Diagnostic Assessment — Convergence Insufficiency
Example 1 of 1 · fictitious patient (Veteran DD)
Diagnostic Assessment
Convergence Insufficiency
No Statement of Principles applies to this condition (non-SOP claim).
ADF History
Veteran DD, date of birth 23 September 1980, Australian Army, Artillery Observer (Joint Fires Team), enlisted 11 January 2000, medically discharged 19 March 2021. Operational service: Iraq, 20 April 2005 to 30 October 2005 (warlike); Afghanistan, 10 February 2010 to 30 September 2010 (warlike).
Occupational History
Artillery observers direct indirect fire and close air support. They work close to firing guns, mortars and explosive impacts during live-fire training and operations, and are repeatedly exposed to blast overpressure. Much of the work involves prolonged close viewing of digital targeting systems, laptops, maps, rangefinders and binocular optics, often for most of a shift and at night.
On operations observers move with infantry and armoured vehicles and are exposed to improvised explosive devices, vehicle rollovers and falls from vehicles and structures, with a high risk of concussion and neck injury. Disrupted sleep and shift work are routine.
History
Veteran DD, an artillery observer in the Australian Army, developed convergence insufficiency on 15 July 2010 during warlike service in Afghanistan, six weeks after a mild traumatic brain injury and whiplash neck injury in an improvised explosive device strike, after years of blast exposure from firing guns and long hours of close screen work. The condition was confirmed by an optometrist in November 2010 and worsened in 2019 and 2020 after a second head injury and the onset of Parkinson's disease.
Timeline
- 04 Nov 2009 — Pre-deployment eye examination by an optometrist. Visual acuity 6/5 in each eye unaided, near point of convergence 6 cm, normal phorias at distance and near, and no symptoms with near work. He had been working 8 to 10 hours a day on digital targeting systems during pre-deployment training since September 2009. "NPC 6 cm, binocular vision normal"
- 02 Jun 2010 — During warlike service in Afghanistan his vehicle struck an improvised explosive device. He was dazed and confused for about 15 minutes with no loss of consciousness, and had a headache, nausea and neck pain. The role 2 facility recorded a mild traumatic brain injury with a MACE score of 22 and an acceleration-deceleration neck injury with cervical muscle spasm. CT head and cervical spine were normal. "mTBI, MACE 22, whiplash"
- 08 Jun 2010 — Review for daily post-traumatic headache and disturbed sleep. Amitriptyline 25 mg at night was commenced and continued throughout the remainder of the deployment and for several years afterwards. He returned to duties at the joint fires cell, working 10 to 12 hour shifts on targeting screens and imagery. "amitriptyline 25 mg nocte commenced"
- 20 Jul 2010 — Presented with five days of eye strain, blurred and doubled print when reading the targeting display, losing his place on maps, and frontal headache after 20 minutes of close work. Near point of convergence was 14 cm with an exophoria at near. The medical officer recorded post-concussive visual symptoms and referred him to an optometrist on return to Australia. "near diplopia, NPC 14 cm"
- 30 Nov 2010 — Binocular vision assessment by an optometrist showed a near point of convergence of 16 cm break and 20 cm recovery, an exophoria of 10 prism dioptres at near and 2 at distance, reduced positive fusional vergence at near and a Convergence Insufficiency Symptom Survey score of 38. Convergence insufficiency was diagnosed. Office-based vergence therapy was recommended but was not funded through Defence health and was not provided. "convergence insufficiency, CISS 38"
- 16 Aug 2018 — During a field exercise in Australia he fell from the rear deck of an armoured vehicle and struck his head, with a brief loss of consciousness and post-traumatic amnesia of about one hour. A second mild traumatic brain injury was diagnosed. He continued to work long hours on screens in an intelligence staff role. "second mTBI, brief LOC"
- 11 Jun 2019 — A neurologist diagnosed young-onset Parkinson's disease on a right-sided resting tremor, bradykinesia and rigidity, confirmed on dopamine transporter imaging. In the same month polysomnography showed moderate obstructive sleep apnoea with an apnoea-hypopnoea index of 24, and he reported chronic sleep loss averaging 5 hours a night. "young-onset Parkinson's disease"
- 14 Mar 2020 — Optometry review for marked worsening of near symptoms, with double vision after five minutes of reading and inability to use a computer for more than 20 minutes. Near point of convergence 28 cm break, exophoria 18 prism dioptres at near and CISS 46. Base-in prism reading glasses were prescribed and he was medically downgraded from screen-based duties. "NPC 28 cm, CISS 46"
Symptoms
At onset the veteran had eye strain, blurred and doubled print at near, frontal headache after short periods of close work, losing his place when reading maps and screens, and difficulty concentrating on detailed tasks. After onset the symptoms became daily, worse in the evening and when tired, and limited his ability to work on targeting displays.
