Specialty Contact Lenses
Scleral Contact Lenses:
Scleral contact lenses were first used for therapeutic purposes over 50 years ago. Their larger size (25 mm - approximately the size of a quarter) provided excellent protection of the corneal surface, limbal transition zone and distal conjunctiva. Ocular surface conditions associated with central corneal irregularity or surface instability such as keratoconus, severe dry eye, Stevens-Johnson Syndrome, chemical injuries, and cicatricial pemphigoid were some of the conditions most effectively managed with these special lenses.
Initial difficulties with surface wetting of the scleral lens material and their reduced oxygen permeability led to the development of small diameter therapeutic rigid gas permeable lenses and soft oxygen permeable bandage contact lenses. These lenses supplanted therapeutic scleral contact lenses for many of their original uses. Scleral lens's greater stability and ability to provide a "protected" surface environment beneath their vaulted surface, however, were properties that these newer lenses could not duplicate.
The development of newer, high oxygen permeable polymers over the past 15 years and the utilization of new design parameters have, in large measure, eliminated the major limitations that had previously been associated with scleral contact lenses. Careful fitting and adjustment combined with these technologic advances has resulted in a significant improvement in the protective effect and wearing time of these lenses.
History of Scleral Lenses
Although Leonardo da Vinci was the first to described contact lenses in the early 1500's, it was not until the 1880's that contact lenses were first produced. The earliest scleral lenses are credited to F.E Muller, a German glassblower, who designed and manufactured blown glass scleral lenses to correct his own severe myopia (1887) and to physiologist A.E. Fick of Zurich, Switzerland (1888). Fick describes filling the lens shells with a thick grape sugar solution, prior to insertion, to promote movement of the lens on the cornea.
The first pre-formed ground glass fitting sets came into use in the 1920's. These glass scleral shells remained the sole contact lens material until polymethyl methacrylate (PMMA) was developed in the 1930's. Corneal-scleral impression techniques were introduced in the 1930's and enhanced the ability of early scleral contact lens fitters to perform custom fittings.
The early 1950's saw the advent of "micro lenses" later known as "corneal" lenses to differentiate them from their larger scleral cousins. PMMA corneal contact lenses gained mass appeal as designs and manufacturing technology improved through the 1950's and 1960's.
The advantages and disadvantages of polymethyl methacrylate as a contact lens material became apparent as these lenses found acceptance in both cosmetic and therapeutic settings. Chief among its drawbacks was its lack of oxygen permeability. Enthusiasm for PMMA or "hard" contact lenses waned in the 1980's with the introduction of the more flexible and oxygen permeable "soft" hydrogel materials. Efforts to blend PMMA with other polymers lead to the introduction of rigid gas (oxygen) permeable (RGP) materials of considerable variety in the late 1980's and 1990's. These new materials had a considerable impact on how contact lenses were used - principally by allowing for longer wearing times, greater comfort, less secondary vascularization and added design options.
The circle was completed with the introduction of RGP materials and new design concepts to the manufacture of scleral lenses. Two groups - one lead by Kenneth Pullum, FCO, CLP (Pullum scleral lens) and the other by Perry Rosenthal, MD (Boston scleral lens) - have played a key role in the study and application of scleral lenses to the treatment of medical disease. As will be discussed in greater detail later in this monograph, the Pullum and Boston lenses have significantly improved our ability to enhance the function and comfort of many patients with diseases affecting the ocular surface. The Pullum lens is being used extensively in Europe, Australia and Japan and to a lesser extent here in the US. The Boston lens is being used solely in the US.
Current Therapeutic Uses
A scleral lens is a therapeutic lens used to manage very difficult corneal problems that fall into two major categories; disorders of surface irregularity and disorders of surface integrity. By vaulting the corneal surface and trapping fluid behind, they are able to provide surface protection by reducing the drying effect of the air and the mechanical effect of the lids. Optical improvement is achieved by these lens's ability to "mask" underlying surface scarring and distortion. Their greater diameter and extension onto the sclera provides both a peripheral "seal" that helps retain fluid behind the lens and greater stability.
