CHAPTER 23 LASIK patient evaluation and selection
History
Contact lens (CL) wearers
Naturally, ophthalmic examination should always be complete and meticulous and the results recorded.
Ocular contraindications
• Sjögren’s disease is an absolute contraindication. This disease is known to produce severe xerophthalmia that could become vision threatening. Both LASIK and PRK are known to produce transient (sometimes permanent) xerophthalmia thus aggravating the disease manifestation.
• Old, inactive herpes simplex keratitis is not an absolute contraindication for keratorefractive surgery; however, it is known that the herpes virus may remain dormant in the corneal stroma for years. Its reactivation may be triggered by stromal surgery or by the steroids prescribed postoperatively.
• Corneal scars: depending on the size and location of the scar, judgment should be made as to whether to operate on such an eye. Scar tissue is hyaline or elastic degeneration, which is followed by calcification. The excimer laser is calculated to ablate corneal tissue and the ablation rate of the corneal tissue varies from that of the degenerative tissue. Consequently, the scar may become optically more ‘pronounced’, sometimes inducing worse, irregular astigmatism.
Systemic contraindications
• LASIK should not be performed on women who are pregnant, lactating, or potentially pregnant. The excimer laser is not known to induce teratogenesis; however, a complication may arise from surgery, e.g. an infection that may require antibiotics or other drugs that may be teratogenic or otherwise affect the fetus. Hormonal changes of pregnancy are known to induce a temporary myopia in some women.
• Contraceptive pills have been reported to induce temporary myopia, thus myopia may be over-estimated. The patient should be asked to abstain from contraceptive pills for 2 months and use a different (non-hormonal) contraceptive method. However, if a previous spectacle prescription shows that the refractive error had not been affected by the pill, the patient may proceed to LASIK without abstaining.
• Collagen vascular disease: as mentioned earlier, Sjögren’s disease is an absolute contraindication for LASIK. Other collagen vascular diseases such as rheumatoid arthritis, systemic lupus erythematosus, as well as patients known to have keloids, are relative contraindications1,2. Healing is irregular in these diseases and the refractive result may be unpredictable.
