❖ Glaucomatous changes in the optic cup: Medical treatment should be initiated where there are signs of glaucomatous changes in the optic cup or where there is a difference of more than 20% between the optic cups of the two eyes.
❖ Any intraocular pressure exceeding 30 mm Hg should be treated.
❖ Increasing glaucomatous changes in the optic cup or increasing visual field defects: Regardless of the pressure measured, these changes show that the current pressure level is too high for the optic nerve and that additional medical therapy is indicated. This also applies to patients with advanced glaucomatous damage and threshold pressure levels (around 22 mm Hg). The strongest possible medications are indicated in these cases to lower pressure as much as possible (10-12mm Hg).
❖ Early stages: It is often difficult to determine whether therapy is indicated in the early stages, especially where intraocular pressure is elevated slightly above threshold values. Patients with low-tension glaucoma exhibit increasing cupping of the optical disk even at normal pressures (less than 22 mm Hg), whereas patients with elevated intraocular pressure (25-33 mm Hg) may exhibit an unchanged optic nerve for years.
Patients with suspected glaucoma and risk factors such as a family history of the disorder, middle myopia, glaucoma in the other eye, or differences between the optic cup in the two eyes should be monitored closely. Follow-up examinations should be performed three to four times a year, especially for patients not undergoing treatment.
Medical therapy. Available options in medical treatment of glaucoma (see also Fig. 10.1):
❖ Inhibit aqueous humor production.
❖ Increase trabecular outflow.
❖ Increase uveoscleral outflow.
Fig. 10.14 and Table 10.3 list the various active ingredients and substance groups available for medical treatment of glaucoma. For the sake of completeness, Fig. 10.14 also lists traditional substances that are no longer used today; these include substances that have too many side effects or have been replaced by more efficient medications. Table 10.3 lists only those medications that are actually used today.
Principles of medical treatment of primary open angle glaucoma:
H Medical therapy is the treatment of choice for primary open angle glaucoma. Surgery is indicated only where medical therapy fails.
There is no one generally applicable therapy plan. However, several principles may be formulated:
❖ Where miosis is undesirable, therapy should begin with beta blockers (Table 10.3).
❖ Where miosis is not a problem (as is the case with aphakia), therapy begins with miotic agents.
❖ Miotic agents may be supplemented with beta blockers, epinephrine derivatives, guanethidine, dorzolamide and/or latanoprost maximum topical therapy).
❖ Osmotic agents or carbonic anhydrase inhibitors (administered orally or intravenously) inhibit the production of aqueous humor. They can be administered temporarily in addition to topical medications. Their side effects usually make them unsuitable for prolonged treatment. The general rule is to try to use the weakest possible medications required to
10.3 Primary Glaucoma 255 Options in medical treatment of glaucoma. -
(cholinergic agents) Carbach°l Aceclidine
Parasympathomimetic agents n.
Reversible Phys°stigmine (Eserine) Neostigmine
Indirect Demecarium bromide
Echothiophate iodide Irreversible Diisopropyl fluorophosphate mimetic agent
Indirect (choline inhibito
Sympatho- Direct mimetic sympatho-agents mimetic agents
Epinephrine (a- und ß-agonist) Dipivefrin (clonidine central a2-agonist)
Improve drainage of aqueous humor
Direct sympatholytic agents
Indirect sympatho-lytic agents
Guanethidine 6-hydroxy dopamine
Carbonic anhydrase inhibitors
Acetazolamide (systemic) Dichlorphenamide
Mannitol Glycerine Ethyl alcohol
Inhibit production of aqueous humor
Reduce ocular volume via osmotic gradient
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