The THINK Study: Testing Hypoesthesia and the Incidence of Neurotrophic Keratopathy in Cataract Patients with Dry Eye

John A Hovanesian Harvard Eye Associates, Laguna Hills, CA, USACorrespondence: John A Hovanesian, Email [email protected]: This study was designed to determine the frequency of neurotrophic keratopathy (NK) among patients presenting for cataract surgery consultation in a suburban US practice.Methods: Patients presenting for cataract consultation were evaluated with corneal staining without anesthetic. Those with grade 1 or greater corneal stain and a tear breakup time (TBUT) of ≤ 10 underwent corneal sensitivity testing with a Cochet Bonnet esthesiometer. The study also evaluated patient SPEED score symptoms, corrected distance visual acuity (CDVA), corneal higher-order aberrations (HOAs), and conjunctival hyperemia.Results: Among the 31 patients enrolled, mean corneal esthesiometry was 40 ± 9.5 mm (range 13 to 55). Esthesiometry of ≤ 40 mm, indicating neurotrophic keratopathy, was detected in 18 (58%, 95% CI 39– 75%) patients. Corneal higher-order aberrations were significantly worse at 0.83 ± 0.22 μ in the group with NK vs 0.67 ± 0.16 among patients without NK (P < 0.028). A nonsignificant correlation was found between reduced corneal sensitivity and reduced symptoms. Older patients had slightly reduced sensation, but this trend was not statistically significant. No trend was seen between reduced sensation and either CDVA or corneal staining.Conclusion: More than half of patients presenting for cataract evaluation with dry eye had stage 1 neurotrophic keratopathy. These patients had significantly worse higher-order aberrations than patients with normal sensitivity. Among patients with NK, symptoms were milder and age was higher, but neither trend was statistically significant. No trend was observed between corneal sensation and either corneal staining or CDVA.Plain Language Summary: We performed this study to determine how common reduced corneal sensation is among patients who present for cataract surgery evaluation when they also have signs of dry eye. Fifty-eight percent of patients met criteria for Stage 1 reduced sensation, and they also had significantly more corneal irregularity than those without reduced sensation. Further study is needed to determine whether patients with reduced sensation should be treated differently from other dry eye patients when preparing their eyes for preoperative biometry.Keywords: neurotrophic keratopathy, corneal sensation, dry eye, cataract surgery