Advancements in corneal imaging and surgical interventions have revolutionized the diagnosis and management of keratoconus and other ectatic diseases. But they have also led to controversies that have limited the creation of much-needed guidelines for the care of these patients.
A recent project—published online ahead of print in Cornea—called on experts from around the world to help clear the air about these often visually debilitating diseases.1 Thirty-six ophthalmologists shared their expertise to come to a consensus on the definition, method of diagnosis and preferred nonsurgical and surgical treatments for keratoconus and other ectatic diseases.
In order to achieve a consensus, nine coordinators from the four supranational corneal societies—the Asia Cornea Society, Cornea Society, EuCornea, and PanCornea—used a modified version of the Delphi method, which included a total of three rounds of questionnaires and a face-to-face discussion. They invited 40 experts to participate, 36 of which were happy to do so. Twenty-nine participated in the face-to-face discussion, which took place in Chicago in October 2014.
|Study in the Spotlight|
Gomes JA, Tan D, Rapuano CJ, et al. Global consensus on keratoconus and ectatic diseases. Cornea. 2015;34(4):359-69.
The 36 experts who agreed to participate were separated into three panels focusing on: (1) definition/diagnosis, (2) nonsurgical management and (3) surgical management. After collecting the answers from rounds one and two, the coordinators brought the experts together to discuss unresolved issues. The final round of questionnaires addressed unresolved issues that arose during the discussion. Each of the three panels came to a consensus on many controversies surrounding these diseases, including:
This panel agreed that the best way to define ectasia is to identify the conditions that should be classified under the term “ectatic disorder,” and those that should be defined instead as “corneal thinning disorders.” Ectatic disorders include keratoconus, pellucid marginal degeneration (PMD), keratoglobus and postrefractive surgery progressive corneal ectasia. Terrian marginal degeneration, dellen and inflammatory melts are considered thinning disorders. They all agreed that “true unilateral keratoconus does not exist” and that practitioners trying to distinguish keratoconus, keratoglobus and PMD should focus on the “the thinning location and pattern.”1 Keratoconus and PMD, in other words, “are different clinical presentations of the same disease,” the report states.1
|Keratoconus Risk Factors1|
• Down syndrome
• Relatives of affected patients, especially if they are young
• Ocular allergy
• Ethnic factors such as Asian or Arabian descent
• Mechanical factors such as eye rubbing
• Floppy eye syndrome
• Connective tissue disorders such as Marfan syndrome
• Ehlers-Danlos syndrome
• Leber congenital amaurosis
While the group recognized that historical classification systems such as the Amsler-Krumeich system fail to take into account new discoveries, creating a new one was beyond the panel’s scope.
They did agree, however, that abnormal posterior ectasia, abnormal corneal thickness distribution and clinical noninflammatory corneal thinning must be present for a diagnosis of keratoconus. Less difficult to define, however, was the progression of ectasia. The group finally agreed that a change of at least two of the following parameters must take place to be documented as progression: steepening of the anterior corneal surface, steepening of the posterior corneal surface, and thinning and/or an increase in the rate of corneal thickness change from periphery to the thinnest point.1 With this in mind, they also emphasized the importance of examining younger patients at shorter time intervals to more closely monitor potential progression.
Concerning diagnostic tools, tomography (Scheimpflug imaging or anterior segment OCT) topped their list of most useful tests because with it practitioners can measure both the anterior and posterior corneal surfaces, create a corneal thickness map and reconstruct the anterior segment.
“There is a tremendous need to educate optometrists and optometry students on corneal elevation vs corneal curvature as a primary method of keratoconus and ectasia evaluation,” says Andrew Morgenstern, OD, director of clinical services at TLC Laser Eye Centers in Washington, DC. “We are still teaching our students that an anterior surface placido disc imaging system is the gold standard for keratoconic evaluation and contact lens measurements. Based on this study, and my experience, this is not true. While placido disc imagers are valuable and very helpful, clearly the present and future expertise in ectasia evaluation and management is via elevation (Scheimflug and OCT) technology.”
The Missing Link
Dr. Morgenstern and Barry Eiden, OD, both point out a key weakness of the “Global Consensus on Keratoconus and Ectatic Diseases” project: it failed to gather input from ODs, who are often the first to diagnose and care for these patients. Additionally, Dr. Morgenstern says, the large majority of keratoconus patients are managed with contact lenses and not surgery—and ODs are often the gatekeepers of keratoconus CL management.
“Optometrists would have been highly valuable to have on the panel to bring perhaps a different perspective, especially in the contact lens management portion of the report, which I felt was one of the weakest sections,” Dr. Eiden agrees.
Contact lenses are the primary modality used to manage keratoconus, Dr. Eiden says, because they mask corneal irregularities, thus reducing high-order aberrations and providing significant vision improvement for keratoconic patients.
“In the past the traditional approach to contact lens management of keratoconus involved almost exclusively the use of rigid corneal contact lenses,” he says. “Today, however, we have a multitude of options. For the mildest cases we can use standard soft contact lenses—including disposables. As the disease severity increases we have custom keratoconic soft lenses, hybrid vaulting lenses and scleral gas permeable lenses to consider, in addition to corneal gas permeable lenses and piggyback/tandem lens systems.”