Corneal Surface Distortion
Disorders in this category lead to corneal surface irregularity. Optically, light is distorted resulting in incapacitating glare and blurred vision.
Specific conditions that can benefit from scleral lenses include
Corneas scarring or irregularity due to:
• Anterior corneal dystrophies
• Prior ocular surgery
Corneal thinning disorders:
• Pellucid marginal degeneration
• Terriens marginal degeneration
Severe Ocular Surface Disease
Diseases in this category are typically associated with recurrent corneal surface defects (erosions, ulcers, etc) and are some of the most difficult problems to resolve. Surface irregularity is quite common and frequently results in incapacitating glare and blurred vision. Specific conditions that can benefit from scleral lenses include:
• Severe dry eye
•raft vs Host Disease
• Radiation injury
• Chemical and thermal injuries
• Stevens-Johnson Syndrome
• Mucous Membrane
• Pemphigoid (previously called Ocular Ciccatricial Pemphigoid - OCP)
• Aniridic keratopathy
• Corneal anesthesia associated with underlying
• Congenital disorders
• Herpes simplex and Herpes Zoster
• Trigeminal cranial nerve disorders and surgery
Impact of Therapeutic Scleral Lenses on Patients
Patients with the irregular surface problems noted above rarely achieve satisfactory visual improvement from glasses. This is related, in part, to the fact that the pathology affecting vision sits behind the glasses (on the cornea) and distorts the light (and related image) after it has been focused by the glasses.
Soft, draping, contact lenses will hide some of the more superficial irregularities but usually are unable to "smooth" out the surface enough to significantly improve vision. A heightened risk of secondary bacterial and fungal corneal infection also exists with these lenses when there are surface healing problems associated with many of these conditions. Rigid, therapeutic gas permeable contact lenses are the only non-surgical approach capable of providing improvement in visual acuity and function in many of these cases.
Scleral contact lenses are a special form of rigid gas permeable contact lens. Their greater size and vaulting, provides better stability than the typical small diameter gas permeable lens as well as a controlled, moist environment behind the lens that protects the cornea in patients with ocular surface disease. The maintenance of a more stable surface combined with the "masking" effect these lenses have on underlying surface scarring and distortion results in significant visual and functional improvement. In most cases, visual and functional improvement would not be achievable by any other means.
With the exception of keratoconus, the ophthalmologic conditions benefiting from scleral contact lenses are usually not considered candidates for corneal transplantation. This is primarily due to the high failure rate caused by problems with surface healing and immunologic rejection.
Many of the patients wearing rigid gas permeable scleral contact lenses are able to return to an independent lifestyle. They no longer have constant foreign body sensation, glare or photophobia associated with surface roughness and recurring erosions. They can read the newspaper, a book or a map. They are able to walk to the bus or subway, drive themselves to work and family social functions or take a vacation and fully enjoy the sights. In short, these lenses can have a dramatic impact on the function and life of patients with corneal irregularity and surface instability.
Scleral lenses are custom fit, manufactured and modified according to the particular pathology and needs of the patient. In some situations a direct mold of the corneal surface must be made before manufacturing can begin. Considerable time is spent, after the initial fitting, modifying these lenses in the laboratory and office. It is very important that there be an optimal fit given the susceptibility that many of these corneas have to surface breakdown and erosion - problems linked to the patient's underlying ophthalmic/medical disease.
The cost of these lenses is not inconsequential – approximately $4000 per lens – however, the hospital charges for a corneal transplant, the eye bank processing fees and surgeon charges are well over $12,000 and have a low success rate in this group of patients.
The following is a breakdown of the steps in the fitting process. This will help to give you an idea as to the frequency and length of follow-up visits.
Scleral lens fitting process: (16-19 hrs)
• Assessment of the underlying disease process and the degree of activity,
• Ocular fornix sizing
• Discussion of expectations
• Pre-fit pachymetry
• Trialing lenses
Lens Supply (#1):
• Three (3) remakes of the lens are included
• Lens care and instruction regarding insertion/removal
• Fit evaluation - Modification/Refit
Lens Supply (#2)
• Fit evaluation - Modification/Refit
• Direct mold/casting to achieve better fit
Lens Supply (#3)
• Fit evaluation - Modification
I month followup, 3 month followup, 6 month followup
Monthly cost of lens maintenance/care
$20-$40 per month in cleaning and lens fill solutions.
