Page 58 - CJO_F17_GLAUCOMA_SUPPLEMENT

C CLINICAL RESEARCH

Conclusion

Glaucoma management begins with identification of individuals at risk of glaucoma in the primary eye exam. A
comprehensive glaucoma assessment is recommended after identification of individuals at risk or with signs of the
disease to gather baseline information and confirm diagnosis. A treatment plan can then readily be tailored to each
individual based on the collection of this information.

As mentioned earlier, the purpose of this evidence-based guideline is to continue to build upon the Canadian
Optometrist's competence and confidence in the diagnosis and management of primary open angle glaucoma. The
authors hope they have succeeded in this purpose and that readers will find it a useful resource to refer back to at
various stages of the glaucoma journey.

APPENDIX 1: GONIOSCOPY

REVIEW OF THE GONIOSCOPY PROCEDURE
To perform indirect gonioscopy:
• Anesthetic is instilled in both eyes.
• The patient is positioned at the biomicroscope, and the lens (with or without coupling solution depending
on type of lens used) is placed on the cornea. It helps to have the patient look up while the lens is
positioned above the lower lid, then look straight ahead while fixating with the fellow eye.

• A scleral lens must be rotated, whereas the slit beam is moved to each of the four mirrors of a corneal lens,
to view different aspects of the angle.

• A systematic approach beginning with the superior mirror to assess the normally widest and most
pigmented inferior angle (where angle structures tend to be easiest to identify) and proceeding clockwise
is recommended.
• Tilting the lens away from, or having the patient look slightly toward the mirror being used facilitates
visualization of deeper angle structures in patients with steeper mid-peripheral irides.

• This will not be the case in those with true angle closure. If excessive lens tilt is required, the angle should
be considered narrow and potentially occludable.

• Ambient lighting should be low and directing the short and narrow slit beam through the pupil should be
avoided, as pupillary constriction can temporarily deepen the angle. 385,386

• Mid- to high (10 to 25x) magnification is required to accurately visualize detailed angle anatomy.

• Interface bubbles are common, particularly with corneal lenses: tilting the lens toward the bubble,
flattening the lens surface on the cornea, will help eliminate them. An occasional bubble is actually a good
sign that the pressure being exerted is adequate but not excessive.

STRUCTURES SEEN ON GONIOSCOPY
With the lens in position, the angle structures can be identified: the following description will proceed from pos-
terior (more open) to anterior (less open). The root of the iris defines the posterior extent of the angle while the
termination of Descemet membrane (Schwalbe line) marks its anterior border.

• Iris:
• Observing the slit beam on the surface of the iris will help identify its contour: myopic eyes often have
a deep chamber, concave iris, and an increased risk of pigment dispersion due to friction between the
posterior iris and zonules, while hyperopic eyes have a shallower chamber, convex iris, and increased risk
of angle closure.

58 CANADIAN JOURNAL of OPTOMETRY | REVUE CANADIENNE D’OPTOMÉTRIE VOL. 79 SUPPLEMENT 1, 2017