He also says recent advancements in the treatment of advanced and irregular corneas include prosthetic scleral lenses based upon impression molds taken of the ocular surface to create a customized lens that exactly contours to the entire surface of the eye.
While the report fails to include this important CL information, it may still prove to be a much-needed step in the right direction.
“The average eye care practitioner (OD or MD) is not typically up to date in the most current thinking in this area. Ongoing attempts at education are needed in order to provide the best quality of care for patients with keratoconus,” Dr. Eiden says. “I think that this report will stimulate discussion and debate and will hopefully lead to subsequent efforts to establish consensus regarding the management of patients with keratoconus.”
A Multidisciplinary Effort for a Multidisciplinary Diagnosis
“We do not want to only address the interests of keratoconus specialists. We want to make various attempts to advance education and knowledge in this field aimed at all ECPs,” Dr. Eiden explains. “If we have, in essence, a ‘portal’ for information, I feel ECPs can gain access to the most up-to-date information in a centralized and easy-to-access manner.”
The new organization, comprised of MDs and ODs, aims to promote ongoing professional education and scientific development, as well as awareness and understanding of the most appropriate and effective treatment strategies for the management of these diseases.“The beauty of this report is that it highlights the exact need for the IKA,” Dr. Morgenstern says. “There needs to be a multi-professional organization that can educate and expand on all of the components of complete keratoconus diagnosis, management and treatment, not just the categories that are specific to one profession or one school of thought.”
This panel stated that the primary focus of nonsurgical management is halting disease progression and vision rehabilitation. The most important measure, they all agreed, is patient education on the negative effects of eye rubbing. Additionally, they emphasized the importance of using topical antiallergic medication for patients with allergy and topical lubricants to reduce the impulse for eye rubbing.
This agreement led to a further discussion on the relationship between keratoconus and dry eye, and they ultimately decided, “there is no direct relationship between keratoconus and dry eye” and that preservative-free eye drops are preferable to those with preservatives.1
The group noted that contact lenses were important for visual rehabilitation, although they neither slow nor halt the progression of the disease. Despite this, the experts admitted to a preference for rigid contact lenses, specifically gas-permeable lenses, for patients unsatisfied with glasses or traditional soft lenses.
Finally, this panel came to a consensus that patients with Down syndrome or other risk factors should be recommended for a keratoconus evaluation. They also agreed that pregnancy could contribute to the progression of the disease.
This, according to the manuscript authors, was the most difficult topic of the three, given the number of surgical options available and the variety of disease presentations. To avoid these complications, the coordinators chose to focus on specific cases in the hopes of gaining a consensus on common scenarios eye care professionals are likely to see in their practice.
But first, the panelists wanted to tackle the question of when to proceed to surgery. By the end of the face-to-face discussion, they agreed, “surgery should be considered when patients were not fully satisfied with nonsurgical treatments.”1 They also recommended using the term “satisfactory best-corrected” over simply “best-corrected” as a way to differentiate patients who may be able to achieve good corrected vision with CLs but are intolerant or unhappy with them.
With this out of the way, the experts then focused on the best surgical advancement thus far: CXL, which is used by more than 83% of the panelists. They emphasize that it is extremely important for the treatment of several patient types, including those with documented progression of keratoconus; postrefractive surgery keratectasia; keratoconus with the perceived risk of progression; and keratoconus in eyes that have previously received other forms of corneal surgery.
Beyond that, most experts preferred anterior lamellar keratoplasty (ALK)—more specifically, descemetic deep ALK (dDALK)—and penetrating keratoplasty (PK) as other surgical options.
A few representative case examples they came to a consensus on include:
- A 15-year-old patient with stable keratoconus satisfied with vision with glasses: prescribe glasses only or in combination with CLs or CXL.
- A patient with stable keratoconus with unsatisfactory vision with glasses but satisfactory vision with rigid CLs and high myopia: prescribe contact lenses, including scleral lenses.
- A patient with stable keratoconus with unsatisfactory vision with either glasses, contact lenses or scleral lenses and moderate myopia: perform dDALK, and consider intrastromal corneal ring segments in eyes with adequate corneal thickness and minimal scarring.
- A patient with severe but stable keratoconus who is unsatisfied with glasses, contact lenses and scleral lenses and has moderate anterior and deep corneal scarring and evidence of previous corneal hydrops: PK alone or attempt predescemetic DALK (pdDALK).
One of the benefits of a project of this scope is the international implications. Although clinical preferences often varied according to geographical region, more often than not the experts were able to come to a consensus—which bodes well for the global advancement of best practices in the diagnosis and treatment of keratoconus and other ectatic diseases.
“The goal of creating a professional consensus on the diagnosis and management of keratoconus is a worthy endeavor,” says Barry Eiden, OD, cofounder and president of the International Keratoconus Academy of Eye Care Professionals (IKA). “The challenge is to find common ground that all eye care providers who specialize in keratoconus would agree with, yet to have a valuable core of information that can be clinically useful and beneficial.”
From the number of agreed-upon items presented at the conclusion of the project, many would consider it a success. The results “should help eye care providers around the world to adopt best practices” for these patients, the project authors say.11. Gomes JA, Tan D, Rapuano CJ, et al. Global consensus on keratoconus and ectatic diseases. Cornea. 2015;34(4):359-69. doi: 10.1097/ICO.0000000000000408.