Effect of Postoperative Ocular Residual Astigmatism (ORA) on Treatment Outcome After Myopic Laser in situ Keratomileusis (LASIK)

Figures & data

Table 1 Pre-Operative and Postoperative Questions Used in Regression Analysis

Pre-operative Questions

○ Think about your vision during the last 4 weeks. Please rate the degree of difficulty you experienced with each of the following symptoms while wearing your glasses or contact lenses.

○ (All symptoms rated on discrete scale between 1 (= no difficulty) to 7 (= severe difficulty):

● Starburst (around lights)

● Glare

● Halo (rings around lights)

● Double-vision and ghost images

Postoperative questions

○ Thinking about your vision during the last week, how satisfied are you with your vision (without the use of glasses or contact lenses)?

● Very satisfied

● Satisfied

● Neither satisfied nor dissatisfied

● Dissatisfied

● Very dissatisfied

○ Think about your vision during the last week. Please rate the degree of difficulty you experienced with each of the following symptoms without wearing your glasses or contact lenses.

○ (All symptoms rated on discrete scale between 1 (= no difficulty) to 7 (= severe difficulty):

● Starburst (around lights)

● Glare

● Halo (rings around lights)

● Double-vision and ghost images

● Dry eyes

Notes: Reproduced with permission from Schallhorn SC, Venter JA, Hannan SJ, Hettinger KA, Teenan D. Effect of postoperative keratometry on quality of vision in the postoperative period after myopic wavefront-guided laser in situ keratomileusis. J Cataract Refract Surg. 2015;41(12):2715–2723. https://journals.lww.com/jcrs/Abstract/2015/12000/Effect_of_postoperative_keratometry_on_quality_of.15.aspx.¹⁹

Table 2 Postoperative PRO Outcome Between 2 Groups: Grouped by Postoperative Ratio of ORA/MRC (Stage 1)

	N	Min	Max	Mean	SD	Median	Q25	Q75	P-value
Starburst**
Group A	179	1	5	1.17	0.63	1	1	1	0.001*
Group B	108	1	1	1.00	0.00	1	1	1
Glare**
Group A	179	1	7	1.75	1.35	1	1	1	0.011*
Group B	108	1	5	1.44	1.03	1	1	2
Halo**
Group A	180	1	7	1.17	0.71	1	1	1	0.098
Group B	108	1	1	1.00	0.00	1	1	1
Double vision & ghost images**
Group A	180	1	7	1.17	0.71	1	1	1	0.006*
Group B	108	1	1	1.00	0.00	1	1	1
Dry Eyes**
Group A	180	1	7	1.72	1.38	1	1	2	0.712
Group B	108	1	5	1.63	1.08	1	1	2
Satisfaction with vision***
Group A	180	1	5	1.58	0.87	1	1	2	0.006*
Group B	108	1	4	1.35	0.70	1	1	2

Notes: Stage 1 = Grouped by ORA/MRC, not matched for MRC // group A = ORA/MRC = 1 or less (= low ORA) // group B = ORA/MRC = 1.1 and more (= high ORA). **, ***All symptoms rated on discrete scale between 1 (no difficulty) to 7 (severe difficulty). *Statistically significant.

Abbreviation: PRO, patient reported outcome.

Table 3 Postoperative PRO Outcome Between 2 Groups: Grouped by Postoperative Ratio of ORA/MRC, Matched for MRC (Stage 2)

	N	Min	Max	Mean	SD	Median	Q25	Q75	P-value
Starburst**
Group A	38	1	5	1.24	0.75	1	1	1.00	0.026*
Group B	36	1	1	1.00	0.00	1	1	1.00
Glare**
Group A	38	1	6	1.71	1.29	1	1	2.00	0.149
Group B	36	1	4	1.39	0.99	1	1	1.00
Halo**
Group A	38	1	4	1.13	0.58	1	1	1.00	0.613
Group B	36	1	4	1.08	0.50	1	1	1.00
Double vision & ghost images**
Group A	38	1	4	1.18	0.65	1	1	1.00	0.090
Group B	36	1	1	1.00	0.00	1	1	1.00
Dry Eyes**
Group A	38	1	5	1.66	1.30	1	1	1.75	0.972
Group B	36	1	5	1.61	1.13	1	1	2.00
Satisfaction with vision***
Group A	38	1	5	1.37	0.75	1	1	2.00	0.787
Group B	36	1	4	1.44	0.81	1	1	2.00

