Decision making nomogram for intrastromal corneal ring segments in keratoconus
Rohit Shetty1, Sharon D'Souza2, Sarika Ramachandran3, Mathew Kurian4, Rudy M M A Nuijts5
1 Head of Department, Refractive Surgery, Narayana Nethralaya Superspeciality Eye Institute, Bangalore, Karnataka, India 2 Consultant Cornea and Refractive Services, Narayana Nethralaya Superspeciality Eye Institute, Bangalore, Karnataka, India 3 Cataract and Refractive Services, Narayana Nethralaya Superspeciality Eye Institute, Bangalore, Karnataka, India 4 Medical Superintendent, Consultant, Cataract and Refractive Surgery, Narayana Nethralaya Superspeciality Eye Institute, Bangalore, Karnataka, India 5 Department of Ophthalmology, University Hospital Maastricht, Maastricht, The Netherlands
Correspondence Address:
Rohit Shetty Narayana Nethralaya, 121/C, Chord Road, Rajaji Nagar 1st R Block, Bangalore - 560 010, Karnataka India
Source of Support: None, Conflict of Interest: None | Check |
DOI: 10.4103/0301-4738.126170
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Purpose: To create a nomogram for the insertion of intrastromal corneal ring segments (ICRS) (Intacs® ) in eyes with keratoconus. Setting: Tertiary eye care center in South India. Materials and Methods: This prospective, non-randomized, interventional case series used a self-designed decision-making nomogram for the selection of ICRS in keratoconus patients based on the centration of the cone, mean refractive spherical equivalent (MRSE), and mean keratometry (Km) values. The 3, 6, and 12 months clinical outcomes were compared to historical controls. Primary endpoints were improvement in uncorrected and best-corrected vision and change in the keratometric values. Results: Group A comprised of 52 eyes of 50 patients that followed the nomogram, while Group B comprised of 25 eyes of 23 non-nomogram historical controls matched for baseline parameters.In Group A, the uncorrected distance visual acuity (UDVA) improved from 0.16 ± 0.15 to 0.25 ± 0.16 (P < 0.001), corrected distance visual acuity (CDVA) from 0.58 ± 0.2 to 0.69 ± 0.21 (P = 0.022), MRSE from -5.41 ± 4.94 to -1.71 ± 2.88 (P < 0.001), Km from 51.77 ± 5.45 to 48.63 ± 4.37 (P < 0.001), and astigmatism reduced from 5.86 ± 2.61 to 4.91 ± 2.72 diopters (P < 0.001).In Group B, improvement in the average MRSE was from -6.44 ± 5.32 to -3.26 ± 2.82 (P < 0.013) and in the average Km from 53.64 ± 5.32 to 50.31 ± 5.02 (P < 0.001). Other parameters did not improve significantly.A statistically significant difference was present in the percentage of patients achieving a good clinical outcome between the two groups (P < 0.001; Chi-square). Conclusion: The nomogram provides a means to choose the appropriate ICRS, hence improving the outcome in patients with keratoconus. |