Therefore, with the inside-out staged concept, cataract surgery is performed with the goal of arranging the inner optics of the eye to result in a final optical endpoint that appropriately presents the cornea as a vision rehabilitative platform for correction by laser vision surgery. Therefore, the internal surgery is performed first (cataract surgery) followed by external corneal surgery. This obtains the best vision potential and designed refractive endpoint for each eye.
For example, in a patient who has undergone RK, cataract surgery can be performed with the goal of achieving hyperopia (in very flat corneas) and followed with laser PRK to steepen the cornea and improve the optical status.
In some cases of steep corneas, flattening of the cornea may be the optimal endpoint and hence cataract surgery could be designed for myopic endpoint accordingly.
This inside-out approach also can be used in cases with a corneal scar to first result in myopic astigmatism from cataract surgery and then followed by laser in PRK mode (Corneoplastique), to both repair the scar and achieve a clearer cornea and reach emmetropia.
Conversely, the outside-in approach can be used in patients in whom the corneal status prevents accurate IOL calculation or when the corneal status is a hindrance to safe, planned cataract surgery. These poorly measureable or scarred corneas need to be corrected (Corneoplastique as described in previous columns) with various modalities, such as Intacs (Addition Technology)/amniotic graft/lamellar graft/laser Corneoplastique, etc., and then with this measureable cornea, we proceed to the final internal IOL placement (cataract surgery) toward emmetropia.