He now reports double vision within five minutes of reading, cannot use a computer or phone for more than 20 minutes without headache, avoids reading, and relies on base-in prism glasses. He has given up driving at night because of visual fatigue.
Imaging
- 02 Jun 2010 — CT head and cervical spine (role 2 facility): "No intracranial haemorrhage or fracture. No cervical spine fracture or malalignment."
- 05 Jun 2019 — Dopamine transporter SPECT: "Reduced tracer uptake in the left putamen more than the right, consistent with a presynaptic dopaminergic deficit."
- 28 Jun 2019 — MRI brain: "Two small foci of microhaemorrhage in the left frontal white matter consistent with previous traumatic brain injury. No structural lesion of the midbrain."
Onset Date
The most likely date of onset of this condition is 15 Jul 2010.
At that date the veteran was on warlike service in Afghanistan, working 10 to 12 hour shifts in a joint fires cell on digital targeting displays and imagery. He was six weeks past a mild traumatic brain injury and whiplash neck injury from an improvised explosive device strike on 02 June 2010, and had been taking amitriptyline 25 mg at night since 08 June 2010.
This date is appropriate because his pre-deployment optometry examination of 04 November 2009 recorded a near point of convergence of 6 cm and normal binocular vision, and he first presented with near diplopia and eye strain on 20 July 2010, reporting five days of symptoms. It falls within continuous full-time warlike service.
For the traumatic brain injury and neck injury causes, the 1 year before onset runs from 15 Jul 2009 to 15 Jul 2010 and contains the blast of 02 Jun 2010. For the blast overpressure cause, the 5 years before onset run from 15 Jul 2005 to 15 Jul 2010, during which he was present at more than 400 live-fire serials as an observer and at the gun line, including in Iraq in 2005 and Afghanistan in 2010. For the near-vision work cause, the 6 months before onset run from 15 Jan 2010 to 15 Jul 2010, during which he worked 8 to 12 hours a day on targeting screens in pre-deployment training and in Afghanistan. For the drug cause, the 1 month before onset runs from 15 Jun 2010 to 15 Jul 2010, during which he took amitriptyline nightly.
For the worsening causes, the period after onset runs from 15 Jul 2010 to the documented worsening on 14 Mar 2020, when the near point of convergence had receded from 16 cm to 28 cm and the CISS score had risen from 38 to 46. The second traumatic brain injury of 16 Aug 2018 and the Parkinson's disease diagnosed on 11 Jun 2019 preceded the worsening. The 6 months before the worsening run from 14 Sep 2019 to 14 Mar 2020, during which he worked 8 to 10 hours a day on screens in an intelligence staff role and continued amitriptyline, and he had obstructive sleep apnoea with chronic sleep loss throughout.
1. What is the formal diagnosis of the condition claimed above?
The formal diagnosis is Convergence Insufficiency (ICD-10 H51.1). No Statement of Principles has been determined for this condition, so it is assessed against the recognised causes on the sound medical-scientific evidence.
Convergence insufficiency is a binocular vision disorder in which the eyes cannot turn inwards and hold alignment adequately for near tasks. It is characterised by a receded near point of convergence, an exophoria that is larger at near than at distance and reduced positive fusional vergence. It causes eye strain, headache, blurred or doubled print, loss of place when reading and fatigue with close work. It is the most common visual disorder after concussion, and it also occurs with Parkinson's disease, after neck injury and with sustained near work and some medications.
The diagnosis followed a mild traumatic brain injury and whiplash neck injury in an improvised explosive device strike on warlike service, on a background of repeated blast exposure and long hours of close screen work. It began on 15 July 2010, was confirmed by an optometrist in November 2010, and worsened in 2020 after a second head injury and the onset of Parkinson's disease.
2. For each diagnosis identified, please also provide the following dates:
When did the veteran first experience symptoms attributable to this condition?
15 July 2010.
When did the veteran first present to a health / medical provider for this condition?
20 July 2010.
When was the condition confirmed / formally diagnosed?
30 November 2010.
When did the veteran first present to you (or your practice) for this condition?
22 May 2025.
3. How was this diagnosis confirmed? i.e. what were the key symptoms and signs, investigation results, specialist opinions?
The diagnosis was confirmed by an optometrist on 30 November 2010 on a formal binocular vision assessment: a near point of convergence of 16 cm break and 20 cm recovery (normal less than 6 to 10 cm), an exophoria of 10 prism dioptres at near and only 2 at distance, reduced positive fusional vergence at near failing Sheard's criterion, and a Convergence Insufficiency Symptom Survey score of 38 (symptomatic above 16). Visual acuity, refraction and ocular health were normal, so the symptoms were not due to refractive error or eye disease.
