Abstract
Purpose: :
To assess anterior chamber (AC) depth in aphakic and pseudophakic patients with Type 1 Boston Keratoprosthesis (KPro) using anterior segment optical coherence tomography (OCT).
Methods: :
Eight patients who underwent Boston Type 1 Keratoprosthesis implantation were evaluated for anterior chamber depth by the non-contact technique of AS-OCT (AC Cornea OCT prototype, OTI, Canada). Longitudinal cuts were used in evaluation of AC depth. Functional AC depth was defined as the distance between the back plate of the KPro and the anterior surface of the iris. Anatomic AC depth was defined as the distance from the posterior surface of donor cornea to the iris. Both functional and anatomic AC depths were measured nasally and temporally. The distance between the back plate of the KPro and anterior surface of the posterior chamber intraocular lens (PCIOL) was also measured nasally and temporally in pseudophakic patients. Axial lengths were measured prior to KPro implantation using standard A scan techniques.
Results: :
Of the 8 patients studied, 3 were aphakic and 5 were pseudophakic. Indications for keratoprosthesis included repeat graft failures. Axial length measurements ranged from 21.06mm to 26.78mm. Anatomic AC depths measured between 0.9mm to 3.3mm. Functional AC depths ranged from 0mm to 3.1mm. In patients who had functional AC depths of 0 to 1mm, axial lengths were 21.06mm , 22.6mm, 23.63 and 25.3mm. Patients who had functional AC depths of >1mm had axial lengths of 23.5mm, 24.15mm and 25.3mm and 26.78mm. Pseudophakic patients had functional AC depths between 0mm and 3.1mm. Aphakic patients had functional AC depths between 1mm and 2.2mm. No aphakic patients had functional AC depths of 0mm. The distance between the back plate of the KPro and PCIOL in pseudophakic patients ranged from 1.1mm to 3.1mm.
Conclusions: :
Optical coherence tomography is a useful tool in the evaluation of anterior chamber depth in patients with keratoprosthesis. AC depth measurement is a valuable piece of information previously unknown in the setting of KPro implantation. Knowledge of the depth between anterior segment structures and the KPro will allow for better understanding of optimal AC depths in aphakic vs. pseudophakic patients, and possible improvements in the KPro model.
Keywords: keratoprostheses • anterior chamber • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)