Ophthalmology: Current and Future Developments

Scleral lenses have existed for centuries, longer than any other type of contact lens. They were first conceptualized by Leonardo DaVinci in the early 16th century and were first manufactured in Europe in the late 1800s. The first scleral lenses were blown glass scleral shells without power made in 1887 by Fredrich A. Müller and Albert C. Müller. The primary indication for these scleral lenses was to manage ocular surface disease. In 1889, Adolf Eugen Gaston Fick described the use of scleral lenses with optics added to correct vision. In 1889, Eugene Kalt described contact lenses as orthopedic appliances for the treatment of keratoconus. In that same year, August Müeller created a scleral lens for himself to correct his own 14D of high myopia. Modern advances of scleral lenses have overcome their previous shortcomings, including lens-induced corneal edema due to poor transmissibility of oxygen through the lens and poor reproducibility. Contemporary scleral lenses have re-emerged from a long history of contact lens successes and some failures. In recent years, there has been a burst of new designs and innovations worldwide. With modern materials, manufacturing, and advanced scanning equipment, scleral lenses are now very innovative and a million miles away from their early beginnings.

Scleral lens terminology is vast and can be confusing. Since there are several designs with different parameters, manufacturers have created new terms for various aspects of scleral lenses. Not only do the parameters have a variety of names, but there are different names for large gas permeable lenses themselves. The Scleral Lens Education Society defined large diameter gas permeable lenses by their respective bearing patterns (corneal, corneo-scleral, and scleral) thereby reducing some confusion. The parameters, however, are more difficult to categorize. In this chapter, the anatomy of a scleral lens is described in four separate zones: optic zone, mid-peripheral zone, intermediate zone, and landing zone. The optic zone not only provides the optical correction but also can be manipulated to increase the clearance over the corneal surface. The mid-peripheral zone also can be manipulated to create more even clearance over the peripheral corneal surface. The intermediate zone is a critical junction between the mid-peripheral zone and scleral landing zone that bridges the limbus and can control the overall sagittal height of the lens. Lastly, the landing zone is the fitting zone of the scleral lens that aligns to the ocular surface and conjunctiva overlying the sclera and bears the weight of the entire lens. Due to the unique properties of the ocular surface shape, the landing zone can be rotationally symmetric or asymmetric to accommodate and facilitate proper alignment to the surface. All the terminology of the scleral lens anatomy is described in detail.

Historically, there was little emphasis placed on the anterior shape of the eye, apart from the corneal shape, but with the resurgence of scleral lenses, recent interest in the anterior corneo-scleral junction has been examined, measured and quantified. Interestingly, the corneo-scleral junction had been found to be predominantly tangential. A variety of technology can be utilized to analyze the anterior ocular surface shape. Instrumentation includes keratometry, Placido-based topography, Scheimpflug topography, optical coherence tomography, and scleral topography. Curvature and elevation data, symmetry or asymmetry are critical in deciding whether a small diameter scleral lens, a large diameter scleral lens – or maybe a toric scleral lens is indicated when fitting a patient. Different metrics and indices define ocular surface shape. Consequences of inappropriate curvatures and parameters of lenses placed on the ocular surface can result in lens misalignment, excessive compression, impingement and/or edge lift that result in patient symptomatology. As with any contact lens, the overall goal is to provide optimal vision, fit and comfort. Therefore, it is crucial to understand the ocular surface shape to improve alignment and centration of the optics for optimal vision. Improvements in alignment reduce ocular signs and discomfort. A general understanding of ocular surface shape can lead to enhanced designs and improved patient outcomes.

Contact lens optics are crucial for patient’s success and scleral lenses are not an exception. Scleral lenses provide an optimal and stable platform for housing standard and custom optics. Scleral lens optics are similar to corneal rigid gas permeable lens optics; however, there are additional variables of the post-lens tear film, decentration and tilt that are associated with scleral lenses. Unique fitting characteristics of scleral lenses may complicate empirical determination of lens power at this time. Practitioners may still need to use a diagnostic scleral lens and overrefract. Nevertheless, current scleral lenses can provide optical correction that rivals spectacles or other modes of contact lens correction. Furthermore, incorporation of higher order aberration correction on a rotationally and translationally stable scleral lens platform may eventually allow patients to achieve better visual acuity than other modes of correction. Looking ahead, the use of a scleral lens as a platform for magnification aids patients with low vision.

