Computer-assisted laser photocoagulation of the retina—a hybrid tracking approach

Abstract

A system for robotically assisted retinal surgery has been developed to rapidly and safely place lesions on the retina for photocoagulation therapy. This system provides real-time, motion stabilized lesion placement for typical irradiation times of 100 ms. The system consists of three main subsystems: a digital-based global tracking subsystem; a fast, analog local tracking subsystem; and a confocal reflectance subsystem to control lesion parameters dynamically. We have reported previously on these individual subsystems. This paper concentrates on the development of a second hybrid system prototype. Considerable progress has been made toward reducing the footprint of the optical system, simplifying the user interface, fully characterizing the analog tracking system, using measurable lesion reflectance parameters to develop a noninvasive method to infer lesion depth, and integrating the subsystems into a seamless hybrid system. These system improvements and progress toward a clinically significant system are covered in detail within this paper. The tracking algorithms and concepts developed for this project have considerable potential for application in many other areas of biomedical engineering.

Pain and accuracy of focal laser treatment for diabetic macular edema using a retinal navigated laser (Navilas®)

“…Most importantly, we have seen photocoagulation become a less painful and more accurate treatment of retinal diseases, and several technical advances have been introduced to laser therapy including subthreshold techniques7 and pattern laser generation 8. However, the advantages of computerized precision (“eye tracking”) known from, eg, refractive surgery, have not become available despite several technical approaches towards that goal 9. Of note, in DME a protocol targeting microaneurysms appears to be advantageous versus a non-targeted early treatment diabetic retinopathy study (ETDRS) laser protocol,10 which may hint the importance of targeting precision when performing laser treatments.…”

Toward automated intraocular laser surgery using a handheld micromanipulator

“…Tracking the retinal surface is an essential feature to accomplish the fully automated laser photocoagulation because of uncontrolled eye movement during operation [6], [8]. Since vitreoretinal surgeons manipulate the eye with a surgical tool to explore region of interest, and since the patient also may move the eye, the voluntary/involuntary motion is introduced to the eyeball, which causes movement in the microscope view of the retina [12].…”

“…For instance, a semiautomated system rapidly delivers up to 50 pulses with shorter pulse duration on predefined spots, using a galvanometric scanner [7]. A fully automated approach was also proposed, based on a hybrid retinal tracking system [5], [6]. For automation, the tracking feature is essential to achieve high accuracy while compensating for the considerable movement of the eye, since the patient is conscious during the treatment and the eye cannot be completely immobilized [8].…”

Handheld‐automated microsurgical instrumentation for intraocular laser surgery

“…For automation, a tracking feature is essential to achieve high accuracy while compensating for the considerable movement of the eye, since the eye cannot be completely immobilized. Later research efforts led to the development of hybrid retinal tracking for automated laser photocoagulation, incorporating global tracking with digital imaging and high‐speed analog local tracking . Finally, computer‐guided retinal laser surgery system has been realized, utilizing digital fundus imaging in real time, and also controlling lesion depth .…”