Putting vital stains in context

Abstract

While vital staining remains a cornerstone in the diagnosis of ocular disease and contact lens complications, there are many misconceptions regarding the properties of commonly used dyes by eye‐care practitioners and what is and what is not corneal staining after instillation of sodium fluorescein. Similarly, the proper use and diagnostic utility of rose Bengal and lissamine green B, the other two ophthalmic dyes commonly used for assessing ocular complications, have similarly remained unclear. Due to the limitations of vital stains for definitive diagnosis, concomitant signs and symptoms in addition to a complete patient history are required. Over the past decade, there have been many reports of a type of corneal staining—often referred to as solution‐induced corneal staining (SICS)—that is observed with the use of multipurpose solutions in combination with soft lenses, more specifically silicone hydrogel lenses. Some authors believe that SICS is a sign of lens/solution incompatibility; however, new research shows that SICS may be neither a measure of lens/solution biocompatibility nor ‘true’ corneal staining, as that observed in pathological situations. A large component of SICS may be a benign phenomenon, known as preservative‐associated transient hyperfluorescence (PATH). There is a lack of correlated signs and/or symptoms with SICS/PATH. Several properties of SICS/PATH, such as appearance and duration, differentiate it from pathological corneal staining. This paper reviews the properties of vital stains, their use and limitations in assessment of the ocular surface, the aetiology of corneal staining, characteristics of SICS/PATH that differentiate it from pathological corneal staining and what the SICS/PATH phenomenon means for contact lens‐wearing patients.

Key words:

• cornea
• fluorescein
• preservative‐associated transient hyperfluorescence
• solution‐induced corneal staining
• vital stains

Acknowledgements

The author receives funds as a consultant for Bausch & Lomb. Editorial and scientific support (writing assistance, assembling tables and figures, grammatical editing, fact‐checking and referencing) were provided by BioScience Communications, New York, NY, USA. BioScience Communications received unrestricted funding support from Bausch & Lomb Vision Care, Rochester, USA. The author would also like to thank Dr Frank Bright for his helpful feedback and use of his figures. Dr Bright has received an unrestricted research grant from Bausch & Lomb and receives funds as a consultant/advisor.

Notes

1. Based on recent findings by Bakkar and colleagues2010 and the group at the Jules Stein Eye Institute,2008 hyperfluorescence/hyperfluorescent is defined as the bright green signal observed after instillation of fluorescein (either free or as a disodium salt) on the cornea (for example, corneal staining) in vivo or ex vivo and cell‐based assays in vitro. Fluorescence/fluorescent is defined as the background glow seen on the cornea in vivo or ex vivo or in cell‐based assays in vitro and the emitted light observed in non‐cell‐based assays using any fluorescent molecule either free or as a label/probe.

2. Throughout this paper, the associated term ‘SICS/PATH’ will be used, as these phenomena are largely synonymous (that is, SICS can be largely attributed to PATH).

Additional information

Funding

Bausch & Lomb Vision Care, Rochester, USA