Decision making nomogram for intrastromal corneal ring segments in keratoconus.
OBJECTIVE
To create a nomogram for the insertion of intrastromal corneal ring segments (ICRS) (Intacs) in eyes with keratoconus.


METHODS
Tertiary eye care center in South India.


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).


CONCLUSIONS
The nomogram provides a means to choose the appropriate ICRS, hence improving the outcome in patients with keratoconus.
Head of Department, Refractive Surgery, Narayana Nethralaya Superspeciality Eye Institute, Bangalore, Karnataka, India.
Rohit
R
Shetty
Sharon
S
D'Souza
Sarika
S
Ramachandran
Mathew
M
Kurian
Rudy M M A
RM
Nuijts
D000328:Adult; D003319:Corneal Stroma / Q000473:pathology / Q000601:surgery*; D019781:Corneal Topography; D003657:Decision Making; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D049451:Nomograms; D011446:Prospective Studies; D019736:Prostheses and Implants; D012029:Refraction, Ocular; D014792:Visual Acuity; D055815:Young Adult