Corneal Reinnervation and Sensitivity Recovery after Pterygium Excision

Abstract

Purpose. To evaluate changes in corneal sensitivity and subbasal nerve density after pterygium excision. Methods. This prospective trial included 22 eyes with nasal primary pterygium and 18 controls. Corneal sensitivity was evaluated using a Cochet–Bonnet esthesiometer in the nasal, superior, temporal, inferior, and center quadrants of the cornea before surgery and 10 days, 1 month, and 3months after surgery. The central cornea was analyzed using in vivo confocal microscopy (IVCM) before surgery and 1 and 3 months after surgery. Subbasal nerve density and other nerve parameters were analyzed using NeuronJ. Nerve tortuosity was evaluated and graded in individual IVCM scans. The tear film break-up time (TBUT) test and Schirmer’s test were performed before surgery, as well as 1 and 3 months after surgery. All the same tests were performed in the controls. Results. All affected eyes showed a significant increase in corneal sensitivity in the nasal corneal quadrant after surgery when compared with preoperative data (F = 37.3; P<0.01). Compared with controls, pterygium patients demonstrated decreased corneal subbasal nerve density (P<0.01), fewer nerve trunks (P<0.01), and fewer nerve branches (P<0.05). However, an increased central corneal subbasal nerve density was observed 1 month after surgery compared with preoperative data, after which the density became stable (F = 9.62; P<0.01). Nerve tortuosity showed no difference between the two groups or across different time points in patients. Similarly, patients with pterygium demonstrated a decrease in TBUT (P<0.01) when compared with controls. A tendency toward increase was observed in the TBUT test after pterygium excision (F = 2.873; P=0.07). However, no difference was observed in Schirmer’s test. Conclusion. Pterygium patients demonstrated deteriorated corneal subbasal nerve fibers when compared with healthy controls in terms of nerve length, nerve trunks, and nerve branches. Therefore, pterygium excision improves corneal sensitivity and increases corneal subbasal nerve density.

Sensory Changes in the Ocular Surface After Pterygium Removal

“… 19 In addition to their important sensory function, corneal nerves provide protective and trophic functions, and they regulate corneal epithelial integrity, proliferation, and wound healing. 15 …”

“…Exclusion criteria were patients with diabetes mellitus, dry eyes, systemic diseases like rheumatoid arthritis, facial paralysis, history of using contact lens, previous ocular surgery, ocular surface diseases or trauma. Pterygium was graded according to the system described by Benitez-del-Castillo et al 15 All patients enrolled in the present study had grade T3 pterygium (episcleral vessels obscured by the pterygium body.)…”

“… 13 However, a search of the literature found only a few studies that examined sensory changes after pterygium excision. 14 , 15 …”

Evaluation of the Effects of Pterygium and Aging on Limbal Structure Using Optical Coherence Tomography

“…Further, two months after the operation, superior conjunctival quadrant sensitivity returned to a normal level. Zhao et al [ 26 ] reported that tear film in patients with pterygium was unstable and that superior corneal sensitivity diminished insignificantly before and after pterygium excision. Therefore, we believe that the substances that cause pterygium also reach the POV of the superior limbus via tear flow.…”

Changes in TRPV1 Expression as Well as Substance P and Vasoactive Intestinal Peptide Levels Are Associated with Recurrence of Pterygium

“…These variations might be due to the presence of previous surgery for pterygium/pterygia, such that post-surgical changes may have altered the structure of newly formed pterygium. Specifically, it was shown that corneal subbasal nerve fibers deteriorated in pterygium patients, and pterygium excision improved corneal sensitivity and increased corneal subbasal nerve density [ 21 ].…”