Molecular mechanisms and treatments for ocular symblephara

Management of Symblepharon Prior to Keratoprosthesis in Chronic Ocular Burns: A Sequential Approach

This report describes two cases with stepwise management of chronic ocular burn sequelae with concurrent total limbal stem cell deficiency (LSCD) and advanced symblepharon. Both were mono-ocular patients with the other eye being phthisical. In both cases, a sequential approach was planned, and at the first stage, the symblepharon was released to stabilize the ocular surface and form the fornices. This was followed by a type 1 keratoprosthesis (KPro) after four months of symblepharon release in the first case, and after nine months in the second case. In the first case, after symblepharon release, the resultant bare sclera was addressed with an oral mucous membrane graft (MMG). Over two years of follow-up, there was no evidence of recurrence of the symblepharon. No further surgical interventions were required. In the second case, after symblepharon release, the resultant bare sclera was addressed with a cryopreserved amniotic membrane (AM). Over eight years of follow-up, six episodes of recurrence of the symblepharon were noted over the optic of the KPro, necessitating trimming of the conjunctiva from over the optic. Thus, with these two cases, we would like to emphasize that addressing adnexal pathologies such as a symblepharon with an oral MMG before implanting a KPro, may help prevent further recurrences of symblephara and the need for multiple surgical interventions. The oral mucosa is a better alternative to the conjunctiva as compared to the AM in a mono-ocular patient where conjunctiva cannot be harvested from the contralateral eye.

PNP Hydrogel Prevents Formation of Symblephara in Mice After Ocular Alkali Injury

Purpose

To create an alkali injury symblephara mouse model to study conjunctival fibrosis pathophysiology and test polymer nanoparticle (PNP) hydrogel as a preventative therapeutic.

Methods

Mice were injured using NaOH-soaked filter paper to determine the optimal NaOH concentration to induce the formation of symblephara. Injured mice were observed for 7 days to detect the formation of symblephara. Forniceal shortening observed on hematoxylin and eosin (H&E)-stained tissue sections was used as a symblephara marker. Alpha-smooth muscle actin (α-SMA) expression, Masson's trichrome assay, and periodic acid–Schiff (PAS) staining were used to determine myofibroblast expression, collagen deposition, and goblet cell integrity. PNP hydrogel, with multivalent, noncovalent interactions between modified biopolymers and nanoparticles, was applied immediately after alkali injury to determine its ability to prevent the formation of symblephara.

Results

Forniceal shortening was observed in H&E images with 1N NaOH for 2 minutes after 7 days without globe destruction. PNP hydrogel prevented forniceal shortening after alkali injury as observed by H&E histology. α-SMA expression and collagen deposition in eye tissue sections were increased in the fornix after injury with 1N NaOH compared with uninjured controls. PNP hydrogel treatment immediately after injury reduced α-SMA expression and collagen deposition in the forniceal region. Mucin-secreting goblet cells stained with PAS were significantly lower in alkali-injured and PNP hydrogel–treated conjunctivas than in uninjured control conjunctivas.

Conclusions

We observed that 1N NaOH for 2 minutes induced maximal forniceal shortening and symblephara in mice. PNP hydrogel prevented forniceal shortening and conjunctival fibrosis after injury. This first murine model for symblephara will be useful to study fibrosis pathophysiology after conjunctival injury and to determine therapeutic targets for cicatrizing diseases.

Translational Relevance

This mouse model of symblephara can be useful for studying conjunctival scarring disease pathophysiology and preventative therapeutics. We tested PNP hydrogel, which prevented the formation of symblephara after injury.