Modern Plastic Surgery, 2013, 3, 130-133 Published Online October 2013 (
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.
Received September 10th, 2013; revised October 6th, 2013; accepted October 13th, 2013
Copyright © 2013 Randal Tanh Hoang Pham. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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.
Copyright © 2013 SciRes. MPS
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-
Copyright © 2013 SciRes. MPS
Combined Carbon Dioxide Laser Lateral Canthotomy and Femtosecond Laser-Assisted Cataract Surgery
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)
Fit LOIObtain inform consent
for LLC
No ERF detectedLLC
Figure 5. Flowchart for pre-op evaluation for FLACS.
Copyright © 2013 SciRes. MPS
Combined Carbon Dioxide Laser Lateral Canthotomy and Femtosecond Laser-Assisted Cataract Surgery
Copyright © 2013 SciRes. MPS
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-
5. Conclusion
CO2 laser lateral canthotomy is a safe and effective ad-
junct procedure for femtosecond laser-assisted cataract
6. Acknowledgements
The author wishes to thank Beverley Murray, PhD for
her assistance in the preparation of this manuscript.
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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