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Anomalies of Accommodation

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1. Presbyopia

• With increasing age, the crystalline lens gradually loses its elasticity (sclerosis of the lens nucleus and cortex)
• The ciliary muscle may also weaken
• When the ciliary muscle contracts, the zonular tension is released, but the hardened lens can no longer change its curvature sufficiently
• The amplitude of accommodation therefore progressively decreases

• At 10 years: ~7 cm (amplitude ~14 D)
• At 20 years: ~8 cm (amplitude ~12 D)
• At 40 years: ~22 cm (amplitude ~4.5 D)
• At 50 years: ~46 cm (amplitude ~2 D)
• At 60 years: ~100 cm or beyond (amplitude ~1 D)

• Difficulty reading fine print at normal reading distance (~35 cm)
• Holding reading material farther away for clarity
• Asthenopia (eye strain, headaches) on near work
• Need for brighter illumination
• Symptoms are worse in dim light (pupil dilates, reducing depth of focus)

• Near point of accommodation (NPA) recedes beyond 25 cm; when too far away for comfortable reading, presbyopia is present
• Measured with the RAF rule

• Convex (plus) lenses for reading - the most common correction
• The add power required: +1.00 D at age 40, increasing by approximately +0.50 D every 5 years, reaching +2.50 to +3.00 D at age 60
• Multifocal spectacles: Bifocals, trifocals, progressive addition lenses
• Contact lenses: Bifocal or monovision correction
• Surgical options:
  • Lens extraction with multifocal/accommodating IOL implantation
  • Monovision (one eye for distance, one for near)
  • PresbyLASIK (laser corneal multifocality)
  • Corneal inlays (refractive, reshaping, or small aperture types)
  • Conductive keratoplasty
  • Scleral expansion surgery (results inconsistent)

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2. Insufficiency of Accommodation

• Debilitating systemic illness (typhoid, influenza, anaemia)
• Neurological disorders affecting the Edinger-Westphal nucleus
• Convergence insufficiency (commonly associated)
• Psychogenic/functional
• Following head injury
• Drugs (e.g., sedatives, tranquilizers)

• Blurred near vision
• Asthenopia (headache, eye strain, difficulty reading)
• Print "swimming" or going in and out of focus

• Reduced amplitude of accommodation for age
• NPA farther than expected
• May be associated with convergence insufficiency

• Treat underlying cause
• Plus lenses for near work
• Accommodative exercises (push-up exercises)
• Cyclosporine eye drops in some cases

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3. Spasm of Accommodation (Ciliary Spasm / Pseudomyopia)

• Reflex spasm - due to uncorrected hypermetropia (the most common cause) - the eye over-accommodates continuously to overcome the hypermetropia
• Miotic drugs - pilocarpine, carbachol, anticholinesterases; these directly cause ciliary muscle spasm
• Spasm of the near reflex (psychogenic) - characterized by the triad of excess accommodation + excess convergence + miosis; this functional condition may mimic bilateral sixth nerve palsy

• Blurred distance vision (pseudomyopia)
• Aching, tired eyes
• Headaches
• Diplopia or blurred vision in spasm of the near reflex
• Symptoms fluctuate (unlike true myopia)

• Apparently increased myopia or newly acquired myopia in young hyperopes
• Marked variation in refraction at different sittings
• In spasm of the near reflex: excess convergence, miosis, and pseudoabducens palsy

• Cycloplegic refraction (using atropine) reveals the true refractive error; the apparent myopia disappears on cycloplegia, confirming pseudomyopia

• Correct underlying hypermetropia with appropriate spectacles
• Cycloplegic drops (atropine, cyclopentolate) to relax the ciliary muscle
• Discontinue offending miotics if drug-induced
• Psychogenic cases: reassurance, low-dose cycloplegics, occasionally psychiatric referral

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4. Paralysis of Accommodation (Cycloplegia)

• Pharmacological (most common): Anticholinergic agents - atropine, cyclopentolate, homatropine, tropicamide; these block muscarinic receptors in the ciliary muscle
• Third (oculomotor) nerve palsy: Interruption of parasympathetic fibers; accompanied by ptosis, mydriasis (iridoplegia), and ophthalmoplegia
• Ciliary ganglion lesions: Damage from trauma, orbital apex syndrome, viral infections
• Diphtheria: Post-diphtheritic paralysis - paralysis of accommodation may be an early and prominent feature (palate paralysis also common); due to exotoxin affecting the ciliary ganglion
• Botulinum toxin: Blocks acetylcholine release
• Systemic drugs: Antipsychotics, tricyclic antidepressants, antihistamines (anticholinergic side effects)
• Encephalitis, meningitis, syphilis
• Trauma (direct injury to ciliary body or nerve)

