Commentary: Digital 3D atlas of ophthalmology.

The authors of the accompanying article[1] used the Unity game engine, the technology behind many 3D smartphone games, to create an immersive three-dimensional atlas of ophthalmic anatomy. It is a great addition to the several innovative smartphone apps for ophthalmologists.[2] By incorporating true retinal images instead of animations, the authors have brought more realism to this virtual atlas.

Why Digital?

Compared to traditional printed book atlases, a digital atlas has numerous advantages. They are easily updated with the highest resolution images, compact, cheaper, interactive, portable, searchable, accessible, easily shared, and can be annotated without damaging the atlas. The authors have made it freely available which is not feasible with a physical atlas, and this can be downloaded on the Android, iOS, and Windows platforms.

Why 3D?

Ophthalmology is a very visual subject where it is imperative to visualize clinical findings in 3D, whether anterior segment on slit lamp, fundus with 90D lens, gonioscopy, indirect ophthalmoscopy, or operating under a surgical microscope. There is a 3D Atlas of Ophthalmology[3] available for free download for Android smartphones on the Google Play store by the developer EyeDoctor DrJohn. This contains 3D clinical images and surgical videos which can be viewed using low-cost, red-blue anaglyph glasses, inexpensive head-mounted virtual reality (VR) headsets or an innovative dynamic parallax method.

Why a Digital Atlas?

A picture is worth a thousand words, while a video is worth so much more. A digital atlas has the ability to incorporate videos, animations, and interactive 3D models as the authors of the accompanying article[1] have done so. This digital atlas is therefore an essential addition to the e-learning resources for ophthalmologists.[4]

Atlas of 3D Ophthalmology

Visualizing clinical and surgical ophthalmic content in stereo 3D helps in better understanding and learning the nuances of clinical ophthalmology. The Eye MG 3D app demonstrates the dynamic, virtual, interactive 3D method to learn about retinal findings in various clinical scenarios. 3D Atlas of Ophthalmology[3] uses static 3D images for clinical images taken from a slit lamp and fundus camera, in addition to 3D surgical videos recorded on 3D surgical microscopes.[5]

Stereo Anaglyph Images

Anaglyph images combine stereoscopic images for the left and right eyes after subtracting a primary color (red and blue) from each. This allows a person wearing red-blue anaglyph glasses to perceive the stereoscopic depth of the 3D image or video. A couple of example ophthalmic stereo anaglyph 3D images can be seen in Figs. 18 and 19 of the “How-to guide for smartphone slit-lamp imaging” article.[6] YouTube and EyeTube also have options for red-blue anaglyph viewing of stereoscopic 3D content. The advantage of this format is the low cost of the anaglyph glasses and the fact that any digital color screen can be used for this content. A major disadvantage is the poor reproduction of colors, which has been improved to a certain extent by using the Dubois algorithm.[7]

Side-By-Side 3D (SBS3D) Format

A rawer format for 3D is the SBS3D format where the left eye and right eye views are stored side by side. In this state, it can be visualized using a stereoviewer or a VR headset. In addition to watching recorded 3D surgeries, some innovators such as Derek Kwun-Hong Ho used a low cost, smartphone-based VR headset to practice a live simulated 3D cataract surgery.[8] This method is a bit cumbersome due to the headset, but gives a better color experience than anaglyph glasses, and is portable compared to a TV.

Parallax 3D

The parallax 3D method is a novel method of displaying 3D images by using the smartphone’s accelerometer and gyroscope sensors to display a dynamic pseudo-3D image. This can also be controlled by touch or mouse input, if required. This provides a good color experience without the need for a headset, but is restricted by how it can be viewed.

3DTV

When available, displaying 3D images on a 3D television would provide a very good visualization, but in addition to the cost, these 3DTVs are currently not available in the consumer market. We hope there is a resurgence of affordable consumer 3DTVs soon.

3D Surgical Videos

3D surgical viewing and operating systems such as the Alcon NGENUITY 3D Visualization System (Alcon Laboratories, Fort Worth, TX), the TrueVision 3D Visualization System (Leica, Wetzlar, Germany), and the ARTEVO 800 system (Zeiss, Oberkochen, Germany) are gaining popularity and slowly becoming more affordable. This will increase the number and availability of 3D stereoscopic surgical videos, which would help the ophthalmologist trainees to learn surgical techniques better.

Future of 3D and Learning

In the near future, 3D ophthalmic content will be more easily available with less cumbersome and more affordable viewing methods, probably with smartphones playing a major role in this process. It would also become easier to make 3D ophthalmic content such as stereoscopic slit lamp photographs, gonioscopy photos, fundus photos, and surgical videos.