These findings meet the accepted clinical criteria for convergence insufficiency used in the Convergence Insufficiency Treatment Trial. The worsening was documented on 14 March 2020, with the near point of convergence receded to 28 cm, an exophoria of 18 prism dioptres at near and a CISS score of 46.
4. What do you consider to be the cause(s) of the condition in this veteran? Give consideration to constitutional and common risk factors, pre-existing injuries or diseases, and occupational or lifestyle risks, as well as direct causative mechanisms.
No Statement of Principles has been determined by the Repatriation Medical Authority for convergence insufficiency. The claim is therefore decided on the sound medical-scientific evidence of what causes and worsens the condition, without the limits a Statement of Principles would impose. The recognised causes below are drawn from the ophthalmic, optometric and neurological literature and are each applied to the veteran's service.
Legislation: the clinical onset of this condition was on 15 July 2010, after 1 July 2004, during continuous full-time warlike service in Afghanistan. This is a Military Rehabilitation and Compensation Act 2004 (MRCA) claim. The more generous reasonable hypothesis standard applies to the veteran's warlike service in Iraq in 2005 and Afghanistan in 2010, and the balance of probabilities standard to his peacetime service, including the 2018 head injury on exercise. Each cause must be related to the person's service. Under the beneficial approach required by the legislation, the absence of documentation does not mean that an event or exposure did not occur: lack of evidence is not evidence of lack.
Recognised causes on the medical-scientific evidence (no Statement of Principles)
Causative factors
Cause 1: sustaining a traumatic brain injury, including a mild traumatic brain injury or concussion, within the 1 year before the clinical onset of convergence insufficiency; — MET
- On 02 June 2010, during warlike service in Afghanistan, the veteran's vehicle struck an improvised explosive device. He was dazed and confused for about 15 minutes, with headache and nausea, and the role 2 facility diagnosed a mild traumatic brain injury with a MACE score of 22. This was six weeks before onset on 15 July 2010, within the 1 year window from 15 July 2009. Convergence insufficiency is the most frequent oculomotor disorder after concussion, reflecting injury to the brainstem and cortical pathways controlling vergence.
Cause 2: being exposed to blast overpressure from the firing of artillery, mortars or other heavy weapons, or from explosive detonations, on at least 100 occasions within the 5 years before the clinical onset of convergence insufficiency; — MET
- From 15 July 2005 to 15 July 2010 the veteran's training and operational records show more than 400 live-fire serials at the gun line and as a forward observer close to impacts, including warlike service in Iraq to 30 October 2005 and in Afghanistan from February 2010. Repeated low-level blast exposure is associated with subconcussive brain injury and oculomotor dysfunction, including receded convergence.
Cause 3: sustaining an acceleration-deceleration (whiplash) injury of the cervical spine within the 1 year before the clinical onset of convergence insufficiency; — MET
- In the same blast on 02 June 2010 the veteran sustained an acceleration-deceleration neck injury, with neck pain and cervical muscle spasm recorded at the role 2 facility. This was within the 1 year before onset. Cervical proprioceptive disturbance after whiplash is recognised to disrupt oculomotor control, and convergence insufficiency is common after whiplash.
Cause 4: performing sustained near-vision work, including work on computer screens, digital displays or optical instruments, for an average of at least 6 hours per day on more days than not for at least the 6 months before the clinical onset of convergence insufficiency; — MET
- From pre-deployment training in September 2009 and throughout warlike service in Afghanistan from 10 February 2010, the veteran worked 8 to 12 hours a day on digital targeting displays, laptops, imagery and maps. This covered the whole of the 6 months before onset, from 15 January 2010 to 15 July 2010, as his duty statement and pre-deployment optometry record confirm. Sustained near work places a prolonged demand on vergence and decompensates a marginal convergence reserve.
Cause 5: taking a drug with significant anticholinergic or sedative effects, including a tricyclic antidepressant, benzodiazepine or antipsychotic, for at least the 1 month before the clinical onset of convergence insufficiency; — MET
- The veteran took amitriptyline 25 mg at night from 08 June 2010, prescribed by a Defence medical officer for post-traumatic headache after the blast. He took it throughout the 1 month before onset, from 15 June 2010 to 15 July 2010. Tricyclic antidepressants impair accommodation through their anticholinergic action, which reduces accommodative convergence and is recognised to cause or unmask convergence insufficiency.
Worsening factors
Worsening 1: sustaining a further traumatic brain injury, including a mild traumatic brain injury or concussion, before the clinical worsening of convergence insufficiency; — MET
- On 16 August 2018, during a field exercise in Australia, the veteran fell from the rear deck of an armoured vehicle and struck his head, with brief loss of consciousness and about one hour of post-traumatic amnesia. A second mild traumatic brain injury was diagnosed. This preceded the documented worsening on 14 March 2020, when the near point of convergence had receded from 16 cm to 28 cm.
