Slit-lamp biomicroscopy has been the hallmark of donor cornea evaluation since the beginning of retrieval of cadaveric whole eyes over the past century and subsequently corneal tissue in viewing chambers or vials over the past nearly 50 years. Tissue evaluation is a fundamental eye bank function and is required by the Eye Bank Association of America to determine surgical suitability. Slit-lamp biomicroscopy in turn has been a fundamental method of tissue evaluation since the Eye Bank Association of America instituted the criteria for eye bank and technician certification in 1980.1 Subsequently, specular microscopy was added relatively recently as another essential method for evaluation of the endothelium in 2001.2
The slit-lamp biomicroscopy technique has not changed essentially in the past several decades. Although the technology has remained unchanged, except for improved optics, slit-lamp examination remains the gold standard for determining surgical suitability. This is in large part due to the dynamic nature of the slit lamp, which allows the evaluator to examine all layers of the cornea from both anterior and posterior perspectives, making it one of the most comprehensive techniques available to eye bankers.
Other modalities, such as specular microscopy and optical coherence tomography, primarily focus on a single corneal layer or cross section, whereas the slit lamp is used to evaluate all layers using different magnifications and illumination techniques to highlight different findings relative to the layer being evaluated (Fig. 1). A technician can easily go from observing the overall tissue with low magnification to sweeping the cornea with a fine slit beam to identify possible stromal pathologies and then using high magnification to scrutinize the endothelium. The most common types of illumination include direct illumination, retroillumination, specular reflection, and sclerotic scatter (Fig. 2). In addition to the cornea, the limbus, conjunctiva, and scleral rim can be evaluated as part of slit-lamp evaluation. Complete and thorough examination of the cornea can be completed in a few minutes.
One caveat of slit-lamp assessment is the relatively qualitative nature of evaluation. It is up to the technician to identify findings and then determine the severity and location to establish surgical suitability. This means the quality of evaluation can vary greatly from technician to technician if care is not taken to appropriately train the technician and maintain consistency between multiple technicians. Providing high-quality training is essential to ensuring appropriate suitability determinations. This is especially relevant because a significant portion of eye bank corneal tissue is processed; accurate baseline evaluation is needed to select appropriate tissue for processing. Using complementary technologies can facilitate more precise evaluations.
With the advent of eye banking in the 1940s through the 1980s,3 tissue evaluation was performed almost exclusively based on the findings of thorough slit-lamp examination. This atlas shows images where slit-lamp examination alone does not yield enough information to make the most accurate suitability decisions. With the use of available and complementary technologies, eye banks can enhance slit-lamp examination and safely maximize the gift of donation.
1. Eye Bank Association of America. Medical Standards. Washington DC: Eye Bank Association of America; 1980.
2. Eye Bank Association of America. Medical Standards. Washington DC: Eye Bank Association of America; 2017.
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3. Aiken-O'Neill P, Mannis MJ. The evolution of eye banking in the United States: landmarks in the history of the Eye Bank Association of America. Int J Eye Banking. 2012;1:1–8.