Surface Imaging of Parasol^TM and Quintess^TM Punctal Plugs following extrusion

Abstract

Purpose : The type and architecture of punctal plugs are believed to affect the rates of punctal extrusion. We used scanning electron microscopy (SEM) and histopathology to study the surface of extruded implants in two brands of punctal plugs (Parasol^TM and Quintess^TM).

Methods : Extruded punctal plugs from 8 human subjects (5 Parasol^TM plugs, 3 Quintess^TM plugs) and an unused control plug from each brand were studied with Hitachi S-3000 Variable Pressure SEM and light microscopy in some specimens. Structural irregularity (dents, scratches, and manufacturing defects) and tissue accumulation were graded (none, mild, moderate, severe) at the collarette, neck, and head regions of each plug. Percentage change for structural irregularities across collarette, neck, and head regions were calculated between extruded and control samples. These were compared for both Parasol^TM and Quintess^TM plugs.

Results : In both Parasol^TM and Quintess^TM control plugs, structural irregularities were mild or absent in the collarette and neck regions. However, the Parasol^TM control head region had severe structural irregularity. In the extruded Parasol^TM plugs, the head region had increased tissue accumulation (4/5 severe Parasol^TM versus 1/3 in Quintess^TM). Sites of tissue accumulation are summarized in Table 1. Histopathology of plugs that showed tissue enveloping the neck demonstrated intact and/or disrupted non-keratinized stratified squamous canalicular epithelium overlying fibrovascular stroma suggestive of a pyogenic granuloma (Figure 1). The percentage increase of surface irregularity when comparing extruded and control Parasol^TM plugs was calculated as 100% in the neck and 30% in the head. The percentage increase of surface irregularity when comparing extruded and control Quintess^TM plugs was calculated as 100% in the collarette, 67% in the neck, and 30% in the head.

Conclusions : Parasol plugs appear to have inherent structural irregularities more concentrated in the head region which may predispose to tissue accumulation in that area. Given the putative role of pyogenic granuloma formation in punctal plug extrusion, it is important to consider such architectural alterations in the plug that may contribute to punctal plug extrusion.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Scoring of sites of accumulation on Parasol^TM and Quintess^TM punctal plugs