Intrastromal corneal ring segments followed by PRK for postkeratoplasty high astigmatism: prospective study

Purpose: 

To evaluate refractive and topographic results of the association of intrastromal corneal ring segments (ICRS) with photorefractive keratectomy (PRK) for the correction of high (>6.0 diopters [D]) postkeratoplasty astigmatism (PKA).

Setting: 

University of São Paulo, São Paulo, Brazil.

Design: 

Prospective interventional study.

Methods: 

Postpenetrating keratoplasty patients, intolerant to contact lens fitting, and with corneal astigmatism higher than 6.0 D were treated by the combination of ICRS and PRK from January 2017 to June 2019. First, patients underwent femtosecond laser–assisted ICRS implantation to reduce and regularize corneal astigmatism, and 3 months later, submitted to PRK for the residual astigmatism. Outcomes were obtained 12 months after PRK.

Results: 

The study comprised 30 eyes of 29 patients. Mean uncorrected distance visual acuity (logMAR) changed from 1.16 ± 0.37 in the preoperative to 0.69 ± 0.40 after ICRS (P < .0001) and to 0.34 ± 0.29 12 months after PRK (P < .0001). Mean spherical equivalent decreased from −5.19 ± 4.81 D in the preoperative to −3.38 ± 4.51 D after ICRS (P < .0001) and to −2.30 ± 2.84 D after PRK (P = .132). Mean topographic astigmatism decreased from 7.88 ± 2.13 D in the preoperative to 5.47 ± 2.29 D after ICRS (P < .0001) and to 4.12 ± 2.93 D after PRK (P = .003). Mean refractive astigmatism decreased from 7.10 ± 1.13 D in the preoperative to 4.61 ± 1.61 D after ICRS (P < .0001) and to 2.58 ± 1.49 D after PRK (P < .0001). After PRK, the mean correction index (CI) for corneal astigmatism was 0.77 ± 0.36. The ICRS/PRK combination resulted in a higher CI than ICRS only, both for corneal and refractive astigmatism. 2 eyes (8%) presented clinically significant opacification. Other complications were endothelial rejection (n = 1, 4%), infectious keratitis (n = 1, 4%), and ICRS extrusion after corneal melting (n = 1, 4%).

Conclusions: 

The association of ICRS and PRK was effective for treating high PKA. This strategy improved visual acuity, spherical equivalent, topographic and refractive astigmatism and resulted in a high CI. Safety questions remain open and must be balanced against benefits.

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