He sees the advantages particularly in the high safety of these methods because no preparation of a corneal flap takes place, thus no enduring weakening of the cornea: “The treatments are in nearly every case painless. Quality of vision is restored within 10 days and remains stable over the long-term.“ In the following Dr. Camellin outlines his techniques and treatment ranges.
In myopia, a central residual corneal thickness of at least 350µm including the epithelium must be considered. The postoperative corneal curvature should be ≥ 32 D to ensure achievement of good vision quality.
The optical zone should normally be at least 7 mm and correspond with the mesopic pupil diameter; I never go below 6.5 mm. In hyperopia, an optical zone of 7.5 mm is preferred in order to minimize the risk of regression and possible halos at night. I never go below 7 mm. When necessary I protect the hinge with a spatula.
Additionally, the postoperative corneal curvature should be around 49 D, on the other side pay attention to preoperative very flat corneas (i.e. 40-42 D), because there might be a bad peripheral transition in case of high corrections (i.e. a significant step).
I use corneal wavefront for hyperopia in combination with astigmatism in cases where the pupil centre differs more than 0.5 mm from the centre of the astigmatism (= corneal vertex). In this way, results and centration are improved. I also use corneal wavefront for all retreatments in order to eliminate higher order aberrations.
TransPRK in combination with corneal wavefront is my treatment of choice for retreatments after a radial keratectomy or transplants. I also use it for haze, scarred corneal tissue and for keratoconus after crosslinking. In keratoconus, I aim at minimizing the ablation of tissue and smoothing the existing astigmatism.
This method makes sense in all cases where a difficult epithelial flap is expected or where the epithelium covers corneal irregularities of the stromal tissue.
Autoserum is used in all cases in the first five postoperative days. Mitomycin C is diluted and applied with a merocel sponge:
- 0.02 % in TransPRK and retreatments over a time period of two minutes.
- 0.01 % for hyperopia and astigmatism more than 2 D (just a brushstroke) as well as for myopia more than 6 D.
- 0.005 % in all other cases (just a brushstroke). The surface is rinsed with a few drops of diclofenac. The usual administration of a larger amount of BSS is not necessary.