Sankara Nethralaya
Sankara Nethralaya
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Digital Biometry


To determine the power of the intraocular lens (IOL) to be implanted in patients undergoing cataract surgery.
It involves measurement of the axial length (the distance between the anterior and posterior part of the eye) and the corneal curvature (curvature of the black portion of the eye ball) of the eye.
Test is done in both the eyes.
Generally corneal curvature is measured first using an instrument called keratometer.
The patient needs to fixate steadily centrally as instructed by the examiner and the readings are obtained. he eye.
This is a non contact procedure.
A Scan:
Axial length is measured using ultrasound A scan
A drop of local anesthesia is instilled on to the eye
The patient is asked to fixate centrally
Examiner gently places a probe on the eye
Ultrasound waves are sent to the eye through the probe
The axial length readings are displayed on to a screen.
The examiner selects the appropriate reading
IOL power calculations are then done accordingly
Axial length measurements are also done in few other cases like
High myopia (high minus powered glasses)
Anisometropia (difference in spectacle power between both the eyes)
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