Herpetic keratitis: dendritic ulcers & disciform keratitis
The cornea is the 'window' of your eye. It is the clear glass-like front.
The herpes simplex virus is very common. Most people have a herpetic infection at some time of their lives. However, only in a few unlucky people does the virus affect the cornea.
No one knows why some people develop corneal infections not others. It has nothing to do with sex ...that is a different type of herpes virus.
The virus causes a special type of corneal ulcer, called 'dendritic' (after the latin term that means 'many fingered').
A dendritic ulcer has many 'fingers', like the branch of a tree. It can be seen with the slit lamp microscope used to examine your eye. Fluorescent yellow drops are used to show the ulcer up more easily.
dendritic ulcer: as seen by your doctor
dendritic ulcer: side view
As the cornea has many nerves it feels pain easily. Dendritic corneal ulcers are painful; your eye feels as though something is scratching it. Sunlight and bright lights feel painful also. As the ulcer is like 'paint on a window' your sight may be blurred.
The treatment is aciclovir cream (eye) 3% ointment 5 times a day for 7-10 days. Depending on your particular ulcer, a different treatment time, and occasionally different drugs, will be needed. With prompt treatment you get a 100% recovery.
Sometimes you get a faint scar, although this is more likely without treatment. Use aciclovir ointment, not the skin cream. Bring it to clinic each visit, with all your other drops and list of tablets you use. It is very safe. Use about 2cm length of cream 5 times a day at the beginning, but later in the episode as your eye heals you need less (5-10mm), although you may still need it 5 times a day. Longer treatment is needed if you are immunosuppressed.
Dendritic ulcers may recur. It is certainly helpful to keep a tube of unopened ointment with you, especially on holiday. If you do develop another episode it is quite safe to start treatment. (Aciclovir is safe even if you are mistaken and there is no infection.)
Use the aciclovir, following typical instructions as above. Most doctors advise you attend an Eye Casualty, such as that in Birmingham and Midland Eye Centre on the City Hospital site (Dudley Road), that day or the next. Treatment is not so urgent as to need to attend late in the evening or the middle of the night.
Like any infection, stress, overwork, or lack of sleep can trigger a recurrence. Dendritic ulcers can be triggered by sunlight. Dark glasses may help prevent a recurrence, and they certainly help during an attack. If you develop frequent episodes, ask your doctor if long term aciclovir cream or tablets may be helpful as prevention.
There is now conclusive evidence that attacks can be prevented with the use of aciclovir, see here (2003). Treatment may be needed for 2-3 years.
- this evidence indicates using aciclovir tablets 400mg twice daily will halve the number of attacks
- if you have frequent attacks, you should ask your doctor to consider this treatment; it is usually very safe
- what are frequent attacks: probably more than one a year
- if you have one attack a year normally you will probably still benefit
- the more severe your attacks, the more you will benefit; if the condition affects the centre of your cornea, prevention is more important
- Aciclovir cream may prevent recurrences, but is not as effective as tablets. Use if patient unwell (other medical problems) instead of tablets
- Aciclovir is generally safe for long term use but rarely causes crystals in the kidneys. As a precaution it is important to drink plenty of fluids, and it is not ideal long-term if kidney function is reduced.
disciform keratitis is a deeper infection the cornea
(deeper than the dendritic ulcer above)
the infection is in the substance of the cornea the condition is called
'stromal keratitis' (also called 'disciform' or 'herpetic').
In this condition, in addition to aciclovir cream, low dose steroid drops may be needed (such as predsol), but only under close ophthalmological supervision.
If you need steroid drops for one episode you may also need them for future episodes.
Stromal keratitis attacks may recur frequently. If they do, preventative treatment may work. Aciclovir tablets 400mg once or twice a day halves the number of episodes, but may be needed for a year or two.
In disciform keratitis the central cornea is cloudy/opaque.
Also, a semi-opaque scar may remain after the infection itself has cleared.
patients with delayed healing dendritic ulcers may need a different antiviral,
but resistance is unusual and this is not usually necessary.
More often, steroid drops are needed. Stromal keratitis will need steroid drops at the onset.
- if a person needs steroid drops to heal their ulcer, then if they get further episodes, steroids will be needed again
- it is best to taper the steroids after the attack, continuing them well after the ulcer has healed. Often drops will be needed for 6-12 months
- treatment starts will full strength drops (prednisolone 0.5%), but then reduced each month, to prednisolone 0.1% (or 0.5% every other day if not available), then ideally to 0.01%, over this 6-12 month period
- Antivirals are needed in addition to the steroid until the 0.01% dilution is reached.
- some infections become resistant to Aciclovir...
- some patients need on-going treatment with low dose topical staerois, such as prednisolone 0.05 or 0.1%. If these are not available, may be alternate day treatment of 0.5% may help.
- 20% of apparent HSV keratitis is HZV
- generally dendritic ulcers (epithelial disease only) do not need treatment with steroids