There are certain questions in ophthalmology which remain unanswered despite the vast repository of modern medical knowledge at our disposal, such as “Why do I feel pressure behind my eyes?” and “Do you know how I can see an ophthalmologist on the weekend?” Nobody knows. Perhaps the biggest question which has eluded ophthalmologists for decades is “why was Han Solo blind after he was freed from his carbonite prison in Return of the Jedi?”
Before we get into Han’s differential diagnosis for complete vision loss, I did a little digging (google search, took like 8 seconds tops) and found a Wikipedia entry put together by some nerds.
This link describes a disease called “hibernation sickness” with symptoms like exhaustion, dehydration, memory loss and “temporary blindness.” Unfortunately this website, which describes itself as a “Wookiepedia” does not go into detail regarding the pathophysiology of hibernation sickness (HS). From a basic physiology standpoint, I can understand dehydration, weakness, and exhaustion. Solo was stuck in carbonite for months without any food, water, IV fluids, or rectal tube I assume. I’d be pretty weak too and probably dead. However, this still doesn’t explain total, no light perception blindness. Even people dying of thirst can see. They may have dry eye, but they can still see. So what happened to poor Han’s eyesight?
Theory 1: Carbonite Toxicity
This is an obvious possibility. Unfortunately, carbonite is a fictional substance, so we have no way of knowing if it is toxic to human tissue, in particular mucous membranes like the eye. Based on the fact that the material is frequently used by criminals to encase terrified humans for an indeterminate amount of time, I’m gonna go out on a limb and say it’s not exactly healthy. Also, it more or less explodes off of Han when Leia presses on a digital keypad to release him, so who knows.
Carbonite could be similar to copper or iron, both of which are extremely toxic when found in the eye, classically by way of an idiot grinding metal without eye protection. However, Han did NOT have an open globe at the time of his carbonite encasement, so there is no reason to think carbonite could have entered the eye. I suppose he could have recently had a trabeculectomy or cataract surgery with a wound leak, but there is no indication throughout the Star Wars saga that Han Solo had glaucoma or early onset cataracts. I never even saw him visit a space ophthalmology. You know, I guess radiation from deep space travel could hasten cataract formation, but you know what, that doesn’t really matter right now.
Not only was there no way for carbonite to enter Han’s eyes, but he had his eyes CLOSED when he was “carbonited,” which makes sense. I imagine it would be kind of like sneezing. You have reflex eye closure while being encased in carbonite. At the end of the day, the carbonite toxicity theory doesn’t hold up against a mild amount of scrutiny.
Theory 2: Under Pressure
Needless to say, we don’t know much about the process of trapping a human body in carbonite. We could ask Jabba, but I don’t imagine he’d be forthcoming with any useful information. One possible cause for Han’s blindness is that his eyes were subjected to an extreme amount of external pressure during the carbonite encasement process. If enough force is applied externally to the eye, the central retinal artery will occlude, resulting in permanent vision loss if the pressure is not relieved in a timely manner. This is why people go blind from a retrobulbar hemorrhage. Posterior pressure on the eye from blood combined with an inability for the eye to move forward because of tight, swollen eyelids, causes the eye pressure to sky rocket into the 60s and 70s, which is enough to cut off blood flow to the retina. Fortunately, a lateral canthotomy with inferior cantholysis can relieve that pressure. Furthermore, studies on Chimpanzees by Sohan Heyreh in the 1970s showed that occlusion of the central retinal artery for 90 minutes results in irreversible vision loss.
Now, why am I bringing scientific evidence into this discussion about carbonite induced vision loss? Because that’s the only way JAMA is going to accept this article, that’s why. Also, if the carboniting process compressed Solo’s lookingballs so severely that it cut off blood flow to his retinae, he would undoubtedly wake up totally blind. The one giant flaw in this theory is the fact that Han very clearly regains his vision shortly after the carbonite explodes off his body. This would not happen after hanging out with an eye pressure of 60 for a few months. Either he developed remarkable adaptive skills which allowed him to fly a spacecraft at high speeds without the aid of a giant white space cane, or there is some other explanation for his vision loss.
Theory 3: Retinal bleaching
As I’ve alluded to throughout this post, the carbonite is not so much removed from Han’s body as it explodes into a brilliant bright light and disintegrates. The retinal bleaching theory contends that during this process, Han opened his eyes temporarily allowing this impossibly bright light to bathe the inside of his eyeballs. Phototoxicity is a known condition seen in prolonged intraocular surgery, and I mean long like 4 hours, not long like an endovascular aortic aneurysm repair where you’re wearing lead and standing for 3 days and uh-oh now you have renal failure. For Solo to develop phototoxicity within seconds, it would have to be a light bright enough to depolarize every single one of his rods and cones rendering them inactive for at least an hour. It’s unlikely, but possible. Then again, Jabba the Hut is a thing in this world, so whatever.
