| Purpose:
|
| To objectively and subjectively compare
two continuous wear (CW) silicone hydrogel lenses during
a 30 day wear period. |
| Method: |
| 20 healthy subjects, all
previously adapted soft lens wearers, with manifest refraction
between -1.00 D. and -7.50 D. and with less than 1 D. of
astigmatism, wore lenses on a 30 day CW schedule,
with weekly followup. In this single masked study,
patients were randomly assigned to a Bausch & Lomb
PureVisionT lens in one eye, and a Ciba Focus Night & DayT in
the other. Subjective responses were evaluated through
standardized questionnaires. Physiological responses,
lens movement and post-lens debris were evaluated
through pachymetry and biomicroscopy respectively.
RESULTS. 17 subjects completed the CW trial. One
dropout was due to an unexplained persistent headache,
one due to a CLPU (contact lens peripheral ulcer),
and one due to a preseptal cellulitis secondary to
a foreign body unrelated to lens wear. Neither lens
demonstrated a significant difference between initial
and final pachymetry, with slight adaptive increases
in overnight edema compared to baseline. Lens movement
for each lens remained constant throughout the study.
Mild hyperemia was noted in 32% of subjects, with
increasing levels of deposits by week four. Dryness
levels and comfort were similar in both lens types.
Other than one case of CLPU, there were no cases
of infiltrative keratitis, CLARE, CLPC, MK, or SEAL
in this short-term study. |
| Results: |
| Bacterial products alone
failed to produce corneal lesions in contact lens wearing
eyes. Corneal ulcers may be produced only in the presence
of live S. aureus, and a superficial trauma on the corneal
surface was required to generate such corneal ulcer. The corneal
lesions demonstrated mild to moderate inflammatory reaction
clinically; they occurred more frequently in peripheral cornea
than in central cornea and healed without the need of antibiotics. |
| Conclusions: |
| Both lenses displayed good
clinical performance, subjective comfort, and physiological
tolerance, with no significant hypoxia differences
between lens types or after lens wear compared to
baseline. Subjective symptoms of dryness were the
most reported. Subjects exhibited no significant
lens preference. Although both products can be safely
prescribed for up to 30 days continuous wear, individual
patient prescribing patterns should be followed,
with close monitoring of all subjects on a continuous
wear regimen. |
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