2.0 convergence insufficiency b


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  • Meter angle (MA)
    The amount of convergence required for each eye to fixate an object located at a distance from the eyes in the median plane
  • "Convergence insufficiency (CI) is a common binocular vision disorder that is often associated with a variety of symptoms, including eyestrain, headaches, blurred vision, diplopia [double vision], sleepiness, difficulty concentrating, movement of print while reading, and loss of comprehension after short periods of reading or performing close activities." 
  • therefore, it is of considerable clinical significance
    aggravated by lack of sleep, reduction of general well-being, and anxiety.
  • Characteristically one eye will be closed or closed while reading to obtain relief from visual fatigue
  • Pupil dilatation may be observed at this stage, which is an additional indicator of convergence failure
  • 2.0 convergence insufficiency b

    1. 1. Convergence Disjugate simultaneous and synchronous inward rotation of both eye which results from co- contraction of the two medial rectus muscles Allows bifoveal single vision maintained at near fixation distance Does not deteriorate with age Can be improved by exercises
    2. 2. Unit of measurement Clinical measurement – Prism Diopter The amount of convergence is calculated by using the formula: 1/d × IPD where d is the distance and IPD is interpupillary distance. Thus, a 6-cm IPD requires 6 dioptres of convergence for a fixation distance of 1 m.
    3. 3. Types Voluntary convergence Tonic convergence Accommodative Convergence Fusional convergence Proximal convergence
    4. 4. Contd.. 1.Tonic due to the tone of the extraocular muscles initiating movement from the anatomical position of rest 2. Accommodative which is initiated by the stimulus of accommodation.
    5. 5. Contd.. 3. Fusional which is initiated by a fusional stimulus. an involuntary vergence movement to maintain BSV 4. Proximal induced by the awareness of a near object
    6. 6. One-third of convergence relates to tonic, fusional and proximal convergence. Two-thirds is accommodative NPC value is greater than 10 cm
    7. 7. Convergence insufficiency Inability of eyes to obtain or maintain adequate binocular convergence Most common cause of ocular asthenopic symptoms.
    8. 8. First described by von Graefe in 1855 and later elaborated by Duane one of the most common causes of ocular discomfort most common cause of muscular asthenopia
    9. 9. Clinical signs of CI 1) Exophoria greater at near than at distance(N>D) 2) A receded near point of convergence 3) Reduced positive fusional vergence at near 4) Low AC/A ratio 5) Little or no lag of accommodation
    10. 10. Symptoms due to muscular fatigue Eye strain and sensation of tension around globe. Headache and eye ache after intense near work and relieved when eyes are closed Difficulty in changing focus from distance to near objects Itching, burning and soreness of eyes and even hyperemia of nasal half of the conjunctiva
    11. 11. Symptoms due to failure to maintain BSV Blurred vision and crowding of words while reading Intermittent crossed diplopia for near under the condition of fatigue If untreated, in some cases, convergence insufficiency can lead to an outward eye turn that comes and goes intermittent exotropia
    12. 12. Less common complaints Nausea motion sickness Dizziness panoramic headaches gritty sensation in the eyes general fatigue
    13. 13. Aetiology of CI Primary or idiopathic: In many cases, exact etiology is not known. May be associate with: Wide IPD Delayed or inadequate functional development General debility Psychological instability Over work or worry
    14. 14. Refractive Associated with uncorrected high hyperopia and myopia High hyperopes (>5D) usually make no effort to accommodate and there is deficient accommodative convergence. Myopes may not need accommodation and thus lack accommodative convergence.
    15. 15. Muscular imbalances Exophoria IXT Vertical muscle imbalances Consecutive convergence insufficiency : May occur following either recession of medial recti or resection of lateral rectus
    16. 16. General physical causes diseases of endocrine gland (e.g. Mobius’ sign in thyroid ophthalmopathy). Psychological causes. include anxiety and neurosis
    17. 17. Clinical features Clinical problem in patient who does intense near work. Children with increased school work. Desk workers Computer users Discomfort usually occurs at the end of the day.
    18. 18. Assessment of NPC The near point of convergence is assessed objectively using either a fixation target or the fixation target on the RAF rule
    19. 19. Assessment of PFV Base out motor fusion range is measured to find out blur, break and recovery N: 21/30/18 D: 8/10/6
    20. 20. Prism Cover test Assess Latent ocular deviation such as exophoria at distance and near Near exophoria greater than distance exophoria Near exophoria distance orthophoria Vertical imbalances Intermittent exotropia
    21. 21. Diagnosis of CI Type I: NPC receded or Decreased PFV Type II: NPC receded or PFV decreased and XP N> XP D Type III: All the clinical signs present
    22. 22. Treatment Optical: Proper refractive correction for any presence of ametropia Myopes given full correction and hyperopes under corrected to stimulate accommodation
    23. 23. Treatment Three approaches Relieving symptoms Base in prism Plus reading glasses Divergence exercises Improving convergence Brock string Aperture rule trainer Pencil push ups Increase amplitude of fusional convergence BI/BO prism flipper Synoptophore Exercise Physiological diplopia exercise using stereogram Diploscope
    24. 24. Training of voluntary convergence Prism therapy: Base –in prism reading glasses or bifocals with prism in the lower segment are useful as relieving prism Relieving prisms and bifocals should be prescribed cautiously in young age
    25. 25. Surgical treatment As a last resort, when all other measures fail. When it is associated with large exophoria at near. Medial muscle resection can be performed in one or both eyes.
    26. 26. THANK YOU!!