Advanced Dry Eye Treatments
Novel approaches for severe dry eye
Boston Scleral Contact Lens
Autologous Serum Eye Drops
Novel Approaches to Advanced Ocular Surface Disease
Dan Carver, O.D., F.A.A.O.
Dry eye remains the most prevalent cause of chronic ocular surface disease, a condition treated almost daily in optometric practice. Experts have formed numerous panels as far back as the mid 90s to provide guidelines for recognizing dry eye signs and symptoms and to provide recommendations for treatment. The Dry Eye Workshop was a respected such effort and follow-up to the National Eye Institute dry eye group which created various subcommittees to look at several different aspects of dry eye including the epidemiology, research done in the field, classification, and diagnosis. Most recently, the Delphi Panel study defined a new paradigm in the treatment of this complex condition. Conventional treatments mitigate the suffering of many patients, however, two novel approaches may be used in advanced or recalcitrant disease.
Perry Rosenthal, M.D., founder of the Contact Lens Service at the Massachusetts Eye and Ear Infirmary and assistant clinical professor of ophthalmology, Harvard Medical School, first introduced the Boston Scleral Lens Prosthetic Device (BSLPD) in the early 90s designed to mask corneal astigmatism inadequately corrected with spectacle lenses and with intolerance to conventional RGP corneal contact lenses. Additional refractive applications included use in corneal ectasia, complications of keratorefractive procedures, abnormal astigmatism following PKP, and corneal scars. While its contribution to visual rehabilitation continues to help thousands, the BSLPD additionally is used to mitigate the suffering from advanced corneal conditions including Stevens-Johnson syndrome, chemical and thermal injuries, ocular pemphigus, neurotrophic keratitis, and severe dry eye associated with Sjogren’s syndrome, chronic graft versus host disease, autoimmune disease, and exposure.
The BSLPD is a fluid-ventilated scleral lens designed to enclose a bubble-free reservoir of oxygenated aqueous fluid maintained at neutral hydrostatic pressure over the entire corneal surface. By avoiding the intrusion of air bubbles, its fluid reservoir functions as a “liquid corneal bandage”. The principle feature of the BSLPD is a series of breaches created between the haptic bearing surface of the lens and the underlying sclera. This facilitates the aspiration of surface tears into the fluid reservoir and prevents suction when the lens decompresses after each blink. The shape of the haptic bearing surface must conform very closely to the underlying sclera in order to maintain a bubble-free fluid layer. Junctionless surfaces and customizable designs are the result of advanced design software programs.
An onsite laboratory enables the custom design of each lens on a desk-top computer. Data is then transmitted to a state-of-the-art precision digital lathe producing a lens within 60 minutes. The process of customizing the design of each lens to the shape of each eye requires the production of an average of three to five devices for each eye although it is not unusual to need 12 or more.
The BSLPD is produced exclusively by the Boston Foundation for Sight in Needham, Massachusetts. The non-profit organization subsidizes those unable to afford the $7,600 cost of fabricating and fitting the devices.
An additional treatment gaining recognition as a viable treatment for advanced ocular surface disease is the use of autologous serum eye drops (ASE). In addition to producing a pure optical surface, tears have antimicrobial, nourishing, and mechanical properties. Epithelio-trophic factors, such as growth factor, fibronectin, and vitamins support proliferation, migration, and differentiation of the corneal and conjunctival epithelium. A lack of these factors exists in dry eye and can result in persistent epithelial defects. Serum (plasma absent of clotting properties) is naturally un-preserved, non-antigenic, and contains biochemical and biomechanical properties similar to natural tears.
As yet, there is no FDA-granted approval or standardization of protocols and preparation of ASE and, as a result, virtually all studies have been conducted outside of the U.S. Studies from Japan and Europe have demonstrated substantive improvement in the treatment of severe dry eye, SLK, recurrent corneal erosion syndrome, persistent epithelial defects, and as adjunct therapy in ocular surface reconstruction with ASE when compared to artificial tears. The protocols to prepare and use autologous serum eye drops varied considerably between studies. Concentrations used have ranged from 20 to 100% (diluted with non-preserved BSS). It has been stored at between -20 to 4 degrees Celsius. Application varies from TID to hourly.
Criticisms of ASE include variations in study populations such as degree of aqueous deficiency among subjects, possible benefit from increased fluid volume rather than the epithelio-trophic properties, variations in production and treatment protocols, cost of production, and convenience of use issues.
These novel treatments as well as others in the pipeline demonstrate thinking “outside the box” with regard to treating ocular surface disease. It is likely that these and future treatments will evolve and will add nicely to our considerable armamentarium.