Notes: Stage 2: grouped by ORA/MRC, matched for MRC/group A: ORA/MRC = 1 or less (= low ORA)/group B: ORA/MRC = 1.1 and more (= high ORA). **, ***All symptoms rated on discrete scale between 1 (no difficulty) to 7 (severe difficulty).  *Statistically significant.

Abbreviation: PRO, patient reported outcome.

Table 4 Postoperative Refractive Outcome Between 2 Groups: Grouped by Postoperative Ratio of ORA/MRC (Stage 1)

Post-Op	N	Min	Max	Mean	SD	Median	Q25	Q75	P-value
K Mean
Group A	609	34.40	44.90	40.38	1.99	40.50	39.10	41.90	0.259
Group B	171	39.10	49.30	40.61	1.96	40.70	39.50	41.80
K Cyl
Group A	609	−3.50	0.00	−0.82	0.46	−0.70	−1.10	−0.50	<0.001*
Group B	171	−6.10	0.00	−1.18	0.61	−1.10	−1.40	−0.90
SE
Group A	609	−1.75	1.62	0.05	0.43	0.00	−0.25	0.25	0.057
Group B	171	−1.12	1.62	0.00	0.41	0.00	−0.25	0.25
Sphere
Group A	609	−1.50	2.25	0.25	0.49	0.25	0.00	0.50	0.226
Group B	171	−1.00	2.25	0.20	0.47	0.25	0.00	0.50
Cylinder
Group A	609	−2.00	0.00	−0.39	0.36	−0.25	−0.50	0.00	0.483
Group B	171	−1.75	0.00	−0.41	0.36	−0.25	−0.50	−0.25
ORA
Group A	609	0.00	2.50	0.70	0.38	0.66	0.42	0.90	<0.001*
Group B	171	0.05	5.94	0.93	0.56	0.90	0.61	1.12

Notes: Stage 1 = grouped by ORA/MRC, not matched for MRC/group A = ORA/MRC = 1 or less (= low ORA)/group B = ORA/MRC = 1.1 and more (= high ORA). *Statistically significant.

Abbreviations: K Cyl, corneal cylinder; K mean, mean keratometry; ORA, ocular residual astigmatism; SE, spherical equivalent.

Figure 1 According to our purpose to examine the effect of postoperative ORA we based our grouping method on postoperative ORA. Reproduced with permission from Archer TJ, Reinstein DZ, Pinero DP, Gobbe M, Carp GI. Comparison of the predictability of refractive cylinder correction by laser in situ keratomileusis in eyes with low or high ocular residual astigmatism. J Cataract Refract Surg. 2015;41(7):1383–1392. https://www.sciencedirect.com/science/article/abs/pii/S088633501500838X

Abbreviation: CA, corneal astigmatism; D, diopter; MRC, manifest refractive cylinder; N, number; ORA, ocular residual astigmatism.

Figure 2 Snellen diagram of the safety index (SI) of stage 1: postoperatively CDVA/ preoperatively CDVA.

Abbreviations: CDVA, corrected distance visual acuity.

Figure 3 Snellen diagram of the efficacy index (EI) of stage 1: postoperatively UDVA/ preoperatively CDVA.

Abbreviation: CDVA, corrected distance visual acuity; UDVA, uncorrected distance visual acuity.

