Scheimpflug-based derived customised corneal aberrometry after implantation of different combinations of intracorneal ring segments (ICRS) in keratoconus

Session Details

Session Title: Cornea - Surgical III

Session Date/Time: Sunday 06/09/2015 | 14:15-16:15

Paper Time: 15:19

Venue: Room 16

First Author: : N.Alejandre-Alba SPAIN

Co Author(s): :    P. Perez-Merino   S. Quintana   P. Pascual   S. Marcos   I. Jimenez-Alfaro        

Abstract Details

Purpose:

To analyze the changes in corneal aberrations induced by different combinations of triangular section ICRS in keratoconic eyes.

Setting:

Keratoconus Unit, Universitary Hospital Fundacion Jimenez-Diaz, Spain

Methods:

86 keratoconic eyes were evaluated. Corneal aberrations were estimated by virtual ray tracing on anterior and posterior corneal elevation maps, using Zemax. Eyes were divided according to the combination (1 or 2) , optical zone diameter (OZ, 5 or 6 mm) and ICRS angle (90, 60, 160, 210 deg); and location (inferior I or superior S) of implanted ICRS: 1-OZ5-160I (6 eyes); 2-OZ5-160I-90S (6 eyes); 1-OZ5-210I (5 eyes) ; 2-OZ6-120I-90S (5 eyes) : 2-OZ6-120I-120S (14 eyes); 2-OZ6-150I- 90S (8 eyes); 1-OZ6-150I (19 eyes); 1; OZ6; 210I (8 eyes).

Results:

ICRS decreased corneal astigmatism by 43% (p=0.001) and corneal coma by 18% (p=0.056). Trefoil increased by 20% and HOA did not decrease significantly. 5 mm OZ ICRS tended to reduce HOA by 39,4% (p=0.09), coma from 1.23±0.54 μm to 0.84±0.50 μm (p=0.05), and astigmatism from -5.4±2.6 D to -3.5±2.4 D (p=0.05). 6 mm OZ ICRS decreased astigmatism from -5.79±3.17 D to -3.14±2.11 D; p=0.001) but not decrease other aberrations. Across groups, coma decreased substantially in 1-OZ5-160I and 1-OZ5-210I (by 21.7% and 39,3%, respectively) and slightly in 2-OZ6-120I-120S (by 12.7%) but increased in 2-OZ6-120I-90S (by 2,9%). Conversely, astigmatism decreased significantly (p=0.05) in the last two groups (by 72,8% and a 55,4% respectively).

Conclusions:

Estimations of corneal aberrations in patients implanted with ICRS allows evaluation of the optical changes, rather than corneal shape alone. 5 mm OZ ICRS decrease efficiently corneal aberrations. While 6 mm OZ ICRS produce the largest improvement of astigmatism. Understanding the relationships between ICRS geometry /implantation pattern and the change in optical aberrations is crucial to refine nomograms.

Financial Interest:

NONE