Cataract Surgery with CoAx4 Illumination

New technology provides stable red reflex for all observers

February 09, 2016

A stable red reflex is one of the most important features of an ophthalmic surgical microscope for cataract surgery. It’s the red reflex that makes the structure of the lens visible and thus makes for a uncompromised view for a successful and secure surgery. One of the challenges with visualization is enhancing the red reflex particularly during phacoelmusification, cataract extraction and also during the intraocular lens surgery.

However, conventional red reflex illumination often decreases during the critical phases of the procedure like phacoemulsification. A new illumination technology with four individual beam paths overcomes these drawbacks.

The Proveo 8 ophthalmic microscope is the first system to feature the new technology. The CoAx4 Illumination provides a stable and consistent red reflex throughout the entire surgical procedure. Both main surgeon and assistant share the same view and full red reflex.

Cataract surgeons rely on a red reflex

The red reflex is the reddish-orange reflection from the retina that is observed through an ophthalmic microscope as coaxial light goes into and out of the pupil of the eye. Cataract surgeons rely on the red reflex and depth of field to precisely view the elements in the eye during each step of surgery, such as corneal incisions, division of nuclear material, removing the cortex, cleaning of the anterior and posterior leaves of the capsular bag, placing the IOL.

Consistent visualization is especially important when performing capsulorhexis which is best judged by the shadow its edge creates with the red reflex. The brighter and more even the red reflex is, the more distinct the capsular edge becomes. This enhances surgical ease in performing centered and appropriately sized capsulorhexis in all types of cataract.

Consequences of a diminished red reflex

Fig. 1: The CoAx4 Illumination provides a stable and consistent red reflex throughout the entire surgical procedure: Four individual coaxial illumination beam paths go down to the patient eye with a perpendicular entrance to the retina. In this graphic there are only shown two beam paths.

As the eye moves or the position of the microscope is changed, the red reflex may decrease, making certain phases of cataract surgery more difficult, even dangerous. For example, with a diminished red reflex it is more difficult to create a round and appropriately sized capsulorhexis, and to determine where within the cataract the phaco tip is being placed.

Most notably, without consistent illumination it is more difficult to view remaining nuclear material in the capsular bag during phacoemulsificaton and the posterior capsule bag during the procedure.

Four beam paths facilitate stable red reflex

A new technology for an ophthalmic microscope makes it possible to work with a stable and consistent red reflex. Four individual coaxial illumination beam paths down to the patient eye with a perpendicular entrance to the retina are providing a straight red reflex throughout the entire procedure (Fig. 1).

Compared to known microscopes, the image appears equal for all possible observers, the main observer, the assistant and the documentation.

Stereo red reflex for all observers

The CoAx4 Illumination is the only technology that makes the red reflex fully visible for both main surgeon and assistant. Surgeon and assistant sharing the same view of the surgical field with excellent contrast and red reflex makes cataract surgery more secure and is a valuable asset to teaching (Fig. 2).

Fig. 2: Both main surgeon and assistant share the same view and full red reflex: Four coaxial beam paths linked to a common zoom system provide the same excellent contrast, red reflex, magnification and 100% stereovision.

Adjustable illumination diameter enhances contrast

The Proveo 8 ophthalmic microscope is the first system to feature the new technology. With an adjustable illumination diameter sizeable from 4 – 23 mm the surgeon can choose via footswitch if he needs to illuminate the whole eye or prefers to match the field of illumination to the pupil size. A reduced illumination diameter produces less sclera reflections and offers more contrast, while a wider illumination is more flexible with respect to patient’s movements (Fig.3).

The CoAx4 Illumination also provides a camera image that is identical to the optical view through the ocular. The light for the camera is taken from the assistant optical path and thus leaves the main surgeon’s view with 100% of the light.

Fig. 3: The adjustable illumination diameter sizeable from 4 – 23 mm allows to align the illumination to each individual patient’s eye.

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