Duration 5min, Q&A 3min
The Subretinal Implant Alpha IMS to Deliver Useful Vision in Photoreceptor Disease
A photosensitive microchip (Alpha IMS from Retina Impant AG, Germany) was placed in the subretinal space in order to provide visual sensations in blind patients with retinal dystrophy.
To restore useful visual sensations to patients blind from photoreceptor dystrophies by surgically implanting an externally powered photosensitive microphotodiode array with 1500 pixels in the subretinal space. A clinical trial has been performed to evaluate safety and efficiency concerning the visual function of patients who have undergone a unique surgical procedure to implant the chip.
A multicentre trial to implant and evaluate the photodiode chip is performed (www.clinicaltrials.gov, NCT01024803). Patients with photoreceptor dystrophy (eg retinitis pigmentosa) with no useful vision were recruited. They were evaluated with preoperative OCT analysis, fluorescence angiography and autofluorescence to help identify patients suitable for the study.
Preoperatively, evaluation of visual function, extraocular movements, fundus photography, axial length measurements, OCT, FFA, electrophysiology, MRI of the orbit and psychological assessments were performed. A multidisciplinary team of surgeons performed the surgery. Post operative evaluation of the patient included electrophysiology, assessment of the chip function and assessment of the visual function with specialized computerized tests and activities of daily living.
Results and Conclusion
All the subjects had successful implantation of the chip. All the subjects were able to perceive light after implantation of the photodiode chip. The visual experiences ranged from perception of light where there was none before surgery, to the ability to see individual letters 4 cm high at a working distance of 40 cm. Motion detection was possible up to angular speed up to 35 deg/s, grating acuity up to 3.3 cycles per degree). In some cases visual acuity measurement with Landolt C-rings was possible up to Snellen visual acuity of 20/546. Additionally, the identification, localisation and discrimination of objects improved significantly in most patients. The study has shown proof of concept that a photodiode chip placed in the subretinal space can provide useful vision for many subjects
[ Keyword ]
Subretinal implant / Retinitis pigmentosa / Photodiode chip / Alpha IMS
[ Conflict of Interest ]