Glaucoma: which drops should you use?

Atlanta, GA-Joseph Sowka, OD, FAAO, Optometry Times Editorial Advisory Board member, shared at SECO some of his recommendations for when certain glaucoma therapy drops should be administered.

“We must tailor therapy to each individual patient,” says Dr. Sowka.

Dr. Sowka says optometrists must let go of the “myth of 21”; there is no guarantee that an intraocular pressure (IOP) lower than 21 will preserve a patient’s vision, or that an IOP greater than 21 will result in blindness. But the greater the degree of damage is, the lower the IOP needs to be due the fragility of the already-damaged nerve.

“Past progression will predict pretty accurately the future progression,” says Dr. Sowka.

A target IOP should be the pressure that minimizes both the impact of the vision loss upon the patient and the impact of treatment upon the patient. The goal is not to make the IOP “normal,” but safe for the patient, says Dr. Sowka.

Prostaglandins

• Excellent IOP reduction at night

• Dosing: QD HS

• Minimal systemic side effects

• Systemic contraindications: pregnancy

• Short half-life, but long duration of action

• Ocular adverse effects include: hyperemia, increased iris coloration, periobitopathy, hypertrichosis, and punctate keratopathy

• Results in chronic angle closure glaucoma are impressive

• Tend not to work in children

• Demonstrated pronounced effect in eyes even with complete PSA angle closure

Due to chemical differences, each prostaglandin behaves differently. If a prostaglandin reduces IOP, but causes unacceptable redness, try another prostaglandin. Also, if the desired IOP reduction is not optimal with one prostaglandin, try another. Dr. Sowka says this category of glaucoma therapy drops is too important to abandon prematurely.

Docsanoids

• Previously linked with prostaglandins

• Big potassium channel activator

• Alternative/adjunct for beta blocker therapy

Adrenergic agonists

• Dosing: TID, but often used BID initially

• BID dosing can leave patients with uncontrolled IOP at certain times of the day

• Significant side effects include: drowsiness and fatigue, headache, and dry mouth

• Other side effects include: conjunctivitis, blurring, burning, and early or late onset of alphagan allergy

• Crosses blood-brain barrier and has CNS effects

• May induce fatigue, drowsiness, and coma in children

• Alphagan is not a proven neuroprotective

Beta blockers

• Most are non-specific, blocking both Beta 1 and Beta 2

• Dosing: BID

• Bilateral effects when using in only one eye due to systemic absorption

• Long-term drift: slow and steady rise in IOP

• Contraindications include: asthma, COPD, myasthenia gravis, cerebrovascular insufficiency, greater than 1^st degree heart block, and hypotension

• Bad for athletes

• Patients considered for topical beta blockers need baseline blood pressure and resting pulse measurement, in addition to review of medical history

• Adverse effects include bradycardia

• Other reported adverse effects include: depression, loss of diabetic control, claudication, anxiety, fatigue, malaise, irritability, confusion, and others

While there are specific contraindications to the use of topical beta blockers, it appears that much of the propagated fears about this class stems from anecdotal case reports or sources without sound scientific background, says Dr. Sowka.

Carbonic anhydrase inhibitors

• Can be difficult to tolerate, as PH level is somewhere around that of tomato juice

• Dosing: TID, often used BID

• Good additive to prostaglandins

• Appears to lower IOP at night

• Side effects include: sulfonamide sensitivity, low endothelial cell count, blurred vision, dyguesia, hyperemia, and others.

While topical carbonic anhydrase inhibitors are not thought of as especially good primary agents in adults, they work especially well and are well tolerated in children, says Dr. Sowka.

Miotics

• Induces ciliary body contractions

• Dosing: QID

• 4 to 8 hours IOP effect

• Oldest anti-glaucoma medication

Miosis

• Side effects include: field constriction, accommodative spasm, myopic shift, and brow ache.

Dr. Stowka says it still has a role today, particularly with exfoliatitive glaucoma, primary angle closure glaucomas, and endstage primary open-angle glaucoma when surgery is not an option.

Therapeutic considerations:

• Medical contraindications necessitate choosing different therapeutic paths

• Typically, start with a prostaglandins and add medications as needed

• With progression, amplify therapy

• Never change therapy based on one bad IOP or field test