• Blurred near vision (inability to read)
• In unilateral cases, near vision is affected in the involved eye
• If the pupil is also dilated: photophobia, glare

• Absent or reduced near point (NPA recedes to infinity in complete cycloplegia)
• Mydriasis if associated iridoplegia
• In 3rd nerve palsy: ptosis, divergent strabismus, ophthalmoplegia + fixed dilated pupil

• Treat underlying cause
• Reading glasses for near vision
• Pilocarpine to reverse pharmacological cycloplegia (in cases without pathology)
• Diphtheria: antitoxin and appropriate antibiotics; accommodation usually recovers

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5. Inequality of Accommodation (Anisoaccommmodation)

• Unilateral cycloplegia (drug-induced or pathological)
• Unilateral third nerve palsy
• Unilateral iridocyclitis
• Following trauma to one eye

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6. Ill-Sustained Accommodation

• Debility, convalescence after illness
• Associated with convergence insufficiency
• Psychogenic

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Summary Table

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1. Presbyopia = physiological, inevitable, begins ~40 yrs - corrected with convex (+) lenses
2. Spasm = pseudomyopia - diagnosis confirmed by cycloplegic refraction showing less myopia
3. Paralysis = cycloplegia - commonest causes: atropine, 3rd CN palsy, diphtheria
4. Diphtheria causes post-infective accommodation paralysis even after the acute illness (palate + ciliary ganglion involvement)
5. Amplitude of accommodation = far point (metres) - near point (metres) expressed in dioptres

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Anomalies of Accommodation - with Classification

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Classification

Duke-Elder's Classification (1963) - Most Widely Used

Anomalies of Accommodation
├── A. Excessive Accommodation
│   └── Spasm of Accommodation
│
└── B. Deficient / Diminished Accommodation
    ├── 1. Insufficiency of Accommodation
    ├── 2. Ill-Sustained Accommodation (Accommodative Fatigue)
    ├── 3. Inertia of Accommodation (Accommodative Infacility)
    └── 4. Paralysis of Accommodation (Cycloplegia)

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Duane's Classification (1915) - Also Referenced

Duane's classification includes inequality of accommodation as a separate category. Duke-Elder replaced "excessive accommodation" with the more specific "spasm of accommodation" and omitted inequality.

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Simplified Classification for Clinical Use

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Detailed Description of Each Anomaly

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A. SPASM OF ACCOMMODATION (Excessive Accommodation)

1. Reflex spasm - due to uncorrected hypermetropia; the most common type
2. Drug-induced spasm - miotics (pilocarpine, carbachol, anticholinesterases)
3. Spasm of the near reflex (psychogenic/functional) - triad of:
   • Excess accommodation
   • Excess convergence
   • Miosis
   • Mimics bilateral 6th nerve palsy (pseudoabducens palsy)

• Blurred distance vision (pseudomyopia)
• Fluctuating vision
• Frontal headache, aching eyes
• Micropsia (objects appear smaller)
• Diplopia in spasm of near reflex

• Apparent myopia or increase in existing myopia
• Near vision often normal or even supernormal
• Cycloplegic refraction reveals true refractive error (less myopia or frank hypermetropia)
• In near reflex spasm: convergence + miosis + pseudoabducens

• Correct underlying hypermetropia
• Cycloplegic drops (atropine 1%, cyclopentolate 1%) to break the spasm
• Withdraw offending miotic drugs
• Psychogenic cases: reassurance, low-dose cycloplegics, psychiatric support

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B. INSUFFICIENCY OF ACCOMMODATION

• Debilitating systemic illness (typhoid, malaria, influenza, anaemia)
• Neurological: lesions of Edinger-Westphal nucleus
• Post-head injury
• Associated convergence insufficiency (very common)
• Psychogenic / functional
• Drugs: sedatives, phenothiazines, benzodiazepines

• Blurred near vision
• Asthenopia: headache, eyestrain, browache after near work
• Print running together, going in/out of focus
• Difficulty sustaining near tasks

• NPA farther than normal for age
• Reduced amplitude of accommodation on RAF rule testing
• Often associated with reduced NPC (convergence insufficiency)

• Treat underlying systemic cause
• Plus (convex) lenses for near work
• Accommodative exercises (push-up / Brock string exercises)
• General health improvement

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C. ILL-SUSTAINED ACCOMMODATION (Accommodative Fatigue)

• Convalescence/debility
• Associated with convergence insufficiency
• Psychogenic states
• Prolonged close work (digital eye strain)

• Vision is initially clear for near work
• Blurring develops progressively during near tasks
• Words "swim" or run together after reading for some time
• Temporary relief on resting the eyes
• Asthenopia after prolonged near tasks