Scleral lens indications are well established in published literature, beginning with descriptions of blown glass shells that were the precursors of scleral lenses in the late 1800s. Fick and Kalt explored the potential for optical correction of corneal irregularity in keratoconus with their original lenses, while Mueller described the use of a blown glass shell to correct significant myopic refractive error. Publications predating the introduction of rigid gas permeable scleral lenses in 1983 described the use of molded scleral shells or lenses to improve vision in cases of significant corneal irregularity, to protect the ocular surface and to correct refractive error. The introduction of rigid gas permeable contact lens materials sparked renewed interest in the scleral lens modality. Since Ezekiel’s description of the use of rigid gas permeable scleral lenses in the management of keratoconus, high ametropia, marked corneal scarring and corneal surface compromise in 1983, interest in scleral lenses has steadily grown. Whenever a scleral lens is placed on a diseased eye, practitioners must be aware that it is a therapeutic medical device. Use of scleral lenses in the management of ocular disease requires an understanding of the disease process. The eye should be monitored carefully to see that the desired outcome is obtained, and the therapeutic approach should be adjusted if the expected outcome is not achieved or if unexpected complications arise. Cooperation and collaboration with other eye care providers and specialists within other areas of medicine will allow practitioners to maximize the benefit for our patients.

A regular/normal/non-diseased cornea is characterized by a prolate surface, with no indices of irregularity, warpage or distortion. For consistency, the term regular cornea will be used in this text. Anterior corneal surface elevation and posterior corneal surface elevation of a regular cornea which do not exhibit ectasia or irregularities of either surface. These patients present with common refractive errors: myopia, regular astigmatism, hyperopia and presbyopia. Prescribing scleral lenses for patients with regular corneas or switching patients from other modalities to scleral lenses is very feasible. First, practitioners determine the need, which is improving vision and/or comfort. Scleral lenses can significantly enhance the lens wearing experience of regular cornea patients, especially in astigmatic, presbyopic or marginal dry eye patient populations. For regular cornea patients and the correction of common refractive errors, the risk-to-benefit ratio needs to be evaluated and an appropriate lens selected. In conclusion, scleral lenses are becoming part of practitioners’ standard armamentarium to improve the contact lens experience of their patients.

When modern scleral lenses became popular, the instruments used to help evaluate the health of the cornea and conjunctiva in the presence of the lenses were somewhat rudimentary. Practitioners observed the cornea and conjunctiva with the biomicroscope, used manual keratometry or Placido topography to map the corneal curvature, and relied on sodium fluorescein to judge the depth of the post-lens tear reservoir. The instrumentation industry quickly fills unmet needs, and the scleral lens market is no exception. In fact, the pace of innovation of instrumentation that is used to evaluate these relatively complex medical devices has been, and will continue to be, dramatic for years beyond the publication of this textbook. At the time of publication, currently available instrumentation is reviewed and may likely change with innovation and technology. Innovations and advances in modern imaging technology have enhanced traditional methods of scleral lens fitting. While not every piece of equipment is required for fitting scleral lenses, any additional information provided by unique instrumentation aids the practitioner to achieve fitting success.

This chapter will cover the process of choosing an initial lens for evaluation when fitting a scleral lens. Topics that will be discussed include what pre-selection factors are helpful with lens selection, what essential design and diameter to select, which lens within a given fitting set to select, as well as alternative methods of lens selection utilizing technology such as OCT and topography.

Systematic evaluation of scleral lens fitting is essential to identify and address areas of concern at the outset with a view to minimizing the risk of potential physiological complications. Thorough and consistent evaluation ensures proper functionality, comfort and safety for the patient. This chapter details scleral lens evaluation techniques ranging from immediately after application to subsequent fitting evaluations. Scleral lens evaluation can be intimidating relative to other contact lens modalities since the lenses are much larger and have more variables that can be changed. Systematic and methodical evaluation ensures that practitioners do not overlook key findings of ill-fitting scleral lenses. After scleral lenses are removed, the ocular surface tells its story as well. At every evaluation, practitioners should always remember to evaluate the eye without the lens to ensure that the patient is not compromised and can continue to enjoy all the properties that a scleral lens offers.

Detailed and careful documentation is crucial for all aspects of the scleral lens patient’s medical care. A thorough medical and ocular history details the patient’s past medical treatments, outcomes, and previous contact lens modalities. This information serves as a platform to diagnose, monitor and initiate new management strategies including scleral lenses. Proper documentation may also aid the patient with government services and insurance reimbursement. Since scleral lens fitting is intricate and complex, detailed observations assist the practitioner with changing parameters, lens designs, and supplemental ocular management. Due to the progressive nature of ocular conditions that require scleral lenses, photodocumentation of baseline findings, topographies, OCT images, and careful notetaking aid practitioners in optimizing management strategies. When communicating with the patients medical team, a careful summary of ocular findings may also aid their medical decision making. Lastly, appropriate documentation may be necessary in medical-legal circumstances.

Most practitioners will agree in that fitting scleral lenses is a very rewarding and fulfilling experience. As the awareness of scleral lenses becomes widespread, the number of patients seeking scleral lenses continues to grow. Due to the rise in demand, proper preparation by the practitioner and the clinic can optimize the patient experience. Patients who wear scleral lenses often have complex and unique ocular conditions. It is important to educate patients on their condition and the scleral lens fitting process to avoid frustration when multiple follow up visits are necessary. Examination flow of scleral lenses is an evolving process, and current standards will continue to change as technology, lens designs and research develop.

