Tag Archives: cataract

Ocular Autofluorescence – More Than Just the Fundus

Over the past decade, fundus autofluorescence imaging has become a commonly used diagnostic technique to document the presence of fluorescent structures in the eye.1-2 The term “autofluorescence” is used to differentiate fluorescence that may occur naturally from fluorescence that is derived from application of dyes such as fluorescein or indocyanine green.

Autofluorescence is most commonly used to document fluorescence of lipofuscin, a fluorescent pigment that accumulates in the retinal pigment epithelium (RPE) as a normal byproduct of cell function.3 Lipofuscin deposition normally increases with age, but may also intensify in certain retinal abnormalities. It is used to document progression of macular degeneration, central serous chorioretinopathy, Stargardt disease, drug toxicities, and several hereditary retinal dystrophies.

In addition to the documentation of lipofuscin in the RPE, there are other fluorescent findings that may occur in the eye. One of the initial uses of autofluorescence was documenting optic disc drusen and astrocytic hamartomas as early as the 1970’s.4 Both of these entities are calcified lesions that are highly fluorescent and can be documented with standard fluorescein excitation and barrier filters.

Fig 1 small
Left: optic disc drusen. Right: astrocytic hamartoma, a calcific tomor associated with tuberous sclerosis

The aging crystalline lens is also known to be fluorescent. In fact, lens autofluorescence was the inspiration for the development of fluorescein angiography by Novotny and Alvis.

LENS faf2
Dense cataract that fluoresces with the standard fluorescein excitation and barrier filter combination in a fundus camera. This image illustrates how fluoresence from the lens can compromise the qulaity of a fluorescein angiogram by adding unwanted fluorescence.

In addition to these well-known entities, there are some additional autofluorescent findings you may encounter in the eye. In 2009, Utine et al reported autofluorescence of pingueculae on the ocular surface.5 This finding may interfere with photo-documentation of topical fluorescein staining patterns in patients with conjunctival lesions.

pinguecula2
Autofluorescence image of a pinguela taken with a fundus camera in external mode. Note that the crystalline lens of this eye also fluoresces.

Certain emboli, presumably calcific, exhibit fluorescence.

plaque3
Patient with a branch retinal artery occlusion. Left image demonstrates classic retinal whitening from the occlusion. Right image identifies the fluorescent calcific plaque associated with the arterial blockage.

We’ve also had a case of corneal blood staining that fluoresced. As it turns out, hemoglobin and hemosiderin are known to be fluorescent and that’s what fluoresced in this case.

hemosiderin
A case of corneal blood staining after a long standing hyphema. Autofluorescence is presumably from either hemoglobin or hemosiderin.
angioid
Another case where blood is hyperfluorescent in a patient with angioid streaks.

There may be other ocular findings that exhibit autofluorescence when excited with light of specific wavelengths. Have you noticed anything else that fluoresces? If so, I encourage you to share them.

  1. von Ruckman A, Fitzke FW, Bird AC. Distribution of fundus autofluorescence with a scanning laser ophthalmoscope. Br J Ophthalmol 1995;79:407-412.
  2. Spaide RF. Fundus autofluorescence and age-related macular degeneration.
    Ophthalmology 2003;110:392-9.
  3. Delori FC, CK Dorey CK, G Staurenghi G, et al. In vivo fluorescence of the ocular fundus exhibits retinal pigment epithelium lipofuscin characteristics. Invest Ophthalmol Vis Sci 1995;36:718-729.
  4. Kelly JS. Autofluorescence of drusen of the optic nerve head. ArchOphthalmol 1974;92: 263-264.
  5. Utine CA, Tatlipinar S, Altunsoy M, et al. Autofluorescence imaging of pingueculae. Br J Ophthalmol 2009;93:396–399.

Me, Myself, and Eye

Although it may seem like a recent phenomenon, the photographic self-portrait has been with us since the dawn of photography. Perhaps the earliest known “selfie” was taken by Hippolyte Bayard (Portrait of a Drowned Man), a Frenchman who claimed to have invented a photographic process prior to the Daguerrotype. The same can be said of William Henry Fox-Talbot (The Reading Establishment).

In recent years, the photographic self-portrait has exploded in popularity into a global phenomenon, fueled by social media sites such as Facebook, Instagram, Twitter, Snapchat, and others. It is estimated that over one million “selfies” are taken every day. A recent search of Instagram returned over 211 million photos with the hashtag “#selfie”. The term “selfie” is believed to have originated in Australia and has been elevated from internet slang to our common vernacular and even inclusion in several formal English dictionaries. In fact, selfie was Oxford Dictionary’s word of the year for 2013!

Everybody seems to be getting into the act including celebrities, politicians, and even the Pope! Selfies are even popular in space.  Astronauts have shared several spacewalk selfies online, and last year, NASA promoted a global selfie project to celebrate Earth Day. They solicited over 36,000 selfies from around the world and created an interactive composite image that can be viewed on their website.

