18.2 Core Workflows and Decision Points

18.2 Core Workflows and Decision Points

Maintenance questions usually describe a triggering event - a between-patient turnover, a monthly check, a dim field, a failed reading - and ask for the next correct step. Knowing the ordered workflow keeps you from skipping a step the exam considers mandatory.

Tonometer prism disinfection (between patients)

1. Remove the prism from the holder and wipe away debris.
2. Soak 5-10 minutes in 1:10 sodium hypochlorite (5,000 ppm chlorine). Under 5 minutes may not inactivate microbes; far longer risks tip damage.
3. Rinse thoroughly with water or sterile saline - residual bleach causes chemical keratitis and corneal epithelial defects.
4. Air dry, then inspect the contact surface under magnification for cracks, swelling, or fluorescein staining of micro-fractures.
5. Document the batch and discard solution per facility schedule.

The CDC also accepts 3% hydrogen peroxide, 70% ethyl alcohol, or 70% isopropyl alcohol for 5-10 minutes, but only sodium hypochlorite reliably inactivates adenovirus and herpes simplex virus (HSV), the agents behind epidemic keratoconjunctivitis outbreaks. For suspected Creutzfeldt-Jakob (prion) disease, use a single-use disposable tip.

Goldmann calibration verification (monthly)

Mount the calibration bar (calibration error check rod) and test at three positions: dial 0, dial 2, and dial 6, corresponding to 0, 20, and 60 mmHg. The drum should tip from one side to the other right at the dial setting; if the feeler arm moves before or after the marked value, the instrument is out of calibration.

A tonometer that reads consistently high is the classic drift pattern and silently over-diagnoses glaucoma; out-of-tolerance units are tagged and sent to the manufacturer or biomed, not used.

Bulb and battery upkeep

Slit-lamp and binocular indirect ophthalmoscope (BIO) bulbs are user-replaceable: power off, let the bulb cool, handle the new halogen bulb with gloves or a tissue (skin oils shorten lamp life and create hot spots), and seat it without touching the glass envelope. Retinoscope and direct-ophthalmoscope batteries are recharged or replaced when illumination yellows - low voltage shifts color temperature and distorts the reflex.

The in-house vs. biomed decision

• In-house: bulb swaps, cleaning, disinfection, lubricating dials, zeroing a lensometer eyepiece, daily autorefractor model-eye check.
• Biomed / manufacturer: electrical faults, frayed cords, optical misalignment, calibration that cannot be corrected, software errors, anything inside a sealed housing.

The exam treats opening a sealed instrument or jury-rigging a frayed cord as a safety violation. The defensible answer is stop, unplug, tag out of service, and submit a service request while documenting the fault.

Lensometer and autorefractor verification

Before declaring a lensometer (lensmeter) broken, the operator must focus the eyepiece (reticle) to their own eye and zero the instrument; a blurry target is usually an unfocused eyepiece, not a fault. The lens or spectacle is then seated against the lens stop, and the power, axis, and prism are read. For an autorefractor or auto-keratometer, the daily routine is a model-eye (test-eye) calibration check: the supplied artificial eye has known values, and a reading outside the model-eye tolerance means the unit needs service, not the patient.

Keeping optical surfaces dust-free with lens tissue and approved cleaner - never a paper towel or household glass cleaner that scratches coatings - preserves accuracy.

Shared contact surfaces and infection control

Disinfection is not limited to the prism. The chin rest, forehead band, joystick, and occluder are touched by every patient and must be wiped between patients, with enhanced attention during viral conjunctivitis clusters. Single-use chin-rest tissues are changed each visit. Hand hygiene before and after every patient contact is the backbone of preventing instrument-mediated transmission, and the exam expects it as a default step rather than an optional extra.

Documentation and tag-out

When a device is removed from service, it should be physically tagged 'out of service' so a colleague does not unknowingly use it, and the fault logged with date, instrument, observed problem, and the person reporting it. This audit trail matters most in exactly the scenarios the exam likes: an outbreak investigation tracing a contaminated instrument, or a quality review confirming that calibration was verified on schedule. An action that is clinically correct but undocumented is still vulnerable when the stem mentions audits, outbreaks, or accountability.

Halogen bulb handling, step by step

Bulb replacement is the most-tested in-house repair, so know the exact sequence. First, power off and unplug the instrument and let the old bulb cool - halogen bulbs run hot enough to burn. Second, remove the spent bulb. Third, seat the new bulb without touching the glass envelope, handling it through a tissue or with gloves, because skin oils create localized hot spots that shorten lamp life and can crack the envelope. Fourth, confirm it seats fully in its socket so the beam aligns. Fifth, restore power and verify brightness and beam position.

If brightness or alignment is still wrong after a correct swap, the problem is no longer the bulb and the unit goes to biomed.

Battery-powered instruments

Direct ophthalmoscopes, retinoscopes, and the BIO often run on rechargeable handles. Low charge yellows and dims the beam and shifts color temperature, which distorts the retinoscopic reflex and the fundus view. The routine is to recharge on a docking station between uses and replace rechargeable cells when they no longer hold a charge. A common trap pairs a dim beam with 'send to biomed' when the real fix is simply charging or swapping the battery - an in-scope, in-house action.