Anterior Chamber Angle Assessment in Patients With Boston Keratoprosthesis Type I
Purpose
To quantitatively evaluate the anterior chamber angle of eyes with Boston keratoprosthesis type I (B-KPro) with and without glaucoma, eyes with primary angle closure glaucoma (PACG) and eyes with narrow angles (NA) using anterior segment optical coherence tomography (AS-OCT).
Methods
Recruited patients prospectively underwent AS-OCT (RTVue, Optovue). Images of the anterior chamber angle were obtained from all four quadrants (inferior-superior-nasal-temporal) in primary gaze position and under dark standard conditions. Angle opening distance at 500µm from the scleral spur (AOD 500), trabecular iris angle (TIA 500) and trabecular iris surface area (TISA 500) were measured using the RTVue angle measurement tool. Images with poor quality or no view of the iris and scleral spur were excluded. Among the visible quadrants, the widest and the narrowest angle of each eye, as well as the average between the angles were included in the analysis. Only 1 eye per patient was analyzed.
Results
Eight eyes from B-KPro patients with glaucoma, 8 eyes from B-KPro patients without glaucoma, 8 eyes from patients with PACG and 10 eyes from patients with NA and patent laser peripheral iridotomy were included in the analysis. The mean VA (decimal) was 0.5 for B-KPro eyes and 0.9 for eyes without B-KPro. Comparing the quadrant containing the widest angle of each eye, B-KPro eyes with glaucoma had significantly lower AOD 500, TIA 500 and TISA 500 than B-KPro eyes without glaucoma (p<0.016 for all) and PACG (p<0.016 for all). AOD 500, TIA 500 and TISA 500 were not statically different comparing B-KPro eyes without glaucoma, PACG, and NA (p>0.05 for all).
Conclusion
AS-OCT allows the quantitative angle assessment in eyes with B-KPro. The significant angle narrowing in B-KPro eyes with glaucoma may contribute to the aggressive nature of the disease. Even B-KPro eyes without glaucoma have angles as narrow as eyes with PACG or NA. AS-OCT can be a valuable tool to monitor patients with B-KPro, regarding development of secondary angle closure glaucoma and its progression.