Throughout my experience as a locum optometrist working at clinics nationwide, I've observed patterns in how we assess accommodation that I believe deserve thoughtful reconsideration. Patients frequently present with eyestrain, headaches, and progressive blurring during computer work or phone use. These symptoms point toward accommodative dysfunction, yet our assessment methods often do not capture the full picture of what a patient is experiencing in their daily life.

Consider the typical primary care workflow: autorefraction, monocular subjective refraction, perhaps NRA/PRA values for new patients, and age-based charts to determine bifocal "needs". While fast and efficient, this approach reduces the assessment of accommodation to too few data points and a lookup table. I'd like to explore why a more comprehensive approach will better serve your patients.

Understanding Accommodation as Dynamic Behavior

Accommodation differs fundamentally from static refractive error. It's an active, neurologically guided process that interacts continuously with convergence, attention, cognitive load, and even emotional state. It is of vital importance that optometrists understand accommodation is more than just something innervated by the autonomic nervous system.

Unfortunately, many optometrists rely on age-related tables for near prescriptions. The problem with this is that age tables were generated before society as a whole began living their lives in front of computer / phone screens, and their background theory focuses primarily on maximum focusing capacity (accommodative amplitude). However, amplitude tells only a small part of the story. What matters more is one's accommodative posture, where the patient actually accommodates during visual tasks.

Two patients of identical age, with identical amplitudes, working at identical distances, may demonstrate significantly different accommodative postures based on their unique neurological programming. The accommodative system seeks to maintain a comfortable balance between clarity, convergence demands, and sustained performance, not simply to minimize effort. Providing "maximum plus" is never optimal; too much plus can disrupt this balance as much as too little (or, none at all).

The Cycloplegic Consideration

Cycloplegic refractions provide valuable information to some providers about a patient's refractive status without accommodative influence. However, patients function in daily life with accommodation chronically active and continuously operating. Very often a prescription based solely on cycloplegic findings will provide more plus than the patient's accommodative-convergence posture can comfortably integrate. This explains why some children resist wearing what you thought were otherwise perfectly prescribed glasses. The lenses compensate for the child's "full refractive state", yet, they provide too much plus for where the child most uses their visual skills (i.e., up close); they become uncomfortable and defeat the purpose of why they were prescribed in the first place.

Recognizing Accommodative Symptoms

Our patients often describe specific accommodative dysfunctions with remarkable precision:

These descriptions provide valuable clinical insights when paired with appropriate accommodative testing.

Beyond NRA/PRA

NRA/PRA measurements offer useful information about the range of clear vision at near, but they don't reveal where the patient actually accommodates during normal near work (accommodative posture), they don't describe the accuracy of one's accommodative response (lag), their ability to sustain accommodation over time (stamina), or their flexibility in shifting focus between distances (facility).

Think of using NRA/PRA to describe a patient's entire accommodative profile as analogous to assessing cardiovascular fitness by only assessing resting heart rate; this provides one data point, but doesn't capture dynamic performance during actual activity.

Measuring Accommodative Posture

To combat this, optometry needs to bring renewed attention to measuring a patient's accommodative posture. This is the functional operating point around which a patient's visual system organizes itself. This can be assessed through nearpoint retinoscopy and the fused and unfused cross cylinder testing, some schools refer to 'binocular cross cylinder' instead of 'fused cross cylinder' but they are the same test.

Through cross cylinder testing and measuring phorias through those different lens powers, we can understand where patients actually accommodate when convergence is released (as found by the unfused cross cyl) and where they actually accommodate when converged (as found by the fused / binocular cross cyl). This reveals the relationship between these two visual skills. Even more fascinating, near-point retinoscopy allows actual direct observation of whether a lens will work well for the patient through the assessment of the color and quality of the retinoscopic reflex.

Individual Variability in Lens Tolerance

Patients adapt to visual stress in characteristically different ways and this influences lens fitting. Optometry historically "case typed" their patients before diagnosing them using the modern Duane-Wick classifications, and case types recognized that different types of patients accept different types of lens prescriptions: patients with primarily accommodative issues could often use more plus at near while those with convergence difficulties might find that full plus worsens their convergence difficulties. Two patients with similar cross cylinder findings might need different prescriptions based on their individual vergence characteristics.

It's long past time that optometry returns to comprehensively assessing a patient's accommodation. It's not hard, it just involves including measurements of accommodative posture, facility, phorias, and vergences through different lens powers at near. This all provides the information needed for individualized prescribing and personalized medicine.

Contemporary Challenges

Research shows that accommodative demands have intensified with increased screen time. Studies demonstrate that even 30 minutes of smartphone use significantly affects accommodation amplitude, facility, and positive relative accommodation while increasing accommodative lag. The accommodative system exhibits constant small oscillations essential for maintaining stable focus, and these fluctuations increase with sustained near work.

Our patients face unprecedented accommodative challenges in their daily lives. Expanding our assessment toolkit helps us address these modern visual demands more effectively.

A Note on Computer Prescriptions

It's worth clarifying that effective computer prescriptions require putting added plus power over the distance prescription, and they may include small amounts of base-in or base-down yoked prism. Blue light blocking coatings alone, without the appropriate spherical power modifications, do not address the accommodative component of digital eyestrain.

Moving Forward

Incorporating more comprehensive accommodation assessments goes a long way towards improving patient loyalty, improving visual health, and ensuring the future success of your practice. I cannot state how many times I've heard "I've never had that test before" after simply doing just the fused cross cylinder. Your patients notice what you do and don't do, and when we measure what they're describing, we can prescribe more precisely for their individual neurological makeup rather than relying solely on population averages. The investment in more thorough assessment will translate directly into better symptom resolution and improved patient satisfaction.