Diffuse lamellar keratitis and epithelial ingrowth are the most common complications of LASIK-related epithelial defects. Most ingrowths develop during the first 8 weeks. In fact, it makes no sense to observe “new” ingrowth after this period. At a later stage, you may observe a dense, white dot (dead epithellal cell accummulation); however, the ingrowth is usually already present.
The ingrowth usually induces a degree of astigmatism. When the ingrowth is treated, the residual astigmatism disappears in most cases. Thus, it again makes no sense to treat the ingrowth and astigmatism with laser ablation at the same time. Surprisingly, the combination seemed to work in this case.
It is unusual to observe a new ingrowth 18 months after LASIK. In any case, however, the epithelial cyst at 6 o'clock is compatible with the residual refraction (+0.50 –0.50 × 170). The logical approach would be to treat the ingrowth again (both stromal surfaces) and perhaps place a radial 10-0 nylon suture at 6 o'clock. I would expect an improvement in the refraction and UCVA.
Although the image is not clear enough, it seems there is a new (delayed) episode of DLK in the left eye, perhaps because of the recurrent erosion. If this is the case, I would aggressively treat it with topical steroids and antibiotics (in the same way as for primary DLK), trying to avoid the use of a therapeutic soft contact lens because of the increased rate of microbial infection. The topical use of sodium chloride 5% solution is helpful in these cases.
The next therapeutic step would depend on the response to the first treatment.