• Normal NPA initially
• NPA recedes on repeated testing (fatigue evident)

• Rest from near work
• General health measures
• Accommodative exercises
• Tinted lenses or low-power reading add in severe cases

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D. INERTIA OF ACCOMMODATION (Accommodative Infacility)

• Debility, fatigue
• Ageing (early changes before presbyopia)
• Neurological (subcortical disorders)
• Psychogenic

• Blurring when shifting gaze from near to far or far to near (e.g., copying from a blackboard to a notebook)
• Delayed focusing when changing fixation distances
• Asthenopia

• Normal amplitude
• Reduced accommodative facility (tested with ±2.00 D flippers - patient reads a near chart while rapidly alternating +2.00 and -2.00 D lenses; normal is ≥11 cycles/minute)

• Accommodative facility exercises (flipper exercises)
• Address underlying cause

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E. PARALYSIS OF ACCOMMODATION (Cycloplegia)

• Sudden or gradual inability to read or do close work
• Hyperopes are more severely symptomatic than myopes
• Photophobia if mydriasis coexists

• NPA recedes to infinity (complete cycloplegia)
• Mydriasis (if iridoplegia coexists - as in CN III palsy or atropine)
• In CN III palsy: ptosis, divergent strabismus, ophthalmoplegia

• Identify and treat underlying cause
• Convex reading glasses for near vision
• Pilocarpine to reverse atropine-induced pharmacological cycloplegia (if needed)
• In diphtheria: antitoxin, antibiotics; accommodation usually recovers with time

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F. INEQUALITY OF ACCOMMODATION (Duane's Classification)

• Unilateral CN III palsy
• Unilateral drug effect (single-eye miotic or cycloplegic instillation)
• Unilateral iridocyclitis
• Unilateral trauma to the ciliary body

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G. PRESBYOPIA (Physiological Diminution of Accommodation)

• Lens fibres are laid down throughout life; older fibres are compressed into the nucleus
• The lens nucleus becomes progressively harder and less deformable
• Ciliary muscle contraction can no longer change lens shape sufficiently
• Loss of lens elasticity is the primary cause (Helmholtz theory)

• Difficulty reading fine print at normal reading distance (~33-35 cm), usually noted from age 40-45 years
• Tendency to hold reading material farther away
• Need for brighter illumination for near tasks
• Headache and asthenopia on sustained near work
• Symptoms worse in dim light (pupil dilates, reducing depth of focus)

• Convex (plus) reading glasses - mainstay of treatment

• Multifocal spectacles: Bifocals, trifocals, progressive addition lenses (PALs)
• Contact lenses: Bifocal CLs, monovision CL correction
• Surgical:
  • Multifocal / accommodating / extended depth-of-focus IOL implantation
  • Monovision (one eye corrected for distance, fellow for near)
  • PresbyLASIK (corneal multifocality)
  • Corneal inlays (small aperture, refractive, or reshaping type)
  • Conductive keratoplasty

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Quick Revision Summary

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Anomalies of Accommodation

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Definition of Accommodation

• It is an active, dynamic, involuntary reflex mediated by the parasympathetic nervous system
• The near reflex triad consists of: Accommodation + Convergence + Miosis
• Mechanism (Helmholtz theory): When the ciliary muscle contracts, zonular tension is released → the elastic lens becomes more convex → refracting power increases → near objects are focused

• Near Point of Accommodation (NPA): The nearest point at which the eye can maintain clear focus
• Far Point: The farthest point at which the eye can focus without accommodation
• Amplitude of Accommodation: The difference between the far point and near point, expressed in dioptres

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Definition of Anomalies of Accommodation

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Classification (Duke-Elder, 1963) - Most Widely Used

ANOMALIES OF ACCOMMODATION
│
├── 1. EXCESSIVE ACCOMMODATION
│       └── Spasm of Accommodation
│
└── 2. DEFICIENT / DIMINISHED ACCOMMODATION
        ├── (a) Physiological  → Presbyopia
        │
        ├── (b) Pathological - Quantitative
        │       ├── Insufficiency of Accommodation
        │       └── Paralysis of Accommodation (Cycloplegia)
        │
        └── (c) Pathological - Qualitative
                ├── Ill-Sustained Accommodation (Accommodative Fatigue)
                └── Inertia of Accommodation (Accommodative Infacility)

• Inequality of Accommodation (unequal accommodation between the two eyes)

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1. SPASM OF ACCOMMODATION

• Blurred distance vision (pseudomyopia)
• Fluctuating vision
• Frontal headache, aching eyes
• Micropsia (objects appear smaller)
• Diplopia (in spasm of near reflex)

• Apparent myopia; cycloplegic refraction reveals less myopia or frank hypermetropia
• In near reflex spasm: convergence + miosis + pseudoabducens palsy (mimics bilateral 6th nerve palsy)

