Keratoconus treatments progress, aiming to eliminate need for surgery
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Keratoconus is a personal area of interest. In this commentary, I will share a few of my current thoughts on the management of keratoconus.
I disclose that I consult widely in this field (see below). In addition, my five cornea specialist partners at Minnesota Eye Consultants and I, our cornea fellows and our optometric associates care for the optical and procedural needs of many patients with keratoconus and have done so for 45 years.
When I started my practice in 1978, the treatment for a patient with keratoconus was glasses, a hard contact lens when glasses failed and penetrating keratoplasty when a hard contact lens failed. Today, we have much better treatments to offer.
The classical cornea textbooks teach that keratoconus is present in one per 2,000 population in the U.S. We now know that the prevalence of keratoconus is much higher. All corneal surgeons decline to operate on at least 10% of patients seeking refractive corneal surgery because they are uncomfortable with the patient’s corneal topography, pachymetry or family history. These patients usually do not have frank keratoconus on presentation, but over time, many develop it. Recent studies in India, Israel, Iran and Saudi Arabia support a keratoconus prevalence of 2% to 4%.
I think of keratoconus as a subset of progressive myopia. Progressive myopia has an onset at age 4 to 5 years. In the U.S. today, 44% of the population is myopic, and most progress between the ages of 5 and 25 years. Beginning as early as age 8 to 12 years, some children with progressive myopia begin to manifest progressive astigmatism and corneal thinning that evolves into keratoconus. The cause of keratoconus is multifactorial, including genetic predisposition and environmental factors, with eye rubbing playing a significant role. Whatever the cause of keratoconus, the goal today is to diagnose keratoconus early and treat it with one or another collagen cross-linking treatment.
It is important for us to identify childhood progressive myopia at an early age so we can treat these patients with behavioral modification, custom optical correction and low-dose atropine eye drops. While following these progressive myopes, as many as 4% to 8% will develop early signs of keratoconus. We want to treat these patients immediately with CXL, preventing the development of clinically significant regular and irregular astigmatism. Worldwide, corneal surgeons agree we should offer CXL immediately at the diagnosis of keratoconus to prevent progression.
Today, in the U.S., we have one epithelium-off approved method for CXL from Glaukos (formerly Avedro). This treatment is FDA approved, having been proven safe and effective for both keratoconus and post-corneal refractive surgery ectasia. The most common side effects are several days of significant pain, corneal haze and a small number of slow-healing persistent epithelial defects with resultant corneal scarring.
In an attempt to make the CXL procedure more patient friendly, several epithelium-on approaches are being investigated worldwide. Leaders in this research in the U.S. include Glaukos and CXLO, and their proprietary epithelium-on approaches are advancing through the FDA regulatory process. Epithelium-on CXL is more patient friendly and will make treating adolescent and teenage patients much easier. Especially exciting to me is iVeena, recently acquired by Glaukos, which is developing a topical eye drop that in pilot studies shows good efficacy and safety in stabilizing the keratoconus cornea.
In Europe, many advancements in CXL, including epithelium-on treatments, accelerated treatments and custom treatment patterns, show promise. We can anticipate continuing advances in CXL, which will be of benefit to the patient with keratoconus.
However, we have another challenge: the rehabilitation of the patient with keratoconus who has already advanced to a visually significant stage of disease. The baseline therapy for even advanced keratoconus remains CXL to arrest progression. Many patients with significant keratoconus can be managed with custom contact lenses, especially scleral lenses, but some desire an improvement in their uncorrected and best corrected vision with spectacles. I have found Intacs (Addition Technology) and/or wavefront- or topography-guided PRK can help many of these patients. In the future, approaches such as corneal tissue addition for keratoconus and stromal cell therapy offer promise. When keratoplasty is required, deep anterior lamellar keratoplasty is replacing penetrating keratoplasty, and synthetic keratoplasty is advancing in clinical trials.
The goal for the younger patient who develops keratoconus is immediate CXL so that no future invasive surgical procedure will ever be necessary. This requires early detection and immediate referral for CXL treatment. We must further educate patients and their eye care professionals to ensure immediate referral of every progressive keratoconus patient for CXL upon diagnosis regardless of age. We also need less invasive CXL therapies, and epithelium-on CXL and the potential for a topical eye drop treatment offer great promise.
In a few decades, we may see scleral contact lenses and keratoplasty for advanced keratoconus become a thing of the past. We have eradicated several infectious diseases in medicine; perhaps in keratoconus, we can eradicate a surgical disease.
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