From the Guidelines
The Maddox rod is a valuable diagnostic tool in ophthalmology for assessing eye alignment and detecting strabismus, particularly in cases where precise measurement of torsion is necessary, as evidenced by its use in conjunction with other tests such as the Lancaster red-green test 1.
Key Points About the Maddox Rod
- It consists of a series of parallel cylindrical lenses that transform a point light source into a streak of light.
- When used, one eye sees a line instead of a point of light, while the other eye sees the normal point of light, helping to determine eye alignment.
- The position of the line relative to the point indicates if the eyes are properly aligned, with any offset suggesting misalignment.
- The Maddox rod works by dissociating the eyes' images, making fusion impossible and revealing the natural tendency of the eyes to deviate.
Clinical Use
- Commonly used in routine eye examinations to detect small deviations that might be compensated for during normal binocular vision.
- Particularly valuable in the assessment of adult strabismus, as part of a detailed sensorimotor examination that includes versions, ductions, saccades, pursuit, vergence, and near reflex 1.
- Helps in distinguishing restriction from paresis of the extraocular muscles, alongside other tests like forced duction and forced generation testing.
Recent Guidelines and Evidence
- The most recent guidelines from 2024 emphasize the importance of a thorough examination, including the use of tools like the Maddox rod for assessing eye alignment and detecting strabismus 1.
- These guidelines highlight the role of the Maddox rod in measuring torsion and determining the magnitude of misalignment in different gaze positions, which is crucial for planning surgical interventions in cases of strabismus.
From the Research
Overview of Maddox Rod
- The Maddox rod is a tool used in the assessment of strabismus, with its optics mechanism being revisited in recent studies 2.
- It is used to measure ocular alignment and cyclodeviation, with various methods of measurement available, including the simple Maddox rod, synoptophore, and synoptometer 3, 4.
Diagnostic Value of Maddox Rod Testing
- Subjectively quantified Maddox rod testing has been shown to improve diagnostic yield over alternate cover testing alone in patients with diplopia 5.
- Maddox rod testing may add clinically relevant diagnostic information to that obtained by alternate cover testing alone, helping to prevent missed diagnoses in the evaluation of patients with diplopia or suspected strabismus 5.
Comparison of Measurement Methods
- Different methods of measuring ocular torsion, including the Maddox rod, synoptophore, and Harm's tangent scale, have been compared in various studies 3, 4.
- The simple Maddox rod and synoptophore have been found to be less reliable than other methods, such as Harm's tangent scale, in measuring ocular torsion 3.
- The set of scaled Maddox rods has been shown to be a reliable method for measuring ocular torsion in primary position, while the dark red glass in front of the Harms tangent screen is suitable for measuring in secondary and tertiary positions 4.
Treatment of Strabismus
- Botulinum toxin has been used as a treatment modality for strabismus, with its efficacy compared to other treatment options, such as surgery, in various studies 6.
- Low-certainty evidence suggests that strabismus surgery may be preferable to botulinum toxin injection to improve or correct strabismus, although the evidence is unclear for certain types of strabismus 6.