Biomicroscopy of the anterior segment is performed to detect signs of underlying ocular conditions that may be associated with glaucoma or ocular hypertension, to evaluate the eye in preparation for glaucoma surgery, and to monitor the function of a previously performed glaucoma surgery. BCSC Section 8, External Disease and Cornea, discusses slit-lamp technique and the examination of the external eye in greater depth.
Eyes with acutely elevated intraocular pressure (IOP) may have conjunctival hyperemia. Long-term use of many ocular hypotensive medications may also cause conjunctival hyperemia. Allergic or hypersensitivity reactions to medications (especially α2-adrenergic agonists) or their preservatives can result in a follicular conjunctivitis. Other potential adverse effects of topical hypotensive drugs include decreased tear production, foreshortening of the conjunctival fornices, and, in severe cases, pseudopemphigoid with conjunctival scarring. Prior to filtering surgery, the presence or absence of subconjunctival scarring or other conjunctival abnormalities is assessed. The presence or absence of any filtering bleb is noted. If a bleb is present, it is characterized as either cystic or diffuse, and its size, degree of elevation, amount of vascularization, and integrity are noted. A Seidel test is performed if a leak is suspected (Fig 1-4).
Figure 4-1 Seidel test. After application of a concentrated fluorescein solution, quenching will block fluorescence unless there is an aqueous humor leak that dilutes the fluorescein. The dark area on the right of these images represents an area of highly concentrated fluorescein. As aqueous humor leaks (arrow, A) the fluorescein is diluted, and an enlarging rivulet of fluorescence is detected (A–C).
(Courtesy of Angelo P. Tanna, MD.)
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.