Section 1
THE VARIOUS LAYERS OF THE LENS
- Anterior and posterior capsule with subcapsular epithelium
- Cortex
- Epinucleus
- Nucleus
To study all the layers a good slit-lamp biomicroscopy has to be done with a well dilated pupil. This helps us to assess the type of cataract and to grade the hardness of the nucleus.
Cornea
The peripheral corneal and limbal anatomy has to be understood before going into the surgical procedure
- Anterior limbus is the attachment of conjunctiva and Tenon's to the cornea
- Mid limbus is behind the blue line. It is important as the Descemets ends there
- Posterior limbus lies 1mm behind the mid limbus
- Care should be taken to prevent damage to the Descemets membrane while making the internal incision. The incision should be either anterior or posterior to its insertion. After making incision care should be taken while introducing the instruments into the eye. Phacotip and IOLs should not cause detachment of the Descemets membrane while introducing into the anterior chamber. Internal incision should be at least 1mm in the clear cornea to create a good valvular effect.
Corneal endothelium
Specular microscopy–normal count should be 1000 to 3500 cells/cubic mm. If cell count falls below 500/ cubic mm, post-operative corneal edema occurs. Endothelium has no capacity to regenerate hence it is important to minimize damage to the endothelial cells during surgical maneuvers.