Worsening 2: having Parkinson's disease at the time of the clinical worsening of convergence insufficiency; — MET
- A neurologist diagnosed young-onset Parkinson's disease on 11 June 2019, confirmed by dopamine transporter imaging on 05 June 2019, and it was present at the worsening on 14 March 2020. Convergence insufficiency occurs in a large proportion of people with Parkinson's disease, and traumatic brain injury, which the veteran sustained twice in service, is a recognised risk factor for Parkinson's disease.
Worsening 3: performing sustained near-vision work, including work on computer screens, digital displays or optical instruments, for an average of at least 6 hours per day on more days than not for at least the 6 months before the clinical worsening of convergence insufficiency; — MET
- From 2018 the veteran worked in an intelligence staff role, analysing imagery and reports on screens for 8 to 10 hours a day. He did so throughout the 6 months before the worsening, from 14 September 2019 to 14 March 2020.
Worsening 4: taking a drug with significant anticholinergic or sedative effects, including a tricyclic antidepressant, benzodiazepine or antipsychotic, for at least the 1 month before the clinical worsening of convergence insufficiency; — MET
- Amitriptyline, increased to 50 mg at night in 2016 for persisting post-traumatic headache, was taken continuously throughout the 1 month before the worsening, from 14 February 2020 to 14 March 2020. Benztropine, an anticholinergic, was added for tremor in October 2019 and also continued through that month.
Worsening 5: having a sleep disorder causing chronic sleep deprivation, including insomnia disorder or obstructive sleep apnoea, at the time of the clinical worsening of convergence insufficiency; — MET
- Polysomnography in June 2019 showed moderate obstructive sleep apnoea with an apnoea-hypopnoea index of 24, and the veteran reported chronic sleep loss averaging 5 hours a night from shift work and post-traumatic headache. Both were present at the worsening on 14 March 2020. Fatigue reduces fusional vergence reserves and decompensates convergence insufficiency.
Worsening 6: inability to obtain appropriate clinical management for convergence insufficiency. — MET
- Office-based vergence therapy, the treatment with the strongest evidence for convergence insufficiency, was recommended by the optometrist on 30 November 2010 but was not funded through Defence health and was never provided. He continued long hours of screen work without prism correction or task modification until 2020, and the condition worsened. Under Brew v Repatriation Commission (1999) this is an inability to obtain appropriate clinical management.
The % contribution of the causes is 100% and significant.
Sequelae
The convergence insufficiency is a sequela of the veteran's accepted mild traumatic brain injuries and whiplash neck injury, and of the amitriptyline prescribed for his post-traumatic headache. It has in turn caused chronic visual headache and eye strain, contributed to his medical downgrading from screen-based duties in 2020 and limits his reading, computer use and night driving.
Unintended Consequence
Met. Amitriptyline was prescribed by Defence medical officers for post-traumatic headache from 08 June 2010, and benztropine by a Defence-arranged neurologist from October 2019. Their anticholinergic effects contributed to the onset and worsening of the convergence insufficiency. This is an unintended consequence of treatment provided by the Commonwealth while the veteran was serving (section 6A of the DRCA and the equivalent provisions of the MRCA).
Inability to Attain Appropriate Medical Management
MET. Office-based vergence therapy was recommended on 30 November 2010 but was not funded or provided through Defence health, and no prism correction, task modification or optometric review was arranged for almost ten years while he continued long hours of screen work. The near point of convergence receded from 16 cm to 28 cm and his symptom score rose from 38 to 46. Applying the objective and subjective tests in Brew v Repatriation Commission (Full Federal Court, 10 September 1999, Merkel J), the absence of the recommended treatment through service health channels amounts to an inability to obtain appropriate clinical management.
5. Please provide a Health Summary and a medication / prescribing history.
See attached report.
References
- 04 Nov 2009, Pre-deployment eye examination, Optometrist
- 02 Jun 2010, Emergency treatment record and CT report, Role 2 facility, Afghanistan
- 08 Jun 2010, Outpatient health record, Medical Officer, Role 1 health facility, Afghanistan
- 20 Jul 2010, Outpatient health record, Medical Officer, Role 1 health facility, Afghanistan
- 30 Nov 2010, Binocular vision assessment, Optometrist
- 16 Aug 2018, Emergency department record, Medical Officer, Garrison health centre
- 11 Jun 2019, Neurology consultation and dopamine transporter SPECT, Neurologist
- 21 Jun 2019, Diagnostic polysomnography report, Sleep physician
- 28 Jun 2019, MRI brain, Radiologist
- 14 Mar 2020, Binocular vision review, Optometrist
