Amantadine therapy for Parkinson's Disease: In Vivo Confocal Microscopy corneal findings, case report and revision of literature

Modified Method for Nanothin Descemet Stripping Automated Endothelial Keratoplasty

PURPOSE

The purpose of this study was to describe a method to achieve a high success rate for nanothin (NT, ≤50 μm) Descemet stripping automated endothelial keratoplasty (DSAEK) graft preparation using anterior chamber pressurizer (ACP) with a modified setting and evaluate its postoperative efficacy.

METHODS

A prospective cohort (study group) of 24 patients with corneal endothelial dysfunction was consecutively enrolled and received DSAEK grafts using the modified ACP method from December 2021 to May 2022. The control group included 24 historical patients who received DSAEK grafts using conventional ACP procedure. Central graft thickness (CGT), graft regularity (3-mm and 5-mm diameter zones), best spectacle-corrected visual acuity, and endothelial cell density (ECD) were compared between 2 groups.

RESULTS

A 100% ultrathin (UT, ≤100 μm) DSAEK rate and 62.5% NT-DSAEK rate was achieved at 3 months postsurgery in the study group, with a 51.3 ± 14.8 μm CGT, while a 70.8% UT-DSAEK rate and 4.2% NT-DSAEK rate was achieved in the control group, with an 89.0 ± 15.4 μm CGT (P <0.001). At 3-month postoperative follow-up, the regularity of graft thickness was significantly better in the study group (central-to-peripheral thickness difference: P = 0.044 and 0.014 for 3-mm and 5-mm diameter zones, respectively, graft thickness uniformity: P <0.001 and 0.012, respectively). There was no statistical difference in the best spectacle-corrected visual acuity (P = 0.170) or ECD (P = 0.833) between 2 groups at 3-month postoperative follow-up.

CONCLUSIONS

DSAEK grafts harvested using modified ACP method were thinner and more regular compared with the conventional ACP method.

Amantadine-induced corneal edema: A case and literature review

Purpose

To present a case of irreversible corneal edema after 10 years of amantadine use. A literature review was carried out to describe the clinical characteristics and outcomes of amantadine-induced corneal edema.

Observations

A 36-year-old woman presented with a 6-week history of gradually progressive bilateral painless visual loss with visual acuity (VA) of 20/350 and 20/300 in the right and left eye, respectively. Examination showed bilateral diffuse central corneal edema with multiple Descemet membrane folds without endothelial guttata, keratic precipitates or intraocular inflammation. This did not respond to hypertonic saline drops and empirical treatment for presumed herpetic endotheliitis with oral acyclovir. Medication review revealed the use of amantadine 100mg daily for the past 10 years, prescribed by her neurologist for fatigue. Despite discontinuing amantadine, corneal edema was irreversible due to a markedly reduced endothelial cell count of 625 (right) and 680 cells/mm2 (left).

Conclusions and Importance

This case highlights the need to consider amantadine as a cause of unexplained bilateral non-guttae corneal edema. A literature review of 33 case reports revealed broadly similar features of amantadine-induced corneal edema; whilst most cases had favorable outcomes with median VA 20/25 (interquartile range IQR 20/20-20/30) and complete resolution of corneal edema within 30 days (IQR 14-35) of amantadine discontinuation, most experienced low endothelial cell density 759 cells/mm2 (IQR 621-1078). Taken together, screening specular microscopy ought to be considered for those in whom amantadine is likely required long-term.