The Eye of the Beholder
While the world’s attention is focused on one disease, others are enjoying a quiet resurgence, unobserved by the spotlight.
Since 2000, several sexually transmitted infections have been re-establishing a global foothold, in both numbers and resistance. Diseases that were mostly relegated to dusty pathology texts need to be coaxed back out and into our diagnostic armamentarium, and that includes the recognition of some of the more unusual presentations, in this case, the ocular manifestations of re-emerging STI’s.
The King of all STI’s is, of course, syphilis. It has returned to us with a vengeance. The cause of this recrudescence is likely to be multifactorial: high risk sexual behaviours, possible change in behaviour of T pallidum itself, global travel (she writes, longingly), HIV coinfection along with the immunomodulatory activity of the anti-retrovirals, and other unknown factors.
Many of the ophthalmological features of syphilis are enshrined in hallowed texts. And not just non-fiction – here is Sir Arthur Conan Doyle writing in a short story: “Something about the man’s way of talking struck me and I watched him narrowly. His lip had a trick of quivering, his words slurred themselves together, and so did his handwriting when he had occasion to draw up a small agreement. A closer inspection showed me that one of his pupils was ever so little larger than the other…I did not say anything, for I had not the heart, but I knew that the fellow was as much condemned to death as though he were lying in the cell at Newgate” Here is the author of Sherlock Holmes describing the Argyll-Robertson pupil of neurosyphilis (and to be apologetically gauche, also known as the prostitute’s pupil: accommodates but doesn’t react).
But there is so much more to the eye in syphilis. In each stage, there are a number of ophthalmologic presentations and complications, and they are worth a systematic review.
Chancres. Like their genital cousins, these are painless erosive ulcers. They can occur on lids and conjunctivae, following the same time-course as the more classic chancres.
Secondary And Tertiary Syphilis
Without treatment, primary syphilis progresses to secondary within four to ten weeks. Now the manifestations begin to get protean, none more so than in the eye, that window to the soul of all things.
Possible ocular features are: granulomatous conjunctivitis, episcleritis, syphilitic interstitial keratitis – an immune mediated inflammation of the corneal stroma which can progress for years and lead to neovascularisation, a result of which is severe, blinding scarring. Uveitis also makes an appearance. Syphilitic uveitis may have granulomatous features, with large keratic precipitates. If we make our ocular way, venturing further back into the posterior segment, we can see all sorts of chorioretinitis, from posterior uveitis to necrotising retinitis. It can be an entire circus of retinal pathology back there, and needs an ophthalmologist, handy with the tools, to delineate what’s going on.
From an ocular point of view, Treponemal invasion can occur at any point from here, and may not be a distinguishing feature between secondary and tertiary.
Once things have hit the tertiary phase, it’s all pretty bad though. We know there is a vast spectrum of manifestations, related to the neurologic and cardiovascular destruction of tertiary syphilis. The great names arise from this phase, such as General Paresis of the Insane and Tabes Dorsalis. The retinae continue to be targets, with a whole dictionary of potential pathologies. Scleritis features more than episcleritis. Vessels and nerves and neural pathways may all be involved.
We ought not forego a discussion of congenital syphilis however, that of the Hutchinson’s teeth, the saddle nose, saber shins, deafness, and, yes, interstitial keratitis.
While we’re discussing the venn diagram crossover of increasing STI incidence, neonatal disease, and ocular manifestations, we would be remiss not to mention gonorrhea. Neisseria gonorrhoeae causes one of the most destructive forms of conjunctivitis known. Caused by direct transfer from an infected birth canal, this presents with a floridly purulent conjunctivitis with severe lid edema and erythema. When the lids are prised open, pus is free-flowing; the pus so corrosively toxic it can melt away a cornea in just hours. Adult gonococcal conjunctivitis is rare, but can be concurrent with genital disease, or a result of autoinoculation from contaminated surfaces. It also presents with profuse mucopurulent discharge, but is a little less aggressive than the neonatal variety.
Even less dramatic is chlamydia of the eye. True Chlamydia trachomatis, causing trachoma and blindness, is a different serotype than that causing STIs. However, we must not forget the inclusion conjunctivitis associated with chlamydia genital infections, plus the association of uveitis with urethritis in Reactive arthritis.
Thus, with STIs coming back a-knocking at our doors, it is nothing but wise to consider the eyes.