Bagolini striated lens test is a subjective clinical exam aimed at detecting the degree of binocular functions. An eye surgeon usually performs the test, which mainly happens in strabismus clinics.
The test detects several conditions such as; microtropia, diplopia, and suppression. However, to come to a diagnosis, the test should incorporate other clinical exams, including the Maddox rod, prism cover test, Worth's 4 dot test, and cover tests.
Necessary resources for the procedure are bagolini striated glasses and a penlight or a distant light source. Alternatively, the eye specialist can use trial frames and lenses or a lorgnette.
The test is used to examine the presence of eye suppression and the nature of the retinal correspondence on strabismus patients.
Compared to Worth's 4 dot test or the synoptophore, the bagolini striated lens test frequently notes a harmonious abnormal retinal correspondence. It can also be used to measure cyclotropia.
Bagolini striated lens test happens under standard lighting. The test can employ one of two approaches that include:
- Placing the bagolini striated lens in trial frames
- Setting up the bagolini lenses in reversible lorgnette frames and then putting them over the patient's glasses.
The doctor then directs light to the bridge between the bagolini lenses, usually the patient's nose. The distance between the light and the patient is (6m) for distant light or (33cm) for near light. However, close tests are the most common.
With the aid of a series of questions, the examiner then asks the patient to describe what they see. The guiding questions consider the following:
- The number of lights
- Number of lines
- Whether the lines cross
- Whether the two lines are visible at the same time
- The occurrence of an intersection through the light
- Presence or absence of gaps in the lines
- Position of the lines
The examiner then records the results by marking a cross.
The test results would confirm the presence or extent of eye suppression, retinal correspondence, microtropia, diplopia, and deviations. The results would be a cross with a light at the two lines' intersection point for a patient with normal binocular functions.
The patient may see only one line, indicating suppression or two lines, which means no suppression. Some may also report seeing one light signaling image fusion or suppression or two lights that may signify diplopia. Despite having an image from each eye, diplopic patients are unable to fuse them.
For alternating deviation, the patient may report seeing one line that keeps shifting from one eye to another. In the case a patient sees a breaking line, it is indicative of a scotoma on the retina.
Microtropic patients would see one light and two lines, one of which has a small break in it due to foveal suppression. The outcome for unsuppressed esotropic patients would be uncrossed images consisting of two lights with one line through each light.
The observation would be two lights with one line through each light for patients with unsuppressed exotropia. As opposed to unsuppressed esotropia, there is crossing of images in unsuppressed exotropia.
In the case of a patient with an uncompressed vertical deviation, the outcome would be one line appearing higher than the other. A higher image vision in one eye, as compared to the other, indicates a lower visual axis in that eye.
Patients may also see two lines with only one of the lines crossing through the fixation light, denoting inharmonious abnormal retinal correspondence. If a patient has a known deviation, but the results interpret a normal binocular function, it proves harmonious anomalous retinal correspondence.
Risks & Complications
The following risks may occur:
- Extraneous light sources may confuse the patient during testing, resulting in possible inaccuracies.
- There may be inaccuracies in the case that miscommunication between the examiner and the patient occurs.
- Interference with the perception of the second stripe due to extensive suppression.