The Case of the Phantom Dry Eye

Not a widely known fact, Sir Arthur Conan Doyle, author of the Sherlock Holmes detective stories, was actually an eye doctor before he became a celebrated writer.  Martin Booth’s marvelous 1997 book, “The Doctor and the Detective”, chronicles the career path of Conan Doyle, and in 2001 our colleague Dr. Sidney Groffman observed in an editorial that paid tribute to Doyle that Sherlock Holmes would have been the quintessential behavioral optometrist:  “He was intelligent, cared deeply about helping people, strongly believed in his profession, realized vision was the primary sensory modality, trained himself to enhance his visual abilities, and knew how to improve vision in other people.”

It is not uncommon for developmental/behavioral optometrists to do detective work in caring for our patients.  Many of the children and adults we see are puzzling, and the clues to their performance problems are not always straightforward.   This was the case with Ryan, a bright 9 year-old, who was struggling with reading.  He remarked to his mother that when he read letters looked like they were shrinking on the page.

Ryan isn’t a complainer, so mom figured there was something odd happening visually.  She took him to an ophthalmologist to be examined, who advised her that Ryan’s vision was fine.  He said that Ryan had “dry eyes”, gave mother a prescription for Systane eye drops, and told her to put a drop in each eye every time Ryan complained about reading.

When Ryan’s mother brought him to see me, she was puzzled.  She had put the drops in as the doctor had directed, but they made no difference at all in Ryan’s perception.  With her background in special education, she sensed that this would be a blind alley.  She was advised by an optometrist, who took the time to gather a good learning-related vision history, that we worked with children who had problems in visual processing, and this sounded more like what Ryan was experiencing.

As much as I sensed that dry eyes had nothing to do with Ryan’s difficulties, I wanted to give the ophthalmologist the benefit of the doubt.  Being a good clinical detective requires gathering the right clues, and ignoring false leads.   Here’s what I found.

Ryan’s eyes looked perfectly normal.  I saw no evidence of an abnormal tear film associated with dryness.  Figuring that the other doctor must have used fluorescein, the dye most commonly used to help diagnose dry eye, I instilled fluorescein expecting to find something abnormal that would have supported the doctor’s prescription of eye drops.

What I found, instead, was that Ryan’s cornea and tear film were as normal as could be. The doctor was likely counting on the drops serving as a placebo.  Or worse, perhaps the doctor was using negative conditioning.  By mother inserting a drop that stung whenever Ryan complained about print shrinking while he was reading, he would stop complaining as to avoid the sting of the drops.

When we conducted tests of visual efficiency and processing, we found that Ryan had problems that could directly account for his perception while reading.  His responses on tests of focusing and eye teaming matched his perception of print shrinking while he was trying to focus.  He has not yet begun vision therapy in our office, but when he does there is little doubt that he will improve significantly.  He is the type of case that we see most frequently, dismissed by one doctor who patronized his mother, but saved by another who believed in him.

It was the case of the phantom dry eye.  Elementary, my dear Watson.

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