Letters & E-mail
10 More Points About Gonioscopy
Editor: I read and enjoyed Dr. Doug Penisten’s article “Get a Better Angle on
the Gonio Exam” (November 1998). I thought that these additional points might also be
of interest.
1. Indications for gonioscopy include: diagnosis of any glaucoma, evaluation of angle
structures following trauma, rubeosis irides, anytime the angle appears narrow, abnormal
intraocular pressure, suspected tumor and pupil block.
2. Contraindications: immediately following blunt trauma, lacerated cornea, open globe
injuries and hypersensitivity to drops.
3. Today, the gonioscopic coupling gel preferred by most clinicians is Celluvisc. Unlike
the traditional coupling agents, gonioscopic solution and Gonak, it does not cause
significant corneal punctate epitheliopathy or require lavage.
4. You can instill topical anesthetic into both eyes to reduce blink re-sponse. This not
only eliminates the stimuli brought on by exposure from fixation, but also allows you to
immediately perform gonioscopy to the fellow eye without additional preparation.
5. Smooth, precise, confident insertion is important. I recommend inserting the
three-mirror gonio prism while the patient looks down. Many clinicians are weary of using
this method because it places the lens directly onto the cornea. However, since the lens
has a smooth, dull edge this approach is reasonable. Further, downward gaze allows you to
immobilize the upper eyelid, the biggest obstacle to insertion most of the time, with your
thumb. The bottom lip of the prism can push the lower eyelid inferiorly. After you rock
the lens onto the cornea, you can instruct the patient to assume a normal forward gaze.
6. Once you place the three-mirror lens onto the cornea, rotate it until you break the
vacuum seal created by the process of insertion. This will allow you to rotate the lens
freely and without friction.
7. Hold the three-mirror gonioprism in a manner I call the “E” technique. This
grip positions the thumb and middle fingers around the edges of the lens with the
forefinger used to support the front (forming the shape of an “E”). This allows
you to freely rotate or spin the prism 360° for continuous, uninterrupted examination,
which is critical for structural comparisons. To more effectively view anteriorly and
posteriorly, use the lens-rocking technique.
8. There has been debate on whether you should orient the light source perpendicular to
the mirror base. I recommend positioning the beam at 90° for the entire procedure.
Taking time to reposition the beam rarely allows you to gain an advantage for viewing and
hampers the fluidity of the
procedure.
9. These principles also apply to the four-mirror gonioprisms without handles. While the
insertion method for the four-mirror lens is less traumatic and can usually be
accomplished with the patient in primary gaze, the keys to successful four-mirror
gonioscopy are minimal pressure and a good central seal.
10. Four-mirror gonioprisms are the instruments of choice for pupil block because you
cannot do indentation gonioscopy with the three-mirror lens (it distributes the forces
over too large an area). In circumstances when IOP is high and corneal edema obstructs the
view, you can apply topical glycerin with a cotton-tipped applicator to temporarily cause
corneal deturgescence and allow viewing.—Andrew S. Gurwood, O.D., associate professor
of clinical sciences, Pennsylvania College of Optometry, Philadelphia, AGur-wood@pco.edu.
Editor’s note: Dr. Gurwood is a contributing editor of Review of Optometry.
An M.D. Weighs In: How Not to Seek Lasers
Editor: I read with interest the point-counterpoint arguments in “Should Optometrists
Use Lasers?” (October 1998). One of the author’s comments in this debate left me
in complete shock and disbelief: Dr. Leland Carr’s admission that he had “been
personally lasered over two dozen times by ... neophyte optometrists who have never
performed the procedure before.”
He asserts further “… and today, I’m not blind.” As an
ophthalmologist who has performed hundreds (if not thousands) of ocular laser procedures,
I was truly disheartened to see these comments. Lasers can cause tremendous benefit or
tremendous harm. With a resource as precious as our eyes and vision, I cannot imagine ever
personally undergoing an ophthalmic laser procedure unless I had a medical condition that
warrants it, even if it was being performed by the best-trained and most-experienced
doctor on the planet, much less a “neophyte … who had never performed the
procedure before.”
Personally, I don’t believe that this rhetoric advances the cause for which he
argues. I’m glad that Dr. Carr is not blind. I hope that he will reserve better
clinical judgment for his pa-tients than he has used on himself.
—James Dickey, M.D., Pittsburgh, JBDICKEY@aol.com
Dr. Carr responds: While I appreciate Dr. Dickey’s concern for my eyes, as well as
those of my patients, I hasten to point out that I have never considered myself to be
“at risk” during the procedures that have been performed on me.
While it is true that the practitioners and residents who performed these procedures were
“neophyte” laser surgeons, each had successfully completed the rigorous clinical
work associated with becoming an O.D. They had already mastered the re-quired basic skills
and performance concepts, and were adequately prepared to do the procedure “for
real.” As a former medical technologist, I think I was at considerably less risk
while sitting for procedures by competent O.D.s than I was while sitting for practice
venapunctures and phlebotomy labs in undergraduate school.
While I apologize to Dr. Dickey if I appear to have trivialized ophthalmic laser work, the
reality is that licensed optometrists are well prepared to judiciously perform the
procedures. I much prefer that our experiences on living human eyes do not occur on
unsuspecting patients who don’t realize that we’ve never done a procedure
before. That, as we all know, is the typical approach taken by many colleagues in related
vision-care disciplines. Let the patient beware!
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