Corneal Guttae in Fuchs Endothelial Corneal Dystrophy Best Viewed With Slitlamp

Corneal guttae, a finding associated with Fuchs endothelial corneal dystrophy (FECD), is best diagnosed via slitlamp examination, and the severity determined using the Krachmer grading scale, according to a study published in Cornea. Advanced technologies such as in vivo confocal microscope (IVCM), specular microscopy, pachymetry, and anterior segment optical coherence tomography (AS-OCT), have limited accessibility due to their inabilities to either directly detect corneal guttae, or the low detail of the images.

Currently, no defined diagnostic criteria exist worldwide for FECD. Similarly, the global standard for severity grading of FECD is unclear. Therefore, researchers conducted a systematic review of the current diagnostic criteria and severity classification to expedite the discussion regarding the global standard diagnostic criteria and severity classification based on the review’s findings. A total of 130 articles were included in the systematic review.

Among diagnostic devices, the slitlamp microscope was the most frequently used diagnostic device and corneal guttae was the most common parameter. The next most common method was a slitlamp microscope in combination with other devices or methods. The slitlamp microscope was also used most commonly for severity classification (89% of articles), and the original or modified Krachmer grading scale was used in 78% of articles.

The other technologies had notable weaknesses, such as Scheimpflug imaging, which has a light scatter with stromal edema, leading to incorrect estimation of posterior corneal curvatures and thus pachymetry. IVCM images of the central cornea result in too many dark areas, even in moderate cases with confluent central corneal guttae, the researchers explain. This makes evaluation of the endothelial cell density or morphology almost impossible. 

However, the researchers suggest that an objective measurement of FECD or corneal guttae is necessary and the development of a novel, standardized diagnostic criteria and severity grading that complements the Krachmer grading scale is not only needed, but is imminent. 

“It can be successfully achieved by using Scheimpflug or AS-OCT images in future therapies and clinical trials. Artificial intelligence (AI)–based diagnosis can be widely anticipated to play a role in the clinical setting in the future,” the researchers speculate. However, for now, “Ophthalmologists can determine the severity grading of FECD in patients using only a slitlamp microscope with the original or modified Krachmer grading scale. The simplicity of these scales is supposedly their greatest advantage.”

Study limitations include that quantitative outcomes like visual acuity or response rate were not considered in the review.