Accommodative insufficiency refers to a condition in which the onset is not sudden and accommodative power is weaker than expected for age. In contrast, ill-sustained accommodation is a condition in which repeated near-point measurements show a recession of the near point.
Ill-sustained accommodation can be considered a diagnostic term unique to Japan. It refers to cases where accommodative power is weak relative to age, or where a constant state of accommodative tension cannot be maintained. It corresponds to ill-sustained accommodation as named in Western countries, but the term originates from the phenomenon of near-point recession (the phenomenon where the near point gradually moves farther away with repeated near-point measurements). It develops due to disharmony of the internal environment.
With the widespread use of VDT (visual display terminal) work, the incidence in young people is increasing. Systemic diseases, mental stress, and overwork are often predisposing factors. Reported prevalence rates vary widely among studies, ranging from 8–18% in school-age children and even higher in children with special backgrounds (Reference 1).
Accommodative disorders are classified according to the type of functional abnormality as follows.
| Classification | English Name | Main Features |
|---|---|---|
| Ill-sustained accommodation | ill-sustained accommodation | Recession of near point on repeated measurement |
| Accommodative insufficiency | accommodative insufficiency | Accommodative amplitude weaker than age-appropriate level |
| Inertia of accommodation | inertia of accommodation | Prolonged accommodation time from far point to near point |
| Accommodative palsy | accommodative palsy | Acute onset of near vision difficulty |
| Accommodative constriction | accommodative constriction | Increased physiological or abnormal tone |
| Spasm of accommodation | spasm of accommodation | Excessive or hypertonic accommodation |
Convergence insufficiency with accommodative insufficiency (combined type) is a condition in which accommodative convergence and fusional convergence become insufficient due to accommodative dysfunction, preventing adequate convergence movement. Even in children diagnosed with convergence insufficiency, there are reports that the main cause of severe symptoms is coexisting accommodative insufficiency, highlighting the importance of evaluating accommodative function (Reference 3).
Presbyopia is a physiological change in which accommodative power irreversibly decreases due to age-related hardening of the lens. Accommodative insufficiency is a pathological condition where accommodative power is lower than expected for age, and it differs in that it can improve with removal of the cause or treatment. In presbyopia, the decline in accommodative power progresses slowly, whereas accommodative insufficiency can occur at relatively young ages.
In accommodative insufficiency and accommodative weakness, patients complain of severe eye strain during near work. Because accommodative and convergence abilities are reduced, prolonged near work leads to exophoria at near, causing crossed diplopia, sensory abnormalities, and eye strain. A typical example is technostress eye syndrome caused by VDT work.
The main subjective symptoms are as follows.
Prolonged near work leads to decreased accommodative and convergence function, and can trigger accommodative dysfunction and accommodative weakness. Long-term use of smartphones and tablets, like VDT work, forces sustained near vision and is considered a cause of technostress eye syndrome. However, individual differences exist, and not everyone develops accommodative dysfunction.
Environmental and Behavioral Factors
VDT work / excessive near work: Prolonged continuous VDT work or reading leads to a sustained decline in accommodation and convergence function.
Inappropriate work environment: Near work in environments with insufficient lighting, screen reflections, or improper working distance worsens symptoms.
Inappropriate prescription of near glasses: Use of bifocals or glasses that do not match the working distance can also be a cause.
Systemic and psychological factors
Systemic diseases: Medical conditions (anemia, hypotension, thyroid disease, etc.) may affect overall accommodative function.
Mental stress and overwork: Mental tension and chronic fatigue can cause internal environment imbalance, predisposing to accommodative weakness.
Other medications and diseases: Drugs with anticholinergic effects, neurological disorders, etc., also affect accommodative function.
The relationship between convergence and accommodation is not proportional but exists with a certain range. Prolonged near work in an inappropriate environment, where accommodative convergence and fusional convergence are active, gradually leads to sustained decline in accommodative and convergence functions.
Diagnosis is made by combining subjective symptoms and the following objective examination findings. First, take a detailed history of VDT work time, near work environment, general condition, and use of near glasses. It is also important to check whether the glasses worn are appropriate for the near working distance.
| Examination | Overview of method | Evaluation points |
|---|---|---|
| Interview | Check VDT work time, work distance, glasses status, and general condition | Identify symptom onset and exacerbating factors |
| Visual acuity test | Corrected and uncorrected visual acuity for distance and near | Evaluate presence of refractive error |
| Cycloplegic refraction | Mydrin P eye drops (2 drops 5 minutes apart, test after 30 minutes) | Evaluate true refractive value and latent hyperopia |
| Accommodation function test | Repeated measurement with near point ruler | Check for recession of near point with repetition |
| Convergence function test | Repeated measurement of convergence near point and fusion range | Check for extension of convergence near point |
| Binocular wavefront sensor | Simultaneous measurement of accommodation, miosis, and convergence | Objective evaluation of the three components of the near response |
| Major amblyoscope | Measurement of fusion range with base-out prisms | Quantitative evaluation of fusional convergence |
When using Mydrin P eye drops as a cycloplegic agent, instill twice at 5-minute intervals; cycloplegia is strongest 30 minutes after instillation, so perform refraction testing at that time.
