InflueInfluence of Size of Nd:YAG nce of Size of Nd:YAG Laser Posterior Capsulotomy Laser Posterior Capsulotomy

on Visual Functionon Visual Function

Ken Hayashi, MDMotoaki Yoshida, MDHideyuki Hayashi, MD

Hayashi Eye Hospital, Fukuoka, Japan

The authors have no financial interest in the subject matter of this

poster.

PurposePurpose

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.

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

MethodsMethods

2-step Nd:YAG laser capsulotomy procedure1) Smaller than the pupillary diameter2) Enlarged to greater than the pupillary diameter (approximately 5.0 mm in diameter) 2 weeks later

Outcome measures1) 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 pupillometer5) Foveal thickness‥ Zeiss OCT-36) Intraocular pressure (IOP)

Patient characteristicsPatient characteristics

AgeGender(M/F)SE(D)Keratometric cylinder(D)Pupillary

diameter(mm) Photopic Mesopic

74.1 ± 8.09/32

After smallcapsulotomy

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*Statistically significant

difference.

Mean foveal thickness, IOP, and increase in IOP after small and large

capsulotomyAfter smallcapsulotomy

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.

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.

ConclusionsConclusions1) 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.