Abstract
Purpose:
To compare the anterior chamber angle (ACA) and presence of peripheral anterior synechiae (PAS) in patients with implanted Boston Type 1 keratoprosthesis including 7.0 mm and 8.5 mm PMMA and 8.5 mm titanium back plate models.
Methods:
A retrospective study of patients who received a Boston Type 1 keratoprosthesis from 2009 - 2014 was conducted. The type of implanted back plate was determined from the operative report. Anterior segment optical coherence tomography images taken at the last postoperative visit were reviewed and ACA measurements and number of clock hours of PAS were recorded.
Results:
29 patients with a 7.0 mm PMMA back plate, 12 patients with an 8.5 mm PMMA back plate, and 7 patients with an 8.5 mm titanium back plate were included in the study with a mean follow up of 16.4, 27.5, and 2.1 months, respectively. Average ACA was 4.7 in the 7.0 PMMA group, 2.7 in the 8.0 mm PMMA group, and 17.2 in the titanium group. The difference in ACA between the titanium and the 7.0 mm PMMA group was statistically significant (p = 0.005), and there was a trend towards significance comparing the titanium to the 8.0 mm PMMA group (p = 0.01). There was no difference between the two PMMA back plate sizes. The average clock hours of PAS were 6.6, 6.0, and 6.0 for the 7.0 mm PMMA group, 8.5 mm PMMA group, and titanium group, respectively. There were no statistically significant differences in clock hours of PAS between groups.
Conclusions:
Our results suggest that patients with titanium back plates may be able to maintain their angle better than patients with PMMA back plates but PAS formation appeared to be similar to all groups. It has been suggested that Boston Type 1 keratoprosthesis titanium back plates incite less post-operative inflammatory response than PMMA back plates, which may in part explain our findings. However, longer follow up is needed to determine the clinical relevance of different back plate materials and sizes.