The selfie is so ubiquitous in today’s pop culture that cell phones and digital cameras often include built-in selfie-friendly apps and features such as extra wide angle lenses, articulating screens or front facing screens that facilitate the selfie pose.  You can also purchase selfie sticks to extend the camera to a better vantage point.  These popular items go well beyond the simple self-timer found on many cameras of yesteryear. Selfies are often purposely self-deprecating, campy, cheesy, or irreverent. They are meant to be spontaneous and fun and are not usually taken very seriously. The selfie craze has even spawned the infamous “duck face” pose.

Despite the fun and seemingly harmless spirit behind them, there is a belief that taking selfies can be a sign of narcissism rather than simple self-expression. There is also some concern it can be addicting and unhealthy. But there is a growing trend in telemedicine where patients can take and forward selfies to their doctors to help diagnose or triage the urgency of their condition.  So maybe there are some legitimate uses for selfies.

As a life-long photographer, I’ve taken my share of selfies over the years. I’ve even attempted a few with the equipment I use for diagnostic ophthalmic photography. Some are goofy, and in the spirit of social media selfies. Some are more practical.

Most ophthalmic imaging devices are not what you’d normally consider selfie friendly, at least not in terms of taking a photo of one’s own eyes. Because the optics of these devices are designed for photographing curved surfaces found in the interior of the eye, they usually create distortion when backed up an appropriate distance to take a facial portrait. The effect of this distortion eliminates the need for a goofy facial expression if your goal is just to post a unique selfie on the internet!

But what about useful diagnostic or artistic photos of your own eyes, photos that go beyond distorted face selfies? It’s not only possible, but surprisingly good images can be obtained with some devices.  Non-mydriatic instruments with a monitor that can be pivoted toward the patient/photographer lend themselves to self-imaging, while those with an optical viewfinder (fundus camera) or fixed monitor position (Cirrus) do not. I’ve been able to obtain eye selfies with the Zeiss Stratus, Heidelberg HRT, Heidelberg HRA/OCT, Clarity RetCam, Tomey specular microscope and various handheld external cameras. But, you might ask, “So what?” or “Why?”

Well, there have been times when I needed to check a device during maintenance or a software upgrade and it was convenient to use myself as the patient. Sometimes while training staff to use a device, I’ll demonstrate the procedure on myself. Other times, I’ve needed a quick example of a “normal” eye for a lecture like those above.

Surprisingly, the ability to take eye “selfies” has helped me identify and track pathology in my own eyes. Two years ago I suffered an idiopathic retinal tear with avulsed bridging vessel and persistent vitreous hemorrhage. This was successfully treated with vitrectomy. Like many patients, I developed a cataract after the vitrectomy. I also began to notice some distortion that corresponded to progression of an epiretinal membrane (ERM) in the same eye.

Any time I noticed a change in vision I would repeat an OCT on myself. Over the course of six months I tracked an increase in thickness of about 100 microns. The cataract also progressed and I was scheduled for cataract surgery. Two weeks prior to surgery I noticed a very subtle change in vision and sat down at the OCT like I’d done several times in the past. The OCT detected some cystoid macular edema (CME) from the ERM. Picking up the CME prior to cataract surgery was very beneficial. Preexisting CME can be exacerbated by cataract surgery, so my surgeon began a course of treatment that reduced the edema. My OCT selfies likely helped us avoid more severe or persistent edema by catching it in advance.

Cataract surgery went as planned, but within a few hours of my procedure I began to notice a new visual abnormality: a paracentral gray scotoma. Upon arriving at the clinic the next day for my post-operative check, I immediately did an SLO/OCT selfie and identified an unusual finding that corresponded directly to the scotoma.

SD-OCT demonstrated an area of hyper-reflectivity in the middle retinal layers just temporal to the fovea (green arrows) and the IR reflectance image showed a distinct dark gray lesion. Fortunately, the scotoma began to fade within a few days and so did the lesion. The jury is still out on the exact cause of the lesion but the selfies have enabled us to track improvement of my condition and possibly publish a case report. We believe it may be a case of paracentral acute middle maculopathy (PAMM), a recently described variant of acute macular neuroretinopathy (AMN). It’s rare enough, that I was able to present it at the OPS Rare Case Symposium in Ann Arbor.

As you can see, image quality can be quite good with a little practice. So good in fact that I’ve received a bill from my institution for OCT images that I’ve performed on myself! Here is a double selfie video of a Spectralis IR fundus image showing how easy it is to capture my own epiretinal membrane.

I’m beginning to think maybe I should stop taking selfies of my own eyes. After all I keep finding abnormalities! But there is a growing trend in telemedicine where patients can take and forward selfies to their doctors to help diagnose or triage the urgency of their condition.

Ophthalmic Photographers taking diagnostic selfies: obsessive, silly, or beneficial?