Table 5 Postoperative Refractive Outcome Between 2 Groups: Grouped by Postoperative Ratio of ORA/MRC. Matched for MRC (Stage 2)

Post-Op	N	Min	Max	Mean	SD	Median	Q25	Q75	P-value
K Mean
Group A	138	34.40	44.60	40.34	2.16	40.60	38.70	42.00	0.875
Group B	138	36.10	45.60	40.51	1.97	40.60	39.39	41.60
K Cyl
Group A	138	−1.60	−0.10	−0.69	0.33	−0.70	−0.90	−0.40	<0.001*
Group B	138	−6.10	0.00	−1.17	0.63	−1.10	−1.40	−0.90
SE
Group A	138	−1.12	1.38	0.02	0.40	0.00	−0.25	0.25	0.750
Group B	138	−1.12	1.62	0.02	0.43	0.00	−0.25	0.25
Sphere
Group A	138	−0.50	1.50	0.19	0.43	0.25	0.00	0.50	0.611
Group B	138	−1.00	2.25	0.22	0.49	0.25	0.00	0.50
Cylinder
Group A	138	−1.25	0.00	−0.34	0.30	−0.25	−0.50	0.00	0.121
Group B	138	−1.50	0.00	−0.41	0.35	−0.25	−0.50	−0.25
ORA
Group A	138	0.06	1.82	0.62	0.31	0.60	0.40	0.80	<0.001*
Group B	138	0.05	5.94	0.93	0.59	0.89	0.63	1.20

Notes: Stage 2: grouped by ORA/MRC, matched for MRC/group A: ORA/MRC = 1 or less (= low ORA)/group B: ORA/MRC = 1.1 and more (= high ORA). *Statistically significant.

Abbreviations: K Cyl, corneal cylinder; K mean, mean keratometry; ORA, ocular residual astigmatism; SE, spherical equivalent.

Table 6 Postoperative Refractive Outcome Between 3 Groups: Grouped by Postoperative ORA Magnitude, Matched for MRC (Stage 3)

Post-Op	N	Min	Max	Mean	SD	Median	Q25	Q75	P-value
K Mean
Group A	38	36.00	44.00	40.64	2.25	40.95	39.02	42.42	0.603
Group B	38	36.80	44.70	40.44	2.08	40.65	39.05	42.08
Group C	38	36.10	45.60	40.95	2.10	40.90	39.90	42.08
K Cyl
Group A	38	−1.30	0.00	−0.57	0.30	−0.60	−0.70	−0.40	<0.001*
Group B	38	−1.80	−0.20	−0.91	0.42	−0.90	−1.25	−0.50
Group C	38	−6.10	−0.40	−1.48	0.91	−1.40	−1.70	−1.00
SE
Group A	38	−0.62	1.00	0.01	0.36	0.00	−0.25	0.25	0.934
Group B	38	−1.12	1.62	0.04	0.45	0.00	−0.12	0.25
Group C	38	−0.75	1.00	0.04	0.43	−0.06	−0.25	0.22
Sphere
Group A	38	−0.50	1.50	0.12	0.41	0.12	−0.19	0.25	0.309
Group B	38	−1.00	2.25	0.20	0.55	0.00	0.00	0.44
Group C	38	−0.75	1.25	0.29	0.51	0.25	0.00	0.50
Cylinder
Group A	38	−1.00	0.00	−0.24	0.28	−0.25	−0.25	0.00	0.002*
Group B	38	−1.25	0.00	−0.31	0.36	−0.25	−0.50	0.00
Group C	38	−1.25	0.00	−0.50	0.35	−0.50	−0.75	−0.25
ORA
Group A	38	0.00	0.98	0.54	0.27	0.57	0.36	0.80	<0.001*
Group B	38	0.16	1.57	0.74	0.34	0.71	0.50	0.98
Group C	38	0.15	5.94	1.13	0.92	0.96	0.69	1.28

Notes: Stage 3: grouped by ORA magnitude, matched for MRC // group A: ORA = 0.49 and less (= low ORA)/group B: ORA = 0.50 to 1.24 (= medium ORA)/group C: ORA = 1.25 and more (= high ORA). *Statistically significant.

Abbreviations: K Cyl, corneal cylinder; K mean, mean keratometry; ORA, ocular residual astigmatism; SE, spherical equivalent.

