Malpractice Management
Lack of Cupping Confuses
Learn the importance of performing one simple test and of only prescribing with the patient in your office.
BY JERRY SHERMAN, O.D, F.A.A.O.

Most clinicians are unaware that glau-coma without cupping is a real clinical entity. When a patient has a dense, repeatable glaucomatous-type field defect but has no corresponding disc cupping, clinicians search for other explanations of the field defect. Read on and see how glaucoma without cupping confused all six treating clinicians in this case.

The patient presents

A 56-year-old white male presented at an O.D.'s office with "a mild infection in his left eye." The patient admitted that his eyelids were stuck shut when he woke up. His general health and eye history were both unremarkable and his best corrected visual acuity was 20/20 OU. The external exam was normal and the O.D. graded the angles as 1-2 in each of this low hyperope's eyes. Slit lamp revealed dilated conjunctival vessels -- greater in the left eye than in the right.

The optometrist noted that the cornea OS had mild stippling but didn't perform tonometry -- perhaps because of the corneal involvement. Ophthalmoscopy revealed normal discs with no cupping and normal maculas OU. The O.D. prescribed prednisolone acetate 0.2%, sodium sulfacetamide 10% (Blephamide) q.i.d. to treat keratoblepharoconjunctitivis in the OS.

Meeting the wife

After using the eye drops for several days, the patient began experiencing increased discomfort in his left eye. At about the same time, he started experiencing flu-like symptoms and back pain. One day later, he noted light sensitivity in his left eye. The patient searched the Internet and found a Web site describing his symptoms as being diagnostic of iritis.

Because of bad weather, the flu and his backache, the patient didn't return to the optometrist's office. He instead sent his wife to the office to pick up different eye drops.

Giving in

The doctor was hesitant to change the patient's treatment without actually seeing him, but the wife was demanding. The doctor reasoned that perhaps the patient was developing an allergy to the sulfa in the sodium sulfacetamide or perhaps he did, in fact, have an iritis. He apparently only considered these two diagnoses and thought that a steroid would help in either case and that a dilating agent would clearly help the possible iritis.

The O.D. gave the patient's wife a bottle of tropicamide 0.5% (Mydriacyl) to use one drop b.i.d. in the left eye and a bottle of prednisolone 1% (Pred Forte) to use one drop q.i.d. in the left eye and to discontinue the sodium sulfacetamide.

Patient worsens

The patient used the new drops as instructed but his symptoms worsened and he presented back at the O.D.'s office days later with worsening pain OS. Visual acuity was still normal OU, but Goldmann intraocular pressures (IOPs) were 20 mmHg OD and 48 mmHg OS.

The results of ophthalmo-scopy were unchanged and the O.D. scheduled a fields test for the next visit. He didn't perform gonioscopy, but discontinued the dilating agent and the steroid and initiated treatment with latanoprost (Xalatan) at night and brimonidine tartrate (Alphagan) b.i.d. in the left eye only.

The patient returned the next day and the IOP in his treated left eye dropped to 9 mmHg. The doctor performed fields and the right field was within normal limits, but the left field revealed a dense inferior arcuate scotoma and nasal step.

Getting a second opinion

Several days later, discomfort and redness returned in the patient's left eye and he sought out a general ophthalmologist who evaluated him. IOP was elevated to 29 mmHg OS in spite of the patient's reported compliance with the latanoprost and brim-onidine.

Fields were again normal OD, but the dense inferior arcuate scotoma OS revealed itself for the second time. A dilated fundus exam was found within normal limits OU and the cup-to-disc ratio was recorded as .1 OU. The patient presented the next day with frank pain OS. Goldmann IOP was 45 mmHg OS.

Passing the patient on

The M.D. consulted a glaucoma specialist in his practice who performed gonioscopy on the patient for the first time. The angles were both judged as quite narrow and the specialist performed a laser peripheral iridectomy (LPI) OS. The specialist's re-evaluation several days later revealed a patent LPI, but again, the pressures were elevated into the 30s OS.

This specialist referred the patient to another glaucoma specialist at a large teaching institution. This specialist performed a second LPI OS and a prophylactic LPI OD.

The case remains a mystery

Since the last LPI, the patient's IOPs have been controlled in his left eye. After the last procedure, the glaucoma specialist obtained the first Heidleberg Retinal Tomograph (HRT), which revealed no cupping in either eye.

The glaucoma specialist couldn't explain the discrepancy of the dense field defect, documented high IOPs on at least three occasions but no cupping observed ophthalmoscopically and no cupping documented with the objective HRT disc topographer.

Visiting another specialist

The University-based glaucoma specialist referred the patient to a retinal specialist who suspected a superior temporal branch artery occlusion as the explanation of the field defect.

The patient now admitted to having uncontrolled systemic hypertension, so an artery occlusion was certainly plausible. A fluorescein angiogram failed to document any disc, retinal or retinal vascular disorder and the retinal expert had no explanation for the field loss.

Suing the optometrist

The patient sued the first doctor for missing the diagnosis of narrow-angle glaucoma and for prescribing dilating drops, which worsened his condition. The defense asked me to review the case as an expert witness, so I had access to the patient's entire record. In my opinion, the O.D. failed to meet the standard of care because he treated the alleged iritis without examining the patient and consequently precipitated an angle closure in the left eye with the dilating agent.

However, I felt that the patient was equally responsible because his failure to present in person cost the doctor the opportunity to measure his IOPs at the time of his worsening symptoms. In spite of my opinion of partial culpability on the part of the treating optometrist, I agreed to help in evaluating the case and in formulating a defense.

Why no cupping?

Fortunately for the O.D. and his insurance company, the plaintiff's experts couldn't explain the absence of cupping OS.

Without cupping, neither expert was able to testify conclusively that the vision loss was a direct result of glaucoma. Moreover, the extent of the field loss and its depth were also question-ed because visual fields are a subjective test. (Neither of the doctors recommended objective nerve fiber layer assessment).

The case was settled for between $100,000 and $200,000 prior to a jury trial and before my deposition.

My explanation

After reviewing the fundus photos and HRT results, I concluded that the patient had subtle disc drusen, which prevented the development of glaucomatous cupping. Note the lumpy disc borders, a characteristic finding in disc drusen.

Disc drusen can be obvious, subtle or even occult. This case has subtle disc drusen, which are often missed clinically, even by experienced clinicians. The HRT provides an accurate representation of the disc contour, but in such a case, the drusen "fill the cup" and hence the contour appears flat.

Disc drusen is the single most common cause of glaucoma without cupping and explains about two thirds of all cases. Also, a rapid rise in IOP, as in this case, is sometimes associated with loss of the nerve fiber layer without obvious cupping. Hence, this patient has two reasons for glaucoma without cupping and neither a branch retinal artery nor AION is the likely culprit. The patient in this case had normal cup glaucoma, which is akin to normal pressure glaucoma.

Take home message

Never treat a patient without fully evaluating him first. Steroid use without exam could lead to the inadvertent treatment of a herpes simplex keratitis or a fungal keratitis with a steroid -- two conditions that typically worsen with the use of a steroid.

Also, you should never use dilating agents in a patient without evaluating the depth of the anterior filtration angle, preferably with a gonioprism. If a patient presents with sky-high pressures, perform gonioscopy to rule out angle closure. 

Dr. Sherman practices at the Eye Institute and Laser Center in Manhattan and is a distinguished teaching professor at the SUNY College of Optometry. To protect the anonymity of the individuals involved in this case, we have not used their real names.