Neves Cruz C, Franqueira N, Mendes JC, Oliveira M, Monteiro T. Intrastromal corneal ring segments: effect of depth of implantation in visual, refractive, and topographic outcomes in patients with keratoconus.
J Cataract Refract Surg 2023;
49:949-955. [PMID:
37379026 DOI:
10.1097/j.jcrs.0000000000001249]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 06/21/2023] [Indexed: 06/29/2023]
Abstract
PURPOSE
To evaluate visual, refractive, and topographic outcomes of intracorneal ring segment implantation in relation to the achieved segment depth, using the manual technique.
SETTING
Ophthalmology Department, Hospital de Braga, Braga, Portugal.
DESIGN
Retrospective cohort study.
METHODS
We obtained 104 eyes of 93 patients with keratoconus submitted to Ferrara intracorneal ring segment (ICRS) implantation, using a manual technique. Subjects were divided into 3 groups according to the achieved depth of implantation: 40% to 70% (Group 1), 70% to 80% (Group 2), and 80% to 100% (Group 3). Visual, refractive, and topographic variables were evaluated at baseline and 6 months. Topographic measurement was performed using Pentacam. Thibos-Horner and Alpins methods were used to analyze the vectorial change of refractive and topographic astigmatism, respectively.
RESULTS
We found a significant improvement of uncorrected distance visual acuity and corrected distance visual acuity in all groups at 6 months ( P < .005); no differences were observed regarding safety and efficacy indexes in the 3 groups ( P > .05). Manifest cylinder and spherical equivalent significantly reduced in all groups ( P < .05). Topographic evaluation showed a significant improvement of all parameters in the 3 groups ( P < .05). A shallower (Group 1) or deeper (Group 3) implantation was associated with topographic cylinder overcorrection, a higher magnitude of error, and a higher mean centroid postoperative corneal astigmatism.
CONCLUSIONS
ICRS implantation with the manual technique showed to be equally effective in visual and refractive outcomes despite the depth of implantation; however, shallower or deeper implants were associated with topographic overcorrection and a higher mean centroid postoperative astigmatism, which explain the lower topographic predictability associated with manual surgery for ICRS implantation.
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