Basic ophthalmic diagnostics and techniques including dos and don'ts (Proceedings)


Basic ophthalmic diagnostics and techniques including dos and don'ts (Proceedings)

Apr 01, 2008

A. History

The importance of a reliable and accurate history that is relevant to the presentation at your examination-can not be overemphasized. As would be the case with any existing systemic condition, it is especially important to determine if there is a current regimen of medications that are being administered, as directed by a previous veterinarian, of which the owner may be hesitant to mention in fear of concern that you may ask why they did not come to you first for dx and tx. This is especially important when assessing such conditions such as miotic and mydriatic pupils-since the #1 cause of both is drug-induced. Additionally, it is also important to be aware of preexisting conditions and current therapy to avoid prescribing any future medication(s) that could cause serious systemic side-effects.

B. Examination

Ocular examination should be performed prior to a rigorous physical exam to avoid effects of stress changes on ocular features. Attempt to have the patient relaxed on the examination table before your hands-on evaluation. Initially look at facial and ocular features from a distance-to more accurately assess unstimulated features. Attempt to avoid using chemical restraint (if safely possible) or rigorous manual restraint-especially in the cervical region. Chemical restraint affects Schirmer Tear Test (STT) readings, intraocular pressure (IOP) measurements and may cause undesirable elevation of the third eyelid. In some cases, pupillary light responses and diameter may also be affected. Aggressive manual restraint around the neck or eyelids can result in dramatic increased IOP readings.

Basic instruments and supplies required: (an ocular examination should be performed in a darkened room to enhance subtle contrasts of extra- and intraocular structures)

Designated ophthalmic examination sheet-preferably 1 page only and ample diagrams

Light source-preferably halogen

Ocular magnifying loupe- 2 ½ x works best---mag. a must, especially for the over 40 group

Schirmer Tear Test (STT) strips

Fluorescein test strips

Eyewash and cotton balls

Topical anesthetic –Proparacaine

Tonometer-preferably TonoPen® or TonoVet ®

Mydriatic agent-Tropicamide

Direct ophthalmoscope (slit beam)-preferably a condensing lens for more panoramic image

Tissue forceps

Lacrimal cannula-preferably 2 sizes (22 to 25 gauge) (low priority)

± Blunt spatula, glass slides and fixative (gram stain), sterile culturettes←(low priority)

Eye model for explanation purposes

Examination Rules of Thumb

  • Always perform diagnostic exam in the same order each time

History→PLR's→STT→ Culture (rare)→Fluor. stain→Top. Anesth.→IOP→Dilate

  • Always examine the adnexa and eye in the same order each time (front to back)

Symmetry→Eyelids→Conjunctiva→Cornea/Sclera→Anterior chamber→Iris→Lens→