The Morphological Changes in Main Corneal Incision (2.2 mm vs. 2.8 mm) Evaluated Using Anterior Segment Optical Coherence Tomography

Jin Hyung Kim; Tae Im Kim; Eung Kweon Kim; Hyung Keun Lee

doi:10.3341/jkos.2013.54.6.877

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Kim, Kim, Kim, and Lee: The Morphological Changes in Main Corneal Incision (2.2 mm vs. 2.8 mm) Evaluated Using Anterior Segment Optical Coherence Tomography

Original Article

J Korean Ophthalmol Soc 2013;54(6):877-886.

Published online: 7 September 2013

DOI: https://doi.org/10.3341/jkos.2013.54.6.877

The Morphological Changes in Main Corneal Incision (2.2 mm vs. 2.8 mm) Evaluated Using Anterior Segment Optical Coherence Tomography

Jin Hyung Kim, MD, Tae Im Kim, MD, PhD, Eung Kweon Kim, MD, PhD, Hyung Keun Lee, MD

The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea

Address reprint requests to Hyung Keun Lee, MD Department of Ophthalmology, Gangnam Severance Hospital #211 Eonju-ro, Gangnam-gu, Seoul 135-720, Korea Tel: 82-2-2019-3440, Fax: 82-2-3463-1049, E-mail: shadik@yuhs.ac

Received 22 June 20123 January 2013 Accepted 15 April 2013

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

To investigate wound characteristics and ultrastructural changes in the 2.2-mm and 2.8-mm main corneal incisions.

Methods

Forty-four eyes of 34 patients undergoing cataract surgery were randomized to receive a 2.2-mm or 2.8-mm main corneal incision. All incisions were evaluated 1, 7, and 30 days postoperatively using anterior segment optical coher-ence tomography. The angle, length, maximal thickness of the incision, and if present, corneal gap length and incision gap area were calculated. The existence of Descemet’s membrane detachment was recorded.

Results

The mean endothelial gap length and gap area of the 2.2-mm wound were larger than the 2.8-mm, with the only statistically significant difference observed on postoperative day 30 (p = 0.015 and 0.027, respectively). There was no dif-ference in the mean incision angle, length, and corneal thickness between the 2 incision sizes. The ratio of Descemet’s membrane detachment increased with older age and low postoperative IOP, but not associated with incision size (p < 0.05).

Conclusions

Both the 2.2-mm and 2.8-mm main corneal incisions showed excellent wound healing outcome without sig-nificant postoperative complications. Older patients with low postoperative IOP required a more careful wound care management. The incision parameters in the present study can be used as an indicator of the healing process to reduce wound-related complications.

Keywords: Anterior segment optical coherence tomography, Main corneal incision, Morphology, Phacoemulsification

References

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Figure 1.

Anterior segment OCT (optical coherence tomography) image showing a clear corneal incision site postoperatively. The definition of incision site parameters: 1) Incision angle (The angle between the line that joins the epithelial and endo-thelial ends of the incision and the tangential line on the cor-neal surface) 2) Incision length (The total length of the main incision measured from the wound entry to its exit point) 3) Epithelial/endothelial gap length (The length that lines inside of the gap, the longer one is selected, if present) 4) Epithelial/ endothelial gap area (The area inside of the gap, if present) 5) Descemet’s membrane detachment 6) Maximal corneal thick-ness at the incision site.

Figure 2.

Results of AS-OCT parameter, (A) Mean angle (°); (B) Mean length (μ m); (C) Mean corneal thickness at incision site (μ m); (D) Mean endothelial gap length (μ m); (E) Mean endothelial gap area (μ m²) (^* p < 0.05).

Figure 3.

The ratio of postoperative Descemet’s membrane detachment by age (^* p < 0.05).

Table 1.

Preoperative patient characteristics

	Group 1 (2.2 mm)	Group 2 (2.8 mm)	p-value
Eyes (n)	14	30
Sex (Male/Female)	7/7	10/20	0.290^†
Laterality (OD/OS)	5/9	14/16	0.495^†
Mean age (year)	66.1 ± 8.2	66.4 ± 6.8	0.580^*
Mean CDVA (Snellen)	0.32 ± 2.22	0.48 ± 0.24	0.111^*
Mean IOP (mm Hg)	9.57 ± 2.65	11.76 ± 3.03	0.187^*
Mean astigmatism (D)	1.56 ± 1.23	1.42 ± 0.74	0.649^*
Endothelial cell count	2752.5 ± 400.5	2792.4 ± 347.3	0.894^*
Cataract hardness (LOCS III)
Cortical density	3.07 ± 1.49	2.84 ± 1.65	0.660^*
Nucleus density	3.42 ± 1.55	2.83 ± 0.97	0.199^*
Posterior subcapsular opacity	2.53 ± 1.97	1.34 ± 1.11	0.049^*

Values are presented as mean ± SD.

CDVA = corrected distance visual acuity; IOP = intraocular pressure; LOCS = Lens Opacities Classification System.

^* Independent samples t-test;

^† Chi-square test.

Table 2.

Comparison of mean surgical parameters between 2.2-mm and 2.8-mm incision group

	Group 1 (2.2 mm)	Group 2 (2.8 mm)	p-value^*
Mean phaco time (sec)	21.14 ± 8.45	21.90 ± 13.91	0.891
Mean operation time (min)	29.78 ± 4.28	27.00 ± 4.97	0.078
Mean fluid used (mL)	103.57 ± 29.34	109.64 ± 34.27	0.385

Values are presented as mean ± SD.

