Human albumin eye drops as a therapeutic option for the management of keratoconjunctivitis sicca secondary to chronic graft-versus-host disease after stem-cell allografting

[Corneal wound healing-Pharmacological treatment]

Physiological wound healing of the cornea is a complex process and involves numerous multifactorial tissue processes. A proper wound healing, especially without the formation of light-scattering scars, is essential to preserve the integrity and function of the cornea. Misdirected wound healing is of vast clinical relevance as it can lead to corneal fibrosis and the loss of optical transparency with subsequent reduction of visual acuity, up to blindness. In addition to the understanding of the pathophysiological mechanisms, the knowledge of therapeutic concepts and options for treating corneal wound healing disorders and fibrosis is essential to counteract a permanent damage of the cornea as early as possible. Nowadays, various pharmacological and surgical options are available for treatment. The decision, appropriate selection and indication for the optimal treatment depend primarily on the genesis and clinical appearance of the corneal wound, fibrosis or scar. The treatment of wound healing disorders ranges from the use of topical therapy and supportive measures up to tissue replacement procedures. As long as the mechanical stability of the cornea is intact and wound healing processes are still ongoing, a pharmacological modulation is reasonable, which is discussed in this article.

Albumin Levels in Tear Film Modulate the Bioavailability of Medically-Relevant Topical Drugs

The breakdown of blood-tear barrier that occurs with ocular pathology allows for large amounts of albumin to leak into the tear fluid. This process likely represents an important restriction to drug absorption in ophthalmology, as only the unbound drug is transported across the ocular tissue barriers to exert its pharmacologic effect. We aimed to investigate the effects of albumin levels in tears on the bioavailability of two commonly used ophthalmic drugs: tropicamide, an antimuscarinic that produces mydriasis and cycloplegia, and latanoprost, a PGF2α analog used for the treatment of glaucoma. Eight female beagle dogs underwent a randomized, vehicle-controlled crossover trial. For each dog, one eye received 30 µl of artificial tears (control) or canine albumin (0.4 or 1.5%) at random, immediately followed by 30 µl of 1% tropicamide (2 days, 24 h washout) or 0.005% latanoprost (2 days, 72 h washout) in both eyes. Pupil diameter (digital caliper) and intraocular pressure (IOP; rebound tonometry) were recorded at various times following drug administration (0 to 480 min) and compared between both groups with a mixed model for repeated measures. Albumin in tears had a significant impact on pupillary diameter for both tropicamide (P ≤ 0.001) and latanoprost (P ≤ 0.047), with no differences noted between 0.4% and 1.5% concentrations. Reduction in the maximal effect (pupil size) and overall drug exposure (area under the effect time-curve of pupil size over time) were significant for tropicamide (6.2–8.5% on average, P ≤ 0.006) but not for latanoprost (P ≥ 0.663). The IOP, only measured in eyes receiving latanoprost, was not significantly impacted by the addition of either 0.4% (P = 0.242) or 1.5% albumin (P = 0.879). Albumin in tear film, previously shown to leak from the conjunctival vasculature in diseased eyes, may bind to topically administered drugs and reduces their intraocular penetration and bioavailability. Further investigations in clinical patients and other commonly used ophthalmic medications are warranted.

TFOS DEWS II Tear Film Report

The members of the Tear Film Subcommittee reviewed the role of the tear film in dry eye disease (DED). The Subcommittee reviewed biophysical and biochemical aspects of tears and how these change in DED. Clinically, DED is characterized by loss of tear volume, more rapid breakup of the tear film and increased evaporation of tears from the ocular surface. The tear film is composed of many substances including lipids, proteins, mucins and electrolytes. All of these contribute to the integrity of the tear film but exactly how they interact is still an area of active research. Tear film osmolarity increases in DED. Changes to other components such as proteins and mucins can be used as biomarkers for DED. The Subcommittee recommended areas for future research to advance our understanding of the tear film and how this changes with DED. The final report was written after review by all Subcommittee members and the entire TFOS DEWS II membership.

[Ocular graft versus host disease : Corneal complications]

BACKGROUND

Ocular graft-versus-host disease (GvHD) following allogeneic blood stem cell transplantation leads to immunologically induced alterations in many ocular tissues, particularly at the ocular surface. Within the framework of the main topic, this article focuses primarily on corneal complications in chronic ocular GvHD.

OBJECTIVE

This article aims to promote understanding of the influencing factors, diagnostics, and therapeutic options pertaining to corneal complications in ocular GvHD. Furthermore, the possibilities for prevention are discussed.

MATERIALS AND METHODS

This analysis is based on a literature review as well as on data from the Ophthalmology Clinic at the University Hospital Essen.

RESULTS

Corneal complications often occur secondarily in ocular GvHD, as a consequence of severe inflammatory alterations of the conjunctiva or eyelid. Spontaneous corneal perforations associated with only mild symptoms are less common during the course of disease. From the ophthalmologist's perspective, it is important that the inflammatory activity of all the different ocular tissues is considered. Treatment may follow a stepwise scheme that includes substitution, immunosuppression, and surgical rehabilitation.

CONCLUSION

Systematic diagnosis of ocular GvHD helps to prevent corneal complications or support early therapeutic intervention. An interdisciplinary approach to diagnosis and treatment planning is recommended, in order to optimize local and systemic immunosuppressive therapy.