Bio Optics World - March/April 2015

continued from page 16 positioning of the scan, recording of line and cube scans, tracking of scans, and review—from the foot pedal. Alternately, these functions can be controlled using the touchscreen if data acquisition is also performed. A vertical and horizontal OCT picture is mirrored into the side and on the top of the surgeon’s right ocular.

Both the standard surgical video and simultaneous OCT video are visible on the screen. The device can be used unaided for anterior segment surgery to measure corneal thickness, anterior chamber depth, iris thickness, and chamber angle. It is suitable for observing and controlling steps in cataract surgery, including corneal/limbal incisions, capsulorhexis, and dynamics of phaco-emulsification. Furthermore, the system can detect residual viscoelastic and control the position of the lens implant during and at the end of surgery.

For posterior segment surgery, either a corneal lens or a wide angle viewing system (Resight) is necessary to gain high-quality pictures. During surgery, pre-retinal vitreous mobility and adhesions, the presence or absence of an attached posterior hyaloid, pre-retinal membranes, or foveal destructions (holes, thinning, edema or iNLOnl-loss, sub-retinal fluid, neo-vascularization, or hemorrhage) can be continuously visualized. Tearing forces applied to the optic nerve and retina can be detected, controlled, and minimized. Scans of sufficient quality can also be acquired under gas, perfluorocarbon (PFCL), or silicone instillation.

A progression

In addition to these currently available
commercial systems, others are being
developed. Bioptigen recently received
a $1.72 million grant from the U.S.
National Eye Institute (NEI; Bethesda,
MD) for development of microscope-
integrated intraoperative OCT technol-
ogy. In September 2014, Hiroko Ter-
asaki of Nagoya University Hospital
(Japan) presented prototype intraoper-
ative endoscopic OCT from NIDEK at
the Meeting of Club Jules-Gonin. Pro-
fessor Terasaki and her group have used
the handheld forward-imaging, 21-gauge
(820 μm diameter) needle endoscope for
ophthalmic OCT inspection of cornea,
lens, and vitreous removed from ex vivo
porcine eyes. The device proved able to
clearly image structures 2. 5 mm from
the probe tip, meaning that it proved
suitable for endoscopic inspections. The
idea is similar to work done by Han et
al., 6 but uses a 23G fiber.
All of these systems are examples of
a major shift in the application of OCT
for surgical guidance. Moving forward,
microscope-integrated examination sys-
tems will surely be used in ophthalmic
microsurgery with increasing frequency.

Integration of OCT in surgical microscopy adds considerable value without loss of time or sterility. Use of the microscope’s optical pathway and inclusion of OCT imagery in the surgeon’s view enables complete and seamless control. This is a fabulous example of how new technology can address familiar challenges. And, as is often the case with new technology, further experience might enable detection of yet-unrecognized processes—and thus yield even greater results. «

DISCLOSURE

The Ludwig Boltzmann Institute (LBI) for Retinology and Biomicroscopic Lasersurgery (LBI) received an unrestricted equipment grant by Carl Zeiss Meditec. LBI received a research grant by Carl Zeiss Meditec in 2011/2012. The author declares no actual or potential conflicts of interest in relation to this article.