Treating Ocular Infections

BY PETER W. SHENON, M.D.
DEC. 1996

All antibiotics are not alike. This guide will help you choose the most appropriate treatment for some common ocular infections.When a patient presents with an ocular infection, your task is to determine the most effective treatment and the proper dosage without triggering an allergic reaction or toxic side effects. In addition, the abundance of antibiotics available seems to compound this task. Here are my specific recommendations on how to treat some common external eye diseases.

PRETREATMENT CONSIDERATIONS

Before discussing specific treatments, there are some general considerations:

• For routine infections, use an older antibiotic that is still effective and well tolerated. Save the newer antibiotics to treat severe infections or resistant organisms.
• Don't use an inexpensive antibiotic to save money unless you know it will be effective. It's more costly overall if, after a few days of treatment, you have to switch to a more expensive antibiotic because the less expensive one didn't work'
• Avoid the 'shotgun" approach to treating infections. Don't use the antibiotic/steroid combinations unless they are specifically indicated. Use an antibiotic drop only.
• Poor patient compliance is a common and potentially serious problem. Too many patients simply do not follow instructions, so I always prescribe antibiotic eye drops every two hours while awake for five days. If you prescribe the medication this frequently, the patient will probably put the drops in at least four or five times a day. If you just prescribe a drop four times a day, they may only use it twice a day.
• Obtain a culture and sensitivity only if you are dealing with a very severe infection. Today's antibiotics will cure most ocular infections, and the information a culture provides will not be necessary.
• Allergic reactions to topical antibiotics can occur, particularly to sulfa drops and solutions containing neomycin. The allergic reaction will cause the skin of the lids to become a dull red color with itching, dryness and cracking.
• Ask every woman with an eye infection if she uses mascara, eye liner, eye shadow or any other eye makeup. If a patient has used any of these products within three or four days of the start of the infection, then have her discard all the makeup and avoid using new makeup until the infection is resolved. Your patients won't like it when you tell them this (makeup is expensive), but if they don't throw it away, the infection will invariably recur.

BACTERIAL CONJUNCTIVITIS

Bacterial conjunctivitis is a common problem. Patients will present with red eyes, purulent discharge and slightly swollen lids that are stuck together in the morning (Fig. 1).

Tobramycin (Tobrex-Alcon, Aktob-Akorn, Inc., Tobramycin Ophthalmic Solution-Bausch & Lomb), one drop every two hours while awake for five days, is the treatment of choice. It is effective, well tolerated and will cure most bacterial conjunctivitis cases with minimal side effects. It can be used in children.

You can prescribe ciprofloxacin (Ciloxan-Alcon) or ofloxacin (Ocuflox-Allergan) if tobramycin drops are not effective. Instruct patients to use them every two hours while awake for seven days. These fluoroquinolone antibiotics should not be used as your primary treatment, but should be reserved for infections resistant to tobramycin.

Gentamicin (Genoptic-Allergan, Gentacidin-CIBA) is an aminoglycoside like tobramycin, but clinically, is not quite as effective. Gentamicin also has more side effects such as burning, irritation, punctate keratopathy and follicular conjunctivitis. It is the second choice as a primary treatment for conjunctivitis.

Polymyxin B/trimethoprim (Polytrim-Allergan) is a combination drop that is reasonably effective but has an elevated incidence of side effects such as redness, burning, stinging and itching. It is promoted to pediatricians for use in children.

Sulfacetamide drops are available from seven different companies. Sulfa drops are not very effective since there are now so many resistant organisms. They should only be prescribed for very mild infections, if at all. Don't prescribe them to patients who are allergic to sulfa.

Avoid neomycin combination drops. Too many patients are allergic to neomycin, and it's not as effective as the aminoglycosides.

Chloramphenicol (Chloromycetin-Parke Davis, Chloroptic-Allergan) is a very effective antibiotic, but because it may cause aplastic anemia, it should be used only if no other antibiotic will work.

STAPH MARGINAL ULCERS

These ulcers along the periphery of the cornea are often a hypersensitivity to staph bacterial conjunctivitis, so treatment requires both steroid drops and antibiotic drops. Start with Tobrex, one drop every two hours while awake for five days. After two days of treatment, add FML Forte (Allergan), Flarex (Alcon) or a similar steroid drop five times a day for three days. Discontinue the steroid drops at the same time you discontinue the Tobrex. An alternative treatment is a tobramycin/dexamethasone combination (Tobradex-Alcon), one drop five times a day for five days.

BACTERIAL CORNEAL ULCERS

These are usually discrete white ulcers on the cornea, and are often seen in patients with extended wear soft contact lenses (Figs. 2 & 3).

FIG 2: MID-PERIPHERAL, SMALL CORNEAL ULCER.

FIG 3: CORNEAL SCAR FROM PSEUDOMONAS CORNEAL ULCER.

The treatment is ciprofloxacin (Ciloxin-Alcon) or ofloxacin (Ocuflox-Allergan), one drop every 15 minutes for the first six hours, then one drop every 30 minutes for the remainder of the day. On the second day and thereafter, have patients use the drops every hour. Follow these patients closely, and reduce the frequency of the drops only when the ulcer is significantly better.

If the ulcer is not starting to clear within 48 hours, add Tobrex every hour on the hour and Ciloxin every hour on the half hour. Using both antibiotics very frequently will usually cure the ulcer.

If the ulcer has not improved in three to four days, then get a second opinion since you may be dealing with a severe viral, fungal or acanthamoeba infection.

If the ulcer is in an extended wear soft contact lens wearer, then in my experience, the underlying problem is a dry eye. After treating the ulcer, consider switching the patient to a daily wear, low water soft contact lens. Treat the dry eyes with artificial tears, have patients use saline drops while wearing the lenses and perform punctal occlusion. Allowing patients to continue in extended wear soft contact lenses is just asking for another ulcer.

ADULT INCLUSION CONJUNCTIVITIS

This chlamydial infection presents as an acute follicular conjunctivitis with mucopurulent discharge (Fig. 4). It can be seen in any patient, but is more common in sexually active young adults.

FIG. 4: ADULT INCLUSION CONJUNCTIVITIS

The treatment is either doxycycline, 100mg by mouth twice a day; or tetracycline, 250mg or 500mg by mouth four times a day, one-half hour before meals and at bedtime for three weeks. (Caution patients not to take the tetracycline with milk products.) Erythromycin by mouth may also be effective. Topical treatment is not effective. If you suspect a secondary bacterial infection, prescribe Tobrex drops every two hours for five days in addition to the oral medication.

Do not use tetracycline or doxycycline by mouth in children under the age of nine.

INCLUSION CONJUNCTIVITIS IN INFANTS

This chlamydial infection commences five to 12 days after birth. The diagnosis is confirmed by using Giemsa stain to demonstrate cytoplasmic inclusions in conjunctival scrapings. Treatment is erythromycin by mouth; the dosage should be determined by the child's pediatrician.

If any infant has a purulent conjunctivitis, perform a Gram stain of conjunctival scrapings to rule out a gonorrheal infection. If it is gonorrhea, the infant must be hospitalized immediately and treated vigorously.

VIRAL CONJUNCTIVITIS

Viral conjunctivitis presents with irritated eyes and a more watery discharge than seen with bacterial conjunctivitis. The infection is usually self-limiting. Tobrex drops may be needed if you suspect a secondary bacterial infection.

Dr. Shenon practiced general ophthalmology in Walnut Creek, Calif., for 33 years with a strong interest in external eye diseases. He recently retired.