• Correct the underlying hypermetropia
• Cycloplegic drops (atropine 1%, cyclopentolate 1%) to break the spasm
• Withdraw offending miotic drugs if drug-induced
• Psychogenic cases: reassurance ± low-dose cycloplegics ± psychiatric referral

---

2. INSUFFICIENCY OF ACCOMMODATION

• Debilitating systemic illness - typhoid, malaria, influenza, anaemia
• Neurological lesions affecting the Edinger-Westphal nucleus
• Post-head injury
• Associated convergence insufficiency (very common)
• Psychogenic / functional
• Drugs: sedatives, phenothiazines, benzodiazepines

• Blurred near vision from the outset
• Asthenopia: headache, eyestrain, browache after near work
• Print running together or going in and out of focus

• NPA farther than normal for age (reduced amplitude from the start)
• Often associated with reduced NPC (convergence insufficiency)

• Treat underlying systemic cause
• Plus (convex) lenses for near work
• Accommodative exercises (push-up exercises, Brock string)
• General health improvement

---

3. ILL-SUSTAINED ACCOMMODATION (Accommodative Fatigue)

• Convalescence / general debility
• Associated convergence insufficiency
• Prolonged close work (digital eye strain / VDT use)
• Psychogenic states

• Vision is clear initially for near work
• Blurring develops progressively during near tasks
• Words "swim" or run together after reading for some time
• Temporary relief on resting the eyes
• Asthenopia that worsens as the day goes on

• Regular rest periods during near work
• General health measures
• Accommodative exercises
• Low-power reading addition in severe or refractory cases

---

4. INERTIA OF ACCOMMODATION (Accommodative Infacility)

• Debility and fatigue
• Early ageing changes (before frank presbyopia)
• Neurological disorders (subcortical)
• Psychogenic

• Blurring when shifting gaze from near to far or far to near (e.g., copying from blackboard to notebook)
• Delayed, effortful focusing when changing fixation distance
• Asthenopia on tasks requiring rapid distance changes

• Accommodative facility testing with ±2.00 D flippers: the patient reads a near chart while alternating +2.00 D and -2.00 D lenses; normal is ≥11 cycles/minute; reduced in inertia

• Accommodative facility exercises (flipper training)
• Address underlying cause

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5. PARALYSIS OF ACCOMMODATION (Cycloplegia)

• Sudden or gradual inability to read or do near work
• Hyperopes are more severely symptomatic (they rely on accommodation even for distance)
• Photophobia and glare if mydriasis coexists

• NPA recedes to infinity in complete cycloplegia
• Mydriasis if iridoplegia coexists (as in CN III palsy or atropine)
• In CN III palsy: ptosis + divergent strabismus + ophthalmoplegia + fixed dilated pupil

• Identify and treat underlying cause
• Convex (plus) reading glasses for near work
• Pilocarpine to reverse pharmacological (atropine-induced) cycloplegia if required
• Diphtheria: antitoxin + antibiotics; accommodation usually recovers with time

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6. INEQUALITY OF ACCOMMODATION (Duane's Classification)

• Unilateral CN III palsy
• Unilateral pharmacological effect (single-eye miotic or cycloplegic instillation)
• Unilateral iridocyclitis
• Unilateral ocular trauma (damage to ciliary body)

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7. PRESBYOPIA (Physiological Diminution of Accommodation)

• It is not a disease but a normal ageing process
• Becomes symptomatic when the near point recedes beyond ~25 cm (usually around age 40-45 years)

• Lens fibres are laid down throughout life; older fibres are compressed into the nucleus
• The nucleus becomes progressively harder and less deformable (nuclear sclerosis)
• Ciliary muscle contraction can no longer change lens shape sufficiently
• Result: inability to increase the refracting power of the eye for near objects

• Difficulty reading fine print at normal distance (~33-35 cm), from around age 40
• Tendency to hold reading material at arm's length
• Need for brighter illumination for near tasks
• Headache and asthenopia on sustained near work
• Symptoms worse in dim light (pupil dilates → depth of focus decreases)

• Reading (single vision) spectacles
• Bifocal spectacles (upper segment: distance; lower: near)
• Trifocal spectacles (distance + intermediate + near)
• Progressive addition lenses (PALs) - seamless transition

• Lens extraction with multifocal IOL / accommodating IOL / extended depth-of-focus IOL
• Monovision - one eye for distance, fellow eye for near (spectacle or IOL-based)
• PresbyLASIK - laser corneal multifocality
• Corneal inlays - small aperture (e.g., KAMRA), refractive, or reshaping types
• Conductive keratoplasty (CK)

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Master Summary Table