1. Hayashi Eye Hospital, Fukuoka, Japan
Influence of Size of Nd:YAG Laser Posterior Capsulotomy on Visual Function
Ken Hayashi, MD
Motoaki Yoshida, MD
Hideyuki Hayashi, MD
Hayashi Eye Hospital, Fukuoka, Japan
The authors have no financial interest in the subject matter of this poster.

2. Purpose
When cataract surgeons perform an Nd:YAG laser posterior capsulotomy for treatment of posterior capsule opacification (PCO), they are often perplexed about what size of capsulotomy should be made. The purpose of this study was to examine the influence that the size of the Nd:YAG capsulotomy has on visual function, such as visual acuity (VA) or contrast sensitivity.

3. Patients
Forty-five consecutive patients with definite PCO between May 2007 and July 2008
When both eyes had PCO, only first-operated eye was analyzed.
Exclusion criteria: out-of-the-bag or asymmetric implantation of the IOL, or anterior capsule contraction, etc.
4 eyes were excluded (8.9% drop-out rate), and 41 eyes remained for analysis

4. Methods 2-step Nd:YAG laser capsulotomy procedure
1) Smaller than the pupillary diameter
2) Enlarged to greater than the pupillary diameter (approximately 5.0 mm in diameter) 2 weeks later
Outcome measures
1) Area of the capsulotomy opening (mm2)
2) Corrected visual acuity (VA)
3) Contrast VA and that in the presence of glare (glare VA)‥ Menicon CAT-2000
4) Pupillary diamter‥ Inflared pupillometer
5) Foveal thickness‥ Zeiss OCT-3
6) Intraocular pressure (IOP)

5. Patient characteristics
After small
capsulotomy
After large capsulotomy
P value
-0.90 ± 0.90
0.86 ± 0.55
2.47 ± 0.43
3.43 ± 0.76
-1.02 ± 0.87
0.83 ± 0.55
2.68 ± 0.69
3.62 ± 0.69
---
0.0897
0.4468
0.0208*
0.1504
Age
Gender(M/F)
SE(D)
Keratometric
cylinder(D)
Pupillary diameter(mm)
Photopic
Mesopic
74.1 ± 8.0
9/32
*Statistically significant difference.

10. Mean foveal thickness, IOP, and increase in IOP after small and large capsulotomy
After large capsulotomy
P value
Foveal
thickness (μ)
IOP (mmHg)
Before
After (2 hrs)
Increase in IOP
174 ± 23
14.0 ± 3.1
15.7 ± 3.5
7.5 ± 3.9
175 ± 20
13.1 ± 2.7
15.1 ± 3.5
7.0 ± 3.2
0.8590*
0.2189*
0.0926*
0.8091*
*No significant difference.

11. Discussion
The impairment of contrast VA and glare VA in eyes with small capsulotomy can be explained as follows.
1) When capsulotomy opening is smaller than the pupillary size, the light entering into the eye is intercepted by the unopened part of the opaque posterior capsule, which may lead to the decrease in contrast sensitivity.
2) As the entering light light passes through the residual capsule, it will be scattered, which may cause glare disability.
3) Even when the capsulotomy is small, the optical center of the pupillary area is not occluded, and light entering along the visual axis may not be restricted enough to decrease the VA.

12. Conclusions
1) Contrast VA and glare VA with a small capsulotomy were significantly worse than those with a large capsulotomy, although corrected VA was similar.
2) The incidence of adverse effects after Nd:YAG laser capsulotomy did not differ between eyes with a small capsulotomy and those with a large capsulotomy.
3) These suggests that a capsulotomy larger than the pupillary diameter is necessary to restore contrast sensitivity and glare disability.