Imaging KPRO

The ophthalmology community needs to develop better imaging techniques for keratoprosthesis (KPro) patients, to ensure any postoperative and long-term ocular complications are detected and managed in time, a major Irish ophthalmology conference has been told.

Presenting at the 2014 Irish College of Ophthalmologists Annual Conference, Dr Emma Duignan, ophthalmologist, Royal Victoria Eye and Ear Hospital (RVEEH), Dublin, said KPro is increasingly being used for patients with serious corneal issues and as the procedure becomes more refined and lasts longer, the ophthalmology profession needs to develop better ways of managing the chronic pathology that can occur in these patients.

Addressing why imaging in KPro is so important, Dr Duignan noted that these patients are a high risk of fundal pathology, including glaucoma (up to 75 per cent of patients) and retinal detachment. Imaging of the posterior segment is important, especially as digital palpation is the method relied upon to evaluate the intraocular pressure, she explained.

Irish data

Dr Duignan presented data from a small Irish study that evaluated the use of non-mydriatic, ultra-wide field scanning laser ophthalmoscopy (Optomap) along with optical coherence tomography (OCT) to image the fundi of nine KPro patients over a six-month period.

All nine patients underwent Optomap fundal imaging, of which eight had a fluorescein angiogram. OCT was obtained in five patients and was of good quality unless there was a retro-prosthetic membrane present (one of the five), she reported.

“Patient cooperation is vital in this setting as the camera must point straight through the centre of the KPro optic, which is longer in the type 2 Boston KPro, which makes it more difficult to ensure that the light is perpendicular to the optic entering the eye and more difficult to achieve wide-angle imaging,” Dr Duignan noted.

Retro-prosthetic membrane was the most common reason for inability to image the fundus, and four patients were excluded from the imaging study due to the presence of a severe membrane.

Summarising, Dr Duignan said Optomap fundal imaging can provide wide-angle images of the retina in KPro patients, though the biggest obstacle to imaging is retro-prosthetic membrane. OCT can also be performed through the KPro optic.

“As new imaging techniques become available we must identify those that give the most accurate and consistent results. With advanced imaging many disorders can be managed in a semi-traditional fashion, Dr Duignan concluded.

Emma Duignan: emmaduignan@rcsi.ie