Evaluation of Systane

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Evaluation of Systane versus Placebo in Corneal
Epithelial Healing Following Photorefractive
Keratectomy (PRK)

• Lt Col Charles D. Reilly
• Major Vasudha A. Panday
• Wilford Hall Medical Center
• Lackland Air Force Base
• San Antonio, TX

Financial disclosure Study medication gifted by
Alcon
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Background

• Post-surgical dry eye is a common problem facing
  all refractive surgeons/patients
• Pre-existing dry eye can be exacerbated following
  refractive surgery
• Variety of artificial tears often included in
  post-refractive surgery care
• Clinical evidence of artificial tear safety needed

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Purpose

• To evaluate the amount of time needed to achieve
  epithelial closure after PRK in patients using
  Systane compared to placebo (BL Sensitive Eyes)
• Subjective patient comfort and dry eye symptoms
  in each eye also evaluated over 6 month study
  period

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Why Systane?

• Unique advanced formulation
• Polyethylene glycol
• Propylene glycol
• HP-guar (a gelling agent)
• Borate ions
• On contact with ocular surface, pH induced
  reaction strengthens bonds between borate and
  HP-guar creating long-lasting polymer gel matrix
• Serves as protective shield and retains
  lubricating demulcents on surface

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Why Systane?

• Adds volume to tear film also promotes
  restructuring of tear film
• Enhances stability of tear film and significantly
  increases TFBUT relative to other artificial
  tears on market 1
• Higher lubricity (ability of fluid to reduce
  friction between two moving surfaces)
• Decreases damage caused by friction between lid
  and ocular surface during each blink

1Christensen MT et al. Evaluation of the effect
on TFBUT extension by artificial tears in dry eye
patients. Presented at 23rd biennial Cornea
Research Conference Boston, MA 2003.
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Methods

• Inclusion criteria
• gt 21 years of age
• Typical candidates for bilateral PRK
• Pre-operative anisometropia lt 2.00 D
• Willing to abstain from using medications known
  to cause dryness for at least 2 weeks prior to
  PRK and through duration of study

• Exclusion criteria
• Intraocular surgery or active rosacea within 3
  months prior to study
• Previous ocular laser surgery
• Evidence of active intraocular inflammation or
  disease
• Use of Restasis within 30 days prior to study

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Methods

• 68 patients, IRB approved, randomized, double
  blind study
• Alcohol-assisted epithelial removal, standard
  8.5mm defect
• Post-operative administration of Systane in one
  eye and placebo in the other
• Right and left eyes randomized
• Day of surgery, study drops were used up to every
  30 minutes as needed subsequently used 2
  times/day, 1-2 drops/dose
• Patients required to document how much and how
  often rescue drops were used

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Methods

• Daily follow up for first 5 days (until closure
  of epithelial defect)
• Vertical and horizontal measurements of
  epithelial defect taken
• Subsequent visits on days 7, 14, 30, 60, 90 and
  180
• On each visit patients asked
• Rate pain on scale from 0-10 with 0 being no
  pain, and 10 being excruciating pain
• Comfort and relief of dry eye symptoms in each
  eye
• Compliance with drops, issues with contact lens

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Mean Epithelial Defect
Time Placebo (n-68) Placebo (n-68) Systane (n-68) Systane (n-68) P Value1
Time Mean Defect Area2 ( SD) Range2 Mean Defect Area2 ( SD) Range2 P Value1
Day 1 39.9 (9) 16.00 64.00 40.1 (10) 13.00 72.00 0.8
Day 2 11.7 (6.7) 0.00 25.00 11.1 (6.1) 0.00 25.00 0.2
Day 3 0.6 (2.3) 0.00 18.00 0.4 (2.2) 0.00 18.00 0.1
Day 4 0.059 (0.4) 0.00 4.00 0.04 (0.4) 0.00 3.00 0.3
1 p-values of paired t-test for between treatment
comparison using paired data 2 Mean epithelial
defect size calculated from the recorded vertical
and horizontal dimensions of the defect at each
observation and presented as square mm.
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Mean Epithelial Defect
Mean Size (mm2)
Post Operative Time
Mean epithelial defect size calculated from
recorded vertical and horizontal dimensions of
the defect at each observation and presented as
square mm.
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Post Operative Discomfort
Comfort Score (0-4) (Lower is Better)
Post Operative Time
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Post Operative Dry Eye Symptoms
Dry Eye Symptoms (0-4) (Lower is Better)
Time Post Operative
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Conclusions

• No adverse impact of Systane on post-PRK
  epithelial healing when compared to placebo
• Demonstrates safety of Systane
• No increase in post-operative ocular discomfort
  associated with Systane compared to placebo
• Very low level of post-operative dry eye symptoms
  with Systane