Insurance Coverage of Scleral Contact Lenses
Most insurance companies do not cover scleral contact lenses under the medical, optical, or durable medical equipment portions of their health insurance policies. In some cases, a request for special consideration to a review panel, will result in the approval to pay a portion or all of the cost. We encourage all patients to investigate payment with their insurance company and have a variety of materials specifically designed to assist them in this effort. This monograph is one example. It is designed to provide you and your insurance company essential, background information that will make it easier to communicate the special purpose and value of these lenses.
Rigid gas permeable scleral contact lenses provide unique therapeutic and vision rehabilitative properties that overcome the therapeutic gaps encountered with conventional contact lens therapies, medical therapy and surgery. Scleral lenses are not a part of mainstream contact lens work, requiring a special interest and commitment to their fitting, special training and a coordinated approach to the management of the underlying pathology. The results, when successful, are very rewarding for the patient and the team of professionals involved in the patients’ care.
Bibliography and Journal Articles
Modern scleral lenses part I: clinical features.Visser ES, Visser R, van Lier HJ, Otten HM, Visser Contact Lens Practice, Nijmegen-Utrecht, The Netherlands.Eye Contact Lens. Jan; 33(1):13-20, 2007
Scleral Contact Lenses: The Expanding Role. Pullum, Kenneth W; Whiting, Mark A ; Buckley, Roger J, Cornea. 24(3):269-277, April 2005. Scleral contact lens overnight wear in the management of ocular surface disorders, M Tappin, K Pullum, R Buckley, Eye 15:162-172, 2001
Scleral contact lenses may help where other modalities fail. O Segal, Y Barkana, D Hourovitz D, S Behrman, Y Kamun, I Avni and D Zadok. Cornea 22(4):308 - 310, 2003
Treatment of persistent epithelial defect with extended wear of fluid-ventilated gas-permeable scleral contact lens, P Rosenthal, J Cotter, J Baum, American Journal of Ophthalmology, 130:33-41, 2000.
The Boston Scleral Lens in the management of severe ocular surface disease, P Rosenthal, J Cotter , Ophthalmol Clin North Am, 16(1):89-93, Mar 2003.
Gas-permeable scleral contact lens therapy for ocular surface disease, T Romero-Rangel, P Stavrou, J Cotter, P Rosenthal, S Baltzatzis, C S Foster, American Journal of Ophthalmology 130:25-32, 2000.
Treatment of ocular surface disorders and dry eyes with high gas-permeable scleral lenses, Kok JH, Visser, R., Department of Ophthalmology, University of Amsterdam, The Netherlands, Cornea 11(6):518-22, November 1992.
Glossary of Terms
Cornea - the clear front covering of the eyeball. Much like the crystal of a watch.
Dry eye syndrome - condition in which the lacrimal gland (tear gland) fails to produce enough tears to keep the cornea properly moistened
Fornix - area where the inner surface of the lid (on for the upper and one for the lower) attaches to the loose conjunctiva covering the eyeball proper.
Hydrogel - soft oxygen permeable plastic-like material used for soft contact lenses
Keratoconus - disease that causes anterior protrusion of the cornea with associated steepening, thinning and irregularity
Limbus /Limbal transition zone - the outer edge of the cornea where the clear cornea meets the white sclera
Myopia - nearsighted
Ocular ciccatricial pemphigoid (OCP) - a systemic immune disease that causes conjunctival scarring and secondary corneal problems
Pachymetry - a device that measures corneal thickness
Polymer - a chemical compound that is made of multiple similar subunits
Polymethyl methacrylate (PMMA) - a rigid plastic (i.e., Plexiglass)
Rigid gas permeable contact lens (RGP) - a contact lens made from a rigid material (vs one that is soft and foldable) that allows oxygen to pass through.
Soft oxygen permeable contact lens (SCL) -a contact lens made from a soft, foldable material that allows oxygen to pass through.
Stevens-Johnson Syndrome - a systemic immune disease that causes conjunctival scarring and secondary corneal problems