Decision making nomogram for intrastromal corneal ring segments in keratoconus.
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Date
2014-01
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Abstract
Purpose: To create a nomogram for the insertion of intrastromal corneal ring segments (ICRS) (Intacs®)
in eyes with keratoconus. Sett ing: 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 signifi cantly.A
statistically signifi cant diff erence 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.
Description
Keywords
Intacs, keratoconus, nomogram
Citation
Shetty Rohit, Souza Sharon D, Ramachandran Sarika, Kurian Mathew, Nuijts Rudy M M A. Decision making nomogram for intrastromal corneal ring segments in keratoconus. Indian Journal of Ophthalmology. 2014 Jan ; 62 (1): 23-28.