In this study, we found a progressively improved healing effect of extract of G. lucidum, from the first 24th hour to the 168th (seven days of treatment). In this study, the indices of healing used to show improvement in the healing process of a purposefully induced corneal injury and then subsequently infested using P. aureginosa – a common, normal floral, but opportunistic microorganism – were eyelid status, conjunctival status, lacrimation, epithelial eruption, corneal staining, photophobia, ocular discharge, corneal edema, and corneal infiltrates. In group A animals (Table 1), there were observable changes in this first experimental group exposed to chemical injury alone using 1 molar sodium hydroxide. Our finding showed that although treatment with G. lucidum extract had a significant anti-inflammatory effect on just a few ocular structures: eyelid status change, reduced lacrimation, reduced corneal staining and edema, the clinical effect of treatment with the extract in all ocular structures observed were highly significant, particularly with lacrimation (47%). These findings are shown in Fig. 1. As shown, both the clinical effect and the observable signs demonstrates that treatment with G. lucidum after the 168th hour significantly improves the corneal healing process following a chemical (alkaline) injury. However, as can be seen from Fig. 1, and as is typical with most chemical injuries, specifically from sodium hydroxide that causes corneal damage through pH change, ulceration, proteolyzes and collagen synthesis defects to the cornea, healing following chemical injuries takes time, way longer than 7 days to achieve both significant physically observable signs of healing . This time limitation was a key challenge in this study. Still, and as noted by Singh , chemical injuries, particularly those of alkaline origin, to the cornea are potentially blinding ocular injuries and constitute a true ocular emergency requiring immediate assessment and initiation of treatment . Our finding demonstrates that instituting treatment with extract of G. lucidum as early as within the first 24th hour of occurrence has potential to prevent extensive and penetrating damage to the cornea, and other ocular surface tissues that present a risk to irreversible vision loss.
Furthermore, among animals in group B (experiment group 2) as shown in Table 2, our finding demonstrates that treatment with G. lucidum extract did not significantly change the ocular morphology of most of the animals after the 168th hours, except for a significant reduction in photophobia and lacrimation. Our findings showed that the differences in the analysis of the quantitative morphological variables observed between the manifestations of various ocular parameters in the animals of this group at the first 24th hour following injury with 1 molar Sodium hydroxide, and subsequent infection with P. aeruginosa 12 hours thereafter (to induce bacterial ulcer), and at the last 168th hour of treatment with G. lucidum, was not significant. Nonetheless, the converse was true for the clinical effect of treatment with the extract of G. lucidum. As shown in Table 2, in all ocular structures observed the differences in the morphological changes between the 24th and the 168th hours were clinically significant (effect size > 5%). This finding, therefore, showed that the clinical effect of treatment with G. lucidum for bacterial infected corneal ulceration is significant. The clinically significant effect (effect size = 93%) was found to be most effective with the reduction of ocular discharges – a good morphological indication of a reduction in microbial load . This finding is also shown pictorially in Fig. 2, thus confirming findings of previous studies [5, 11, 12], that the antibacterial effect of G. lucidum on non-ocular related inflammatory injuries and infective ulcers in other parts of the human body is clinically effective. In addition, our finding demonstrates that G. lucidum has proven to be effective in managing bacterial infections that have shown resistance , as well as shown to be an effective alternative to treating bacterial infections and inflammatory injuries to the human body , may as well be an effective alternative to the management of inflammatory and ulcerative conditions of the corneal and other tissues of the ocular adnexa.
Going forward, our study compared the treatment effect of extract of G. lucidum with existing standard treatment protocol for chemical (alkaline) induced ocular injury and bacterial induced corneal ulcers consisting of two hourly drops of fluoroquinolone (ciprofloxacin), six hourly drops of corticosteroid (betamethasone), and eight hourly drops of atropine [16, 17]. We found that after the 168th hour of treatments with G. lucidum on animals in group B (experimental group 2) and treatment with the standard treatment protocol on animals in group C (positive control group), treatment in group C had better clinical effects than in group B (effect size > 5%), as shown in Table 3. However, as can be seen from Table 3, the difference between the two treatment protocols was not statistically significant (p > 0.05). This finding is also shown pictorially in Fig. 3. The implication of this finding, therefore, is a demonstration of the fact that treatment with extract of G. lucidum may be an effective alternative to the treatment of bacterial induced corneal ulcerative and inflammatory injuries. This further justifies the finding of infective and inflammatory injuries to other non-ocular tissues of the human body .
Finally, to further demonstrate the healing effects of extracts of G. lucidum on the cornea and other ocular adnexa, we compared the morphological changes after 168th hour between animals in group B (experiment group 2) and those in group D (placebo – negative control group). As shown in Table 4, we found that after 168 hours of treatments with G. lucidum in group B, and treatment with atropine only on animals in group D, there was no statistically significant difference (p > 0.05), observed in both groups. However, our finding further showed a clinically significant effect, in the healing observed in group D animals over those group B animals (Fig. 4). This was an interesting finding of our study that the animals in group D (negative control) that were administered with atropine sulphate alone showed better clinical improvement than those treated with G. lucidum. Atropine sulphate was purposively administered to control ciliary spasms in the eyes of the animals in the negative control group. It was interesting to observe that atropine (primarily a cycloplegic agent) also known to show anti-inflammatory secondary effects [20, 21], resulted in significantly better healing effects compared with G. lucidum. This finding may explain the importance of introducing an anti-inflammatory treatment protocol as early as possible in the management of both chemical and bacterial induced corneal ulcerations.
To summarize, therefore, we note that while there was limited empirical data in literature on the ocular-related healing effects of G. lucidum to compare our findings with, we found extracts of the mushroom to show an observable reduction in the severity of changes in the ocular parameters affected following induction of chemical injury and subsequent bacterial corneal ulceration. Specifically, we note a significant reduction in eyelid swelling and lacrimation in animals treated with G. lucidum after the 168th hour of treatment. This is evident with the animals in groups A and B, where the eyelid and conjunctival severity were significantly reduced progressively (Figs. 1 and 2). Although no significant change was noticeable in a few (epithelial eruption, epithelial staining, corneal fluorescein staining, and corneal edema), we found the clinical healing effects of G. lucidum extracts to be highly significant, particularly for the reductions observed with ocular discharges, photophobia and corneal infiltrations. This we found, while not being consistent with the healing effect observed in a study on paw edema following intra-muscular instillation of G. lucidum , was nonetheless consistent with the healing effect observed in another study on gastric ulcers . Other studies that compared the clinical healing effects of extracts of G. lucidum with commonly used antibiotics, such as gentamycin sulphate  and fluoroquinolones , found it to be equally effective in other body structures. We found this not to be the case with ocular healing effects, as standard treatment with a combination of fluoroquinolone, corticosteroid and atropine sulphate, and even with using atropine sulphate alone, turned out to show better clinical effect than with treatment with G. lucidum alone.