He published his theories in a paper in 1898 discussing incisions to reduce irregularity in the cornea. It was not until the 1930s that the theories were implemented, when a Japanese ophthalmologist, Tsutomo Sato, started doing surgery on military pilots to correct their vision using corneal incisions. His incisions were made on the inner surface of the cornea, causing corneal opacification and decompensation, limiting its popularity. In the 1960s, a Russian ophthalmologist, Slava Fyodorov, evolved the procedure using anterior corneal incisions, leaving a central clear optical zone. The procedure removed up to 8.0 diopters (D) of myopia with immediate results. The procedure made its way to the United States in the 1970s by Leo Bores, increasing the interests of US ophthalmologists (Figure 1-1).3
The PERK (prospective evaluation of radial keratotomy) study was published in 1982. This was the first study of the safety and efficacy of RK as well as corneal curvature postoperatively over time. After several peer-reviewed publications, RK was established as a safe procedure. There were some side effects, including visual fluctuation, irregular astigmatism, and long-term hyperopic shift observed in these patients (Figure 1-2). Surgeons were able to reduce myopia, farsightedness, and astigmatism using different cuts on the cornea. The surgery gained more and more popularity in the 1980s and 1990s, due to the appeal of minimal surgeon training and the potential to help a multitude of patients. In addition, the procedure was lucrative as a cash procedure in a time of declining insurance reimbursements.4
RK was followed by automated lamellar keratoplasty manufactured by Chiron Inc. This procedure used a microkeratome to create a deep cut in the cornea to induce a controlled steepening of the central cornea. Vision outcomes for this procedure noted myopic progression beginning as early as 3 months postoperatively, long-term refractive instability, and loss of best-corrected visual acuity.7 Other serious complications included increased inferior steepening of the cornea leading to the development of iatrogenic keratoconus, irregular astigmatism, and ectasia.8 Patients with enough postoperative ectasia required corneal transplantation. Due to extremely poor outcomes, this procedure is no longer performed.
The advent of the excimer laser in the 1980s allowed an opportunity to safely use it on the corneal surface.9 The laser was originally created and used to make computer chips with incredible accuracy. This safety and precision allowed eye surgeons to remove exact amounts of tissue to correct refractive error better than using RK.3 Photorefractive keratectomy (PRK) was the first surface ablation refractive surgery performed. This technique required the corneal epithelium be debrided, followed by excimer laser ablation to correct the refractive error. The epithelium was allowed to grow back. Healing caused a bit of discomfort, and there is a risk of stromal scarring, but visual acuity results and advanced nomograms to improve predictability exceeded expectations. By 1995, 2 excimer lasers were approved by the Food and Drug Administration for PRK.10
In an effort to perform a less painful procedure and reduce healing time, microincisional instruments were developed to precisely cut into the anterior corneal stroma to create a superficial flap that could be lifted and returned to its original position. A new surgery was developed called LASIK that combined corneal flap creation with excimer treatment of the refractive error on the anterior corneal stroma (Figures 1-3 and 1-4). This allowed for minimal postoperative pain and faster healing, as well as a wow effect for postoperative day 1 patients. While the corneal flap was created with a microkeratome blade in the beginning and is still used, modern LASIK utilizes femtosecond laser technology. The femtosecond laser greatly reduces any complications in the creation of the LASIK flap.11–13