Ophthalmologists of Iran-Tehran Noor Eye Hospital are able to assess axial length (The distance between the anterior and posterior poles of the eye ball) using advanced diagnostic techniques. In this section we briefly introduce these techniques.
1. A-scan / B-scan
- The A-scan technique is used to measure axial length and intraocular lens (IOL) power for cataract surgery .
- The B-scan technique is used to diagnose retinal detachment, vitreous haemorrhage, intraocular foreign body and also to examine the orbit. This technique is most commonly used to examine hidden posterior segment lesions, when ophthalmoscopy is not possible, mainly due to opacification of the transparent media (e.g., cataract or corneal edema).The ultrasound waves are used in this technique; the B-scan probe can be placed directly on the eye or on the eyelid after using anesthetic drops.
2. IOL Master
It is an advanced device that can measure the axial length and corneal curvature within one minute, no need to contact with the eye. Therefore, the use of this device does not have the dangers of the devices which requires to contact with the eye and also there is no need for anesthesia to use it.
It is used to calculate intraocula lens power for use in cataract surgery. This technique is usually a manual method for determining the lens number.