For understanding the pathophysiology of pathological abnormalities, it is useful to objectively measure the three components of the near response (accommodation, miosis, convergence) simultaneously using a binocular wavefront sensor.
The basis of treatment is to identify and eliminate the cause. Treatment of the underlying disease (systemic or ocular disease) and environmental improvement are most important.
First, aim to improve the environment so that continuous VDT work time is limited to a maximum of 1 hour, followed by a 10–15 minute break. Also provide guidance on appropriate lighting, working distance, screen height, and brightness adjustment.
Eyeglasses must be worn with appropriate near work distance and corrected refractive values. Therefore, after performing a refraction test using cycloplegic agents, prescribe near-vision glasses tailored to the actual VDT working distance.
During VDT work, dry eye due to decreased blinking is common.
If a systemic disease is the cause of accommodative dysfunction, prioritize treatment of the primary disease. If mental stress or overwork is the cause, rest and stress management are important.
Over-the-counter eye drops (for tired eyes) are symptomatic treatments and do not address the root cause of accommodative insufficiency. The basics of treatment involve identifying and eliminating the cause, prescribing appropriate glasses, and improving the environment. If dry eye is also present, artificial tears may be helpful, but first, a thorough eye examination is necessary to obtain an accurate diagnosis and appropriate treatment.
The relationship between convergence and accommodation is not proportional but operates within a certain range. Within this range, accommodative convergence and fusional convergence work together to achieve near vision. Prolonged near work in inappropriate conditions (e.g., constant working distance, ill-fitting glasses) can disrupt this coordination, leading to persistent decline in accommodative and convergence functions.
This condition arises when accommodative dysfunction leads to insufficient accommodative convergence and fusional convergence, resulting in inadequate convergence movements. Prolonged near work first reduces accommodative function, which then triggers a decline in convergence function. VDT work is a major trigger, making this a representative occupational eye disorder in the modern digital society.
Technostress eye syndrome is a general term for eye symptoms associated with VDT work, and accommodative insufficiency and accommodative weakness are core pathologies (Reference 4). The rapid spread of smartphones and tablets has increased both the intensity and duration of near work, contributing to the rise in accommodative insufficiency among young people. A prospective observational study reported that children with longer daily smartphone use had significantly higher digital eye strain scores (Reference 5).
In accommodative weakness, the sustained contractile ability of the ciliary muscle decreases in response to repeated accommodative stimuli. As a result, accommodative power declines with each measurement, and the near point gradually recedes—a phenomenon known as near point recession.
Improving the VDT work environment, wearing glasses appropriate for the working distance, and using artificial tears are effective, and many cases show symptom improvement. If a systemic disease is the underlying cause, treating the primary disease may restore accommodative function.
In recent years, objective accommodation function evaluation using accommodation function analysis devices (e.g., Accommodometer, Fk-map) has become more widespread. Simultaneous measurement of accommodation, miosis, and convergence using binocular wavefront sensors enables visualization of functional abnormalities that were difficult to capture with conventional subjective near-point measurements. These devices can quantify the response speed, sustainability, and variability of accommodation, and are expected to contribute to establishing objective diagnostic criteria for accommodative insufficiency and accommodative weakness.
With the spread of digital devices, research on the impact on accommodation function in children and young adults is progressing worldwide. The relationship between factors such as near work distance, duration, luminance, and blue light exposure and accommodative dysfunction is being investigated, and further accumulation of evidence is expected.
Research on the effectiveness of accommodation training (e.g., push-up method, flipper training) for accommodative insufficiency is limited compared to evidence for convergence training for convergence insufficiency. A randomized controlled trial in children with convergence insufficiency and coexisting accommodative dysfunction reported that clinic-based convergence and accommodation training significantly improved accommodative amplitude and accommodative flipper compared to placebo (Reference 2). However, high-quality evidence is lacking for treatment protocols for isolated accommodative insufficiency and comparisons between low-plus lenses and training (Reference 1), and further verification through randomized controlled trials is needed.
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