Too often, we focus on the details and, in doing so, miss the bigger picture. We tend to categorize things as black or white, leaving little opportunity for grey.
Just as there is a spectrum of colors, there too is a spectrum for many of the conditions we diagnose every day. In the world of binocular vision, it is rare that a diagnosis is as textbook or straightforward as we are led to believe. This column will focus on approaching conditions as if they are a spectrum and not a single set of findings that must occur to earn a specific label.
One of the most common binocular vision conditions is convergence insufficiency (CI). From double-blind, placebo-controlled studies, we believe that in-office vision therapy is superior to all other treatments.1,2 In those studies, the diagnosis of CI was based on reduced near point of convergence (6cm or greater), reduced base-out vergence ranges at near (having a positive fusional vergence value of less than twice that of the near phoria and failing Sheard’s criterion or having a minimum base-out break of 15 on the positive fusional vergence) and a greater exophoria at near (at least 4).1,2 The patients needed to be symptomatic as well.1,2 Other signs include a low AC/A ratio, reduced vergence facility, low MEM, low negative relative accommodation and trouble clearing plus on accommodative facility. These three cases all seen by the same student in the same morning session on the same day will help highlight our treatment philosophy.
The spectrum of signs and symptoms of any condition, including CI, is similar to the color spectrum. Click image to enlarge.
An 11-year-old male presented with a history of frontal headaches for two years. His primary care physician referred him to determine if his vision was the issue, as sinus-related causes were also under investigation. The headaches were not task-specific or associated with visual blur, nausea or vomiting. He was an average student, read on grade-level and took Vyvanse (lisdexamfetamine dimesylate, Shire) for attention deficit hyperactivity disorder.
The patient’s quality of life score was a 25, which was a red flag. His visual acuities were 20/15 at distance and at near OD, OS and OU. Stereopsis showed 20 seconds of arc, and the cover test showed orthophoria at distance and 12 exophoria at near. Retinoscopy and binocular balance were +1.50 OD, +1.75 OS and +0.75 OD, +1.00 OS, respectively. His accommodative amplitudes were 16D OD and OS. The near point of convergence was “to the nose” X 3, which binocular balance confirmed. The vergence ranges at near were X/24/11 base-in and 10/24/-1 base-out.
He was diagnosed with CI and sent to vision therapy, with instructions to continue to use his near vision glasses.
A 15-year-old male presented complaining that he had been experiencing constant near vision blur during the previous year and trouble while reading. He had been wearing near vision glasses (+0.75 OU) for the past five years and said they help. He received good grades and read on grade level.
The patient’s quality of life score was a 10. His visual acuities were 20/15 at distance and at near OD, OS and OU. Stereopsis showed 20 seconds of arc, and the cover test showed orthophoria at distance and six exophoria at near. Retinoscopy and binocular balance were +1.00-0.50 X 180 OD and OS and +0.75 OD, +1.00 OS, respectively. His negative and positive relative accommodations were +2.00 and -2.75, respectively. His accommodative amplitudes were 8D OD and OS. The near point of convergence was 15/17cm X 3, which did not improve with low plus. The vergence ranges at near were X/20/13 base-in and X/12/5 base-out.
He too was diagnosed with CI and sent to vision therapy.
A 10-year-old female presented with complaints of blurry vision at distance for the past year despite wearing glasses (-0.75 OD, -0.25 OS). She suffers from headaches when she does not wear them. She was a good student and was on grade-reading level.
Her quality of life score was a 15. Her unaided visual acuities were 20/125 OD and 20/25 OS and OU at distance and 20/25 OD, OS and OU at near. Retinoscopy and binocular balance were both -2.00 OD and -0.25 OS, providing 20/20 acuity at distance and at near OD, OS and OU. Her uncorrected cover test showed orthophoria at distance and six exophoria at near. The near point of convergence and stereopsis were 14/17cm X 3, and stereo acuity was 70 seconds of arc. The vergence ranges at near were X/18/12 base-in and X/16/4 base-out. The near point of convergence and stereopsis were repeated with binocular balance in a trial frame. While stereopsis improved to 30 seconds of arc, the near point of convergence remained the same.
She was also diagnosed with CI but, unlike the last two cases, was referred to a research study investigating treatment options.
While studies must be stringent in their inclusion criteria for a variety of reasons, clinicians have flexibility in practice. Even though many, if not most, cases tend to fit the textbook definition of CI, none of these three cases did. However, that should not—and did not—stop clinicians from making the diagnosis as they see fit.
In the first case, the patient’s near point of convergence was not reduced, and he barely squeaked by when considering Sheard’s criteria, but the cover test showed a much greater exophoria at near. In the second, the near point of convergence was reduced, and the cover test showed greater exophoria at near, but the patient barely passed Sheard’s. In the third, the cover test showed greater exophoria at near, and the near point of convergence was reduced, but the patient passed Sheard’s. Only the first reported a level of symptoms that should cause concern.
As when considering autism, multiple sclerosis and glaucoma, we must pay close attention to a spectrum of signs and symptoms as we clinically evaluate potential binocular vision issues. Withholding necessary treatment just because our findings do not fit a certain criteria is not an acceptable way to practice. Neither is trying to make something fit into a box it doesn’t belong in. Our patients deserve the best treatment we have to offer, regardless of what box they do or do not fit into. Luckily, we’re trained to find the answers our results don’t always give us.
1. Scheiman M, Mitchell GL, Cotter S, et al. A randomized clinical trial of treatments for convergence insufficiency in children. Arch Ophthalmol. 2005;123(1):14-24.
2. Convergence Insufficiency Treatment Trial Study Group. Randomized clinical trial of treatments for symptomatic convergence insufficiency in children. Arch Ophthalmol. 2008;126(10):1336-49.