Table 7 Postoperative Safety Index (SI) of All Stages According to Our Method of Grouping

Post-Op	N	Min	Max	Mean	SD	Median	Q25	Q75	P-value
Stage 1
Group A	609	0.00	1.50	1.05	0.15	1.02	1.00	1.12	0.796
Group B	171	0.00	1.60	1.04	0.17	1.02	1.00	1.11
Stage 2
Group A	138	0.00	1.39	1.04	0.17	1.00	1.00	1.11	0.941
Group B	138	0.00	1.60	1.03	0.18	1.02	1.00	1.11
Stage 3
Group A	38	0.83	1.33	1.06	0.11	1.01	1.00	1.10	0.270
Group B	38	0.70	1.32	1.03	0.09	1.02	1.00	1.09
Group C	38	0.00	1.42	1.06	0.21	1.09	1.00	1.15
Stage 4
Group A	15	0.91	1.25	1.08	0.11	1.09	0.99	1.17	0.643
Group B	23	0.00	1.42	1.04	0.26	1.08	1.00	1.13

Notes: Stage 1 = grouped by ORA/MRC, not matched for MRC // group A = ORA/MRC = 1 or less (= low ORA)/group B = ORA/MRC = 1.1 and more (= high ORA). Stage 2: grouped by ORA/MRC, matched for MRC // group A: ORA/MRC = 1 or less (= low ORA)/group B: ORA/MRC = 1.1 and more (= high ORA). Stage 3: grouped by ORA magnitude, matched for MRC // group A: ORA = 0.49 and less (= low ORA)/group B: ORA = 0.50 to 1.24 (= medium ORA)/group C: ORA = 1.25 and more (= high ORA). Stage 4: grouped by ORA magnitude, matched for MRC, subdivided for corneal astigmatism (CA) magnitude // group a: ORA = 1.25 and more and CA 0.74 or less // group b: ORA = 1.25 and more and CA 0.75 or more.

Abbreviations: CA, corneal astigmatism; MRC, manifest refractive cylinder; ORA, ocular residual astigmatism.

Table 8 Postoperative Efficacy Index (EI) of All Stages According to Our Method of Grouping

Post-Op	N	Min	Max	Mean	SD	Median	Q25	Q75	P-value
Stage 1
Group A	609	0.00	1.40	0.98	0.18	1.00	0.90	1.07	0.876
Group B	171	0.00	1.53	0.98	0.19	1.00	0.89	1.09
Stage 2
Group A	138	0.00	1.33	0.97	0.18	1.00	0.90	1.05	0.845
Group B	138	0.00	1.53	0.97	0.19	1.00	0.88	1.09
Stage 3
Group A	38	0.00	1.30	0.99	0.22	1.00	0.91	1.09	0.700
Group B	38	0.30	1.17	0.96	0.16	1.00	0.92	1.04
Group C	38	0.00	1.38	0.99	0.23	0.98	0.90	1.12
Stage 4
Group A	15	0.76	1.26	1.02	0.17	0.96	0.87	1.17	0.858
Group B	23	0.00	1.38	0.97	0.27	1.00	0.91	1.09

Notes: Stage 1 = grouped by ORA/MRC, not matched for MRC // group A = ORA/MRC = 1 or less (= low ORA)/group B = ORA/MRC = 1.1 and more (= high ORA). Stage 2: grouped by ORA/MRC, matched for MRC // group A: ORA/MRC = 1 or less (= low ORA)/group B: ORA/MRC = 1.1 and more (= high ORA). Stage 3: Grouped by ORA magnitude, matched for MRC // group A: ORA = 0.49 and less (= low ORA)/group B: ORA = 0.50 to 1.24 (= medium ORA)/group C: ORA = 1.25 and more (= high ORA). Stage 4: grouped by ORA magnitude, matched for MRC, subdivided for corneal astigmatism (CA) magnitude // group A: ORA = 1.25 and more and CA 0.74 or less // group B: ORA = 1.25 and more and CA 0.75 or more.

Abbreviations: CA, corneal astigmatism; MRC, manifest refractive cylinder; ORA, ocular residual astigmatism.

Schallhorn SC, Venter JA, Hannan SJ, Hettinger KA, Teenan D. Effect of postoperative keratometry on quality of vision in the postoperative period after myopic wavefront-guided laser in situ keratomileusis. J Cataract Refract Surg. 2015;41(12):2715–2723. doi:10.1016/j.jcrs.2015.06.034

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