Combined Carbon Dioxide Laser Lateral Canthotomy and Femtosecond Laser-Assisted Cataract Surgery

doi:10.4236/mps.2013.34027

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Modern Plastic Surgery, 2013, 3, 130-133

http://dx.doi.org/10.4236/mps.2013.34027 Published Online October 2013 (http://www.scirp.org/journal/mps)

Combined Carbon Dioxide Laser Lateral Canthotomy and

Femtosecond Laser-Assisted Cataract Surgery*

Randal Tanh Hoang Pham1,2

1Aesthetic and Refractive Surgery Medical Center, San Jose, USA; 2Advanced Surgery Medical Center, San Jose, USA.

Email: [email protected]

Received September 10th, 2013; revised October 6th, 2013; accepted October 13th, 2013

License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

Purpose: The purpose of this study was to evaluate a new procedure aimed at lengthening the palpebral fissure to fa-

cilitate femtosecond laser-assisted cataract surgery in patients with small eyes. Method: A quick procedure using the

CO2 laser was adapted for patients with small eyes undergoing laser-assisted cataract surgery using the Catalys system.

The UniPulse CO2 laser (Nidek) was used for laser lateral canthotomy on patients with small palpebral fissures to allow

fitting of the Liquid Optic™ Interface eyepiece. Results: Lateral canthotomies were performed on 19 women and 7

men (ages ranged from 45 to 93 years) with lower eyelid lengths equal to or shorter than 32 mm who then underwent

femtosecond laser-assisted cataract surgery. A total of 33 eyelids received laser lateral canthotomy with the CO2 laser;

only one eyelid had lateral canthotomy with cold-steel tenotomy scissors. Dockings were completed for all 34 eyes with

eyelids receiving lateral canthotomies. The 33 eyes with eyelids that received laser canthotomy with the CO2 laser had

successful femtosecond laser-assisted cataract surgery. The one eye with the eyelid that received cold-steel canthotomy

could not have femtosecond laser-assisted cataract surgery despite successful docking because of pupillary constriction.

The findings were statistically significant; Fisher Exact Test showed a p-value of 0.0294. Conclusion: Laser lateral

canthotomy with CO2 laser is a safe and effective method to allow docking and completion of femtosecond laser-as-

sisted cataract surgery.

Keywords: Cataract; Laser; CO2 Laser; Femtosecond Laser; Femtosecond Laser-Assisted Cataract Surgery; Refractive

Surgery; Laser Refractive surgery; LASIK; PRK; LASEK; ALK; RLE; EpiLASIK; PRELEX; ICR; Phakic

Intraocular Lens Implant; AK; RK; Cataract Surgery San Jose

1. Introduction

Femtosecond laser-assisted cataract surgery (FLACS)

has recently been available in the United States and

around the world. The advantages of this technology in-

clude the ability to create a perfectly sized, shaped and

centered circular anterior capsular incision, the perfect

positioning of the intraocular lens held by a complete

edge of the anterior capsule and the ability to break up

the cataract, which in turn reduces phacoemulsification

time and energy [1,2]. During the procedure, a suction

ring is placed directly on the eyeball and the laser is at-

tached to the ring using suction; this interface stabilizes

the eye relative to the laser. Several factors can affect the

ability to create a stable laser-eye interface using the suc-

tion ring. In cases where the eye has a short palpebral

fissure i.e. short lower eyelid length (LEL), fitting the

suction ring to the eyeball may be difficult. In addition,

suction can be lost with excessive eye, head and/or body

movements [3]. This retrospective study was conducted

to identify eyelids that required lateral canthotomy due to

a short palpebral fissure, factors that were responsible for

femtosecond laser docking failure and to evaluate the

safety and efficacy of laser lateral canthotomy (LLC) as

an adjunct procedure to femtosecond laser-assisted cata-

ract surgery. A review of the literature showed that this

study was the first of its kind to compare cold-steel and

laser lateral canthotomies when combined with laser-

assisted cataract surgery and to address issues related to

docking and completion of the femtosecond laser-as-

sisted cataract surgery.

2. Materials and Methods

Charts were reviewed for all patients who had undergone

femtosecond laser-assisted cataract surgery with the

*Financial Disclosure: The author has no financial disclosure or con-

flict of interest.

Combined Carbon Dioxide Laser Lateral Canthotomy and Femtosecond Laser-Assisted Cataract Surgery 131

Catalys™ Precision Laser System (Optimedica, Santa

Clara, CA, USA) combined with either cold-steel or laser

lateral canthotomy with the Nidek Unipulse CO2 laser

(Nidek, Fremont, CA, USA) between September 2012

and July 2013. Demographic data (age, sex, race), use of

anticoagulants, indications for lateral canthotomy (expo-

sure resistant factors [ERF’s]), and occurrence of post-

operative complications (infection, bleeding, non-healing

and scarring of lateral canthus, lower eyelid ectropion

and formation of conjunctival cysts and cataract surgery

complications i.e. ruptured anterior or posterior capsules,

dropped nucleus intraoperatively or hypotony, shallow/

flat anterior chamber, distorted pupil, intraocular lens

dislocation, vitreous herniation, loss of nuclear or cortical

materials into the vitreous, retinal detachment and endo-

phthalmitis) were noted for each patient. The minimum

lower eyelid length required (MR LEL) for femtosecond

laser docking with patient interface-Liquid Optic™ In-

terface (LOI) (Optimedica, Santa Clara, CA, USA) was

also determined. Cold-steel and laser lateral canthoto-

mies were compared with respect to successful comple-

tion of femtosecond laser-assisted cataract surgery. Sta-

tistical significance was assessed using the two-tailed

Fisher Exact Test.

