Table 4 – RK Intraoperative complications

Inaccurate visual axis marking

Inaccurate marking of the visual axis may result in incisions that penetrate the optic zone, causing glare, substantial irregular astigmatism, and even monocular diplopia

Intersection of incisions

Patients with these symptoms frequently have recurring, open corneal wounds that are difficult to heal. A surgical treatment plan will be described later in the chapter

Microperforations

Aqueous loss is minimal in microperforations. There is no shallowing of the anterior chamber, and the procedure may be continued at the surgeon’s discretion

Initially, the microperforation incidence ranged from 0.006% to 35% [32, 33]. More recent reports employing an ultrasonic pachymeter indicate that the incidence increased from 2 to 10% following calibration [34].

Microperforations occurred more often in the inferotemporal corneal region because these regions are typically the thinnest [35].

Decentralization

The smaller the clear zone, the more the decentralized effect, with increased obfuscation and occurrence of irregular astigmatism. Other possible intraoperative issues included incisions along the visual axis, the wrong number of incisions, and incisions that crossed the limbus, which increased the risk of corneal neovascularization, especially if the patient used gelatinous contact lenses

Incisions beyond the transparent cornea

RK incisions may extend from the optical zone of the cornea to the corneal–scleral limbus or the limbal vascular arcades. Due to the incision's concurrent vascularization, limbus-penetrating incisions can render the patient intolerant to contact lenses. Because of the concurrent vascularization of the incision, limbus-penetrating incisions can render the patient intolerant to contact lenses. Fibrovascular development may cause corneal destabilization over time, resulting in considerable diurnal variation and advancement of the refractive error

Endothelial loss

Late corneal decompensation after Sato's procedure was a significant issue at the onset of the American experiment. The loss of endothelial cells in the initial years following THE ranged from 3 to 10% [39]. Endothelial cell loss was more significant in eyes with microperforations than in those without. Additionally, eyes with central optical zones ranging from 3.0 to 3.5 mm exhibited a statistically significant mean cell density, cell perimeter, and lateral length shift. These characteristics did not change in eyes with central optical zones ranging from 3.75 to 4.50 mm