Theory 4: Deep Freeze
One popular theory, and I use popular very loosely in this context, is that Han Solo was "frozen" in carbonite and developed corneal edema which slowly resolved after he was thawed. There are several problems with this theory. First, the freezing process was instantaneous. I have to assume that the corneas were locked into a state of suspended animation in a split second, including the corneal endothelial cells, which are vital in maintaining corneal clarity. Why would his corneas decompensate when the rest of his body appears to be functioning pretty normally after he was thawed instantaneously. Again, the carbonite encasement process is a little short on details. Maybe we should ask these guys, they seem to know what they're doing...
Secondly, after the initial freezing, Solo is not hooked up to any machinery to maintain a hypothermic state. Why would he still be a frozen block of ice months later? He is hanging out in a desert with Jabba the Hut who probably smells like ass from the heat.
I'm not buying the deep freeze theory.
Theory 5: Functional Vision Loss
The stress from an extended stay in carbonite may have caused Solo to experience non-organic vision loss. This is a distinct possibility, in which case, Leia did the right thing in reassuring Han that he will get his vision back. Couldn’t have handled it better myself.
the following is a Letter to the editor, which is me
Thank you for this thoughtful review of an interesting topic that is unfortunately largely void of definitive data. You thoughtfully propose and address a number of hypotheses for Han Solo’s temporary blindness after his release from his carbonite prison, traditionally written off as simply a symptom of “hibernation sickness,” a controversial diagnosis (or, more likely, syndrome) which appears in neither ICD-10-CM nor DSM-V. I applaud your efforts but unfortunately I have a few issues with your review which require addressing.
First, carbonite is hardly fictional. While its exact composition is unclear, there are currently two well-understood substances known as carbonite. One is the carbonite anion CO2(2-) – the conjugate base of C(OH)2, which is known to form salts with alkali metals at very cold temperatures (15K), suggesting a potential application as a freezing and storage agent. Another is an early explosive used in coal mining, which may help explain the rather dramatic thawing process. (This “carbonite” is a less-precise mixture of various substances, and not a formal chemical compound.)
Next, it is possible that rather than being weakened by dehydration and poor nutrition, he was simply frozen in a cryostasis which slowed his physiologic processes, obviating the need for food, water, IV fluids, or elimination.
As to your theories on potential pathophysiology for temporary post-carbonite-freeze blindness, we have little experience with direct carbonite toxicity and it is certainly plausible that carbonite anions could slowly leach across his eyelids during his imprisonment. Similarly, during the thawing process, his carbonite encasement “explodes into a brilliant bright light” as it disintegrates, potentially bright enough to overcome the relative flimsy barrier of a human (even Corellian) eyelid, indeed potentially bright enough to “depolarize every single one of his rods and cones rendering them inactive for at least an hour.” Leia’s disguise as Boushh included a full helmet, likely serving the dual purpose of both infiltration and eye protection.
You ask, “Why would his corneas decompensate when the rest of his body appears to be functioning pretty normally after he was thawed instantaneously[?]”. It is not clear that the carbonite thawing process would affect every body system in the same time frame. As we know, corneal endothelial cells are particularly sensitive to various types of insult. And, their lack of a direct blood supply provides a plausible mechanism for their delayed thawing.
I would add another possibility: we know little of the microbiota of the Star Wars galaxy in general, let alone Cloud City or Tatooine in particular; or, what spores or other dormant microbes a bounty hunter’s ship picked up over the years; or, if/whether there are microbes that thrive in a frozen stasis environment. It is plausible that much as some archaea are extreme thermophiles, extremophiles from the other end of the thermal spectrum can cause infectious complications in such a cold and otherwise stable environment. One might suggest a relative of the midichlorian, but explaining away a complex phenomenon with a simple, poorly explained but easily measurable microbe would be ridiculous.
Lastly, your characterization of Ugnaughts as “boar-human hybrids” is inaccurate. While decidedly porcine and humanoid in appearance, they evolved independently of both boars and humans and represent analogous, not homologous, evolution.
Future research is needed into the epidemiology, pathophysiology, natural history, treatment, and prognosis of temporary post-carbonite-freeze blindness, and as to whether it is part of “hibernation sickness” syndrome or its own, independent entity.
N. Seth Trueger, MD, MPH, FACEP