Surgical Technique

The patient was placed on the Catalys™ Precision Laser

System operating table (Optimedica, Santa Clara, CA,

USA). The Liquid Optic™ Interface (Optimedica, Santa

Clara, CA, USA) was fitted on the eye. If the Liquid Op-

tic™ Interface could not be fitted or successful docking

could not be achieved, then the patient was prepared for

lateral canthotomy. Successful docking was defined as

achieving a suction level accepted by the Catalys™ Pre-

cision Laser System and maintained throughout the pro-

cedure. The lower eyelid length was measured and

marked with a fine tip Devon™ marking pen (Covidien,

Mansfield, MA, USA). A photograph of the lateral can-

thus of the operative eye was taken using the Nikon

7100D camera (Nikon, Melville, NY, USA). Application

of the topical anesthetic EMLA cream (APP, Lake Zu-

rich, IL, USA) to the lateral canthus of the operative eye

followed by injection of 0.5 cc of 2% Lidocaine with

1:100,000 epinephrine local anesthetic solution (Hospira,

Lake Forest, IL, USA) into the lateral canthus of the op-

erative eye was performed. The patient’s lateral canthus

of the operative eye was prepped with 5% Betadine solu-

tion. For non-laser lateral canthotomy a hemostat was

placed over the lateral canthus for 5 minutes to control

hemostasis. Tenotomy scissors were used to make an

incision into the lateral canthal commissure to achieve

the minimum lower eyelid length required for femtosec-

ond laser docking of the interface eyepiece. Pressure was

applied to the lateral canthus to control hemostasis. For

laser lateral canthotomy a non-reflective metal forceps

(Oculoplastik, Montreal, Quebec, Canada) was used to

protect the eye during laser lateral canthotomy. The lat-

eral canthal commissure was incised with the Nidek

Unipulse CO2 laser set at 5 watts in Unipulse mode level

III (mid-level between coagulation and cutting modes) to

achieve the minimum lower eyelid length required for

femtosecond laser docking. For laser lateral canthotomy

pressure to the lateral canthus was not performed. For

both cold-steel and laser lateral canthotomies no wound

closure was performed. FLACS was then performed on

all patients starting with the fitting of the LOI. The de-

tails of FLACS technique was previously described [1,2].

3. Results

An adequate exposure for fitting and successful femto-

second laser docking with the Liquid Optic™ Interface

required a minimum lower eyelid length of 32 mm.

Thirty-four eyelids (from 26 patients) were identified to

receive lateral canthotomy because of fitting failure or

loss of suction; eight patients had bilateral combined

lateral canthotomy and cataract surgery performed on

different days. The patient ages ranged from 45 to 93

years. Nineteen patients were female and seven were

male. Twenty-two were Asians and four were Caucasians.

Six patients were on anticoagulants (two on warfarin,

four on aspirin). Of these six patients, seven eyelids had

lateral canthotomy (1 eyelid with cold-steel and 6 with

laser). Post-operative follow up for all patients ranged

from 3 to 12 months.

The following exposure resistant factors were identi-

fied: small palpebral fissure (32 eyelids), excessive

squeezing (1 eyelid), excessive eye movements-nystag-

mus (2 eyes), excessive body movements (1 eye), ab-

normal eyelid-dermatochalasis (23 eyelids), entropion (1

eyelid), and abnormal conjunctiva-pingueculum (2 eyes).

No infection, non-healing or scarring of lateral canthal

wound, conjunctival cysts, or ectropion was noted in this

study (Figures 1-4). One case of lateral canthal bleeding

occurred after cold-steel lateral canthotomy in a 93 year-

old Asian female patient who was taking anticoagulant

(warfarin) at the time of surgery. Docking was successful

in this patient but femtosecond laser procedure was not

completed because of pupillary constriction after several

docking attempts. Conventional cataract surgery, how-

ever, was performed. When this patient underwent cata-

ract surgery for the second eye laser lateral canthotomy

was performed; no canthal bleeding was noted and fem-

tosecond laser-assisted cataract surgery was completed

without complication. Comparison of cold-steel versus

laser lateral canthotomy showed that all eyes that had

laser lateral canthotomy had completion of femtosecond

laser procedure. Two-tailed Fisher Exact Test showed a

p-value of 0.0294. No complication either from conven-

Combined Carbon Dioxide Laser Lateral Canthotomy and Femtosecond Laser-Assisted Cataract Surgery

132

Figure 1. Pre-op photograph of right eye with cataract and

intact lateral canthus.

