I would like to continue my summary of our 2015 AAO annual meeting 2015 in Las Vegas. As always, most of my observations / discussion / comments lean toward working / teaching in the developing world.
Dr. Elisabeth Cohen spoke about Varicella Zoster Virus ( VZV ): Epidemiology, Presentation, Diagnosis, and Vaccines. In regards to the epidemiology of Herpes Zoster ( HZ ) there are over 1 million new cases of HZ per year. Incidence is increasing with 10-20% of HZ cases involving first division of CN V, resulting in Herpes Zoster ophthalmicus ( HZO ). Although the rate of HZ goes up with age, greatest # of cases of HZ, including HZO, occur in people in their 50's. HZ is common disease in people less that 60 years old. Varicella / chicken pox is the primarily infection. Over 99% of people age 40 years and above born in USA have had chicken pox, whether or not they know it. Herpes zoster is caused by a reactivation of VZV virus in people who have had chicken pox. Typically results in unilateral, painful, vesicular rash in dermatomal distribution obeying the midline. In absence of rash, diagnosis is difficult and can be missed. Zoster vaccine live ( Zostavax, Merck ) approved in 2006 ; CDC recommended since 2008 for persons age 60 years and older without disease or treatment resulting in impaired T-cell immunity. Reduces burden of disease by 61%, postherpetic neuralgia ( PHN ) by 66%, incidence of HZ by 51%. Efficacy against incidence declines with increasing age. Efficacy wanes after 8 - 10 years for incidence, burden of disease, and PHN in persons over age 60 years and older.
HZV has been declared the leading cause of infectious blindness in developed countries. The global incidence of ocular HSV is about 1.5 million new cases and about 9 million recurrent episodes per year, associated with about 40,000 new cases of severe monocular visual impairment each year. About 50,000 new and recurring episodes of ocular HSV are diagnosed in the USA and an estimated 500,000 people in the USA have a history of ocular HSV. The recurrence rate of HVZ eye disease after an initial episode is approximately 27% at year one, 50% at 5 years, and 63% at 20 years; the rate accelerates with the number of recurrences.
HSV can affect any tissue of the eye. Fortunately, posterior segment disease , such as acute retinal necrosis, is uncommon. Ocular HSV is almost always unilateral. Recurrent and isolated lid or conjunctival HSV is an unappreciated common entity. Unilateral follicular conjunctivitis is almost always caused by HSV. In regards to making the diagnosis, the patient should be asked about a past history of ocular HSV with symptoms of pain, redness, discharge, blurred vision, and photophobia. Checking for decreased corneal sensation before any drops is useful but often not done. Iris evaluation for transillumination defects is quite useful if present.
With HSV keratitis, gentle debridgement with a Q-tip soaked in Betadine ( povidone-iodine) 5 % or 10% is a good start in the developing world. Oral acyclovir is often available in the developing world ( 400 mg 5X daily ) and cheaper than valaciclovir or famciclovir. Topical medications may not be available in the developing world and also quite expensive.
Fungi constitutes nearly 40% of all isolates from keratitis cases in developing nations with a tropical climate. As I have mentioned previously, fungal keratitis often do quite poorly in the developing world due to several factors: #1. patients often show up quite late with advanced, diffuse, severe disease #2.the possibility of a corneal culture often isn't possible #3. the patient often has already self medicated with steroids, #4. patients often have limited financial support, #5. many patients are unable to keep return appointments, and #6. the treatment course is often quite long / drawn out. In the developing world, you often do not get a history of minor eye trauma with vegetable material. The talk on "which antifungal is best" for fungal keratitis had some interesting conclusions: Voriconazole, despite having several theoretical advantages, does not result in a superior cure rate when compared to natamycin. Rather Voriconazole has a disadvantage of being associated with a higher risk of corneal perforation. #2. Which fungal species did not affect the outcome of treatment. #3. There was no difference in clinical cure between voriconazole and natamycin ( shake well ). Antifungal drugs show a poor correlation between in vitro activity and rate of clinical cure. Ketoconazole orally is often available in the developing world and should be taken with an acidic beverage such as Coke or Pepsi.
In Dr Jeremy Keenan talk, with regards to adding steroids in bacteria keratitis after 48 hours or more of moxifloxacin, there appeared some benefit in BSCVA, central corneal scarring, and deep ulcers in regards to final V.A. With Nocardia ulcers the results were different and steroids should not be used in those cases. In the developing world, I would go really slow adding steroids as the ulcer could be fungal.
Allergic conjunctivitis has itch as its predominant symptom. Signs can include mild redness, tearing, and edema of conjunctival/ caruncle. Vernal keratoconjunctivitis is fairly common in the tropics usually in boys around 6 -12 years of age. Can be difficult to treat with the exacerbations. Need to have serious conversation with the parents about disease process, treatment, relapses, etc.
One of the saddest / worst cases I saw last year in Haiti was a female teenager who was recovering from Stevens-Johnson Syndrome. The disease process was about 3 -4 months along and her skin appeared to be healing. But she had bilateral frozen lids ( all four ) and could not blink / close her lids. She already had diffuse corneal scarring / opacities. The prognosis obviously was quite poor. Marked lid scarring and diffuse symblepharon. Horrible. Not a good disease.
Surgical management of the perforated corneal ulcer by Sonal Tuli was of interest to me. I've been there a lot in the developing world. One thing he mentioned, and I agree, is with an older perforation, a negative Slidell test, iris prolapse, formed / quiet A.C. one good option is to do nothing. Usually an epithelial coating ( membrane ) has grown over the exposed iris. Don't do anything. Leave it. With time the iris will flatten out ( smooth down ) and you are left with only an adherent leucoma. Later if you need to, you can make a new pupil ( pupilloplasty ) with a Yag and an argon ( diode ) laser. Don't forget the pilocarpine 2% x3 with the laser treatment. Also Dr. Tuli notes you can use air to tamponade a corneal leak ( + Slidell ) before applying cyanoacrylate glue to a dry ulcer bed. Sometimes a conjunctival pedicle flap is useful.
That finishes what interested me in the corneal symposium.
Quotes for this blog:
I see you see as I see. --- a note from Johnny Cash to his daughter.
Always do right, this will gratify some and astonish the rest. --- Mark Twain
By the time medicine got to me, however, words spiritus and anima had been banished from the medical vocabulary. I had no concepts for describing what I'd seen. Perhaps it had been autopsy --- from the Greek auto-opsia: seeing for oneself that brought about the disappearance of those words from the Western vocabulary. --- from God's Hotel by Victoria Sweet.
Wage Peace, Baxter