Corneal Nerve Damage Found in Almost One Third of Dry Eye Patients

A new study published in Clinical Ophthalmology reveals that nearly one-third of eyes with both signs and symptoms of dry-eye disease (DED) show reduced corneal sensitivity—a key precursor to neurotrophic keratitis (NK). Involving 395 eyes, the study found that nerve damage may be more prevalent than previously recognized, particularly in older adults and those with DED. This research highlights the role of routine corneal sensitivity testing to ensure early detection and better preservation of long-term visual function. Photo: Paul M. Karpecki, OD. Click image to enlarge. There’s no shortage of scientific evidence that dry eye disease (DED) is on the rise and highly prevalent, estimated to affect anywhere from 5% to 35% of individuals. However, its impact on corneal sensitivity is generally less well studied. The damage DED can inflict on the corneal epithelium exposes corneal sensory receptors and nerves to injury, resulting in poor wound healing. The more prolonged the deterioration is, the further the reduction in corneal sensitivity, ultimately leading to neurotrophic keratitis (NK) in many cases. It’s believed that NK affects less than 200,000 patients in the United States, but studies on DED prevalence suggest it may actually be more widespread in reality. This seems to be confirmed in a newly published study in Clinical Ophthalmology that demonstrates reduced corneal nerve sensation—a precursor to NK—is apparent in 30% of eyes with signs and symptoms of dry eye, and nearly 10% of all eyes generally.The retrospective, single-center study included a total of 395 eyes of 198 patients who presented to an eye clinic in South Carolina. The average age was 67.7, 60.6% of patients were female 80.3% were Caucasian or white. All patients underwent corneal sensitivity testing using a noncontact esthesiometer, regardless of their chief complaint or reason for visit. Dry eye symptoms were assessed using the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire. Corneal sensitivity loss was observed in 9.4% of all eyes, and 12.6% of patients had reduced corneal sensitivity in at least one eye. When assessing eyes with signs of DED (Oxford scale ≥2), 19.7% had corneal sensitivity loss. This prevalence increased to 31.4% in eyes with both signs and symptoms of DED. Conversely, the prevalence was 5.5% in eyes without dry eye.In the discussion of the study, the author wrote, “Interestingly, 96% of patients who had reduced corneal sensitivity also had co-existing DED and were using preservative-free artificial tears, and eyes with reduced corneal sensitivity loss had significantly worse signs and symptoms of DED. In fact, of those eyes with corneal sensitivity loss, 89% had some degree of corneal staining.” This study also found the risk of corneal sensitivity loss doubled with every increase in corneal staining score based on logistic regression (OR: 2.0). When assessing eyes with mild to moderate superficial punctate keratitis (Oxford grade ≥2), the rate of reduced corneal sensitivity increased to 20%. Other significant risk factors associated with reduced corneal sensation included a history of stroke and herpes zoster virus. “Compared to healthy eyes, eyes with herpes zoster ophthalmicus have a significant decrease in total nerve length, number of nerves, and number of nerve branches, which was found to be significantly correlated with corneal sensation,” according to the paper. “Similarly, patients with history of ischemic stroke have been shown to have significantly greater corneal nerve damage, including reduced corneal nerve density and fiber length. Thus, these risk factors should be screened for, as they are known to incite corneal nerve damage and increase the risk of developing NK.”Those with DED are most likely to be treated with artificial tears which do not target or treat the underlying corneal nerves, therefore the author suggests prioritizing therapies that prevent worsening of NK and visual function, such as cryopreserved amniotic membrane.Although this study was conducted retrospectively, the author says corneal sensitivity testing and the other assessments, such as the SPEED questionnaire and corneal staining, were conducted on the same day, which helps to ensure data accuracy. They also note that, because corneal sensitivity testing is subjective, future studies may benefit from objective measurements. In summary, this study shows the prevalence of corneal sensitivity loss and higher-than-previously thought rate of corneal nerve damage. “Routine clinical testing is imperative, particularly in those patients with higher risk factors, to ensure timely diagnosis and treatment and ultimately preserve vision,” the author concluded. Click here for the journal source.  Stolz M. The prevalence of corneal sensitivity loss in patients with and without dry eye disease. Clin Ophthalmol. April 18, 2025. [Epub ahead of print.]