Figure 2. Immediate post-op photograph of right eye after

combined LLC and FLACS. Photograph showed complete

hemostasis of lateral canthus with no suture placed.

Figure 3. Day 1 post-op photograph of right eye after com-

bined LLC and FLACS. Photograph showed complete lat-

eral canthal wound apposition.

Figure 4. Day 5 post-op photograph of right eye showed

complete wound healing of lateral canthus.

tional cataract surgery or from FLACS was identified.

4. Discussion

Patients undergoing femtosecond laser-assisted cataract

surgery required a minimum lower eyelid length of 32 mm

in order to fit the Liquid Optic™ Interface over the eye-

ball, thus ensuring adequate exposure of the eye to the

laser beam. It was noted, however, that the circumference

of the LOI provided adequate stabilization once the in-

terface was fitted on the patients’ eyes. This stabilization

could not be achieved with interfaces that had circum-

ferences smaller than 32 mm. Lack of stabilization could

cause loss of suction during femtosecond laser procedure.

Stabilization was also affected by the ERF’s. The ERF’s

identified in this study fell into three categories: inade-

quate exposure, irregular conjunctival surface and exces-

sive eye and/or body movements. All ERF’s for each

patient should be identified prior to surgery and these

findings should be incorporated into the pre-operative

plan. ERF’s and lateral canthotomy should be discussed

with patients pre-operatively and inform consent ob-

tained. This approach will ease the patient’s anxiety and

provide the surgeon with a well-defined protocol to fol-

low on the day of surgery. A flowchart is included to

assist in the decision making process prior to surgery

(Figure 5). This flowchart can be applied to other patient

interfaces using the following formula:

Interface Circumference/2 (in mm) = Minimum Required

Lower Eyelid Length (MR LEL) for interface (in mm).

Carbon dioxide laser was found to provide superior

hemostasis when compared to cold-steel [4]. A previous

study also showed that use of the CO2 laser in the lateral

canthal area was safe and effective [5]. The only patient

in the present study who developed lateral canthal bleed-

ing had cold-steel canthotomy. This patient, who was the

author’s first patient to receive FLACS, required addi-

tional time for pre- and post-canthotomy hemostasis and

multiple attempts were needed to achieve adequate suc-

tion for placement of the Liquid Optic™ Interface. Pu-

pillary constriction occurred in this patient and the fem-

tosecond laser-assisted procedure could not be completed.

When the same patient underwent cataract surgery for

the second eye laser lateral canthotomy was performed

and completion of femtosecond laser procedure was

achieved. This case illustrates the importance of hemo-

Algorithm for Pre-op Evaluation for FLACS

LEL > MR LEL (32 mm)

no ERF

LEL > MR LEL (32 mm)

+ ERF (s)

LEL ≤ MR LOL (32 mm)

+ ERF

(

)

Fit LOIObtain inform consent

for LLC

LOI Fit

No ERF detectedLLC

FLACS

Figure 5. Flowchart for pre-op evaluation for FLACS.

Combined Carbon Dioxide Laser Lateral Canthotomy and Femtosecond Laser-Assisted Cataract Surgery

133

stasis control should lateral canthotomy become indi-

cated for femtosecond laser-assisted cataract surgery.

This patient was one of the six patients in the study who

received anticoagulants and one of two who was on war-

farin. None of the patients undergoing CO2 laser lateral

canthotomy developed canthal bleeding. This observa-

tion reinforces the finding that CO2 laser lateral can-

thotomy provides superior hemostasis compared to cold-

steel and is therefore indicated in patients who receive

anticoagulants [4]. Continued use of anticoagulants is

currently considered the standard of care for patients

undergoing cataract surgery in many communities in

North America, Europe, and Japan [6-8].

CO2 laser lateral canthotomy can be used as an adjunct

procedure for conventional cataract surgery and other

refractive surgeries such as LASIK, LASEK, PRK, ALK,

RLE, EpiLASIK, PRELEX, ICR, phakic intraocular lens

implant, AK, RK, etc. In addition, in patients with multi-

ple ERF’s, CO2 laser lateral canthotomy can be effective

in reducing incidences of suction loss during femtosec-

ond laser refractive surgery. This advantage helps achieve

successful completion of femtosecond laser-assisted pro-

cedures.

5. Conclusion

CO2 laser lateral canthotomy is a safe and effective ad-

junct procedure for femtosecond laser-assisted cataract

surgery.

6. Acknowledgements

The author wishes to thank Beverley Murray, PhD for

her assistance in the preparation of this manuscript.

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Abbreviations

LEL: Lower Eyelid Length

MR LEL: Minimum Required Lower Eyelid Length

ERF: Exposure Resistant Factor

LOI: Liquid Optic™ Interface

LLC: Laser Lateral Canthotomy

FLACS: Femtosecond Laser-Assisted Cataract Surgery