Overview
This lecture covers different anomalies of accommodation in the eye, focusing on types, causes, clinical features, diagnostic tests, and treatments.
Types of Accommodation Anomalies
- Anomalies are classified into excessive (e.g., spasm) and diminished/deficient accommodation.
- Diminished accommodation includes physiological (e.g., presbyopia), pharmacological (e.g., cycloplegia from drugs), and pathological causes.
Pathological Decreased Accommodation
- Four main types: insufficiency, ill-sustained, inertia, and paralysis of accommodation.
Accommodative Insufficiency
- Accommodative power is less than normal for age (not age-appropriate as in presbyopia).
- Causes: premature lens sclerosis, systemic illnesses (anemia, diabetes, malnutrition), stress, certain ocular diseases, or increased intraocular pressure.
- Symptoms: difficulty with near vision, eye strain, headaches, intermittent diplopia, heaviness of eyelids.
- Test findings: low amplitude, receded near point, lag of accommodation, high NRA, low PRA, difficulty clearing minus lenses.
- Treatment: address systemic causes, appropriate refractive correction, prescribe weakest necessary plus lenses for near work, accommodative exercises.
Ill-Sustained Accommodation
- Normal amplitude initially, fatigues quickly with prolonged near work.
- Symptoms: blurred vision after near work, difficulty with minus lenses, reduced facility.
- Test: accommodative facility test shows quick fatigue.
- Treatment: plus lenses for near, exercises (flipper lens, heart chart), visual hygiene (breaks, good lighting).
Accommodative Inertia
- Delayed shift in focus between near and distant objects (slow response).
- Treatment: correct refractive errors, accommodative facility exercises.
Accommodative Paralysis
- Complete loss of accommodation due to neurological, pharmacological, or pathological causes.
- Causes: congenital anomalies, cycloplegic drugs, systemic/ocular diseases, cranial nerve III lesions.
- Symptoms: inability to accommodate for near vision.
- Treatment: discontinue causative drugs, symptomatic relief (dark glasses, plus lenses), bifocal/progressive lenses if needed.
Key Terms & Definitions
- Accommodation — The eye's ability to change focus from distant to near objects.
- NRA (Negative Relative Accommodation) — Measurement indicating the ability to relax accommodation, tested with plus lenses.
- PRA (Positive Relative Accommodation) — Measurement of the ability to stimulate accommodation, tested with minus lenses.
- Accommodative Facility Test — Examines how quickly and accurately the eye can change focus.
- Flipper Lens Exercise — Alternating plus/minus lenses to improve accommodative facility.
- Heart Chart Exercise — Alternating focus between near and distant reading charts to enhance accommodation.
Action Items / Next Steps
- Practice accommodative exercises (flipper lens, push-up, heart chart).
- Apply the 20-20-20 rule (break every 20 minutes, look 20 feet away for 20 seconds).
- Ensure appropriate lighting and ergonomic positioning during near tasks.
- For exam prep, review test findings and differences between types of accommodation anomalies.