is the image landscape extent whether it be small-angle or wide-angle as well as the patient contact issue whether it be lens contact to the cornea or noncontact lens. Most standard cameras provide small-angle viewing, whereas a

9  few specialized systems that provide wide-angle viewing include Pomerantzeff equator plus camera, RetCam™, Panoret™, Optos™, and manual montage or auto-montage on standard cameras. Most standard cameras and the Optos™ systems are noncontact, whereas Pomerantzeff camera, RetCam™, and Panoret™require contact with the eye using either a panoramic contact lens, camera lens, or transillumination probe.

9.1.1  Standard Images

Several standard slit lamp camera systems provide smallangle, high-resolution photography of the posterior pole, measuring approximately 30˚, 45˚, 65˚, and 80˚ of the posterior segment (measured from the center of the vitreous cavity). Photography of the fundus anterior to the equator of the eye is particularly difficult with standard slit lamp photography systems. Additionally, imaging of large fundus abnormalities is sometimes inadequate with these systems as the abnormality is documented in a piecemeal fashion without the desired broad perspective of the entire lesion. To document larger fundus abnormalities, manual or automatic montage capabilities have been designed.

9.1.2  Wide-Angle Images

There are three wide-angle color digital imaging systems currently available, including RetCam™, Panoret™, and Optos™. The Pomerantzeff camera and the Panoret™ system are still used at some institutions but no longer manufactured.

9.1.2.1  Pomerantzeff Equator Plus

The Pomerantzeff camera, or technique, was the first true wide-angle imaging system for the ocular fundus. Pomerantzeff and associates designed this new concept wide-angle imaging system in the early 1970s, in which they separated the illumination source from the camera observation aperture [1–4]. Using a panoramic contact lens on the eye, their “Equator Plus” camera was capable of photographing a field of approximately 148˚ from equator to equator. With experience, imaging of the retina near the ora serrata and occasionally into the ciliary body was achieved. In this method, the intraocular lighting was

provided with an external fiber-optic source placed on the sclera to transilluminate the globe. Next, a standard camera with images through a panoramic lens allowed for wide-angle images. The transillumination technique was key to this technique, as it provided illumination without glare or reflection from the lens. Satisfactory photographs with adequate resolution were obtained in 87% of the 700 eyes imaged in this fashion and there were no local ocular complications [1]. In retrospect, this breakthrough in fundus wide-angle photography provided remarkably broad, film photographs of large portions of the fundus. However, details were often limited, because the necessary brilliant transillumination bleached out adjacent details; therefore, strategic placement of the light source distant from relevant details was important. This nondigital technique continues to be used at a few centers in the United States and is applicable only in the clinic setting as a slit lamp camera is required. Cooperative children can occasionally be imaged in this way.

9.1.2.2  RetCam™

RetCam™ is a novel, wide-angle fundus imaging system designed mainly for retinal imaging in children. There have been many reports on its use for retinopathy of prematurity screening, retinoblastoma evaluation, shaken baby syndrome, and many other pediatric conditions [5–12]. This system is regarded as simple, easy to manipulate, and with high-quality digital imaging. We have used this system for approximately 6,000 sessions, mostly in children with retinoblastoma, Coats disease, and other pediatric retinal congenital and vascular abnormalities. The system is manageable by the surgeon without the need for a dedicated photographer. We have used RetCam™ in young adults and older adults, but the older the patient and greater the lens opacity, the poorer the image.

RetCam™ Camera Description

RetCam™ is a mobile camera on wheels that can be transported to an operating room. The imaging is most often performed on children under anesthesia, but occasionally it can be used in the office with proper restraint of the child. The unit involves a console with dual DVD-RAM for backup, camera light box, fluorescein angiography light box, storage drawer for lens, color printer, tri-function foot-control for adjusting light intensity, focus, and video or image capture, and a standard hand-control panel for image adjustment and capture (Fig. 9.1). Atop the console is an LCD display with real-time video. The image is taken with a hand-held video camera that is lightweight, with a long fiber-optic cable, and five changeable lens. The lens include the standard baby lens for pediatric and young

adult patients providing 120˚ images, the premature infant lens with smaller lens contact area and 130˚ field of view, the high magnification lens to evaluate fine detail of 30˚ field of view, the 80˚ lens for higher contrast, and the flat portrait lens for external full face or cutaneous imaging. All lens are simply clicked into place for rapid usage.

RetCam™ Technique of Image Capture

The hand-held camera is placed gently and directly on the corneal surface atop ophthalmic lubricant or gel (Fig. 9.1). The fundus view will be immediately visualized on the display and should be adjusted so that the image is upright and properly oriented. Focus and lighting can be