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Optometry is not practiced in isolation from the rest of medicine. The medications patients take for systemic conditions can profoundly affect the eye—and ophthalmic medications can cause systemic effects. Paraoptometric staff who understand these interactions provide better care, take more accurate health histories, and help prevent adverse events. This topic appears on both CPO and CPOA certification exams.
During intake, paraoptometrics collect the medication history. This section should be thorough—including prescription medications, over-the-counter drugs, vitamins, and herbal supplements. Items to specifically document:
Eye drops are absorbed systemically through the nasolacrimal drainage system. The nasal mucosa provides rapid, highly bioavailable absorption—bypassing hepatic first-pass metabolism. This is why even "local" eye drops can have significant systemic effects:
Instruct patients on NLO technique to minimize systemic absorption of drops with significant side effect profiles:
Free CPO and CPOA exam questions including drug interactions and ocular pharmacology.
Broad overview of all medication categories used in optometric practice.
Dilation drops used in optometric examination.
Antihistamines, mast cell stabilizers, and allergy management.
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Many systemic medications have significant ocular side effects, and many ophthalmic medications have systemic effects. Knowing a patient's medications helps the doctor identify the cause of new symptoms (e.g., dry eye caused by antihistamines, color vision changes from hydroxychloroquine), avoid prescribing drugs with dangerous interactions (e.g., avoiding non-selective beta-blocker eye drops in asthmatic patients), and time dilation drops appropriately. Paraoptometrics taking the health history should record all medications—prescription, OTC, vitamins, and supplements.
Many medication classes reduce aqueous tear production or increase tear evaporation: antihistamines (both systemic and topical), diuretics (reduce fluid production), antidepressants (especially tricyclics and SSRIs), antipsychotics, antihypertensives (some beta-blockers), isotretinoin (Accutane—severe dryness and meibomian gland dysfunction), oral contraceptives, and anticholinergic medications. Documenting these in the health history is critical, as they explain many dry eye presentations and affect management decisions.
Timolol (a non-selective beta-blocker used to lower IOP in glaucoma) can cause systemic cardiovascular and pulmonary effects through nasolacrimal absorption. Risks include: bradycardia (slowed heart rate), hypotension, bronchospasm in asthmatic patients, and masking hypoglycemia symptoms in diabetic patients. These risks are significant because patients often don't consider eye drops as "real medicine." Paraoptometrics should document respiratory conditions and cardiac conditions during health history, as they are critical contraindications for certain glaucoma medications.
Hydroxychloroquine (HCQ), used to treat rheumatoid arthritis, lupus, and malaria, can cause bull's eye maculopathy—toxic damage to the macula with a ring-shaped pattern of retinal cell death. Vision loss can be permanent if not caught early. The American Academy of Ophthalmology recommends annual screening with OCT and visual field testing starting at 5 years of use (earlier in high-risk patients). Dose exceeding 5 mg/kg/day is the primary risk factor. Paraoptometrics should flag HCQ on the medication history and ensure the doctor is aware.
Nasolacrimal occlusion (also called punctal occlusion) involves pressing on the inner corner of the eye (over the lacrimal sac/punctum) for 1–2 minutes after drop instillation. This blocks the nasolacrimal drainage pathway, preventing drop absorption into the systemic circulation. NLO is most important with drops that have significant systemic side effects: beta-blockers (timolol), cycloplegics (particularly in pediatric patients), and mydriatics. It also increases the amount of medication staying in the eye, improving therapeutic efficacy. Combined with eyelid closure, NLO reduces systemic absorption by up to 70%.
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