^* Independent samples t-test.

Table 3.

Postoperative changes in mean UCVA and IOP and astigmatism by autorefractor

	Group 1 (2.2 mm)	Group 2 (2.8 mm)	p-value^*
Mean UCVA (Snellen)
1 day	0.62 ± 0.15	0.68 ± 0.26	0.290
7 days	0.69 ± 0.23	0.73 ± 0.23	0.620
30 days	0.72 ± 0.23	0.71 ± 0.21	0.836
Mean IOP (mm Hg)
1 day	9.92 ± 2.99	11.25 ± 3.65	0.235
7 days	9.30 ± 2.83	10.44 ± 3.22	0.293
30 days	9.00 ± 2.52	10.80 ± 2.83	0.090
Mean astigmatism (D)
1 day	1.07 ± 0.47	1.16 ± 0.85	0.767
7 days	1.05 ± 0.45	1.27 ± 0.89	0.459
30 days	0.75 ± 0.78	1.04 ± 0.58	0.219

Values are presented as mean ± SD.

UCVA = uncorrected visual acuity; IOP = intraocular pressure; D = diopter.

^* Independent samples t-test.

Table 4.

Results of AS-OCT parameters

Parameter	All Patients	Group 1 (2.2 mm)	Group 2 (2.8 mm)	p-value
Mean angle (°)
1 day	45.29 ± 7.0	39.75 ± 7.6	47.00 ± 6.0	0.098^*
7 days	42.50 ± 5.0	38.62 ± 5.5	45.08 ± 2.4	0.112^*
30 days	40.22 ± 6.3	38.28 ± 5.5	47.00 ± 1.4	0.082^*
Mean length (μ m)
1 day	1494.1 ± 295.1	1603.0 ± 319.4	1460.6 ± 285.3	0.239^*
7 days	1468.8 ± 243.1	1514.5 ± 258.9	1444.5 ± 239.8	0.524^*
30 days	1288.4 ± 212.9	1317.0 ± 216.6	1231.2 ± 216.6	0.483^*
Mean maximal CT at incision site (μ m)
1 day	1028.1 ± 70.5	984.0 ± 95.7	1035.4 ± 64.5	0.133^*
7 days	998.3 ± 103.0	964.6 ± 138.6	1008.4 ± 91.9	0.373^*
30 days	753.3 ± 76.5	769.7 ± 85.5	730.4 ± 63.0	0.406^*
Mean endothelial gap length (μ m)
1 day	201.0 ± 104.0	254.0 ± 111.4	184.7 ± 98.1	0.100^*
7 days	162.6 ± 90.8	197.0 ± 102.2	144.2 ± 81.8	0.191^*
30 days	63.4 ± 55.7	86.8 ± 48.9	16.8 ± 37.5	0.015^*
Mean endothelial gap area (μ m²)
1 day	2614.4 ± 1741.1	3560.0 ± 1937.5	2323.5 ± 1605.1	0.079^*
7 days	1981.3 ± 1224.7	2400.5 ± 1166.2	1757.8 ± 1234.1	0.239^*
30 days	508.5 ± 737.5	737.6 ± 815.9	50.4 ± 112.6	0.027^*
DM detachment (%)
1 day	79.4	75.0	80.7	0.089^†
7 days	39.1	37.5	40.0	0.785^†
30 days	0	0	0	-

Values are presented as mean ± SD.

^* Independent samples t-test;

^† Chi-square test.

Table 5.

The ratio of postoperative Descemet’s membrane detachment by age

	50-59 (years)	60-69 (years)	70-79 (years)	80-89 (years)	p-value^*
DM detachment (%)1 day	40	85.7	100	100	0.035
7 days	0	46.2	100	100	0.337
30 days	0	0	0	0	-

DM = Descemet’s membrane.

^* Chi-square test.

Table 6.

Parameters of groups with and without Descemet’s membrane detachment

	Non-DMD	DMD	p-value^*
Mean age (year)
1 day	59.80 ± 7.75	67.80 ± 6.49	0.025
7 days	62.00 ± 6.29	70.77 ± 4.81	0.002
Mean UCVA (Snellen)
1 day	0.48 ± 0.29	0.52 ± 0.22	0.713
7 days	0.76 ± 0.26	0.75 ± 0.22	0.919
Mean IOP (mm Hg)
1 day	14.20 ± 2.38	10.42 ± 3.64	0.039
7 days	10.85 ± 2.07	8.13 ± 3.39	0.033
Endothelial cell count
1 day	2631.8 ± 146.4	2881.5 ± 354.7	0.141
7 days	2798.7 ± 420.7	2766.0 ± 503.9	0.870
Mean phaco time (sec)
1 day	28.14 ± 2.81	21.35 ± 15.35	0.070
7 days	21.25 ± 14.71	15.68 ± 11.11	0.427
Mean operation time (min)
1 day	25.00 ± 2.34	26.85 ± 5.52	0.474
7 days	29.30 ± 4.47	30.33 ± 2.91	0.554
Mean corneal thickness (μ m)
1 day	1052.0 ± 33.7	1285.9 ± 250.1	0.001
7 days	1117.5 ± 181.3	1288.8 ± 214.0	0.056

Values are presented as mean ± SD.

DMD = Descemet’s membrane detachment; UCVA = uncorrected visual acuity; IOP = intraocular pressure.

^* Independent samples t-test.

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