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Feature | May/June '18

Navigating Keratoconus

Insights into the diagnosis and management of this complex condition.

The incidence of keratoconus is higher than previously thought, meaning increasingly more patients and families must come to terms with the impact of this condition.1 As a cornea specialist in private practice, I am frequently confirming a diagnosis of keratoconus or introducing the concept to the patient for the first time. In these cases, my goals are threefold: first, to provide a general understanding of the pathophysiology of the condition; second, to go over the management of keratoconus and highlight which options are most appropriate for the particular disease stage; and third, to offer compassion and empathy in the face of a difficult diagnosis.

PATHOPHYSIOLOGY

I tailor my explanation of keratoconus to each individual; however, there are certain key points that I strive to convey to all patients. The majority of patients who are referred to me for keratoconus have been complaining of changing refractions and poor vision, despite wearing glasses and soft contact lenses. Some patients are diagnosed during LASIK screenings or have developed post-LASIK ectasia after undergoing LASIK years ago, when the posterior cornea was not included in topographic imaging.

Unless keratoconus was discovered inadvertently, most patients want to know why they cannot see well, so I start there. I explain that the root cause of their issues is irregular astigmatism, which stems from asymmetric steepening and thinning of the cornea. The second point I aim to convey is that keratoconus is progressive, but there are many options to provide vision, and blindness is not a guarantee. Last, I inquire into family history and suggest examinations with topography of all immediate family members if it has not yet been done.

MANAGEMENT

An important point that I like to impress upon patients is that the management of keratoconus is multidisciplinary, usually involving both an optometrist and an ophthalmologist, and consists of two goals: (1) visual rehabilitation and (2) monitoring for progression. Contact lens fittings are required for most patients with mild to moderate keratoconus to achieve their best possible vision, and some patients undergo intrastromal corneal ring segment insertion to improve their corneal shape; however, neither of these procedures will cure or halt the progression of the disease. Therefore, management is a delicate balance of cautious observation and well-timed treatment, whether with corneal crosslinking (CXL) or corneal transplantation. My aim is to encourage patients to continue regular follow-up with topography and to prevent them from assuming the problem is resolved because they can see well with contact lenses.

CONTACT LENS FITTINGS

I like to prepare patients for a contact lens fitting prior to referring them to optometrists for rigid gas-permeable or scleral lenses. When patients first hear “contact lens,” most assume it is a soft contact lens and are not aware that the fitting process can be as time-intensive and challenging as it may be. I explain to patients the reasoning behind a rigid lens and why it is so important in their case—that the rigid lens essentially negates the irregular curvature of their cornea and provides a uniform surface to focus light.

CXL AND CORNEAL TRANSPLANTS

With the FDA approval of CXL, many patients are already informed of this option and inquire about the procedure. For patients who have a new diagnosis of keratoconus, I introduce the concept of CXL. I explain that UV light triggers the collagen fibrils of the cornea to form extra bonds with adjacent fibrils, and this provides extra stability to the cornea while halting disease progression.

Although CXL is a major step in keratoconus management, it is critical to impress upon patients that it does not cure the condition and does not guarantee visual improvement. Following CXL, many patients still require contact lenses to achieve their best vision; however, contact lens fitting is often easier in these cases due to improved corneal curvature. I also mention that not all individuals are candidates for CXL, and it is primarily considered in patients with progression on topography, changes in refraction, or worsening of UCVA or BCVA.

COMMONLY FIELDED KERATOCONUS QUESTIONS

“Am I going to go blind?”

“Keratoconus is a progressive disease, and, as it progresses, it leads to greater reduction in vision. That being said, once you have been diagnosed with keratoconus, there are two components to your management: visual rehabilitation and monitoring for progression. Visual rehabilitation usually involves working with an optometrist who is comfortable with complex contact lens fittings. At the same time, we should monitor you with serial corneal topography scans to watch for shifts in the curvature and thickness of your cornea. In the event of progression, we may consider surgical procedures, including corneal crosslinking and corneal transplantation.”

“Why can’t I see well with glasses and soft contact lenses?”

“Glasses and soft contact lenses are excellent for correcting regular astigmatism. With this kind of astigmatism, the steepening of the cornea is symmetric. With keratoconus, astigmatism is irregular and asymmetric. This kind of astigmatism cannot be corrected reliably with glasses and contact lenses, as they may end up inducing astigmatism in another direction of the cornea. In eyes with keratoconus, vision is optimally corrected with rigid gas-permeable contact lenses. These rigid lenses serve to mask the shape of the underlying cornea and provide a regular surface with which to focus light to the back of the eye.”

“What can I do?”

“The most important thing to do is continue regular follow-up and call your physician as soon as you notice any changes in your vision.”

“Can LASIK fix this?”

“In patients with overt and subclinical keratoconus, LASIK is contraindicated. In fact, LASIK is dangerous in such cases and can be detrimental to patients’ vision. During LASIK, we ablate corneal tissue and thin the cornea, which can destabilize a keratoconic cornea and lead to rapid progression and decrease in vision. In patients with subclinical keratoconus, or keratoconus suspects, the process of removing corneal tissue during LASIK can unmask keratoconus and trigger progression. During LASIK screenings, one of the most important things we look for is whether a patient has keratoconus that has not been diagnosed or has forme fruste keratoconus, the subclinical form, and is at risk for developing it.”

“Since this is going to progress anyway, can I do a transplant now and get it over with?”

“I strongly advise against choosing to undergo corneal transplantation without any evidence of progression, poor vision despite contact lenses, or intolerance of contact lenses. This is a surgical procedure with risks, and we should choose that option only when the benefits far outweigh those risks.”

Patients typically ask whether they should undergo epithelial (epi)-on or epi-off CXL. I explain that the FDA-approved protocol is the original 30-minute epi-off procedure; however, many specialists are trying variations of this, including epi-off and accelerated protocols, that are of much shorter duration. The effectiveness of these different variations is still under study.

In patients with severe keratoconus and significantly reduced vision, scarring, or thinning, I discuss the option of a corneal transplant, including penetrating keratoplasty or deep anterior lamellar keratoplasty. When I introduce the concept of transplantation, I explain that we replace the abnormal part(s) of the cornea with a donor cornea, which offers the opportunity for a clear, more uniformly curved surface to focus light.

CONCLUSION

A diagnosis of keratoconus can be challenging to navigate for physicians and patients alike. However, armed with the necessary information and understanding of this condition, physicians can help guide their patients through the physical and psychological effects.

1. Godefrooji DA, et al. Age-specific incidence and prevalence of keratoconus: a nationwide registration study. Am J Ophthalmol. 2017;175:169-172.

author
S. Asha Balakrishnan, MD
  • Cataract, Cornea, and Refractive Surgery Specialist, Colvard-Kandavel Eye Center, Encino, California
  • sabalakrishnan.md@gmail.com
  • Financial disclosure: None
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