Scleral lenses have become a mainstream option for the treatment of distorted corneas and ocular surface disease. Well-fit scleral lenses vault the cornea and are supported entirely by the sclera. They create a tear layer reservoir which helps neutralize an irregular, damaged or diseased cornea while creating constant lubrication and necessary oxygen supply. They provide optics comparable to corneal gas permeable lenses, with equivalent comfort to soft contact lenses. Like any type of medical treatment, there must be first and foremost an understanding of the disease process and pathology being treated when fitting scleral lenses. Without true understanding of the disease process and its limitations, practitioners may inadvertently induce complications. A comprehensive understanding of the intended scleral lens design and fitting parameters is paramount. Equally important is establishing a close relationship with the lens manufacturing laboratory and their consultants. This is particularly critical when troubleshooting challenging cases. Establishing appropriate scleral lens follow up and close communication with the referring corneal or medical specialist is very important. Proper understanding of the disease process and its limitations are important to avoid scleral lens induced complications. Appropriate follow up and adequate collaboration with specialists is also essential to ensure successful treatment with scleral lenses. From the care and handling aspect as well as disease management strategies, patient communication and involvement can improve compliance and favorable outcomes.

Scleral lenses have become more of a mainstream option for the treatment of distorted corneas and ocular surface disease. Well-fitted scleral lenses vault the cornea and are supported entirely by the sclera. They create a tear layer reservoir which helps neutralize an irregular, damaged or diseased cornea while creating constant lubrication and necessary oxygen supply. They provide optics comparable to corneal gas permeable lenses, with equivalent comfort to soft contact lenses. Like any type of medical treatment, there has to be first and foremost an understanding of the disease process and pathology being treated when fitting scleral lenses. Without true understanding of the disease process and its limitations, practitioners may inadvertently induce complications. A comprehensive understanding of the intended scleral lens design and fitting parameters is paramount. Equally important is establishing a close relationship with the lens manufacturing laboratory and their consultants. This is particularly critical when troubleshooting challenging cases. Establishing appropriate scleral lens follow up and close communication with the referring corneal or medical specialist is very important. Proper understanding of the disease process and its limitations are important to avoid scleral lens induced complications. Appropriate follow up and adequate collaboration with specialists is also essential to ensure successful treatment with scleral lenses. From the care and handling aspect as well as disease management strategies, patient communication and involvement can improve compliance and favorable outcomes.

Despite a recent resurgence in popularity of scleral lenses, the literature to date is quite limited regarding challenges faced by practitioners. Practitioners may manage one or multiple challenges daily. This chapter explores different topics from the contributors’ personal perspectives. Authors were asked to write about their unique experiences and fitting philosophies for a variety of situations that scleral lens practitioners may encounter. Common topics are included, however not every possible challenge is covered.

The establishment of a specialty scleral lens practice can be a timeconsuming but worthwhile process. The practice can be both financially and personally rewarding. Expending the necessary resources to develop the practice can result in a loyal and long-term patient base. According to some specialist practitioners, they attract patients who have consulted numerous other eye care practitioners with little success. Once these patients realize the quality of life improvement that can be achieved with properly fit scleral lenses, they become patients for life who recommend the practice to others. By making the patient a top priority, business will be successful. Patients wearing specialized contact lenses will return on an annual basis and refer their family and friends. Successful practitioners are very talented at building value into every aspect of their practice and therefore building a contact lens specialty niche. In order to continue to grow the practice, an investment in advertising and networking can aid in referrals. Staying up to date with scleral lens and equipment technology can streamline the scleral lens fitting process, thus saving time for the practitioner and patient. Establishing relationships with contact lens laboratories is critical to a thriving scleral lens practice.

As technological advances in scleral lenses have improved the comfort and function of these lenses for patients, there has been increasing acceptance and use of scleral lenses by ophthalmologists. Historically, scleral lenses were most frequently used for visual rehabilitation of patients with corneal ectasias such as keratoconus, pellucid marginal degeneration and keratoglobus. Scleral lenses are also indicated for other patients with high or irregular astigmatism such as in post-keratoplasty patients or after complications of LASIK vision correction. Increasingly, scleral lenses are used in patients with severe ocular surface disease such as Stevens-Johnson syndrome (SJS), graft versus host disease (GvHD), and ocular cicatricial pemphigoid. Few ophthalmologists have expertise in fitting contact lenses, much less specialty lenses including scleral lenses. When patients are referred for scleral lenses by a comprehensive ophthalmologist, or more often, a corneal specialist, the patient is best served if the fitting practitioner understands the purpose of the referral. Scleral lenses have altered how corneal specialists manage patients with a variety of diseases. They have helped to decrease the progression to corneal transplantation in patients with corneal ectasia and irregular astigmatism. Scleral lenses have also helped to improve the quality of life for patients with severe ocular surface diseases. It is important for all eye care providers to be aware of the utility of these lenses for even the most complex eyes.